JohnK

Yup. That's exactly why I'm going to the trouble of explaining what I've had to work with (and I guarantee that the particular version of my car is different in lots of different respects than the majority of this make) and how I've approached dealing with it. But, for those who have Caterhams I'm letting them know I think, from what I've learned about what it takes to make a car "handle", that I feel they've made a very good choice. And maybe, if they don't want to bother working on their car but are just curious in what such work can be all about, I'm doing my bit sharing experiences and what I THINK I've learned. And it should be added, there're a lot of different things people are interested in in a Se7en. Some people are really pleased if it just goes like a scalded cat, others like the way it turns, or LOOKS - I think all of us, regardless of the make, are pretty flattered by the attention we get whenever we stop for gas or at, say, a Hooters restaurant .

Now when I got the car on the road I thought I had it all covered. The program let me figure out what spring rates to at least start with, and what rates of front and rear ARBs would give me balanced front/rear weight transfer when I put the car into a corner that generated 1.0G lateral force and a bit less than 2 degrees chassis roll. Koni Racing (after I supplied them with a bunch of measurements that defined the setup that the shocks would be used in) had delivered a set of shocks that were dialed in across the board for the car I described. I was ready to rock and roll (after a few minor adjustments). At the end of the summer (and having made those “few minor adjustments”), I found myself with a car that was really great in many respects, but whose rear end really wanted to come around on me when I pushed it. I had spend a lot of time changing springs and ARB bars and rates and the car was felt comfortable and well balanced when tossed into a corner – but the rear persisted in its goal of trying to be the first one out of the corner. Back to the books that I had thought at the time I understood perfectly, and to the program that showed me what was happening (IF I asked it the right questions.) Re-reading stuff I found that Smith illustrates and describes what I was going through clearly, but whoever you read says essentially the same thing: parallel links of equal or unequal length links don't work in roll – if you want to keep your tires perpendicular to the road surface when the chassis rolls. Regardless of what you do with your springs, shocks and ARBs, the harder your turn the worse the oversteer gets. Dragging out the program, after the euphoria of thinking it was going to deliver wonderful Camber behavior everywhere because I could see that it'd do in in bump, we get the proverbial pie in the face when we ask the question, “And by the way, what happens when the chassis goes into ROLL? . . .” Asking the right question, the program shows us, and allows up to measure, how much the tops of the rear wheels move toward the outside of the corner when the chassis rolls. It turns out the degrees of traction-destroying positive camber created when the chassis rolls are nearly the same as number of degrees that the chassis is rolled. The more the roll the greater the camber change, and of course the change is in the wrong direction if you want to generate traction (a degree or a degree and a half of negative camber change would improve things, especially with race tires.) This is shown in the diagram https://www.dropbox.com/s/6cesllwg4xmm6qq/Original_Ride0Roll0.jpg?dl=0 which gives the values calculated when there are two degrees of roll in the positive direction ( generated by turning left). This is shown by looking at several values and remembering that you're looking at the car from th rear (unless you've changed it from the default view to any one of several): at the center, “Roll” has an arrow next to the value of 2.00 pointing to the right which indicates the direction of the force, to the right the “Travel” value is negative and shows an arrow pointing downwards showing that the chassis has moved downwards, further to the right the third value down in the column of parameters on the right of the wheels shows that the Spring has been compressed (two arrows with their heads facing toward each other next to a negative value showing the spring compression in inches (changeable default setting), and below that is Load which is positive and greater than Load on the left side of the diagram (it is negative indicating load removed > from the at-rest value. You can see the degrees of roll illustrated by vertical lines anchored in the center of the tire footprint next to true verticals at each wheel. ---The reason I'm going through all of this is that it's easy to get confused as to which direction things are happening. Mitchell's convention is that the positive roll we see here comes from making a left turn which is indicated by negative steer. Keeping oriented is a continual hassle due to the nature of the problem. - Looking at https://www.dropbox.com/s/av1bgulujv9ext0/Original_Ride0Roll-2.jpg?dl=0 shows you the results of 3 degrees of chassis roll, and the next two diagrams show you the results of turns to the right generating 2 and 3 degrees of chassis roll. https://www.dropbox.com/s/av1bgulujv9ext0/Original_Ride0Roll-2.jpg?dl=0 https://www.dropbox.com/s/2398kdw4sps2si2/Original_Ride0Roll-3.jpg?dl=0 So we ( I ) learn that this is a show stopper. The more the chassis goes into roll, the more the outside tire goes into positive camber. The only way to stop it is to dial up the ARB at the rear so the chassis doesn't roll which is stupid for more reasons that one needs to write about. - Back to the books and several readings of Smith and others brings us back to the punch line I quoted earlier (and apparently didn't think applied to ME): From Carroll Smith's "Tune to Win". page 54: “ ...While it is possible to control wheel camber either during vertical movement or during chassis roll, it is not possible to achieve very good camber control under the combined conditions --- we have and "either --or" situation. ... “ So now what? Fortunately, although at the cost of reading Smith et al. even more closely and having my hair begin to hurt as a result of the mental effort, the answer is there, in the few pages leading to Smith's quote above - and you have to really understand to what the quote is telling: -you you can't have it all, -you can only achieve a compromise, AND -there's no yardstick you can use to measure what a good compromise is. - ---What I KNOW is that 'as is' the car has really wonderful camber control in bump and just plain awful camber control in roll, and as verified by driving the car, THAT just does not work. So thinking to myself that the car's ALWAYS gonna roll, and that bump is a transient condition (and paying Madam Zelda to recite the proper incantation while she sacrifices a live rooster at the dark of the moon over the the car's differential, just for good measure), I think to myself “how about we focus on good camber control in roll and then see what happens to bump as a result?” (Hmmm. Is it better to be shot or hung?) - Getting to work, there were two phases to this: the first was to use the program to test different configuration of the links and find one that seemed workable, and then figure out how to actually BUILD that configuration (you may have noticed that there's not a lot of free space In a Se7en that you have where you can put extra stuff). Smith led me through the sequence of relationships that described the fix (although getting to the point where I understood it still made my hair hurt). In essence, you shorten the top links and then make it so that the shortened top links (I. e., the links that form the upper A arm) are placed higher than before at the ends where they attached to their upright – you want the top links to run downhill toward the center of the car. Figuring out how much to shorten and how much to raise took a lot of trials with the program and then assessing what each compromise was going to result in – the operative word here being “compromise”. And then I had to go back and forth between what the program showed as good, and the car said was possible, making prototypes (out of all the sorts of things one has lying around) to test that there was room for the design (these parts have to be able to move through a area in the car and not run into anything - duh!) and on top of that, verify that what I was doing with the program actually reflected reality (it is really easy to make mistakes here). - I was able to come up with something that looks hopeful. I found a configuration where camber change is pretty flat, and also reduces the movement of the roll center (recall this is important for giving feedback to the driver, and is generally is associated with good suspension behavior.) There's quite a bit of Camber change in bump, but it's in the negative direction, which is less bad than positive change, and the amount of movement of the wheel in bump is usually not that much, particularly on a track - while chassis roll of 2 degrees is quite a bit. Compromise. Next time I'll post the graphs that show the values this configuration delivers. The parts are fabricated and I've installed them temporarily (need to clean and paint) on either side and aligned the rear and verified its movement and behavior (not chassis roll, however. Think about that. What's happening with roll is very different from bump, even though it would seem to be the same – I mean, in both circumstances, the wheel's going up and down, right?) Anyway, physically, it works without anything running into anything else, the wheels go where they're supposed to, and the hardware and software agree with each other. A reader alert here. At some point I'm going to have to post pictures of the “deliverables”. So far my fabrications have been sound (welding just keeps getting better and better) and robust, in that nothing I've designed has proved too weak and failed. But just the same, to those out there with either refined sensibilities in matters of mechanical/automotive construction, or weak hearts that might be overstressed by a bout of hysterical laughter, I'll offer a heads-up to you that viewing pictures of my solution may be offensive or hazardous. And to those with perhaps more insight than mine who can see that this solution can only fail catastrophically, you'll be able to say “I KNEW that couldn't possibly work!” should the results of this project produce a picture in the media showing smoking remains. Next, assessment of the results.

I've been seeing for some time now - say 30 years - that people are just too busy. Developing skill and insight are hard and part of the process is failing and all take time. Our economy seems to have thriven (?) by promising instant gratification and that's the culture now. I think it can only come to a bad end, but then I'm just a dinosaur and the world changes. Still I'll join you in mourning the passing of such things. (When the journey is as important as the destination.)

One thing I should add here. I spent a lot of time fiddling with, reading the manuals of, reading the on-line documentation of and in general doing a whole lot of cuss'n at WinGeo3. BUT, this IS a very well developed program and allows you to do all sorts of very sophisticated analyses and see what the car's doing from many many different perspectives. It's used by more than a few big guns out there. Just don't expect it to take you by the hand and lead you through everything you need to know. Which is another way of saying that understanding suspension is one complicated issue and don't expect that answers are easy to come by. - All the terms that Mitchell uses are SAE, or have SAE counterparts, so they have very explicit and clear definitions. He provides definitions and explanations with his Win Geo 3 software, some in hardcopy, lots in the application itself. - Also, if you have a car whose handling you're really happy with and don't fancy all the work req'd to measure the car, but are interested in learning about how it works in this regard, you may find it worthwhile getting a copy of the pgm and exploring what it does. I think there are some light-weight versions and version that focus on specific areas of a car's suspension. While I haven't looked, it may be possible to find the measurements for your car on the Web, which would make the pgm more than academically useful. WindGeo3 can reveal lots of different things that are neither obvious nor intuitive, and the addition of Rowley's application allow you do do things like a WinGeo3 specification and determine what will happen to the suspension when you put that spec in a corner with, say, 1.2 G lateral force and +0.3G acceleration. There's an interface to WinGeo3 that allows for recording displacements as the car is driven, so you can watch what all the bits are doing as the car goes around a track, even multiple laps! This allows you to analyze all the curves generated by the different suspension members so you can optimize their adjustment into the 'sweet spots' where they travel through their most linear ranges. (I need another dozen years or so added to my lifetime – and a lottery win or two). - All of which is by way of preparing for what's coming next... - Definition: Virtual Swing Axle. This term is used to understand Camber change and to calculate other things, like roll center. Imagine you've got a wheel standing upright on the floor and it's attached rigidly to an axle, and the free end of the axle is held roughly horizontal and attached to a pivot. If you step over to the pivot end and lift the pivot location up and down a few inches, kind of like it would be were it attached to a differential in a car and the car was rising and falling on its suspension, you'd see the top of the wheel move a few degrees outward or inward. Now if you did exactly the same thing but used an axle that was really long, you'd see that the top of the wheel moved less in response to the the axle pivot's up/down movement. You can think of this wheel's movement when the pivot moves up and down as camber change, and understand that the amount of camber change is going to be less when the axle is long and more when the axle is short. And of course small changes in Camber during changes in Ride are a very good thing. - Looking at the rear suspension in its resting position - https://www.dropbox.com/s/6cesllwg4xmm6qq/Original_Ride0Roll0.jpg?dl=0 ----- Consider the left side, take the upper and lower suspension links (brown) and project them out laterally until the top and bottom projections intersect, and the point of intersection is called the Instant Center. Measure from the Instant Center back to the the upright's upper and lower ball joints and that length is the Virtual Swing Axle or Instant Center. With regard to Camber change, at that Instant Center length the suspension acts just like an actual axle would act if it were that long, as per the above paragraph. If the upper and lower suspension links are perfectly parallel, the Instant Center would be infinitely far away and the Camber change would be zero. In most cars the links are not parallel so there is Camber change, and the Virtual Swing Axle 's length changes when the upright (pivot) moves up or down – which means that your car's Camber changes not only with upright movement, but with position as well as the wheel (suspension) moves and the Instant Center changes. - The measurements entered into WinGeo3 show that the links are nearly the same length and are nearly parallel. This gives the suspension really long Virtual Swing Axles (lns. Cen. In the graphic) on the order of 5,000 inches – so this tells you that when the wheel moves through its 5” travel in Ride, the Camber change at this distance from the pivot of the axle, is really small. This is a property of all suspensions that have links that are roughly parallel and roughly equal. For the results this design produces when it works, look at https://www.dropbox.com/s/zh5tmcmej4cumi7/Original_Ride-2Roll0_0_4.jpg?dl=0 which shows 2” of bump and https://www.dropbox.com/s/jykmynkd6tsbvwq/Original_Ride%2B2Roll0.jpg?dl=0 which shows 2” of droop. Thus you can observe that, with this design, there are very small changes in Camber associated with these changes in Ride height. However, you may also notice that the Instant Centers change value a lot, but they're all relatively large so there's little effect on Camber change. N. B. That none of the numbers/values come out even here because the data that the program performs all its calculations with is from the physical measurements taken from the car, which is not perfectly true and by a human who is neither accurate nor precise at times. With practice and patience you can make pretty consistent (precise) measurements, and by using good quality laser builders' tools like plumb bobs and levels which, in combination with a collection of 1/8” wall 2 x 2's, you can develop a methodology and some technique that'll yield pretty good data. Also, using the program, you learn which measurements have to be dead on and which can give useable results even if off a bit. But then again, it never hurts to be obscenely wealthy in this department. https://www.dropbox.com/s/0xmzscr9q7bt62f/phoca_thumb_l_phoenix.jpg?dl=0 Besides providing a true platform on which to set up the car and adjust corner weights, notice the lengths of the links: since they're really long and nearly parallel, they provide very long virtual swing arms which gives very small changes in Camber in Ride, but note the difference in the positions of the links' pickups on the chassis – this is one way to solve a problem that I'll identify that my configuration has In the next several JPGs. (Can you find the ARB in this picture? WinGeo3 has a template for modeling this particular front suspension configuration. The Rack & Pinion (red and blue) is the same as what I designed into my car, 'cept mine is power assisted. N. B also how the engine coolant heat exchanger is positioned, catching dirty (turbulent) air following the front suspension links – Colin Chapman was the first to recognize the value of placing this exchanger in this location – doing so not only allowed the car to have a smaller frontal area (better aero / less wind resistance and better penetration than when there's a 'barn door' of a radiator at the front of the car). His design also moved weight toward the middle of the car lowering the polar moment of inertia of the car allowing the car to turn more quickly) - THIS is why Newton invented Physics!

Staying with https://www.dropbox.com/s/6cesllwg4xmm6qq/Original_Ride0Roll0.jpg?dl=0 --Being a curmudgeon at heart I'll gleefully introduce a topic that's really important, that reveals something really important to understanding what the suspension is doing, and is just really involved. (Note that this figures heavily in the fix I wound up making to fix the behavior of my rear suspension – so it's not just academic.) On the WinGeo3 diagram, at or near the vertical centerline, are four boxes: one is a bit above axle height, two are nearly on top of each other about ground-level inside a containing box, and the third is off to the right a bit with a diagonal cross in it. The highest one is the CG, the vertical value of which is a guess on my part because I've never been able to successfully measure it although I've gone through the procedure that's supposed to deliver it. In addition, I've never even thought about measuring the CG's lateral location because I've never been in a situation where I needed to see the the consequences of adjusting its lateral location. (Ignorance is bliss?) Unfortunately, what I do know is that there is NOTHING that improves a car's handling more than lowering its CG and I can't find a doable way to measure it so I can fit it into the spec and obtain an accurate picture of what's going in. Still, as I build things, I always work to put things as low as I possibly can on the chassis. (The battery placement I did is a fabrication that's pleasing – see build pages) -- With respect to these other 3 boxes - Now, there is a measure that locates on the rear suspension that point at which the car rolls about as it is cornering. You can feel (or develop the ability to feel) this point with the small of your back or your butt as you're driving 'round a corner, and it lets you know what the rear end of the car is doing. This is called the roll center, and we're pretending that it's as simple as the single point identified in this diagram (shown as Roll Cen. 7.252, 0.339, meaning that its 7.252” right of the long axis and 0.339” above ground with all the suspension components at their shown locations). SAE defines it as “The point in the transverse vertical plane through any pair of wheel centers at which lateral forces may be applied to the sprung mass without producing suspension roll. “ And this is why you spend hours re-reading and re-imagining things and re-running your suspension mode – so you can get a sense of what this means and how it affects your car. One facet of this is “Push on this point an none of the members of the suspension will move.” --Now depending on the design of the suspension, the roll center may move. If it moves only a little, your butt may not notice anything's out of the ordinary, i. e., you know right where the rear end of the car is as it's in motion going around the corner. If the roll center moves a lot, your butt will likely inform you that whatever the rear end of the car is up to, it has just dropped out of the picture and you're on your own. Relevant, huh? From the suspension gods: “A high roll center usually means more jacking force, which tends to raise the chassis, but a high roll center minimizes body roll. A low roll center, which can even be below ground level, minimizes the jacking effect but creates more body roll.” Jacking force is the overturning force I spoke of earlier. Look at the distance between the CG and the roll center and think what's happening there and you can understand the above – that distance is a moment arm (a lever) – the longer it is, the greater leverage the car (sprung weight) has to turn the chassis through the roll center. Thus if you could make the CG and roll center identical, nothing would move as the car cornered. Along with this, the roll center determines cross-ways weight transfer – a low roll center results in less weight transfer from the inside to the outside wheel. When both wheels have similar loads, they provide more traction than if the weight is moved from the inside to the outside wheel and the outside wheel is heavily pressed to the road. Smith does a nice analysis of this (Listening HOTTCAR?.) Nett: low roll centers give you better traction by keeping both wheels pressed on the ground. --Staniforth writes that years of poking about at the pits and analyzing photos and picking brains has shown him that the wizards design their race cars with roll centers that stay where they're put within a couple of ten-thousandths over their range of suspension movements. (I'll guess that the guy who designed my suspension thinks 'roll centers' are something to do with a Bugler Cigarette rolling machines.) --The reason there are these different boxes on the diagram having to do with the roll center is that there are different ways of deriving where the roll center is. The conventional value (Kinematic roll center) is gotten by intersecting lines on either side of the car, looking at a figure drawn using the Instantaneous Swing Axle and the tire contact patch The Force-Based Roll Centers (Force Application Point, F.A.P values) are the product of a second means of satisfying the SAE definition, and more realistically represent the SAE description of the roll center. Mitchell spends quite a bit of time explaining how F.A.Ps are derived and I'll compare the two if anyone's interested. His WinGeo3 even includes a separate application just to illustrate step by step how the loads are transferred through the suspension. So, this is a really significant result of how your suspension is deisigned. --Consider that the take home here is, for the price of measuring your car very accurately, you can enter the data and SEE the things that determine what the car's going to do as it's driven- without having to take anything apart or buy new parts. Next, what happens when things move.

One of the best reference sources I've run into involving steering is Woodward Precision Power Steering, which sells to oval/dirt track folk. The catalog has descriptions in it on R&P setup and steering that are the best I've run into, including Carrol Smith's. It just takes a bit of thinking to translate it to sportscars from what people do on an oval track. There's a really great couple of paragraphs explaining why really quick steering is so valuable. When I got to the point where I understood what he was saying I wound up not only with quick steering (1 1/3 turns lock to lock) but power (hydraulic) assisted too. Had anyone told me that steering that quick was useable in anything other than some sort of extreme race car I wouldn't have believed it. But after a couple of thousand miles out on some really twisty country roads whose surfaces are less than ideal it's a revalation what such a setup allows you to do. But you do have to have all the pieces working right (lousy tires made the car a hassle until I changed to relatively ordinary sporty tires). But, yes - you can learn a lot from dirt track folk. There's a lot of experience and knowledge in that realm.

--It's hard to find a place to start if you want to do something to change, or even just learn about the handling of your car. This is particularly true if there's nothing that you know of that is actually wrong and you don't have a framework of some sort for reference purposes as to what's better or what's worse, not to mention a target of what you'd like to accomplish. --When you sit down and think it through, the actuality is that the suspension at any one corner of your car is pretty complicated all by itself, and when the car is being driven there are an awful lot of pieces that are contributing as systems and subsystems to deliver what one experiences at the wheel. If you buy a new or recent Caterham, all the work related to the suspension being dialed in properly certainly with respect to the hardware, and the car's handling set-up should have, or can be done for you by a competent shop (not to be assumed here, lots of schlock operations out there) – so there's really no reason to touch anything unless there's something broken, or the car is doing something that can be objectively identified as 'wrong'. --So I had a bit of an advantage in that what showed up on my driveway wasn't what you would call “finished” in any sense, and the most prudent approach to be taken was to very carefully verify the operation of every part of the car. That meant I had to really UNDERSTAND how each bit worked within its environment. A lot of the fundamental things that were done are described at http://usa7s.com/vb/showthread.php?t=7421 but all of this work provided me a good mindset when it came time to tackle the suspension. And it gave me time to consider - - - while I was really enjoying getting the car together, the thing that was at the back of my mind was: “Y'know, If I don't get this (whatever part of the car I happened to be working on) RIGHT, it could very well fail and fail like all of a sudden, and if it does so at just the right time, it may well toss the car off the road and KILL ME.” (Think about Kitcat's Datsun driver – hanging by his seatbelt with his roll bar keeping his car from landing on his head.) So I had a built-in motivator to do a damn good job of UNDERSTANDING what I was doing as well as making sure it was done correctly. I'll leave it to each reader to develop this attitude on his/her own when working with their car. --With respect to the each corner of the car, the very general rule (Costin & Phipps) is that an outside, or laden, wheel wants to be perpendicular to the road surface, regardless of what posture the chassis is in. This is just not achievable (Staniforth, Smith) so one must try to find a good compromise, and there is no measure of what a 'good compromise' is– I'm not being flippant here, there are lots of pictures of cars going fast around corners where the only wheel that's where it's supposed to be is the front outside, with its mate on the other side looking like it's been disconnected from the car, and this only happens with the outside wheel under a narrow range of ride-roll combinations . Look at the head-on pictures of a Caterham mid-corner. The outside/laden front wheel is straight up. The inside wheel is ….. well, I wound up spending an awful lot of time reading – the benefits of which I really can't convey without putting everyone to sleep, so I'll offer some pictures and a description of a problem/situation that illustrates what's going on. --My current struggle is getting rid of oversteer – i. e. the rear isn't as firmly planted as the front, so you're always fighting a car that wants to come around on you. This is not good. I improved it a lot by playing with the anti-roll bars (ARBs) but SOMETHING was clearly wrong. Smith and Mitchell provided the solution. Smith, in Tune..., compares the different arrangements of the links that rear suspensions have with a large collection of drawings and comparative values and explanations, and Mitchell gave me a means of visualizing how those arrangements behaved over a range of small increments and of testing their behavior. Since I busted my butt getting pretty accurate measurements of the chassis and the suspension when it was aligned properly, what those pictures showed actually represented the reality that I experienced when driving the car. Take a look at https://www.dropbox.com/s/6cesllwg4xmm6qq/Original_Ride0Roll0.jpg?dl=0 which is the rear suspension viewed from the back of the car. The springs, shocks and uprights should be obvious, the horizontal gray bar and its arms are the rear's ARB system. At the top, in green, are displacements showing Ride (negative is Bump, Positive Droop), Roll (negative means the car is being turned to the RIGHT, positive when the car is turning to the LEFT), on either side of the of the wheels and below ground level are all the sorts of parameters you want to know when the car's being turned and the suspension is assuming any configuration. What's especially useful (and very cool!) is that you can step this thing through increments in Ride, Roll, Steer, ...and watch what's happening to the camber, and how much load is gained or lost on each wheel – so you have a MEASURE of what each spring has to do and how far the shock is being displaced – and you can seen the contribution of the ARB, …. next, the roll center.

And Well what have I gotten myself into. (HOTTCAR's questions are particularly good) This is gonna take a while but I think/hope I can write something that'll give folks a little comfort here, a little insight, and perhaps a little sense of direction if they want to try something on their cars. This'll be a multipart reply 'cause I'm not smart enough to run it all down coherently and at once, but I'll try to keep things together enough to make sense and be practical. Just to be clear at the outset, my measure of what constitutes a really wonderful car is how it feels in the middle of a corner when both ends of the car are sliding. If you're in that situation and you feel absolutely confident that you can brake or accelerate, turn in or out, steer with the throttle to adjust your line, ... with the sense that you and the car are the same thing, then you've got a really wonderful car. If it goes like a scalded cat, that, of course, is nice, but only if it handles too. First of all, Caterham has spent years improving their cars (finding ways of making them more robust but still really really light while also stiffening the chassis - all to the end of making them handle better and better), and they started out with the basics supplied by the good Mr. Chapman - so the chances of an ordinary guy, or even a remarkably smart guy, going in and twiddling with something and actually making an improvement are really unlikely. As one instance of the kind of work Caterham's invested in their car, spend time appreciating what the link https://dl.dropboxusercontent.com/u/49212285/oconnell.pdf is telling you, ... think about what such equipment allows one to adjust/determine/measure/experiment with, not to mention the understandings that are necessary just to tie a car down on that setup and make sense of what all the paraphernalia is capable of telling you about the car and what questions you should figure out how to ask, and ... I spent well over a year doing engine tuning with two different dynos (all to myself!) and working with a small collection of different engines and ECMs, and ended with what could be called success - and a profound appreciation of the importance of being able to measure things, which included the cost of the time required to develop a protocol for making collections of measurements. I also got yelled at a lot because I found (and said out loud) that it is completely hopeless to try to tune your engine by looking at an Air/Fuel meter and fiddling with the ECM's calibration on a laptop while driving. A while back Kitcat noted that, in his experience, just making sure that the suspension on his Caterham was in spec as per the Factory seemed to be the best course of action if he wanted the car to work optimally. And possibly fiddling just a bit with tire pressures to see if there was a difference. Now think back on how well a Caterham handles, that it does so while providing a ride so comfortable that it feels like a family 'saloon', exhibits chassis roll that looks absurd, and then abandon any hope that you're going to be able to fiddle sensibly with anything on the suspension that's likely to improve its handling - or even make sense. What I attempted to do when I got my Se7en was to start with a car that was not highly developed in this regard (which in my humble experience is anything that is not a Caterham) and see if I could use it as an experimental subject to learn about handling and hopefully produce something that worked pretty well. Predictably, as a scientist, I live the Caterham motto, “The journey is as important as the destination.” I have gotten pretty close to my goal. After a couple thousand miles out on local twisties last year, the car does several important things very well and I feel pretty pleased - especially that my newly learned welding skills have stood up without fail. I have two hurdles I've yet to overcome that'll get me in the ballpark of where I'd like to be before I put away the torch and dedicate a big chunk of time to driving the thing, and exploring the way it works. For reference, I have quite a few years spent playing with what were called cafe racers back in the 60's, a collection of wonderfully twisty roads not too far away, and 20,000 miles spent on an early sportbike driving really irresponsibly on these roads. So, next I'll describe how I approached the problem of understanding handling, what I found useful to inform myself about, the tools I used to gather the information, the procedures/protocols I had to develop to actually accomplish things, and ways of assessing the work. The goal of all of this is to understand the things that contribute to the car's handling and what can be productively adjusted and to what end and at what cost.

Just so you guys know... When you work with this stuff you'll run into the term 'overturning force' or vector or whatever. Any vehicle whose center of gravity is above ground can be turned over, if the tires generate enough friction and the cornering force is sufficient. Think of the stunt car drivers of yore that would get old sedans balancing on their wheels (I think they used a ramp, but I've seen it done with no more than a quick yank on the steering wheel), or a wine glass unsuccessfully slid across a tablecloth. Even something as flat (really low CG) as a go-cart can go over, which is why their drivers are hanging way off the inside as they corner. Sidecars are a real study in physics here, as well as fun to watch the difference between the monkey's antics going from left to right hand corners. That's also the reason why LSDs are important - since you don't have very good traction when the rear inside wheel is waving in the air as the overturning force is lifting the car up onto its outside wheels. The guy in the Datsun (I'm guessing) had no idea what the results were going to be when he stiffened up the suspension and went to toss his car into the corner like he was used to. Isn't Science fun?

My experience is that most folk (including myself, at times) are looking for a 'magic bullet'. A single fix that going to make their car handle wonderfully in one fell swoop. There just ain't no such animal. Enlightenment isn't that easy to achieve, if it actually is ever achieved. The pursuit is not for the timid. The Lotus 7 and today's Caterhams deliver handling that is magical – just ask the Porsche and Ferrari drivers that can't keep up with one on 'name-your-track'. This did not come about by accident. It involves a huge amount of study, experience, insight and experimentation. Learning what this stuff is all about is a great opportunity to acquire humility. For starters, see my recent post http://usa7s.com/vb/showthread.php?t=9238&page=2 and spend some time pondering the link that's attached to that post. You might also find things of value in my extended (or extremely tedious) post, Ithaca Lemonade. Here are a collection of resources which, along with a fanatical desire to make some sense of what is going on when your car is going 'round a corner with both ends broken free, will get you a glimpse of what 'handling' is all about. -Competition Car Suspension by Allan Staniforth is a delightful read, and what he summarizes so nicely will deliver insights for years into the future. (Great pictures, too) -Racing and Sports Car Chassis Design by Michael Costin and David Phipps is a classic and should be on your bookshelf - and read carefully. -Race Car Vehicle Dynamics by William F. Milliken and Douglas L. Milliken (father and son, I believe), the nearest thing to a Bible in this field, is stuffed with golden truths, but at a price. -Carroll Smith's collection of "_____ to Win" books is a a treasure and one of them has the punch line in it - and here it is, but it will take you years before you get to the point where you can think to yourself "Yes! that is indeed exactly what is going on! I understand now!" From "Tune to WIn". page 54: ...While it is possible to control wheel camber either during vertical movement or during chassis roll, it is not possible to achieve very good camber control under the combined conditions --- we have an "either --or" situation. ... Staniforth says the same thing, but in more accessible/less rigorous language. If you're really, really serious, buy Wm. Mitchell's WinGeo3 suspension software and the companion book by his friend Rowley's book, Race Car Engineering, which comes with analysis software that allows you to see the data that Mitchell's software allows you to collect and organize in dynamic circumstances. (http://www.mitchellsoftware.com/) … no relationship, financial or otherwise, of any kind here. (Unhappily I found out that Bill Mitchell died January of 2014. I am one among many who are saddened by the industry's loss of his contribution to the sport. As of april 2015 I haven't found if anyone is taking responsibility for distributing his product. See http://www.apexspeed.com/forums/showthread.php?t=61960 for an explanation of his passing. ) Figure the program out (it is NOT a polished finished piece of software and involves comprehending LOTS of critical definitions) and then spend, perhaps a week, maybe two, measuring your car (I did it three times, and I'm still not completely happy with the results) and when you start playing with the results you'll see what the limits are of your measurements and why NASCAR and F1 teams spend tens of thousands of dollars on things like Romer Arms to get suspension link and ball joint postions to the nearest 'thou (not to mention chassis centerline and suspension pickup locations.) All in all, the many, many days I spent learning the software and learning how to ACCURATELY measure my car, paid off handsomely and has been and continures to be well worth the effort and cost. (And makes me realize how much simpler it would have been just to by a Caterham, not fiddling a bit with it, and just enjoy driving the damn thing in blissful ignorance :-) ...

This exemplifies the reason why I've spent YEARS trying different combinations in suspension software, fabrication of front and rear anti-roll bars, large amounts of time and money spent on shocks and springs, and hours spent trying to understand what Carroll Smith and Millikin & Millikin were teaching about sports car suspension. I was particularly (and proof-of-the-pudding) inspired by a ride in Kitcat's old x-flow Caterham that had as comfortable a ride as you could ask for as damn near ANY car and then some out on local bumpy two-lane asphalt, not to mention one that had you sitting right over a solid rear axle, yet the car (and of course a damn good driver) clearly kicked ass out on the track. I've seen other shots like this where a Caterham is cooking around a course damn near on its door handles (if it had any) -AND THE DAMN THING HANDLES WONDERFULLY IN SPITE OF A HUMONGOUS AMOUNT OF CHASSIS ROLL! You can read for years and the conclusion you get is that, when a car rolls, it makes the suspension move in ways that take it way outside of all the different angles that you want for keeping the tire happy on the road. Besides, and dispite the fact that fitting roll bars is nearly as much work as it is tuning them to balance the front-rear weight transfer, people put them on to reduce chassis roll and all its attendentant handling-destroying behavioirs. And of course you get a car that rides like a buckboard. So how has Caterham figured out how to get a wonderfully compliaint (confortable!) ride and allow huge amounts of chassis roll - and still provide road holding that is phenomenal? There's a post out there I made with a title something like "another thing to keep in mind when considering what Se7en to buy" that points to work a contractor did for Caterham* - but even with all that technology, there's some wizard behind the scenes that really, really understands what handling is all about. I sure wish I could find the person and pick their brain about it. *see https://dl.dropboxusercontent.com/u/49212285/oconnell.pdf

I'd recommend finding the Koni catalog on line. They have a worksheet for ordering shocks and organize the data you need to specify such nicely. My front suspension is relatively stock, but "stock" is a relative term when it comes to S2Ks. My rear suspension is completely different. One thing I would recommend doing very carefully is measuring the range of motion that your links allow and then making sure that the shock you use keeps within that limit. The shock max length should keep the links from running into the chassis on droop, and the shock min length should do so, conversly, for bump. I happen to know that Koni advises that you use their shock to limit bump stroke/bottoming, and they also supply Silasto bump rubbers to cushion that bottoming. These come in a range and can be used to tune the suspension's behaviour. The shocks that originally came with my "kit" were QA-1 and they recommended AGAINST using the shock as a limiting device. Once you accomplsh the above, THEN you can start worrying about ride height and compliance and how the thing actually handles. Be assured, suspension tuning in a black art - and an occasional rooster sacrificed over the hood of the car at the dark of the moon is probably a reasonable safeguard if you have a local shaman around you can count on to keep the spell focused on the problem. Landrum supplies springs that are reasonably priced and in ranges that are suitable for an S2K. Just to be completely clear "There is no configuration or formula or practice that will deliver a correct suspension setup - if there is such a thing." The bright side is that the time you spend dialing in what you feel is a good setup can be a lot of fun as well as a very interesting challenge - 'specially when your neighbours become accustomed to the fact that, just because they find you coming towards them in the middle of a local corner really sideways, you're not out of control. Good luck.

(1) We (the government) want the banks to do well because when they're profitable they a) hire people b) provide capital for industry and c) provide a good return to their investors (which I feel safe in assuming includes both you and me.) So when these guys come to Congress and lobby (explain their situation to) the lawmakers to ensure that there aren't difficulties created which stand in the way of them being successful, lawmakers at least listen carefully. Since any large bank can pay for a large and talented staff, they can give the lawmakers well crafted descriptions and justifications of what they want – much better than any lawmaker's staff can put together. And of course the lawmakers want their constituents employed and the companies in their districts to do well, it seems a no-brainer that they should give the banks what they need to be successful. And if the bankers make a lot of money, hey, that's what Capitalism is all about right? (And what no one mentions is that Capitalism has as its fundamental principle ripping off the next guy better than the next guy can rip him off – it's called exploitation and it's what our economy is based on. Hardly the basis for a fair and equitable society, not to mention an informed populace.) (2) Years ago I realized that the same scene has been playing out over and over in different countries in South America: the citizens in a country would rise up against terrible rulers and at ghastly costs, throw them out - and in time other terrible rulers would come into power or new kindly rulers would decide to use their circumstances to enhance their own situation at the citizens' expense. It's not enough to get rid of a bad situation, you have to REPLACE it with something that prevents such from recurring. And no one's figured out how to do that. (3) As Walt Kelly said in Pogo years ago, “We have met the enemy and it is us.” (4) Capitalism has some really, really bad properties and no one's figured out how to get rid of them (- without promoting blood in the streets like we're seeing in lots of other places today.) It doesn't help that Economics isn't a science so it can't give us a foundation to work from - so we're a ship without a rudder until someone figures out something that works AND can actually be put in place. A good article in Scientific American (Mirsky?) described how the founding fathers were trying to come up with a balance between freedom and laws, that they knew that such a balance was dynamic (needed continuous examination and modification) and that the Liberal Democracy that they crafted was an EXPERIMENT – no civilization had ever attempted such a thing before. So I take anyone who rants about “the government” not doing its job in providing what they think it's supposed to is so out to lunch about the facts as to be considered the 17-year-old I described.

Study history to learn what people who made rules were influenced by. Build big systems with other folk to learn how good and sensible ideas produce consequences that no one could have predicted (or intended). Become a Biologist so you can observe how poplulations of animals behave over time (which will eventually get you to the point of saying, "Hey! people do the same damn thing!") Like it or not, it's all in our hands and if we don't teach ourselves and learn how to face the realities, and if we think that someone else is going to fix things for us then we're no better than the typical 17-year-old who thinks that the one or two things he/she knows explains it all and winds up being able to do nothing better than develop an attitude.

Really excellent, in several respects. The photo really captures the look of what I think of as a 'true' Se7en. Aesthetically it just looks very cool - 'though I know little about photographic technique. But also, it makes it really clear that the 'ur-Se7en*' is a very tiny car,emphasized by the (obviously and rightfully proud) owner posing in front of it. I've had any number of driving experiences over the many years spent on the road, especially on a motorcycle (cafe racer back in the 60's and beyond, sport bike recently) that reinforced my habit of being very paranoid as a guard against becoming suddenly very dead. Unhappily I've noticed that, even with the protection of a frame, the larger size of a Se7en, and the ability to drive off the road in an emergency, a Se7en is considerably lower than one finds oneself on a motorcycle - which diminishes the ability to see ahead to avoid hazards, and my Se7en is aparantly quite a bit taller than a Caterham (as reported by Kitcat's assessment after driving it). While my Se7en is absolutely the most wonderful thing I've ever enjoyed driving, I do find myself occasionally on the verge of freaking out over the vulnerablity that comes from one's being out in traffic with its poplulation of idiots paying attention to anything other than controlling their car. Kind of like scuba diving when you get down below 60 feet or so and look up and it dawns on you how far the surface is away and wonder what you'd do if 'somethining' happened and you suddenly couldn't breathe. Under water there's "spare air" and training exercises and all, but texting adolescents forgetting completely where they are in 70 MPH traffic and only waking up when they're off the road ... In my 20's I remember toasting the demise of Wolfgang VonTripps at Imola with a buddy wishing for "A quick and firery death before the age of 25." So maybe it's just that a Se7en offers, in one of its many facets, another blessing in disguise. Gotta be better than lingering expensively in a hospital. * "ur" is a German prefix that indicates that something is really, fundamentally original - like the original ancestor or the true, perfect, original source.

Anybody got a formal definition of "vapor lock"? I've heard people use this term over the years and, y'know it SOUNDS good, but exactly what is it?

Solstice! Saturnalia! (http://phys.org/news/2013-12-roman-christmases-similar.html) The former's been recognized for 30,000 years (give or take a few centuries) and the latter last seven days is a LOT of fun (memories of high school Latin club). Return of the sun and a new year and an excuse for bundling up with someone and finding interesting things to do in the dark - (like talk about how badly I need a new differential for my car that has the proper ratio). Merry Ho Ho to all.

Oh Mike, you just don't appreciate the satisfaction one gets from throwing mud at a wall, especially when there're so many different colors and it occupies so much time - while (hopefully) not harming anything 'cept perhaps the bank account.

You're breaking my heart (other than the fact that it's been raining cats and dogs this weekend here in Cincinnati.) All my car fun (if you can call it that) has been fighting with LKQ trying to get a proper differential for my car - three in a row, all wrong type/ratio in spite of their promises! So what's the matter with a little road grime when it pays for a chance to enjoy your car on the shortest day of the year! Happy Solstice Season to all.

That's funny !

And the whole blinking system is a Ponzi scheme. Ever heard of "The Dismal Science"? One quote from a graduate student I was chatting with at a really prestigeous university was "Economists largely try to understand history, and they don't do that very well." Because our study of economics has no principles that it relies on (none that anyone has been able to discover) there's no way of showing that anything is true or false - so you can claim ANYTHING about an economic situation and it's all make believe. So the talk show hosts instead just concentrate on how well they can keep people wound up - rather than trying to help the situation - and what a great way to get rich - write pieces on the problems of economics and no one can call you a liar because there's no way to tell what's a lie.

I've heard answers to all this on NPR in comments by the different folk there, and at heart, they stem from the fact that we have capitalism as our economic system. Capitalism has some awful properties that ordinary citizens exploit (after all, capitalism is all about exploiting the other guy so you can get ahead at his expense), and the killer is that we don't have anything to preplace it with. All economic systems have the ability to be subverted by ordinary citizens. ( I'm pretty certain that the TEA party will be shown to have caused much harm to the country when the historians sort it all out and they will tell you that they're ordinary citizens, self-righteous ones to boot.) Again, it comes down to "We the people..." and the people just don't have it together enough to handle things - education is one point, and another is being able to reason objectively. I don't see that there's anything to pin it on but us.

Ah, but all citizens are ordinary and equal under the law - but some are more ordinary than others (paraphrasing A. Huxley)

I don't think anyone has trouble getting really angry about the political theater that ALL the politicians are staging, but getting angry doesn't solve anything. It absolutely does all come down to "We the People..." and it is up to US. But the Constitution was constructed when there weren't so many people and life was both a whole lot harsher and had a lot fewer pieces for a person to manage. And all of those involved in setting up and running the country were highly educated and had historical precedent to guide them in what they could all agree upon made sense - BUT THEY KNEW THAT WHAT THEY WERE PUTTING TOGETHER WAS AN EXPERIMENT. NO CULTURE BEFORE OURS HAD ATTEMPTED TO IMPLEMENT A LIBERAL DEMOCRACY (which is what our government is in the grand scheme of things). And whether we like it or not, it's still an experiment and we still have to pay attention to how it's playing out and keep on making adjustments to it based on what comes about next, and without knowing what those adjustments are going to result in in the future. We have to figure out how to manage things, and we don't have any rules to use. And we don't have a device to measure how we're doing. The scarriest issues that I see (admitting mine is only one small view - just like everyone else's) are that the Country has gotten so big and the systems (like capitalism, and government, and health, and cultures, and social organizations, and technology, and the economics ...) have become so complex that it takes a lifetime for a smart and dedicated person to get their mind around anyone of them, and any one issue by itself is not going to show the way to making things better. All these different facets of what we live in affect us and these facets all influence each other in ways that very few (if any) people understand. It seems to me that what came out of the 1600's is the most workable approach mankind has produced: and that is that the world appears to operate according to natural laws, and that if we conduct experiments designed to reveal these laws and study and reason out the results of our experiments among ourselves, we can discover what these laws are and then decide how to use them to our benefit. The guy who cuts my hair knows in his heart that his particular bible and his or his minister's particular interpretation of its words hold the key to making the world work right. I don't understand how to accept something as true that has no substantive foundation, other than how it feels to me. My barber doesn't know how to accept something that is the result of investigation-produced factual results verified and examined by those knowledgeable in that area. My barber works and pays his taxes. I work and pay my taxes. We both vote in hopes of making things better, or at least keeping them from getting worse. Perhaps what the two of us, and the millions of others who are doing the same thing, is going to produce is a culture which is stew of our different views. I have no idea how such a process will produce anything other than chaos. But, having become old, I take comfort in two things. The first is that (I hope) I will eventually finish my car and have a grand time driving it. Second that I will, hopefully on my own terms, get to die and leave this whole mess behind.

Never found an advantage to hateing anyone - it just doesn't buy me anything and wastes my time. Anytime ANY politician gets ANYTHING changed, some people get helped and some get hurt, and it takes 10 years, at least, before dust settles and it becomes possible to see what the actual value of an action was. My reference point is Harry Truman. There was damn near hysteria when he got elected. England's prime minister said publicly that with Truman's election he feard democracy in the U.S. was doomed. When the historians looked at the results their conclusion was that Truman's actions were of great benefit to the United States.