Handeling Thread

[JohnK]

I think you are selling your self short.

Thanks, but I'm trying to be what I call rational. The people I've met who actually do know a lot have almost all been really humble - at least when they're talking seriously about their craft/trade/profession. Carrol Smith is a good example. He's a real hard-ass when it comes to getting a car to work right but he's not arrogant, he just doesn't have any patience with people who slap something together and think that allows them to go head to head with the 'Big Dogs' . I began studying math in addition to my main interest just so I had another tool in my kit to understand what I wanted to do and learned what it could and couldn't do and how much work it took to accomplish something. Perhaps I did learnsomething about the field because I think it's awsome what can be done (like I understand that when they came up with quantum mechanics in 1900 and had no idea what what they thought they'd figured out. But if fact they laid the foundation for the thing I'm using to write to you with - how transistors operate is defined by and operates according to quantum mechanics and if they hadn't developed that field of mathe/physics we absolutely would not have computer technology today. I ALSO know that if I dropped everything I'm doing and spent the next 20 years studying, I very likely would not get to the point where I understood the field. That, and running into engineers who would wave their textbook knowledge around and say "That can't possibly work!" - when some old mechanic had figured out how to accomplish whatever years ago.

 

But the bike scene is lightyears different than the car scene. Due to the huge power to weight ratio of a modern bike (dirt or street) Most bikers do not spend a lot of time messing with the engine. And most concentrate on handling. Which of course is (normally) quite the opposite to a car person. I would say that the vast majority of car people are only slightly aware that their car even has suspension.

You've got a better picture of this than I do - my 'sense' has been that you can do a lot more with bike engines because the masses (pistions, rods, ...) are all smaller and lighter and, in matters of scale, are easier to get power out of - and perhaps that folk like Honda and Ducati and Yamaha maybe had a little easier time doing all their research and development in a smaller-scale, easier-to-produce environment.

I agree with you about the differences between car & bike with respect to engine and handling. While there's a lot to be said for the joy of touring cross country, when you get on anything sporty it's all about how it goes around corners. Car folk do seem to be dialed in on what happens when the stoplight changes and the guy in the next lane.

 

I've been fortunate that as a (now former) biker I spent a few years working at a bike shop. And since 1982 when I first started riding I've owned 38 bikes. I've had the racer bikes (Suzuki RG Gamma, Ducati 888 SPO LTD). Touring bikes (2 Goldwings, BMW K12LT) Dirt bikes (CR250R, KDX200, KTM 620 adventure, Yamaha WR450F) Even 2 supermoto bikes (KTM duke II, Husqvarna SM610)

I'm really envious. The main guys in stable were a 250 Ducati Diana Mk III which I learned on an modified quite a bit and a Villiers-engined (Starmaker) Trials bike made by a small company in England and called a Sprite which was an utter joy to ramble about in the woods on, looking for the best challenging section of creek bank or hill side.

[Mondo]

I think there are a lot of former (and some still) motorcycle riders/racers here. If it wasn't such a hassle to get to a good riding area I'd probably still be into dirt bikes. Did the sportbike thing for a few years but I'm used to learning from mistakes on dirt bikes and tossing a sportbike down the track is kind of an expensive way to learn;)

 

So the 7 is my best compromise. Now if I only could get my priorities to change and free up a few bucks to throw at the dang car... especially in the set up area (new heim-joints, corner weighing, shocks and a full-cage). I really want to explore the limits of the car. Or should I say myself.

[bigdog]

I think there are a lot of former (and some still) motorcycle riders/racers here. If it wasn't such a hassle to get to a good riding area I'd probably still be into dirt bikes. Did the sportbike thing for a few years but I'm used to learning from mistakes on dirt bikes and tossing a sportbike down the track is kind of an expensive way to learn;)

 

So the 7 is my best compromise. Now if I only could get my priorities to change and free up a few bucks to throw at the dang car... especially in the set up area (new heim-joints, corner weighing, shocks and a full-cage). I really want to explore the limits of the car. Or should I say myself.

 

Truth be told, I still love bikes. But I don't ride anymore for three reasons.

1, I know that my reactions are slowing a bit, And my brain says slow down but my right wrist says WFO baby.

 

2, Other riders. By that I mean that the typical response I get when I say "let's go for a ride" Gee bigdog that would be great, I do have fifteens minutes on Sunday afternoon three months from now. So I got tired of riding alone.

 

3, When I was 49 (I'm 56 now) I had a bad fall on my dirt bike and ripped my right thumb from it's socket, broke the ball in half on the fifth metacarpal bone on my left hand, Blew out the bursal (sp) sack on my left knee cap. So there I was both hands in casts and my left knee wrapped up for 6 weeks. Life was difficult when I ended up not having the use of my hands. My right thumb and left knee still bother me. I sold that dirt bike and haven't been on the dirt since then.

Edited January 28, 2014 by bigdog

[JohnK]

Years ago when I first learned about road racing I, first time at a track (Nelson Ledges) I saw some guy come off his bike mid corner and flew threw the air! That really bummed me out but later I found that he was fine - saw the same kind of thing with a sidecar. What I learned was that most commonly people broke collar bones, and maybe a wrist but it wasn't as potentially damaging a sport as I first thought (now this was a while ago and things may have changed). Then, being exposed to Moto Cross -there at the BEGINNING (good stories here about the revolution)! - anyway. In general, it seemed that if you were riding a road racer and messed up you slid off the track; if you were riding in a MX and messed up you fell down, stayed on the track and people ran over you. Correct me if I'm way off here, but unless you're a GP star racing at Oporto on city streets or the Isle of Manx, which I heard they've stopped, RR isn't too hazardous. Also, a little experience on an AJS 410 (really dating myself here) was that it was enormous fun but took huge amounts of strength and endurance - all the guys I knew who did it had chests and arms that were scary, not to mention legs. RR requires a really good nervous system and some strength (but you can get a used GP 125 bike for not a horrible amount of money and not need the strength to muscle around a 1 litre production bike. I expect to hear that I am so far out of date on what's going on, but then I am out of date

[Mondo]

Probably ought to get back to suspension... but I quit racing dirt bikes when it turned more into an aerial show (never liked being that high in the air). I loved the big road track at Willow Springs but couldn't help thinking my bike is toast if I loose it at those speeds (more worried about it than me). Guess I should feel that way about the 7 but don't for some reason.

[rotus8guy]

John, love the info on your suspension redesign project. To continue the thread hijack the Isle of Man (Manx is what the natives are) TT is alive and well. Scheduled for 26 May to 6 June this year. It is surprising that in this PC, safety first, age it is allowed, but the Island still has some autonomy from the UK, and the Tourist Trophy is important to them. Check out videos online of it, absolutely nuts. Triple digit speeds through village streets lined with stone cottages.

And now back to your regularly scheduled thread.

Cheers,

John

[MeteorMotorsport]

So a question to the suspension gurus. What damper adjustment will help with bottoming out when hitting frost heaves at 70-80 mph range? I had issues with the front bottoming out going up the bumps and the rear bottoming going down them. It made for and interesting game of throttle control whenever I saw the ripples in the road.

 

PS forgot to add that its a Caterham SV with the stock suspension. I do have some AVO adjustable shocks that I bought off another member. Still haven't gotten around to getting them rebuilt tho.

 

It can be resolved but its always a compromise.

 

Currently you will have quite soft springs (nothing wrong there but they are a little to soft) coupled with damping that is not bad at the slower wheel speeds but at higher wheel speed eg holes in the road or race track kerbs there is no significant increase in the damping - it sort of flatlines after 6"/sec.

 

So with an aftermarket damper you can tune this out - particularly with a two or threeway unit.

 

I would recommed slightly heavier springs but quite a bit more compression/bump damping. This won't hurt the cars ride over the more general stuff but will help on track or over those frost heaves you speak of.

 

Of course you could just slow down:blueangel:

[jlumba81]

Thanks for the reply. That's what I was thinking when I got those avo damper, a bit more spring and damping. Its for my annual drive to visit relatives in Anchorage, Alaska. I take a ferry up to Haines and its a 750ish mile drive to Anchorage. The Alaska Highway is mostly empty so I try to keep a fairly high mph average. The Yukon (Canada) side of the highway has the worse of the frost heaves. With the Seven being so low sometimes its hard to see the bumps and dips until you are right on them.

[BruceBe]

It can be resolved but its always a compromise.

 

Currently you will have quite soft springs (nothing wrong there but they are a little to soft) coupled with damping that is not bad at the slower wheel speeds but at higher wheel speed eg holes in the road or race track kerbs there is no significant increase in the damping - it sort of flatlines after 6"/sec.

 

So with an aftermarket damper you can tune this out - particularly with a two or threeway unit.

 

I would recommed slightly heavier springs but quite a bit more compression/bump damping. This won't hurt the cars ride over the more general stuff but will help on track or over those frost heaves you speak of.

 

Of course you could just slow down:blueangel:

 

1) Are the frost "heaves" bumps or holes? How high/deep are they?

2) Are you hitting a bunch of these in succession?

 

The "jacking" effect mentioned earlier is a result of excessive rebound damping over a series of critical bumps. The rebound damping does not allow the suspension to completely return to an equilibrium point before another bump repeats the cycle. The net effect is a jacking-down of the vehicle on the effected corner/end of the car. I seriously doubt that is the case here.

 

Stiffening the car may mitigate some tendency to harm the chassis over these frost "heaves" at 70-80mph, but they're not going to make the car *handle* much better. In fact, we generally want more compliance and overall travel in a suspension, to cope with this particular scenario (bumpy track).

 

-Bruce

[JohnK]

I was impressed by the range of bump rubbers that Koni offers - and of course these can be used on any other shock that they can be fitted on - and after interpolating the curves one can draw using what Koni publishes on these items and then talking with Koni Racing Tech found that folk like Audi use them to get very compliant rates in the middle shock movement ranges with progressive springing that can be gotten from the Silasto as Bump moves into the more extreme displacements. Anyone tuning Caterham suspension exploring what this shock component has to offer?

[BruceBe]

Nonlinearity in wheel rate is definitely an acquired taste. Most modern GT sports-cars incorporate progressive rate springing - taking these cars hard into the first phase of a corner usually feels like the car is falling over on itself, and then as the spring rate rises and rate of roll decreases, things start to feel more rational and predictable. However, it's a bit of a leap of faith, as the tires on the laden side of the car quickly start working harder during this wheel rate increase.

 

Stock Caterham CSR springs are progressive rate, and IMO, do not inspire confidence when driven hard. With the rear weight bias, it's a better idea to get the rate of roll under control early, and give the driver a predictable, (nearly) linear response.

 

Perhaps Silasto tuning could navigate a middle-ground between the typical progressive spring response, and a linear spring with (always) higher rate. A similar effect to a sway bar, without the negative impact of inside tire-lift.

 

-Bruce

[Croc]

Stock Caterham CSR springs are progressive rate, and IMO, do not inspire confidence when driven hard. With the rear weight bias, it's a better idea to get the rate of roll under control early, and give the driver a predictable, (nearly) linear response.

 

This would explain a lot about the handling characteristics on my car compared to other non-CSRs I have driven on track. I have learned to bust through this feeling over time but it was a confidence barrier early on. I suspect it also has a link to why my car can get airborne on the back hump of my local track where other Caterhams do not. Very interesting - thank you for that detail.

[HOTTTCAR]

Brucebe

 

Very informative description ......thanks

 

 

Croc ...airborne off the track....? this is not usually good if the bump is on a corner. Is this a trade off / compromise for great traction entering the corner?

 

Gale

[xcarguy]

Brucebe

 

Very informative description ......thanks

 

 

Croc ...airborne off the track....? this is not usually good if the bump is on a corner. Is this a trade off / compromise for great traction entering the corner?

 

Gale

 

I think I know what 'back hump' Croc is referring to . . . . I'd like to get a photo of him pulling an Evel Knievel in July. :jester:

[Kitcat]

I think the only reason I don't get airborn there is I am so much slower! My car does get very light through that spot tho.

[yellowss7]

There is NO WAY that Croc gets airborne. Come on People, he's driving a WideBody, Sumo Version CSR. I don't care if he calls it a "CSR Superlight", but a Barge is a Barge is a Barge. :jester::jester::jester:

 

Shane, where he "thinks" he gets airborne is on TBolt so you won't get to see it for yourself, but he does tend to go off track a bit on Lightning. :svengo:

 

He is faster that most of us thru there, but Airborne, Nah!

 

Tom

[xcarguy]

There is NO WAY that Croc gets airborne. Come on People, he's driving a WideBody, Sumo Version CSR. I don't care if he calls it a "CSR Superlight", but a Barge is a Barge is a Barge. :jester::jester::jester:

 

Shane, where he "thinks" he gets airborne is on TBolt so you won't get to see it for yourself, but he does tend to go off track a bit on Lightning. :svengo:

 

He is faster that most of us thru there, but Airborne, Nah!

 

Tom

 

Roger that. Watching the vids, I figured it might have been turn 5 (?) on Lightning.

[yellowss7]

I guess you could get airborne on turn 5 on Lightning, but you'd have to be really crazy to take that at full throttle as it is a turn, and totally blind, so you do want some control coming over that one. Hopefully everyone checks the flag station before going over the crest. I've come over that crest a few times to find a car or two, facing the wrong way.

 

Taking that turn you also have to be careful as it drops off down hill and off camber, and the track is still turning right, so it is CRITCAL that you take the right line as any variance will cause you to go off the track to the left. IF you do go off there, just ride it out, DO NOT try to correct to stay on track or the tire wall on the right side of the track will be your next stop. :ack:

Edited February 4, 2014 by yellowss7

[AndyB]

The good and bad of being airborne in a Seven.

 

The good

 

http://www.pbase.com/sarrana/image/154380112.jpg

 

The bad

 

http://www.pbase.com/sarrana/image/154380185.jpg

[xcarguy]

I guess you could get airborne on turn 5 on Lightning, but you'd have to be really crazy to take that at full throttle as it is a turn, and totally blind, so you do want some control coming over that one. Hopefully everyone checks the flag station before going over the crest. I've come over that crest a few times to find a car or two, facing the wrong way.

 

Taking that turn you also have to be careful as it drops off down hill and off camber, and the track is still turning right, so it is CRITCAL that you take the right line as any variance will cause you to go off the track to the left. IF you do go off there, just ride it out, DO NOT try to correct to stay on track or the tire wall on the right side of the track will be your next stop. :ack:

 

Tom,

 

Your two paragraphs sum me up pretty good; crazy, blind, critical, over the hill and a bit off camber, but I'm not very technical. :cheers: But hey, on a more serious note, you've confirmed what I've wondered about (regarding turn 5) in the videos I've been watching. All things considered, I would think that a driver (especially one new to the track . . . such as me:willy_nilly:) would definitely want to make a conscious effort to ensure that the car is 'settled' prior to adding any additional steering input on the off-cambered, downhill side of turn 5. Either that, or 'Hey, here's the tire wall I was telling you about! Enjoy!" Feel free to 'wade' through my wording here and rearrange/correct as necessary for the benefit of all.