danilo Posted January 20, 2011 Share Posted January 20, 2011 (edited) I am methodically assembling parts for a Lotus 'clone' build. S3 or caterham hopefully. I have a late model Spitfire steering rack. freshly rebuilt. Just checked now and it's 4.25 turns lock to lock. Current Caterhams have 1.93 turns Clearly this ancient OEM rack ain't gonna impress. or is it? Saw a Victoria British 'clone' Triumph Spit/gt6 quick ratio rack for $119 . Anyone know how many turns this thing has? Any thing else I should be leery of before I order this one? Also, I'm wondering on trying to upgrade from the venerable but difficult to get Lotus/triumph 3.75" Bolt pattern wheel / mounts. Besides being odd these are NOT hub centric and having owned 2 Lotii in the past I have unpleasant memories, experiences with the difficulties in getting this primitive wheel mounting setup to actually run true, trying to avoid facing this yet again.. willingly :-) Edited January 20, 2011 by danilo Link to comment Share on other sites More sharing options...
JohnK Posted January 20, 2011 Share Posted January 20, 2011 Have you taken into account steering arm Length? Depending on the upright you run, you may use only a small fraction of the rack's stroke. Also, you may beable to shorten the steering arm to quicken the steering. Link to comment Share on other sites More sharing options...
solder_guy Posted January 20, 2011 Share Posted January 20, 2011 according to the http://www.englishparts.com website .. the quick rack is 2.5 vs 3.5 turns. Link to comment Share on other sites More sharing options...
Dave W Posted January 20, 2011 Share Posted January 20, 2011 I,m using a 1974 shortern Sprite rack. Which gives me about 2.5 to 2.6 turns lock to lock. The rack travel is 1.78" per rev. As mentioned it all depends on the steering arms that you are using. Just figure that you need about 20* of turn angle for a road car, for the tie rod attachment point on the steering arm. Dave W Link to comment Share on other sites More sharing options...
11Budlite Posted January 20, 2011 Share Posted January 20, 2011 FYI: Any MG Midget from chassis 114487 on used a Spitfire rack and pinion. The change occured sometime around the 1972 model year. Link to comment Share on other sites More sharing options...
Kitcat Posted January 20, 2011 Share Posted January 20, 2011 The stock Caterham may be under 2 turns lock to lock but it has the turning radius of a Ford 150, at least mine does. So it turns quick, but not sharp. Link to comment Share on other sites More sharing options...
JohnK Posted January 20, 2011 Share Posted January 20, 2011 If you're interested, or curious, I have an unused MG-B aftermarket rack (sold by Flaming River) that I'd love to find a new home for. This is used on the WCM Ultralite. Link to comment Share on other sites More sharing options...
danilo Posted January 20, 2011 Author Share Posted January 20, 2011 OK thank you all for input. My accumulated suspension bits (so far) are ..ALL.. Mk4 1500 Spitfire sourced. Was just horrified to discover that my rebuilt Spit rack takes 4.25 turns to crank it from one end to the other. Also that a reproduction rack of quickened ratio was available for V little coin. Are these Chinese (where else?) mfg'd reproduction racks of passable quality?? Although the oem triumph racks in my previous Loutii :-) S2 and Europa, both requred replacing as they grew serious wear/slop on their central rack tooth(s) So clearly, oem Triumph ain't of outstanding quality either IMO:-) IF I understand it correctly, the Caterham uses TR6 intended Trunnions which feature a Steering stop bolt/stud. Wouldn't removing that bolt seriously decrease the U turn radius? Although I suspect that steering stops are there to 'save' the cycle fenders from fouling the body ?? My old clamshell winged S2 had no such U turn radius issues, easily doing an about face in my Drive. Europa on the other hand was poor at this. As digression if I might : I have 'on hand' my pore old Saab 900, which I'd hate to send it to the crusher after 27 years of loyal service.. but? It features V nice Uprights (actual ball joints, No trunnions :-) , massive ATE Brakes and hub centric design Ronal magnesium alloy wheels, of surprisingly light weight. Granted these suspension bits ..are.. heavier than the Venerable Triumph one.. but also of 20/25 years more advanced /evolved design. My question is: is this an inappropriate choice of suspension parts ? Has anyone tried this before ? Just trying to explore other possibles.. while I still can Thank you. Link to comment Share on other sites More sharing options...
JohnK Posted January 21, 2011 Share Posted January 21, 2011 Chile, if my source is correct, and Flaming River supposedly pays about USD $35 for each. However, . . . one cred point that I added to my decision to buy an Ulralite "kit" was that the cars had run the One Lap of America, and suffered no chassis and chassis-related failures. I did replace the rack on my car for reasons other than the quality (or lack of it) of the rack. "If it works, ..." You might look at Woodward Precision Power Steering's MR series racks, if you're interested in flexibility (Mosteler and Saleen both run them in their race cars, and the basic unit is the favorite of the soon-to-be mechanical engineers' Formula SAE cars). But this is NOT a bolt-the-thing-in type of job. It took me many weeks to get very quick steering and absolutely ZERO bump-steer. If you don't know what bump-steer is and that it ruins the driver's ability to tell what the car's doing, it would be good to do some reading. The SAAB bits sound like they're worth a look. Link to comment Share on other sites More sharing options...
danilo Posted January 21, 2011 Author Share Posted January 21, 2011 Johnk: thank you for the info. Chile? well what the heck, seems as good a pace as any. . Triumph rack worked fine in my experiences.. it just wore out quickly. No big deal at that price though. Yikes! Flaming River seems to have Usurious pricings. Didn't find a Triumph type rack (is there one?) Yes I'm aware of bump steer. Wife made it to national runner up in Solo in our/my seven .. 20+.. years ago though :blush: Although I know that 'bump steer' can be of serious concern to designers, I also know that it's.. far less.. significant in real life. Reasonably close has proven.. more.. than 'good enough' at the speeds/conditions Sevens invariably operate at. I too, often succumb to the fantasy of having everything as perfect as humanely possible. A common affliction it seems: witness the Overweight 50 yr olds on their multi thousand $$ Carbonne Bicycles :-) I too, was initially fascinated by the Ultralite when it first appeared. But despite is pricing advantages (over caterhams) I decided that it didn't appeal.. no spark/lust trigger felt :blush: it just didn't look 'right'. Brunettes vs Blondes I suppose. Link to comment Share on other sites More sharing options...
JohnK Posted January 22, 2011 Share Posted January 22, 2011 danilo, A wife who races, and does well at it! I'm impressed - and a little envious :-) My interest in (and hopefully not obsession with) understanding how all the bits work together and also understanding how to dial everything in as well as possible comes from relying on Carroll Smith for those understandings. One of his lesson is "It all comes down to tenths." I think that some cars feel amazingly wonderful to drive because some talented people got all the parts to be of an especially optimal and harmonious mix and dialed everything just as it is supposed to be. Kitcat gave me a ride in his ho-hum ordinary Caterham and I was amazed at the combination of agility and the comfort of the ride the car provided. I've seen pictures of Caterhams going around corners on their door handles (metaphorically speaking) and wondered how they could corner so well and yet have so much body roll. Somebody understands what they're doing. The ultralight caught my attention with its IRS (actually I found out that it's adapted from a (gag) strut layout) and drive train. I spent over a year tuning only a few cars with ECUs on a dyno and knew that the stock S2000 would give me better power and especially drivability than anything I could get otherwise - and that I wouldn't have to touch it. The successes people have had with it in the One Lap of America also added to its creds. However I agree with you that "It just doesn't look 'right' ". The engine's too tall and quite heavy - it changes the look and especially the 'sense' of the car with respect to a Lotus or Caterham. Plus, the build (redoing stuff that really had to be redone) has taken too long. And, even though I really have enjoyed all the development work, it would have made much more sense to just by a plain cross-flow engined Caterham from someone and enjoy driving the thing. And, with what I've developed, the only thing that'll really be missing is my having the nervous system of a 23-year old. Good luck with your clone, and watch out for those after-market vendors. Link to comment Share on other sites More sharing options...
Kitcat Posted January 22, 2011 Share Posted January 22, 2011 John K: I don't think a person can be too obsessed when it comes to cars, esp se7ens:). Do you have a semi-solid projected date when your thoroughly re-engineered se7en will be done (I see the six year anniv date is approaching)? BTW, as neat and tidy as the Crossflow is, I'd love to have your 240 hp! Mike M. Link to comment Share on other sites More sharing options...
danilo Posted January 22, 2011 Author Share Posted January 22, 2011 Wow 5 years in the making.. at least you've started, I've been thinking about this for 10 years or so. How heavy IS that pesky Honda unit? I ask as Hyabusa drive units are reputedly 65KG all in. Not too shabby @ 194 hp /1300cc plus a nice 6 speed sequential. Clutches can be shortlived, but it's $150 parts and an hours' work, start to finish to replace Test drive video: http://super7cars.com/video%204%20jolyon.html Older (pre 2000 my) Saab 2.3 engines, albeit even heavier than an s200.. easily.. out performs the Honda.. 300hp & 350 ft lbs is seriously effective.. by any yardstick. Dunno.. if one wants that much pig iron in the front of the car though :-). Crossflow engine although not even close to current durability yardsticks is a decent engine, once balanced and revalved :-) A Madza 2.3 could be a V good substitute IMO. I wouldn't overly worry about state of art unless it's a personal achievment issue... it's the operator much more than the machine. Semi recent story of an international Ice fishing contest (who woulda thought ?) a few years back in Northern Ontario. US team showed up with every technological gizmo possible. Latvian 'team' (2 guys) lost their gear in transit.. they borrowed lines and a few hooks... they subsequently Won the contest. I've currently been obsessing over getting big enough brakes for my build.. poring over catalogues and parts lists to see what is possible.. Wife chimes in by saying there is No problem with the OEM S7 brakes .. besides you just don't use them.. they only slow you down. Nice shot of reality? Link to comment Share on other sites More sharing options...
Mondo Posted January 22, 2011 Share Posted January 22, 2011 I don't think there's a 7 out there that has left the factory (or initial builder) and not needed some tweaking. It's funny that I didn't like the look of the Caterham and found the stubbier, bigger S2K more to my liking... like you said, to each there own. Though my car is a little more minimalist than I prefer, it's easier to add some creature comforts than trying to remove weight etc... Back to the subject, I love the way my car steers. And that's with 17in wheels, I imagine if John's unit fits it would be great for small tired 7s as well. Link to comment Share on other sites More sharing options...
JohnK Posted January 23, 2011 Share Posted January 23, 2011 Lots of questions to answer! I don't think a person can be too obsessed when it comes to cars, esp se7ens:). Do you have a semi-solid projected date when your thoroughly re-engineered se7en will be done (I see the six year anniv date is approaching)? BTW, as neat and tidy as the Crossflow is, I'd love to have your 240 hp! Mike M. Too obsessed? Perhaps... :-) I'm expecting to be on the road this coming Summer. The list of things that have to be done is getting pretty short. A trip to Koni Racing with a list of specs in hand to order the shocks - which will be expensive. Logistics will consume time, like getting a trailer and tow to get to the inspection station, and figuring out where I can test drive it safely. After so much work I don't feel like risking the thing out on the highway without some serious stress testing. And then . . . there's finding a local experienced Seven pilot to spend some time with it to provide an un-biased assessment of the thing, and perhaps some help in dialing in the shocks - hmmm, I wonder how I can accomplish that? ;-) Power: back in my motorcycle days, the word was that you learned on something that handled well but didn't have a lot of power. That way you found out how to go fast by learning to drive - how to get every bit of traction out of your machine and exploit all the momentum you could generate in every corner you went around. Then, when you could afford something that had lots of power, you'd know what to do with it. > danilo Wow 5 years in the making.. Perhaps as much as the whole first year was spent in a deep funk as I found one thing after another that had to be un-done, figured out and then built correctly. After that it went downhill for another stretch when the picture became even more clear :-( >How heavy IS that pesky Honda unit? If I remember correctly, 405 lbs including transmission. I think the lightweight here is the Rover at around 270 lbs for engine and trans - there's a thread on this site on that topic. >Older (pre 2000 my) Saab 2.3 engines, albeit even heavier than an s200.. easily.. out > performs the >Honda.. 300hp & 350 ft lbs is seriously effective.. by any yardstick. Positive manifold pressure will get you that :-) >Dunno.. if one wants that much pig iron in the front of the car though :-). And who was it who said "Add lightness"? >Crossflow engine although not even close to current durability yardsticks is a decent > engine, once balanced and revalved :-) A Madza 2.3 could be a V good substitute IMO. When you're facing the confines of an empty chassis, you find that it's really difficult to find room for everything. The Ford T-9 bellhousing is really narrow, which makes for very tidy packaging. Everyone else's engines have pretty wide ones. >I wouldn't overly worry about state of art unless it's a personal achievment issue... >it's the operator much more than the machine. My feelings exactly. >I've currently been obsessing over getting big enough brakes for my build.. >poring over catalogues and parts lists to see what is possible.. I did that from scratch and it takes some doing. Wilwood can be very helpful. Their selection of calipers is huge, and they have pedals and master cyls - and very good advice if you call them. Also Coleman Machine (Wilwood recommends them) is set up to provide made-to-order rotors and hats - they have quite a selection and are reasonable. Caveat emptor - they can be really sloppy occasionally. Check measurements thoroughly. The tricky part for me was figuring out how to mount the caliper to the upright. I was able to arrive at and implement a complete system that gives balanced front-rear braking, that has real, HD, cast-iron, vented rotors, and that allows running Diamond 13" wheels. It was a lot of work! I started with a (now out of print) copy of Fred Puhn's Brake Handbook >Wife chimes in by saying there is No problem with the OEM S7 brakes .. besides you just don't use >them.. they only slow you down. She DOES know how to drive, and I've heard that before. Maybe going into a corner way too hot and finding out your brakes have faded lets you know you can go a lot faster - after your pulse gets back to normal. Mondo: I replaced my rack when I found that I could not get rid of significant bump steer due to the dimensions of the rack. But, I have to plead considerable ignorance here because I've never driven an Ultralite and am going completely on the numbers I got when attempting to align the car. I hope that as the years go by some other Ultralite owners will have a chance to drive my car to provide a comparison. Perhaps I'll find that the very challenging work of fitting a new rack was largely an academic exercise. As a (very, very good) reference to guide the work, I used what's written in the Woodward Precision Power Steering catalog. Were I wealthy enough to afford what I wanted appearance-wise, I'd look to something like a early 60's Alfa or Maserati sports racing car, and have seldom thought of a Seven in any terms other than what it is like to drive. But still, every time I've been able to walk up to and admire a Lotus 7 or Caterham, or a Bug-eye Sprite, I get this big smile on my face. I think it's some sort of ancestral memory. It's certainly not anything to do with reasoned thought, so I should excuse myself from making any comments as to a particular Seven's appearance. Happy planning danilo. Link to comment Share on other sites More sharing options...
Mondo Posted January 23, 2011 Share Posted January 23, 2011 (edited) John, I really look forward to seeing your car (post some pics) and hope it lives up to your expectations. The roads here sure can test suspension (not including the potholes). I didn't really notice bump steer but the car did felt a little twitcy to me. I found that caster adjustment made a lot of difference on composure as it doesn't take much to turn the wheel and more castor helps keep the car wanting to go straight (might not be the best for autocross though)... that and relatively soft springs that weren't riding on the bottom of the shock's stroke helps keep the car in contact with the road. I wouldn't want to speak for handling on the track... don't have the talent for that. Edited January 23, 2011 by Mondo Link to comment Share on other sites More sharing options...
danilo Posted January 24, 2011 Author Share Posted January 24, 2011 You had a Bug eye? I had one of those too. Helped some girl push one on wet night (long ago/ misspent youth) and offered her $200 She happily took it. Was Fun to use, it had an 1100 cc engine retrofitted, trans, in typ Austin fashion had barely there synchros and as I was deep into campainging a Cooper 'S"... it was easy to rehabilitate with parts on hand. Fun to drive at reasonable speeds, but the Scuttle Shake was horrific.. I thought for sure the front end would 'fatigue off' at 100 mph. It didn't .. but I sold it at the end of that summer.. even got most of my expenditures back.. almost Link to comment Share on other sites More sharing options...
Kitcat Posted January 24, 2011 Share Posted January 24, 2011 Lots of caster is good for auto-x: It helps get the wheels back to the neutral position to start steering for the next turn. John K-the local race shock guru is Kumar. He also did many chassis set ups for OEM vehicles, including the track Viper. Haven't heard form him in a while tho, I know his garage closed. IF you cld find him, he cld take your car for a spin and give you tons of info. He cld revalve your shocks that wld max out car's potential also. Cant wait to see the finished product. Link to comment Share on other sites More sharing options...
danilo Posted January 25, 2011 Author Share Posted January 25, 2011 Been busy (late nights) on Autocad trying to get my 'copy' of a Caterham SV chassis sorted. Going over my old Lotus manuals gleaning bits of info and specs, I found that Sevens (S 2/3 at least) were designed with the typ 5 degrees castor and the built into the triumph upright of 9 degrees kingpin inclination. BUT in what seems odd, the Europas (and presumably S4's as they used the self same suspender parts) were set for a 3 degree castor. Curiously the teeny tiny stamped steel, as opposed to tubular, A Arms are only a 1/2" shorter than those on the S2, S3 (and gawd knows how many Caterhams) Their mountings are quite rigid as well. Clearly a later design than the venerable S1 tubular one that never seems to go away :-) Untill now I thought of the Europa design as a Tonka Toy setup.. live 'n learn. Having owned an Europa for over a decade and having competed the seven against the rascals, they were No slouches at Parking Lot racing..serious competitors indeed. Real trouble with a half decent driver. Arguably even 'better' cars than Sevens. Just real Ugly pancake cars :-) Consequently the castor bit is confusing this old guy. The fact that there is a choice, more than anything I suppose :-) Design with the typical proven 5 ? or play with the Europa setup of 3 degrees?? Link to comment Share on other sites More sharing options...
Mondo Posted January 25, 2011 Share Posted January 25, 2011 From what little I know, if you can adjust between 2 & 5 degrees you should have it covered Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now