Support Team Shaun_E Posted August 13, 2004 Support Team Share Posted August 13, 2004 Replying to a thread in chit chat got me thinking...my Superlight is a real handful on bumpy roads such that I have to back off (somtimes to well below the NSL) to avoid being thrown into the hedge. I guess the suspension is track biased but do other SL owners suffer the same thing? It's worse since I replaced the AO21Rs with A048Rs. Does this sound like something which could be sorted with a bit of fettling from the likes of Freestyle or is there a more fundamental problem? Would resolving the problem likley decrease track performance or should I be able to get a better compromise? I really don't want to soften the car too much but if I could get a better road ride without sacrificing track handling then I'd be very happy. I am doing a full rebuild over the winter so that is my opportunity to change the suspension if necessary. I have no idea what the current setup is but assume it is the standard Superlight setup from 1997. Shaun Yellow SL #32 Edited by - Shaun_E on 21 Aug 2004 19:36:26 Link to comment Share on other sites More sharing options...
Wahey Posted August 13, 2004 Share Posted August 13, 2004 Any setup will always be a compromise but my SL is excellent on the road and fine on track. It is not upset by small bumps and I would comfortably say that it would be quicker down any country lane I know than just about anything else. Reference points include, modified Impreza, 306 gti-6 and it would be a close call between SL and an Elise, although I do think the SL would have the slight advantage. The only factor I find slowing it down are large compressions or ridges in the middle of the road where you have the potential to ground the sump. Setup is pretty standard. Link to comment Share on other sites More sharing options...
shn7 Posted August 13, 2004 Share Posted August 13, 2004 Shaun, Could simply be a case of running with toe out. This will result in a very pointy front end that is hard to keep in a straight line on bumpy roads. Pop round to your nearest (decent) tyre shop and get the tracking checked. A change to straight ahead or a litle toe in could well be a cheap solution and should be the first thing to get checked IMHO. Steve. Link to comment Share on other sites More sharing options...
Mike C. Posted August 13, 2004 Share Posted August 13, 2004 No problems with my SL on AO48s. I consider a compliant ride and secure handling to be the best compromise. There is no enjoyment 'fighting' to keep the car on the road. Ok, some road surfaces will deflect the car, but I reckon the Superlight to be an excellent compromise and the AO48s very predictable. Mad Manx Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted August 13, 2004 Author Support Team Share Posted August 13, 2004 Steve - thanks, that's just the sort of advice I was looking for. I'll get that done. It is possible that the car has stiffer springs than standard - I have little information on what's been done to it but as it's had several modifications by the last but one owner (Stack, removal of spare wheel, etc.) then it is quite likely that springs,anti-rollbars, etc. have been changed. After my winter rebuild I'll be getting it flat-floored so will get more advice then but in the mean time any suggestions for easy (low cost) adjustments would be appreciated. Yellow SL #32 Link to comment Share on other sites More sharing options...
shn7 Posted August 13, 2004 Share Posted August 13, 2004 Shaun, I'm a fan of cheap solutions it they are available and appropriate 😬 Steve. Link to comment Share on other sites More sharing options...
frankyknuckles Posted August 13, 2004 Share Posted August 13, 2004 you might also want to check your tyre pressure. I run 20psi in the 48's which I find to be excellent, I use this as a cold pressure on the road and also hot pressure on track. Interestingly I forgot to adjust the pressures back to cold after Silverstone, so lets say they are 18psi cold at the moment. I went for a drive last night and found the car to be more of a handful, ie, it followed the tracks in the road alot more. I think that the 48's are very sensitive to pressure, at Keevil I had terrible understeer during one session, I came back to the pits and immediately checked my pressures on the front, they were 21psi, I adjusted to 20psi went back out into the same track conditions and the car was transformed and the front actaully started to grip round the slow corners. www.R300.net Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted August 13, 2004 Author Support Team Share Posted August 13, 2004 Franky, That could have an impact too. When I had the 48s fitted they were at over 20psi cold so I dropped them to my usual 17/18 (had AO21Rs previously). I'll refine those pressures a bit and aim closer to 20 hot. Thanks, Shaun Yellow SL #32 Link to comment Share on other sites More sharing options...
Richard J Darnell Posted August 13, 2004 Share Posted August 13, 2004 Shaun - it may well be due to non-standard springs. I upgraded from narrow track to wide-track and at the same time (at Ratrace's suggestion) had stiffer springs fitted. The handling was much better and the ride is fine on smoothish roads but I do find the car is now less able to deal with the bumps. It seems this is the price you pay for making the car better on track. I agree some toe-in might help. Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted August 13, 2004 Author Support Team Share Posted August 13, 2004 Richard, I suspect you are right. My car corners very flat and on a smooth road/track generates a huge amount of grip. I just wish I knew exactly what was on the car so that I know where I am starting from. I don't suppose there is an easy identification method for springs, anti-rollbars, etc., especially as mine are "well used" and a bit grimy. If there is anything left in the budget after my rebuild then I will take a trip to Freestyle. Shaun Yellow SL #32 Edited by - Shaun_E on 13 Aug 2004 13:23:43 Link to comment Share on other sites More sharing options...
shn7 Posted August 13, 2004 Share Posted August 13, 2004 Anti-roll bars can be identified from the colour of their bushes though I can't recall the relationships between colour and diameter. I'm sure a search would turn it up. Steve. Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted August 13, 2004 Author Support Team Share Posted August 13, 2004 Found this by searching Bar..........Colour....Stiffness 3/8 inch...orange....0.33 1/2 inch...blue........1 5/8 inch...red.........2.5 18 mm....green......4 19 mm....purple.....5 Now just need to check which one I have. Next step - identify spring rate. Anyone got any ideas on this? Yellow SL #32 Edited by - Shaun_E on 13 Aug 2004 14:04:03 Link to comment Share on other sites More sharing options...
Dave Rothwell Posted August 13, 2004 Share Posted August 13, 2004 Shaun, My SL has ACB's on and it follows white lines like a Blackpool tram on rails. Also have much the same drive on bumpy lanes as yourself. Sticks like glue on the flat though. Just changing over to AO 48R's so I will post how the behaviour changes. Cheers, dave. Who needs a Helmet - Get an Affro ! Clickhere to see Car and AFFRO ! Member 6790 Superlight 0075 - K7 LYT Link to comment Share on other sites More sharing options...
millsn Posted August 13, 2004 Share Posted August 13, 2004 Simple stuff like loose wheel bearings will also give you this problem Nigel Mills - 2.0 Zetec TB's. Got my cams, bugger it's quick Link to comment Share on other sites More sharing options...
stevefoster Posted August 13, 2004 Share Posted August 13, 2004 If you have the progressive rear springs (decreasing number of sprials) then these are already pretty soft and you should look elsewhere for the problem. Check the rear ARB is on the 2nd from farthest out setting for the road. I assume you have the trailing arm on the 'handling' = lower setting. If you don't know what you have and want to change then you could get the springs you have checked. However springs are fairly cheap.... Try 250 lb front (assumes widetrack) and 150 lb rear as a good road / track compromise. You might try loosing the rear ARB altogether = better traction out of bends. With these poundages I would try Freestyles adjustable front ARB on hardest in the dry or the 5/8" one. Check you do not have M1 dampers as these are a bit too highly damped for the road. Bilsteins are stamped M0 or M1 fairly near the top where the piston rod goes in. If changing from ACB's (assume you have 0.25 deg -ve camber) to Yoko's then you need about 1.5 deg -ve camber and an ear change to get it. CR500's don't seem so fussy. I am happy with mine on 0.25 deg -ve on the road. Please report back as it adds to the database of info... Hants (North) and Berkshire Area club site here My racing info site here Edited by - stevefoster on 13 Aug 2004 22:44:40 Link to comment Share on other sites More sharing options...
Joe 90 Posted August 13, 2004 Share Posted August 13, 2004 Shaun, It might be worth checking bump steer. My car is so much easier to drive since I adjusted it. Email me if you want to come round and get it checked. SEP field working, not spotted in 102,200 miles. Some photos on webshots, updated 10 June Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted August 16, 2004 Author Support Team Share Posted August 16, 2004 Steve, Thanks for that information. I'll check that stuff this week and report back on what I have. I never really took much notice of the suspension until the change to A048Rs when the ride took a turn for the worse. Nigel - I'm pretty sure the wheel bearings are OK as I have checked and tightened the fronts recently. Will check them again. Oliver - YHM and I'll get in touch later this week. Thanks folks and keep 'em coming. I've learned a lot on this thread already. Shaun Yellow SL #32 Link to comment Share on other sites More sharing options...
Graham Sewell Posted August 16, 2004 Share Posted August 16, 2004 Oliver - how do you check bump-steer? Low tech luddite - xflow and proud! Link to comment Share on other sites More sharing options...
stevefoster Posted August 16, 2004 Share Posted August 16, 2004 Another bit of info I squirelled. The first LHD Caterham's had shocking bump steer due to the steering rod route and rack positioning. Bump steer measure notes (Author unknown) Take spring off shocker and move the wheel up and down through normal range of travel and watch for steering movement. You can make a hinged board with pins on it as described in some of the suspension set up books, but you can get a good indication by removing wheel and clamping a long piece of wood or metal to disc and watching end of said long piece - this exaggerates movement. I think it is never possible to illiminate all bump steer but generally it seems the rack is set too low, giving you the option of shimming it upwards. Both cars I have adjusted need 4 to 8mm under the rack, I would start with 6 and see how it feels. You will need longer bolts (available from Caterham) otherwise your nylocs will not nyloc! Hants (North) and Berkshire Area club site here My racing info site here Link to comment Share on other sites More sharing options...
Joe 90 Posted August 16, 2004 Share Posted August 16, 2004 Pretty much as Steve said. Alan Stanisforth's book is also good. I made a slave wheel in plywood so that I've got something flat to measure and I made a hinged dial gauge holder as per the book. I agree you can't eliminate bump steer completely, and the rack must not be set too high, but you can make a significant improvement. I always plot the data in excel as I go along so that I can be confident of the results. If the rack needed 8mm adjustment, it must have been pretty lively . SEP field working, not spotted in 102,200 miles. Some photos on webshots, updated 10 June Link to comment Share on other sites More sharing options...
Jason Plato Posted August 16, 2004 Share Posted August 16, 2004 I used 5mm of shim . It does make a difference , although my ride height has now changed so I realy should do it all again . Dave Link to comment Share on other sites More sharing options...
Support Team Shaun_E Posted August 21, 2004 Author Support Team Share Posted August 21, 2004 Update on my car. Went round to Oliver's and using his set up measured the bump steer and calculated that it was actually not far out. We shimmed the steering rack by about 1.5mm as that was all that was required. Checked the toe in and found the wheels to be just about parallel. We made a half turn adjustment to the track rods to give a very slight toe in. The results: the car is transformed and on bumpy B roads no longer makes a bee line for the hedge. I am much more confident in where the car is going and B road speed is now much higher. For information, the rear springs are not progressive so I don't know what spring rate they are (or the fronts). The front anti-roll bar has green bushes so is probably the 18mm one and it is pretty chunky. I may well go the freestyle route and get their adjustable one. Didn't check the rear ARB settings so will do that later. Thanks for everyone's input and especially to Oliver for giving up his afternoon to help me. Shaun Yellow SL #32 Link to comment Share on other sites More sharing options...
shn7 Posted August 21, 2004 Share Posted August 21, 2004 Excellent news. A nice cheap solution as was suspected. Steve. Link to comment Share on other sites More sharing options...
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