F355GTS Posted March 30, 2002 Share Posted March 30, 2002 So having done Goodwood today the car is suffering from a severe case of body roll to see a pic http://www.esses.co.uk/ Spec is 1.6K widetrack,adjustable platforms, road springs on front (I'm told) with 1/2 inch? anti roll bar and uprated springs (allegedly!) on rear with AR bar set on stiffest setting. think the dampers are original Bilstiens Ride height needs to be dropped by at least 25mm but what to do with the springs/dampers, I'm happy to go for new ones 95% track use 5% road use on AO32R's S and SS or ACB10's (maybe slicks in the future when I buy a dry sump and another 60 or so horses) WHAT WOULD YOU BUY/DO TO SORT THE PROBLEM? Mark Edited by - F355GTS on 30 Mar 2002 23:10:47 Link to comment Share on other sites More sharing options...
stevefoster Posted March 31, 2002 Share Posted March 31, 2002 That is quite a roll on! I have the sports pack springs from Caterham for the Wide track. Been on since new never felt the need to change them. I have an 18mm ARB on the front and the green bushes. What do you have? Sports progressive springs on the rear and I run the rear ARB on the 2nd from the front position. Mine doesn't roll that much. It is compliant and forgiving. Good in the dry and wet IMHO. Some will say that the first thing you want to do for track use is junk the prog springs.... For pure circuit only use that is probable true but as a compromise I find them fine. Stiffening things up may make it roll less but there is a limit to these things. It depends how you like your car to handle. ARB's are "Nasty coarse undamped springs" Colin Chapman. "But I for one do not like my sports car to roll much" Senior engineer at Caterham. What is your rear ARB thickness? Not sure if Caterham do different thickness ones... I know some K series can have very thin front ARB's, check this first. I have a homemade cornerweight/flatfloor facility and suspension geo checking kit I use on my car and friends cars. Edited by - stevefoster on 31 Mar 2002 09:20:17 Edited by - stevefoster on 31 Mar 2002 09:20:45 Link to comment Share on other sites More sharing options...
Miraz Posted March 31, 2002 Share Posted March 31, 2002 Looks like you were having fun..... There's a useful faq on suspension here - click here - there is some information to help you work out your current setup. My car was supplied with the standard 150lb fronts and progressive rears (110-130-200) which I found too soft for road use - the ground clearance had to be set very high to avoid bottoming the car out on the road. I'm now running with 200lb fronts and the stiffer progressive rears (138-200-246) which has made a vast improvement, but still leaves the car very driveable on rough roads. I've left the dampers and arb's untouched for the moment (1/2" front, underslung rear on stiffest setting) - I don't think there are any alternative arb's available for the SV yet. In your case if you are going to be spending a lot of time on the track then I'd try the SLR setup, which (I think) is 250lb front/215lb rear and possibly a 5/8" front arb. Doubtless the next opinion given will be totally different... Miraz Link to comment Share on other sites More sharing options...
F355GTS Posted March 31, 2002 Author Share Posted March 31, 2002 thanks Guys Steve Front anti roll bar is 1/2" in orange bushes Miraz That link is excellent, it's given me loads of useful info, excuse my ignorance (I'm proably going to get shot for this) Who's Steve Lambert? Mark Link to comment Share on other sites More sharing options...
R500 CYA Posted March 31, 2002 Share Posted March 31, 2002 Mark, We should have swapped notes yesterday! I'm running 250 lb springs on the front and 300 on the back with a widetrack. The theory is that a stiffer back end will give more grip to the front and help reduce understeer. I'm too naive to say if this is true but it seems to work considering our cars comparative lack of power. Also using the 5/8th front anti roll bar. Nick Link to comment Share on other sites More sharing options...
Miraz Posted March 31, 2002 Share Posted March 31, 2002 Simon Lambert is the Caterham aftersales bod Miraz Edited by - Miraz on 31 Mar 2002 11:08:28 Link to comment Share on other sites More sharing options...
stevefoster Posted March 31, 2002 Share Posted March 31, 2002 Right first thing is to whack on a stiffer ARB front. Springs are next stop. At least sports ones stiffer as suggested if you are really keen. Very stiff won't work so well in the wet. I would not personally use stiffer rear than front. Do one mod at a time to allow you to evaluate. Link to comment Share on other sites More sharing options...
Carburet Posted March 31, 2002 Share Posted March 31, 2002 This looks a bit weird. To get that much roll you must have been cornering quite fast. You dont appear to be understeering or out of line with oversteer, assuming you were on approximately the right line, looks like the cicane leading onto the start/finish straight. I would get the ride height sorted and then see how things pan out. I'm dubious about stiffer rear springs with standard fronts, sounds like a recipe for oversteer (which is not obvious in this photo). I remember the late departed Powder Puff had a similar photo in Low Flying a while back, perhaps he'll come out of retirements with the solution. Link to comment Share on other sites More sharing options...
A10ROX Posted March 31, 2002 Share Posted March 31, 2002 just changed the set-up of my superlight set up for ACB10 green front ARB 220(?) front springs 200 rear (linear not progressive) lower location for rear radius arm flat floored set up by Sebah in Nottingham certainly alot stiffer on the road still awaiting the first trackday! the not so light Superlight Link to comment Share on other sites More sharing options...
F355GTS Posted March 31, 2002 Author Share Posted March 31, 2002 Carburet I was getting a little understeer on the way in but not much (nowhere near as much as at brands two weeks ago) changing pressures helped that, I could provoke a little oversteer on the way out of the chicane but again not much. If you rock the car at rest it is definately very soft, we compared it to another and the difference was amazing. Mark Link to comment Share on other sites More sharing options...
EFA Posted March 31, 2002 Share Posted March 31, 2002 Pinky..., 300 on the back???? Running over a 50p must give a bigger jolt than your worst ever landding....!!! Without divulging my own setup which shall remain secret until May 19th I suggest the way to combat body roll is to use around 150 - 200 lb springs on the rear and 250 - 350 lbs on the front, reducing front ratings by approx 30lbs if you do not have a wide track front. On the rear, the lower value improves traction and stability on bumpier surfaces as well as giving more "feel". The harder setting will on a smooth track give the faster time, but the car will be twitchier. Rear ARB 3/8 hard or 5/8 soft. I can also make some recomendations about ARB's, but not where P. Carmicheal esq can take my findings and build a computer model of the chassis dynamics. Of course the above could alll be cobblers just to put PC off my scent. You'll have to ask me to find out! Fat Arn Visit the K2 RUM siteid=red> See the Lotus Seven Club 4 Counties Area Website hereid=green> Link to comment Share on other sites More sharing options...
EFA Posted March 31, 2002 Share Posted March 31, 2002 Oh forgot to say Widetrack and ditching the crappy std Bilsteins fopr something which can have the damping set to your spring rate is essential if you are serious about reducing understeer. Fat Arn Visit the K2 RUM siteid=red> See the Lotus Seven Club 4 Counties Area Website hereid=green> Link to comment Share on other sites More sharing options...
F355GTS Posted March 31, 2002 Author Share Posted March 31, 2002 Arnie you have mail! Mark Link to comment Share on other sites More sharing options...
Mike C. Posted April 1, 2002 Share Posted April 1, 2002 Mark, You've clearly been bitten by the Caterham bug. Why not do now, what you will inevitably do eventually, and trade up to an SLR or R500? Mad Manx Link to comment Share on other sites More sharing options...
F355GTS Posted April 1, 2002 Author Share Posted April 1, 2002 Mike funny that!, I'm already talking about selling the 355!!!!! Mark Link to comment Share on other sites More sharing options...
F355GTS Posted April 2, 2002 Author Share Posted April 2, 2002 So it looks like I'm going with the following Reduce ride height by 25mm 250lb fronts Linear 215lb rears Linear upgrade the front and rear anti roll bars to 5/8"s but which dampers would be best (with adjustable platforms)? Mark Link to comment Share on other sites More sharing options...
Peter Carmichael Posted April 2, 2002 Share Posted April 2, 2002 Have you got an over or underslung ARB at the rear? The underslung are only available in 1/2in. The 215lb/in is almost certainly too high for the rear. I would maybe go with the Caterham 21 progressives. There are two issues with front end grip: 1. Amount of weight transfer; 2. Keeping the wheels flat. It can be the case that a thicker ARB on the front gives more grip at the front (the de Dion stays flat in roll anyway). Gordon Cardew improved his car to class winning spec from a very similar starting point to yours, just by swapping to an 18mm front ARB. Try it for the 35 quid it costs. There is nothing badly wrong with the standard Bilsteins. They are certainly better than the *race* Bilsteins which are valved inappropriately. Arnie, I don't seem to remember having any problems achieving a chassis setup. Link to comment Share on other sites More sharing options...
F355GTS Posted April 2, 2002 Author Share Posted April 2, 2002 Peter It's over, least I think it is, ie it's above the rear axle Grip wasn't an issue at Goodwood, the car was extremely well balanced, very slight understeer on turn in to the chicane and the second part of St Mary's but not worth worrying about, Mild oversteer on exit of chicane but only if provoked All I really need to do is get rid of the body roll! Mark Edited by - F355GTS on 2 Apr 2002 14:58:24 Link to comment Share on other sites More sharing options...
1400rs_0of30 Posted April 2, 2002 Share Posted April 2, 2002 Mark, I tested out my new suspension also at goodwood sat. Paul Harvey did the lot for me and I was very impressed with the results..here are the details.. http://freespace.virgin.net/mckeown.sean/mods.htm sean The original 1400 K Series Roadsport Prototype My Caterham Website Link to comment Share on other sites More sharing options...
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