Matt Sullivan Posted February 17, 2003 Share Posted February 17, 2003 Spent the day at Donington on Sunday slithering around Tiff Needel. What pressures should 7.0-20 Avon slicks be running at? I have to say I didn't notice a massive difference over 32R's with slightly less front end grip (I'm running -.25 camber) and pretty similar rear-end traction. Well confused ...... Matt. Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted February 17, 2003 Share Posted February 17, 2003 Possible reasons - old slicks - eg been left out in winter or put through a few too many heat cycles. Different tyre sizes - I tried bigger rear tyres and smaller fronts and the car was very tail happy due to the raised rear ride height Pressures too high - I find 15 to 17psi is about as much as I want in a x-ply slick Compound too hard or too soft - My soft compound ACB10's are useless on a track as they overheat and loose grip. 🤔 Link to comment Share on other sites More sharing options...
Tight fart Posted February 18, 2003 Share Posted February 18, 2003 I would have thought that you would have trouble getting any heat in them. Until they are hot they are cr*p. Link to comment Share on other sites More sharing options...
Trevor Phillips Posted February 18, 2003 Share Posted February 18, 2003 As Richard says, at this time of year it is very difficult to generate heat into your tyres. You need to borrow a pyrometer to find out what is happening. Racing pics and items for sale here Link to comment Share on other sites More sharing options...
EFA Posted February 18, 2003 Share Posted February 18, 2003 Does that tell you the filling then? Fat Arn Visit the K2 RUM website See the Lotus Seven Club 4 Counties Area Website here Link to comment Share on other sites More sharing options...
Trevor Phillips Posted February 18, 2003 Share Posted February 18, 2003 Tried helium but got too much lift! Racing pics and items for sale here Link to comment Share on other sites More sharing options...
Matt Sullivan Posted February 18, 2003 Author Share Posted February 18, 2003 Donnington on Sunday morning had to have been the coldest place on Earth. I had them at 20psi all round, and yes, they warmed up, but not massively. Its the first time I've tried slicks, but I'm not new to trackdays. I guess I was just expecting something a little better, but they just didn't do it for me. Understeer I could accept (I'm a fat bloke in a Vx), but the lack of rear end grip was quite alarming. I was still the quickest thing there 😬, (apart from this raced up GT2 thing ), so I kept the 7 end up ...... Link to comment Share on other sites More sharing options...
Paul Bowden Posted February 18, 2003 Share Posted February 18, 2003 Slightly off topic, but related....I was spinning my CR500's at Santa Pod on Sunday in 3rd gear with about 140bhp...great fun but did not help my times. Link to comment Share on other sites More sharing options...
WILL FLY Posted February 18, 2003 Share Posted February 18, 2003 Matt Sounds like the combination of overpressure (try 16 psi) and bloody cold day was your problem. Wait a month or two and try again, starting at 16 psi and go up in steps of 1 psi to 18 or 19 max and see how it goes. If you can borrow a tyre temp meter (pyrometer) then all the better. Roy See willfly.net for more info. If you don't spin you ain't trying Happiness is knowing you have just a tad too much power Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted February 18, 2003 Share Posted February 18, 2003 Paul, Something very wrong there. I can't spin my wheels in 2nd with 240BHP for more than a squeak of squeal on a good dry surface with CR500's. 🤔 Alex Link to comment Share on other sites More sharing options...
Ian_Brandon Posted February 18, 2003 Share Posted February 18, 2003 Well I'm in Matt/Paul's camp as far as wheelspin goes. My dear departed standard crossflow ran soft compound hillclimb 8 inch slicks last year and I could never give it more than about 3500rpm off the line because otherwise I was buzzing it against the limiter. This was off a steep, maybe 1 in 5 start line covered in rubber but still, not exactly a gripfest. The first couple of bends were also usually a bit loose at the back, but I just thought they all did that and its good for growing bigger b**ls! Maybe I need to revisit my set-up and tyre pressures (usually about 14psi) Inbetween 7's - anyone flogging a Superlight 🤔 Link to comment Share on other sites More sharing options...
captain chaos Posted February 18, 2003 Share Posted February 18, 2003 Alex, Maybe it's something to do with how much weight you have over the back wheel 😳 😬 Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted February 19, 2003 Share Posted February 19, 2003 Wheelspin off the start in first is easy. True wheelspin, in the dry, in second gear is another thing altogether. OK, you can do it from low speed and by dumping the clutch violently but in normal full rpm shifting, it shouldn't spin. If you're managing it in third, something ain't right. (in my case, it turned out to be the clutch burning up) Using A24 compound slicks, my tyres are up to temperature and working well after 1 hard lap. They are pretty slippery before this. The other thing to bear in mind is that it isn't a big leap in grip from 32R's, CR500's or ACB10's to slicks. Certainly nowhere near the leap from Michelins to Yoko's. CC, I think you're right but as I often say, the lump in the front needs a lump in the back to balance out the handling! Edited by - Alex Wong on 19 Feb 2003 00:39:33 Link to comment Share on other sites More sharing options...
Paul Bowden Posted February 19, 2003 Share Posted February 19, 2003 So what could be up. My car is a standard SL apart from a SLR exhaust hence about 140 bhp. At Santa Pod I was shifting on the light, which is 7200rpm? and it was definatly spinning the 205 CR500 in 3rd i.e after the second change up. People spectating commented on it. The pressures are at 18 psi. I have no problems on the road. Any ideas anyone Link to comment Share on other sites More sharing options...
robmar Posted February 19, 2003 Share Posted February 19, 2003 Matt - the other could be that if they are 2nd hand slicks then you may not have matched fronts to fronts and likewise the rears. I borrowed some 2nd hand acb10's of Will SPIN for cadwell last year and it transformed my car from a perfect handling (on 032'rs) superlight to a twitchy and scary drive. I put this down to 3 things, namely they where old tyres of dubious history, and also I had them likely not matched so had possibly a front on at the nback and at the opposite corner a rear on at the front and 3 the car was setup for radial (however have used slicks int hepast witht his setup no problem) Iput the 32's back on and the car was perfect again you coukd put this down to the reason why will SPIN has his nickname but I do not think he was using them when SPINNG[E] I have used 2nd hand slicks int he past as you know and even on coldish days (although probably not as cold as last weekend) found them great once they heat up. rob *smile* Link to comment Share on other sites More sharing options...
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