QuestionQUESTION: Hi dan. Spoken before, I race a ford sierra lightning rod 1/4 mile oval in england (other way round) I am now the proud owner of a pyromoter and have some tyre readings. question is should i aim for a dead equal setting or should the camber edges be slightly hotter as they are working harder (on straight) the readings are n.s.f o/s 136. mid 127 .i/s 137....o.s.f o/s 99.. mid 118 i/s 125..... n.s.r o/s 105...mid 116 i/s 126 ......o.s.r o/s 93 mid 109 i/s 112 as you can see the hotter edges are all on the camber edge. (the front n/s tyre looks to be under inflated but it runs at the recommended tyre psi 30 when hot should i go over on the psi to get the temp correct. i cant get any more camber on this wheel ive added an inch to the lower arm and moved the fixing point an inch the max allowed in my rules. any thoughts appreciated ,,,cheers mark
ANSWER: Hello Mark !
You've got it very close.
I'll take these in order of occurance.
1) nsf needs a touch more air pressure, no more than 1 LB. PSI and probably not that much.
2) osf is close, but needs a touch less air amd a touich less camber say 1/2 deg.
3) nsr has a bit too much air as well
4) osr appears over inflated, but the tyre simply isn't hot enough to give a true pictur, though I would add a tot of camaber, given the rules . If it were mine I might add a bit of ballast on that corner, or raise the ride height by perhaps a half inch. This would serve to 'tighten' the car up a bit, (reduce oversteer)
Ideally all tyres should read the same on the os and center, and about 15 Deg.F more on the inside edge. This all assumes you are allowed to use a racing tyre that is either slick or has a minimum tread depth. Fully =treaded tyres are difficult to read and tend to even out temperature wise , before the crew can get to them.
Finally, have you done anything to increase the caster angle ? All my chassis guru's this side of the pond asy "caster is faster". With more caster, there is significanatly more camber gain in the turning stages. This would serve to add grip to the front. Once you start adjusting caster you will eventally find the car difficult to steer at pit and paddock speeds. Once it gets difficult to steer on track, you have too much.
ALWAYS Remember, do ONE thing at a time and take copius notes. Driver comments should be accurately recorded, though off colour words may be omitted at the discretion of the logger.
See if you can get a book store to order for you, the book: "How To Make Your Car Handle" by Fred Puhn- - -it's dates but full of valuable grassroots level info about 'setting up' for both road circuits and ovals.
Chin up- Damn the torpedoes, what was it that the Ozzies yelled at Galipoli ?
Dan Liddy
Sarasota, Florida, USA
---------- FOLLOW-UP ----------
QUESTION: Hi dan . THANKS. The off side rear is running posotive camber i can increase this . or were you thinking in terms of your racing going the opposite way round .the offside is the tyre nearest the centre of track here...i have to use yokohama A021 tyres. (treaded) i run more caster on the n.s.f. trying to find a way to increase this, but if i crank the lower arm forward to give me more caster i loose my camber.(i cant modify the top mount)i have 3/8" longer wheel centers on the n/s than the o/s ... i have the book great
AnswerHi Mark:
Your follow-p clarified my thinking somewhat, You should DEcrease the positive camber on the OSR in order to heat up the inside band a bit. It needs to be 15 deg F warmer than the outside and middle. Maybe reduce the pressure in that one to cool off the center some
It really should read something like this:
Outside edge 115 Deg.
Center, 115
Inside 130
Once you have the temps closer, try to add weight either by weight jacking or adding ballast. Every time I say ballast In Re: a race car it makes me cringe ! Weight is supposed to be the enemy, but if it balances the car - - -so be it.
FYI I strictly run road circuits, the Sebring course is my faveorite, and I once was honored to shake the hand of Sir Stirling Moss there- - -about 1957.
Dan
