To: Lowered without traction
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Le Mans Master
Joined: Aug 2000
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From: Austin Texas
To: Lowered without traction
Last week a gentleman ask about a traction problem exiting turns after he lowered his can and put on bigger tires.
I went to my library and found another answer in "Race Car Engineering" by Paul vanValkenburg. He states that many people who modify their cars for maximum latteral acceleration on a skid pan will find that the cars have little traction as one tries to power out of the turn.
I think that this is what has happened with this gentlemans car. He has -2.5 deg camber front with 275 tires and 'only' -1.5 deg camber rear with 315 tires. He indicated that the car turns well, and has little understear, but won't put poweer down exiting turns.
The 315's may make up for the lack of camber in the pure cornering mode around the skip pan, but (I believe) this combination has too little camber to enable him to lay down some power exiting the turn.
Since you can't add more negative camber at the rear, I suggest you subtract some camber from the front. You might try -1.8 d front with the -1.5 d rear to reduce front grip in the turns so that you can accelerate out of the turns better. You must understand that this is a game of balance not a game of maximums.
Finally: the gentleman indicated that the wear pattern on the rear tires was only on the outside 1/3'rd. This could be comming from one of two places. First, If he put the 315's on the rims where 295's use to go, the sidewalls of the tires are considerably flexed, and the cornering loads and power applied could roll the inside sidewall up--preventing grip on the inside edge of the tire. Alternately, the combination of cornering, and power applied could be causing suspension deflection and jacking--allowing the tire to un-camber itself.
Good luck
I went to my library and found another answer in "Race Car Engineering" by Paul vanValkenburg. He states that many people who modify their cars for maximum latteral acceleration on a skid pan will find that the cars have little traction as one tries to power out of the turn.
I think that this is what has happened with this gentlemans car. He has -2.5 deg camber front with 275 tires and 'only' -1.5 deg camber rear with 315 tires. He indicated that the car turns well, and has little understear, but won't put poweer down exiting turns.
The 315's may make up for the lack of camber in the pure cornering mode around the skip pan, but (I believe) this combination has too little camber to enable him to lay down some power exiting the turn.
Since you can't add more negative camber at the rear, I suggest you subtract some camber from the front. You might try -1.8 d front with the -1.5 d rear to reduce front grip in the turns so that you can accelerate out of the turns better. You must understand that this is a game of balance not a game of maximums.
Finally: the gentleman indicated that the wear pattern on the rear tires was only on the outside 1/3'rd. This could be comming from one of two places. First, If he put the 315's on the rims where 295's use to go, the sidewalls of the tires are considerably flexed, and the cornering loads and power applied could roll the inside sidewall up--preventing grip on the inside edge of the tire. Alternately, the combination of cornering, and power applied could be causing suspension deflection and jacking--allowing the tire to un-camber itself.
Good luck
