Help Needed ASAP - Traction Control Issue
Thread Starter
Safety Car
Joined: Aug 2005
Posts: 3,968
Likes: 867
From: Tulsa Oklahoma
Help Needed ASAP - Traction Control Issue
Getting ready for the track tomorrow. Put on my track tires, 265/35/18 all the way around. Drove to the tire shop to have 2 new 285/30/18 mounted on the rear. Since leaving the shop the "Traction Control System Active" comes on whenever I get on the gas a little. Traction is NOT being lost or an issue. Power output goes way down when the system activates. I turn traction control & active handling off and all is well.
I disconnected the battery to reset the computer. No difference.
What's going on? The 285's on the rear are a bit shorter (i.e., lower profile) than the fronts.
Is the car confused due to the 18's on both the front and rear AND the lower profile tire on the rear?
Your thoughts?
Rick
I disconnected the battery to reset the computer. No difference.
What's going on? The 285's on the rear are a bit shorter (i.e., lower profile) than the fronts.
Is the car confused due to the 18's on both the front and rear AND the lower profile tire on the rear?
Your thoughts?
Rick
Burning Brakes
Joined: May 2005
Posts: 992
Likes: 2
From: Granville Ohio
St. Jude Donor '06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16'17-'18-'19-'20-21
If the overall height of the 285's are shorter than the fronts, they will be rotating faster than the fronts. That would be the problem. Simulated loss of traction
Burning Brakes
Joined: May 2005
Posts: 992
Likes: 2
From: Granville Ohio
St. Jude Donor '06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16'17-'18-'19-'20-21
If you have your car on jacks and put into drive or engage the clutch, with the front wheels stationary, the traction control will activate. Same type of simulation.
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Race Director
Joined: Oct 2002
Posts: 16,477
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From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
Originally Posted by rikhek
Yes, they are a good 1/4" "shorter" than the fronts. I didn't realize the traction control gets input from the fronts to determine spin?
Traction Control works by comparing front and rear wheel speeds. That's it.
If your rear wheel speeds become faster than the fronts, the computer senses you have lost traction and well, you see what happens...shorter tire = faster wheel speed.
Tech Contributor
Joined: Oct 1999
Posts: 41,058
Likes: 9,820
From: Charlotte, NC (formerly Endicott, NY)
The only way for the system to know the wheels are slipping is to compare wheel speeds front to rear. It just doesn't cut throttle. It will apply the rear brakes before cutting the throttle. Find a hill and put the car into nuetral then activate TC and let the car drift down hill. The EBTCM will apply the brakes and slow the car.
Bill
Bill
Thread Starter
Safety Car
Joined: Aug 2005
Posts: 3,968
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From: Tulsa Oklahoma
These are Kumho V700 R compound race tires. The next size up is a 305 which is too big for 9.5" wagon wheels. I do have 2 more used 285's on the way which will eliminate the problem. I run in competetive mode at the track so it won't be an issue.