Traction control HELP!!!!!!
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Joined: Nov 2003
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From: Central & South-Beach FLORIDA
St. Jude Donor '19
Traction control HELP!!!!!!
--------------------------------------------------------------------------------
I have a 99 FRC. Sometimes When I driving the T/C will come on and the Dick will say" traction control active" The car will not accelerate until I disengage the T/C by pushing the button. This occurs when I am going straight and in turns. The car is not holding any codes after it does it. So, I have to have a tuner ride in the car and hope it does it while it plugged into the diagnostic computer. We are thinking; yaw sensor, wheel sensor or electrical harness problem. Has anybody had this problem?
I have a 99 FRC. Sometimes When I driving the T/C will come on and the Dick will say" traction control active" The car will not accelerate until I disengage the T/C by pushing the button. This occurs when I am going straight and in turns. The car is not holding any codes after it does it. So, I have to have a tuner ride in the car and hope it does it while it plugged into the diagnostic computer. We are thinking; yaw sensor, wheel sensor or electrical harness problem. Has anybody had this problem?
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Joined: Oct 2002
Posts: 16,477
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From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
Yaw sensor has nothing to do with traction control. It would affect Active Handling.
Wheel speed sensor very possibly.
Have you changed tires recently, and even if they have been on for awhile, what sizes are you running?
Wheel speed sensor very possibly.
Have you changed tires recently, and even if they have been on for awhile, what sizes are you running?
Thread Starter
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Joined: Nov 2003
Posts: 694
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From: Central & South-Beach FLORIDA
St. Jude Donor '19
I put 18's (motorsports) all the way around with kuhmo 275 all the way around too. What are ya thinking? No problems before the new rims and tires by the way
Race Director
Joined: Oct 2002
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From: Gone
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St. Jude Donor '03
I'm thinking you found your problem.
How Traction Control works:
It compares front wheels speeds to rear wheel speeds via a sensor at each wheel. If the rear wheels spin, this is detected by the difference in wheel speeds, and Traction Control engages.
The stock rear tires are 1" taller than the fronts. (NOT just the wheel dia, but the tire OD is 1" larger too). The TC computer is programmed for ths tire height difference, which affects the wheels speeds, and "expects" the rear wheels to be turning slightly slower than the fronts due to the larger diameter tire.
Whenever you lessen this 1" height stagger between the front and rear tire diameters, you come that much closer to the TC threshold. With less height stagger, the TC computer perceives your rear tires turning too fast compared to the fronts, and although there is a good tolerance built-in there, you eventually reach a point where the computer "thinks" your rear wheels have lost traction (spinning too fast) due to the faster rpm's of the shorter rear tires it expects to see.
Some people have run the same size tires all around and claim no problems, others (like you) have not been as lucky. There doesn't seem to be any cut-and-dry threshold point, but the less of a height stagger between fr/rear tires you run, the closer you are to having this sort of TC issue.
For this reason, I never recommend anyone run with less than a 1/2" tire height stagger.
You only said you'e running 275's all around...is that 35 series, or 40? To truly cure this problem, you'll need new tires on one end or the other. The profile you're running will determine which tires you'll need to replace.
How Traction Control works:
It compares front wheels speeds to rear wheel speeds via a sensor at each wheel. If the rear wheels spin, this is detected by the difference in wheel speeds, and Traction Control engages.
The stock rear tires are 1" taller than the fronts. (NOT just the wheel dia, but the tire OD is 1" larger too). The TC computer is programmed for ths tire height difference, which affects the wheels speeds, and "expects" the rear wheels to be turning slightly slower than the fronts due to the larger diameter tire.
Whenever you lessen this 1" height stagger between the front and rear tire diameters, you come that much closer to the TC threshold. With less height stagger, the TC computer perceives your rear tires turning too fast compared to the fronts, and although there is a good tolerance built-in there, you eventually reach a point where the computer "thinks" your rear wheels have lost traction (spinning too fast) due to the faster rpm's of the shorter rear tires it expects to see.
Some people have run the same size tires all around and claim no problems, others (like you) have not been as lucky. There doesn't seem to be any cut-and-dry threshold point, but the less of a height stagger between fr/rear tires you run, the closer you are to having this sort of TC issue.
For this reason, I never recommend anyone run with less than a 1/2" tire height stagger.
You only said you'e running 275's all around...is that 35 series, or 40? To truly cure this problem, you'll need new tires on one end or the other. The profile you're running will determine which tires you'll need to replace.
Le Mans Master
Joined: Dec 2003
Posts: 5,561
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From: Atlanta metro Ga.
Originally Posted by Y2Kvert4me
I'm thinking you found your problem.
How Traction Control works:
It compares front wheels speeds to rear wheel speeds via a sensor at each wheel. If the rear wheels spin, this is detected by the difference in wheel speeds, and Traction Control engages.
The stock rear tires are 1" taller than the fronts. (NOT just the wheel dia, but the tire OD is 1" larger too). The TC computer is programmed for ths tire height difference, which affects the wheels speeds, and "expects" the rear wheels to be turning slightly slower than the fronts due to the larger diameter tire.
Whenever you lessen this 1" height stagger between the front and rear tire diameters, you come that much closer to the TC threshold. With less height stagger, the TC computer perceives your rear tires turning too fast compared to the fronts, and although there is a good tolerance built-in there, you eventually reach a point where the computer "thinks" your rear wheels have lost traction (spinning too fast) due to the faster rpm's of the shorter rear tires it expects to see.
Some people have run the same size tires all around and claim no problems, others (like you) have not been as lucky. There doesn't seem to be any cut-and-dry threshold point, but the less of a height stagger between fr/rear tires you run, the closer you are to having this sort of TC issue.
For this reason, I never recommend anyone run with less than a 1/2" tire height stagger.
You only said you'e running 275's all around...is that 35 series, or 40? To truly cure this problem, you'll need new tires on one end or the other. The profile you're running will determine which tires you'll need to replace.
How Traction Control works:
It compares front wheels speeds to rear wheel speeds via a sensor at each wheel. If the rear wheels spin, this is detected by the difference in wheel speeds, and Traction Control engages.
The stock rear tires are 1" taller than the fronts. (NOT just the wheel dia, but the tire OD is 1" larger too). The TC computer is programmed for ths tire height difference, which affects the wheels speeds, and "expects" the rear wheels to be turning slightly slower than the fronts due to the larger diameter tire.
Whenever you lessen this 1" height stagger between the front and rear tire diameters, you come that much closer to the TC threshold. With less height stagger, the TC computer perceives your rear tires turning too fast compared to the fronts, and although there is a good tolerance built-in there, you eventually reach a point where the computer "thinks" your rear wheels have lost traction (spinning too fast) due to the faster rpm's of the shorter rear tires it expects to see.
Some people have run the same size tires all around and claim no problems, others (like you) have not been as lucky. There doesn't seem to be any cut-and-dry threshold point, but the less of a height stagger between fr/rear tires you run, the closer you are to having this sort of TC issue.
For this reason, I never recommend anyone run with less than a 1/2" tire height stagger.
You only said you'e running 275's all around...is that 35 series, or 40? To truly cure this problem, you'll need new tires on one end or the other. The profile you're running will determine which tires you'll need to replace.
Race Director
Joined: Oct 2002
Posts: 16,477
Likes: 26
From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
You don't need to revert back to 17's on the front. You can fix this with different tire sizes.
The obvious easy answer would be to keep the front tires as-is, but use a 275/40/18 on the rear.
The Kumho Supra's aren't made in that size though.
If you'd like to keep the tire model the same all around, based on their available sizes, the only option I see for you would be to switch the front tires to the 255/35/18 size.
The 275/35 you're now using is 25.5" tall, the shorter 255/35 would be an even 25" tall, so your rears would be 1/2" taller, and that's probably enough to not throw off TC. The 255 will fit up to a 10" wide wheel, so it will fit your (probably 18x9.5") wheels ok...just realize they are shorter, which will lower the front of the car some, and also give you a little more fender gap.
Or, doing nothing, just live with turning TC off at startup, and wait until you need new tires and size them properly then.
The obvious easy answer would be to keep the front tires as-is, but use a 275/40/18 on the rear.
The Kumho Supra's aren't made in that size though.
If you'd like to keep the tire model the same all around, based on their available sizes, the only option I see for you would be to switch the front tires to the 255/35/18 size.
The 275/35 you're now using is 25.5" tall, the shorter 255/35 would be an even 25" tall, so your rears would be 1/2" taller, and that's probably enough to not throw off TC. The 255 will fit up to a 10" wide wheel, so it will fit your (probably 18x9.5") wheels ok...just realize they are shorter, which will lower the front of the car some, and also give you a little more fender gap.
Or, doing nothing, just live with turning TC off at startup, and wait until you need new tires and size them properly then.
Last edited by Y2Kvert4me; Nov 10, 2004 at 06:34 AM.
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Race Director
Joined: Oct 2002
Posts: 16,477
Likes: 26
From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
If you're getting all new tires anyways, and want to keep the 275 size in the front, check out the Kumho Ecsta MX and use a 275/35/18 front, 275/40/18 rear. That is probably the best sizing option for both the car and your wheel widths.
