Active handling ?

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Apr 30, 2007 | 07:51 PM

MR.KIDD

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From: NORFOLK VA.

Active handling ?

One of my Buddys 01 active handling comes on at 140mph is this normal if you don't turn it off.

Apr 30, 2007 | 09:00 PM

Bill Dearborn

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From: Charlotte, NC (formerly Endicott, NY)

What do you mean by the AH turns on? What does the car do? Are the rear brakes being applied or are the front brakes being applied? Is one brake being applied on front or rear? Does the car swerve?

Based on your comment I will assume he is going in a straight line and the car is slowing down and the traction control indicator is turned on and the car is slowing. I suspect that he may be having the Traction Control turn on. This could be due to a tire size problem. What size tires does he have front and rear?

Bill

May 1, 2007 | 12:29 PM

MR.KIDD

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From: NORFOLK VA.

Quote:

Originally Posted by Bill Dearborn

Does the car swerve? Yes

Based on your comment I will assume he is going in a straight line and the car is slowing down and the traction control indicator is turned on and the car is slowing. I suspect that he may be having the Traction Control turn on. This could be due to a tire size problem. What size tires does he have front and rear?

Bill

He has 18s all around is this tricking the wheel sensors at high speeds?

May 1, 2007 | 03:08 PM

Bill Dearborn

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From: Charlotte, NC (formerly Endicott, NY)

Quote:

Originally Posted by MR.KIDD

He has 18s all around is this tricking the wheel sensors at high speeds?

Corrected.
What size? 295, 265, 275, 305?? If the rear tire diameter is smaller than the front tire diameter the TC system will be unhappy. Usually it will stay happy if the tire diameters are equal and will definitely be happy if the rear is larger than the front. I run 17 inch 25.3 inch diameter tires all the way around when on the track. This has not upset my AH or ABS even at speeds of 150. The few times I have forgotten to turn off TC I haven't had a problem but I haven't been at that high of a speed with equal size tires with TC turned on. However, at 140 the rear tire rotation speed may be close enough to the front that the system intreprets the tire as slipping. This may be due to a design variation in dead band size as vehicle speed increases thus limiting allowable wheel speed differences as speed increases.

Bill

Last edited by Bill Dearborn; May 2, 2007 at 11:38 PM.

May 1, 2007 | 06:33 PM

robvuk

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From: Los Angeles

Quote:

Originally Posted by Bill Dearborn

What size? 295, 265, 275, 305?? If the front tire diameter is smaller than the rear tire diameter the TC system will be unhappy. l

If front is equal or smaller, system will be HAPPY. I know what you meant but it might have been confusing to him.

Furthermore, when running equal tires all the way around, it is not uncommon to wear down the rears faster than the front creating an ever so slightly smaller diameter in the rear. At high enough speed, this could compound and translate into enough of a mph difference that the computer interprets slippage.

May 2, 2007 | 01:29 PM

BowTieRocket

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From: Chico CA

Quote:

Originally Posted by robvuk

If front is equal or smaller, system will be HAPPY. I know what you meant but it might have been confusing to him.

I'd read somewhere else on the forum (and been advised by a technician) that the fronts should be between 0.5 and 1.0 inches smaller than the rears (I think that was height, not circumference, but can't remember for sure). In any event, sounds like everyone agrees that equal sizes frt/rr can cause problems...

May 2, 2007 | 08:50 PM

naturalgas

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i have 265-35-18 up front and 295-35-18 in rear and my car swerved at hi speed and tc light came on this doesn't happen all the time. I think i will just t/off tc from now on kind of feels like one rear break could be comming on.

May 2, 2007 | 11:41 PM

Bill Dearborn

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From: Charlotte, NC (formerly Endicott, NY)

Getting ready for an open track event today I put about 20 miles on my car with 315/35/17s all the way around. Left the AH in full mode with TC active. Speeds peaked at 80 down to 20 and back up (burnishing pads/rotors). No problem with the TC or AH.

Bill