LSD vs. TCS

[Taff]

Hi,

Does anyone know of a standard / common fault with the Traction Control System which causes it to cut in unexpectedly. Its been damp the last couple of days but going round even the slowest of bends has been causing the TCS to noticeably cut the engine power. This may be linked to a slight noise I'm getting from the LSD when I go on/off the power,(ie a slight clunking). So my question is, would a deteriorating set of LSD friction plates affect the amount of slip to such a degree that it would affect normal operation of the TCS. Straight-ahead speed / acceleration, even on damp roads still doesn't cause the TCS to cut in.

Any ideas guys. How much of a job is it to cure a noisy LSD for instance ? Can you just re-line the plates with new friction material ?
As the car only gets street use, (ie no track use)can the LSD be backed off ? Most specs talk about LSDs being approx. 25% - 40% slip, is this necessary for the Street, would less put a smaller strain on the tranny ?

Any help appreciated....

Taff

 

[nsxxtreme]

What size wheels and tires are you running? If they are not stock you may have put a wrong combination of tires on your car.

 

[nsx4fun]

LSD tight or not, puts no additional strain on the tranny. All the strain is located in the axles and differential spider gears. The only strain the tranny sees is the transfer of power from engine to the ring & pinion gears.

nsxxtreme is right. If you changed the diameter of tires on one axle (front or rear) and didn't change the other axle proportionally the same, you could be confusing the TCS causing it to kick in inappropriately. Have you checked your tire pressures lately? If one side of your car has a different tire pressure than the other side, this can also cause misinformation to be sent to the TCS computer.

Good Luck, Fritz

 

[rcarlos]

Mine has the slight clunk when I put it into drive also. I think this is normal.

 

[Taff]

Re. the TSC problem.

I have just changed the front tyres from 215 to 225s. I'm going to check the tyre pressures too. They don't seem that far out by giving them a squeeze, I'll check with a guage though...would a couple of psi make that much difference....I'll tell you later when I've checked.

As the Traction Control presumably only works on the rear (ie the driven wheels) I wouldn't have thought this would make much difference. Both rear tyres are identical.
Cheers guys.

 

[Taff]

Sorry,

Forgot to ask again how much of a job (parts and labour ) a diff rebuild is????

 

[V12NSX]

TCS needs the proper ratio of diameter between fronts and rears. By going from 215 to 225 you have increased the diameter of the fronts, but not the rears. TCS now thinks it's "slipping" when it's not. If you go to 255 rears, then you should be OK.

S.L.

 

[Taff]

TCS problem solved - 2 pounds/sq inch difference between left and right hand side tyres !! Only 2 !

I was sceptical about the front - rear tyre diameter ratio and hence front/rear angular velocity ratio. Many people in the forum seem to be experimenting with different set ups and no-ones mentioned TCS problems before...have they ?

 

[Andrie Hartanto]

I did use 225/45/16 and 245/40/17 for a while. And they screw up the TCS almost every hard acceleration. This with the front half worn and new rear.

Front/rear ratio is real. Very real.

 

[nsx4fun]

Taff, glad to hear the tire pressure solved your problem, but it probably is only the straw that broke the TCS back. Your front to rear changes I am sure contribute to the problem making the tire pressure side to side more sensitive. TCS is a complicated system that basically knows how fast all 4 tires should be spinning with respect to each other based on how far your steering wheel is turned. When it decides things are too far out of expectations, it concludes the vehicle is out of control and it cuts the throttle. For optimum performance of the TCS, I would recommend at your next tire change, change the size of the rears to match the ratio change of your fronts. The ratio being old rolling circumference vs. new rolling circumference.

Fritz

 

[Taff]

You're right, the TCS still comes on under under hard accel.

Damn!

 

[sjs]

Originally posted by Taff:
Many people in the forum seem to be experimenting with different set ups and no-ones mentioned TCS problems before...have they?

Wow, you really are new around here!!

This is a much discussed topic. Check the FAQ, then you can search the forums and read for hours more.

 

[4g62bt2c30a]

Originally posted by Taff:
You're right, the TCS still comes on under under hard accel.

Damn!

TCS.... Bye Bye, Now everything is Wonderful.....

 

[Taff]

Yep, agree, bye bye TSC....

 

[Taff]

The FAQs related to the TCS and appropriate Fr/Rr tyre diameter ratios etc. quote a 5%tolerance.

Speaking as an engineer, do they mean +/- 5%, or +/- 2.5% ie 5% in total ??

The difference is obvious, but the answer isn't!