Front Torque Problem

[pimpek]

Hey guys,

I was wondering if someone could lend me hand here, I got a 92 R32 GTR and recently changed the clutch and put new tyres on ( Federal 595 - 235 front 255 back on volk racing GT-C 17 inch) and im having this problem where my front torque gauge keeps showing torque going through to the front tyres through every gear even on low acceleration and while going the speed limit on the highway and when going into corners the torque drops. Finding this a real pain because prior to the change in clutch and tyres the torque gauge was reading 0 unless i did a heavy launch or back would come out when cornering then it would go up. the ATTESA line where bled and there are no air bubbles in the line, was also told the difference in tyres isnt mmore thatn 3mm, also i did have the 4wd light on the dash pop up a few times and sometimes stay on for long periods of time until car was switched off and restarted.

Problem is really buggin me. dont know the cause but im thinking its the difference in the tyres thats put the system out of whack, and if so can it damage the system at all

help would be much appreciated

[wlspn]

Are your tyres the same rolling diameter? ie. Same profile front & rear?

Wouldnt expect that to make a huge amount of difference but.

Guessing here but most likely cause sounds like ATESSA fluid...

[Pezhead]

Stop driving the car - right now!

This has been covered a lot in previously. You cannot put differient diameter tyres on a GTR. The rotation sensors think the tyres are slipping and tries to put power to the fronts.

Since front and rear are spinning at different speeds, the lock up of the transfercase has to absorb the difference. Wouldn't take long to burn out your clutch packs. Take one set of tyres off and get them replaced with the same size.

Since your's is a 32 you may be able to pull the fuse to disable the 4wd system until you can get the correct sized tyres on. (can't do that on an r33 or r34 due to the 4wd system preload).

[Moodles2]

Are you using 235/40/R17 at the front, and 255/40/R17 at the rear?

As long as the profile (used to determine rolling diameter) is the same (which I used 40 in this case, would keep the speedo accurate at least), ATTESSA shouldn't be putting power to the front, the different widths shouldn't be an issue though understeer wise you should have the same width all around... GTRs have natural understeer, which is made worse less with narrower tyres at the front.

Are the wheels staggered offset (front are different than the rear) by any chance?

Which set of tyres are newer? because the difference in tread can alter the rolling diameter and make the ATTESSA system think the rears have lost traction.

As a precaution I recommend pulling the 4WD fuse until the torque split issue is fixed (only do this with R32 GTRs), ATTESSA was never designed to transfer power full time, it could overheat the clutch packs in the transfer case.

[StealthX]

Are you using 235/40/R17 at the front, and 255/40/R17 at the rear?

As long as the profile (used to determine rolling diameter) is the same (which I used 40 in this case, would keep the speedo accurate at least), ATTESSA shouldn't be putting power to the front, the different widths shouldn't be an issue though understeer wise you should have the same width all around... GTRs have natural understeer, which is made worse less with narrower tyres at the front.

profile changes depending on the width of the tyre dude.

255/40 is a taller tyre than a 235/40 - thats where the problem is.

cos the "40" is a percentage of the width.

so a 235/40 tyre is 235mm wide and 40% of 235 = 94mm of sidewall height.

and a 255/40 is 250mm wide and 102mm of sidewall.

so in order to have the tyres the same rolling diameter, the fronts need to be 235/45s - even then they are a little out.

a GTR is an AWD car, get all tyres the same size, they dont need to be staggered.

[pimpek]

Thanx for the help guys ive pulled the fuse and im ordering new tyres tomorow same as the rears 255/45 federal 595. Just curious cause the rear rim is slighlty wider then the front would that come into play at all or would everything be fine after all 4 tyres are 255/45???

just want to make sure so im not spending cash on tyres i wont be able to use again

Thanks in advance

[pimpek]

i was using a 235/45 front and a 255/40 rear was told there isnt more than 3mm of difference in it and shouldnt affect the attesa. but from wat ive told u guys and your responses its seems it is and the tyres are the problme

[Moodles2]

Thanx for the help guys ive pulled the fuse and im ordering new tyres tomorow same as the rears 255/45 federal 595. Just curious cause the rear rim is slighlty wider then the front would that come into play at all or would everything be fine after all 4 tyres are 255/45???

I didn't know about the sidewall height was a percentage, but yeah the poster after me is correct. The mix of 235's and 255's is the most likely cause of the ATTESSA issues, it might even just be something simple as mismatched tyre pressures front and rear.

Even though the rolling diameter difference is marginal, it's enough give issues as ATTESA expects the same rolling diameter all around.

From http://www.1010tires.com/TireSizeCalculator.asp:

I have 225/50/R16 front and rear, front are new and rear were very 2nd hand and I had front torque issues just because of the difference of tread between the newies and the 2nd handers.

[blind_elk]

i was using a 235/45 front and a 255/40 rear was told there isnt more than 3mm of difference in it and shouldnt affect the attesa. but from wat ive told u guys and your responses its seems it is and the tyres are the problme

How many fricken times do we have to tell people that Nissan AWD cars need to run same size rim and same size tyre on all four corners. If you deviate from that rule, you are simply asking for trouble.

The bozo who fitted this tyre combo should be shot.