Torsen V8 rear diff swap! How-to.

[kaaperdaja]

With torsen only in the back it was more like "tail happy" (but still better than stock), the rear was more controllable in sideways than the front and I had more work with the steering wheel to control the car. With torsens back and front the car was very smooth when sideways, front and rear acted the same way and you didn't have to "play" with the steering so much, you just hold the steering wheel in one position and the whole car hold same sideways angle. It's maybe little difficult to describe but I was very positively surprised when the front differential was also changed. I use my car every day and we have long winters so I have had plenty of time to enjoy it. This is one of the reasons I haven't replaced my cars because whatever newer Audi I will buy it will not act like this (maybe R8 but I can't afford it ) Even Evos have open diffs in the front.

One thing I noted is that after driving about one year the differentials started to make little noise (both of them) and I checked what was the issue and took apart one stock differential and measured the "play" between the gears in it and it was only 0,01mm so the gears didn't have almost any movement at all. My changed torsen diffs had more play in it which I also saw from the gear tooth that the contact wasn't correct. Then I bought different size adjustment shims from Audi local dealer for the diffs and adjusted my diffs with the same way (0,01mm). It's actually not so easy that you take the torsen out of V8 diff and use it another casing, there are minor size differences between gear tooth which you have to adjust afterwards. Finally I also changed few bearings and now all diffs are quiet.

For front I have used the same V8 rear differential that I used in the rear. Again there was some small modifications to be made. If I remember correctly then we had to cut down one end of the torsen diff to have it fit, nothing really special. I think it's on of the best modifications to improve the Audi understeer issues so far.

[butchone]

No, only a Audi V8 has a torsen rear diff.



Thanks for the info

I have a S2 so no problems with EDL

And what was your experience with only a rear torsen diff? Bad handling? And what type off torsen diff do you use in the front?

torsen is boss diff, loads of easy drifts and fun. just dont launch it, its too weak. ive done 3 torsens in launching. 4th diff no launches =no problems at 550lbs t

[V6quattro]

With torsen only in the back it was more like "tail happy" (but still better than stock), the rear was more controllable in sideways than the front and I had more work with the steering wheel to control the car. With torsens back and front the car was very smooth when sideways, front and rear acted the same way and you didn't have to "play" with the steering so much, you just hold the steering wheel in one position and the whole car hold same sideways angle. It's maybe little difficult to describe but I was very positively surprised when the front differential was also changed. I use my car every day and we have long winters so I have had plenty of time to enjoy it. This is one of the reasons I haven't replaced my cars because whatever newer Audi I will buy it will not act like this (maybe R8 but I can't afford it ) Even Evos have open diffs in the front.

One thing I noted is that after driving about one year the differentials started to make little noise (both of them) and I checked what was the issue and took apart one stock differential and measured the "play" between the gears in it and it was only 0,01mm so the gears didn't have almost any movement at all. My changed torsen diffs had more play in it which I also saw from the gear tooth that the contact wasn't correct. Then I bought different size adjustment shims from Audi local dealer for the diffs and adjusted my diffs with the same way (0,01mm). It's actually not so easy that you take the torsen out of V8 diff and use it another casing, there are minor size differences between gear tooth which you have to adjust afterwards. Finally I also changed few bearings and now all diffs are quiet.

For front I have used the same V8 rear differential that I used in the rear. Again there was some small modifications to be made. If I remember correctly then we had to cut down one end of the torsen diff to have it fit, nothing really special. I think it's on of the best modifications to improve the Audi understeer issues so far.

Thanks for the grade info! Can't wait to try. But for the record, how much power do you running?

[V6quattro]

torsen is boss diff, loads of easy drifts and fun. just dont launch it, its too weak. ive done 3 torsens in launching. 4th diff no launches =no problems at 550lbs t

Do you mean launching with full throttle in first gear or use launch control?

For drag-race its the best to use the lockable s2 diff then

[auditude]

The crown and pinion gets worn together - switching one out will kill the other - hence, they always swap as a pair!

Question about this wearing in of the crown and pinion teeth: Is it important to keep the relationship between the crown and pinion exact, such that the same specific teeth continue to mesh together? Or, do each tooth on one of them actually eventually mesh with every one of the teeth on the other part?

I hope my question makes sense. I suppose if the number of teeth on the ring are different than the number of teeth on the pinion, the relationship would always change. I assume that's the case, since nobody mentioned anything about orientation of the crown to the pinion, only that they should be kept as a set.

[butchone]

Do you mean launching with full throttle in first gear or use launch control?

For drag-race its the best to use the lockable s2 diff then

they broke into a thousand bits at manual launch at around 3-4000rpm in 1st gear. i was really surprised how easy they broke. the car didnt even move an inch. i have r888, around 500hp and 550lbs torque.
yes use S2 rear diff for drag

[Error404]

Question about this wearing in of the crown and pinion teeth: Is it important to keep the relationship between the crown and pinion exact, such that the same specific teeth continue to mesh together? Or, do each tooth on one of them actually eventually mesh with every one of the teeth on the other part?

I hope my question makes sense. I suppose if the number of teeth on the ring are different than the number of teeth on the pinion, the relationship would always change. I assume that's the case, since nobody mentioned anything about orientation of the crown to the pinion, only that they should be kept as a set.

You MUST use the crown wheel from he original diff. You must then check and if necessary adjust the backlash in the crown wheel / pinion so the tooth mesh is correct

[andy10v]

Hi is asking if the same crown wheel teeth must meet the same pinion teeth, but as the crown wheel has more teeth than the pinion I think everything just wears.

If they were both the same size/teeth I would have thought it would make senst to do so.

You could scribe it if you want to put it back together in the same place anyway.

[scottmandu]

I used to do this, until Torsens started failing with catastrophic results. Failure rate was 80% after about 3 years.

[hiloran]

Audi V8 88-93

you can use both the auto or rare manual ones

Can you only use AFV and AXZ or is there some other as well?

[caterpillar]

you have to use the cron and pinoin, as a PAIR.... they do not interchangable... so does you have 4,111 in the cron and pinion are NOT the same as in the other 4,111 with thorsen... change ONLY the thorsen UNIT.... really nice infor about using thorsen in front;THANKS@ kaaperdaja !!!

[Randersson]

Can i use the 90Q diff? And use the V8 driveflange on both sides so i can get 108mm?

Edit: Yes i can, i think. I have read through the whole thread now.

Maybe i will do this then!

/ Rikard

[mcandmar]

I dont think so, the flanges are shorter than the regular ones.

[|CL|NIKI]

Audi S2 rear diff = Audi 90 Coupe Quattro rear diff except CV holders (bells). Just take 108mm CV holders/bells and put them to CQ rear diff - here You got S2 rear diff. Tested. No problems with launch, or r888 at 1bar or 650-750hp. No issues with diesel g.box 1st or other gears too.

[mcandmar]

I just had a thought, did Audi spec the same 75w90 GL5 oil for the V8 torsen diff or something different?

Confirmed: workshop manual lists Hypoid Gear Oil GL5 SAE 90 for the 3.6 and 4.2 V8.