dave968M3

Can anyone give me an estimate for installation time/ costs to install a Porsche 968 Torsen style limited slip?
txs
-Dave

whakiewes

I can do it in about 6hrs. Depends on the mechanic and his knowledge. If he has to pull the tranny it will probably be more. This is me just doing it in my garage with basic power tools.

Wes

JET951

about 3 hours in the car, or 5 hours on the bench.

mikew968

I think If it is done on the car (the TA does not have to be removed) it is 3-4 hr job


Mike

968turbos2

Uh...do not do that. The Transmission must come out of the car if you are to do it right. you may as well buy tapered diff bearings while you are at it. You must, 1.) remove the tranny 2.) remove the diff 3.) remove the rear section of tranny (the last two secitions) from the diff housing. 4.) buy 2x2.5mm shims for your new diff from porsche, keep the ones on your existing diff and maybe buy sizes 1.8,2.0,2.2 and 6x0.25mm shims 5.) you must have a dial gauge......and so on....what you are essentially doing is setting up the pre-load and adjusting for the factory backlash which is stamped on your gear/ring set combo. Some changes (changing the diff housing which is what you would be doing) require certain procedures to be followed that if not service life is seriously affected.

968turbos2

Time, still about 5 hours but you must know what you need to do or you will be just planning for a new tranny. The parts cost me around $310 and i have xtra shims

Weston Dillard

968turbos2:

Good info, but I don't understand why you have to remove the rear section of the trans if you are using the same ring & pinion. Isn't it then just a matter of properly shimming the carrier side to side?

West

968turbos2

Hey Weston. Well here is how it should go. You need to remove the rear section to set the preload if you use new bearings. However; if you are changing the Diff Housing with say a Quaiffe or GT unit then the Differential Housing has changed which is the basis of the pre0-load measurement. So that requires you to set the pre-load even if you are not changing the Tapered roller Diff bearings.

So the procedure:
1.) Remove Diff and remove bearings and the shims that were with them. Note the amount on each side just for your own reference.
2.) Add a 2.5 mm shim to each side of the diff and put the bearings back on.
****This is why you need to remove the pinion section (the rear section) With 2.5 mm on each side most likely when you install the diff to measure the distance you need to make up in shims the pinion gear in in the way. If you installed the diff and torqued the housing bolts down the ring gear would be binding on the pinion. So removing it allows you to assemble it (Diff housing with just diff installed) and measure the play when you lift the diff up and down. This gives you the amount in shims that will set the correct distance and add the .25 mm preload shim

3.) Now you have 2.5mm+2.5mm(each side) + 1.4mm (mine) + .25mm (pre-load constant)= 6.65 m total
4.) now 6.65/2(each side) is 3.325mm, factory says start your adjustments by removing .7 mm from the cover side of the diff (in shims). Try to picture this becuase at this point addiing shims to one side must be subtracted from the opposite side so you always end up with 6.65mm total so back off the cover side by .7 to (3.325 - .7 = 2.625 - round up to 2.7) Then 6.65-2.7 = 3.95 So all this means is that to start measuring backlash I am going to put 3.95 in shims on the side of the diff that does not have a cover and 2.7 on the side of the diff with the cover. 6.65 total

5.) now 2.7 is less than what was on there when I started (remember i said take a note on what shims were on each side) If you took off 2.9 in shims on the cover side for example thne starting at 2.7 means most likely you will be adding to that side anyway so what I did was start at 2.75mm and 3.9

Assemble and use a dial gauge to measure backlash The backlash value you want to achieve is printed on the ring gear in the format F0,17 which would mean .17mm set at the factory for the quietest operation of the set.

My final adjustment ended up being 3.8 on the inside and 2.85 on the outside. gave me a backlash of .13 .05 less than the specified amount is acceptable. Anything over the specified amount is considered a serious NO-NO At high rom you just send the diff into orbit or it will sound like it is!

RajDatta

Great stuff turboS2.
Have you done a pinion bearing before? I am considering tackling this task and was wondering if you had hands on experience doing this. Might as well learn how to do this. Its a known problem with our cars and I am getting tired of paying people to fix it.
Thanks.
Raj

968turbos2

Yeah TurboS. By the way I never realized the name I chose. Wasn't on purpose. I have pictures of the process and may redo it again to do a DYI. Even where to get the tools and how to fashion your own extension to measure backlash instead of buying the factory VW part.

968turbos2

Now the pinion bearing is another story. Yes I have done a couple and it is really patience. If you can not get that 1.7 mm shim cause they have to freight it in from germany then wait the time. The temptation is to change a few numbers here and there to make it work quick. What happens is that once the bearing seat in the noise starts. The pinion failure was just that. At the a specific audi factory where the trnnies were made, the machine that preloads the pinion bearing was not using enough. So the bearing seat in in a few thousand miles and now they get noisy. Noisy means metal gone means new bearings.

968turbos2

patience young grasshopper is what I had to tell myself. Knowing what can happen ... the price of error .. better to take one's time.

968turbos2

I was installing the GT G50 Torsen Differential. This tranny did not have the factory limited slip. I thought about those and then while looking around fell upon GT as an alternative to Quaiffe (more expensive) Both are great and are closely priced now.

Weston Dillard

968turbos2:

Great info. Thanks! I assume that both ring gear and side bearings/races require a press to R&R?

West

968turbos2

Yeah they do. I ended up buying a press. With Manufacturing in China now, the Shady Tree Mechanic can get some nice tools for limited use...cheap. Anyway, after all the wheel bearings and races and hack methods I have used to work with them I finally broke down and got a press. 20ton.