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What about backlash and things like that? How easy is it to swap out the diff? I dont have an lsd, but want one. I am a fairly competent DIYer, but have never done a diff setup.
What about backlash and things like that? How easy is it to swap out the diff? I dont have an lsd, but want one. I am a fairly competent DIYer, but have never done a diff setup.
If you are servicing an existing LSD the removal and install is a fairly simple affair, just need to be careful when removing the diff from the transmission as it is heavy and awkward.
If you are replacing an open diff with an LSD these is alot more work involved. The process of setting the backlash is a long iterative process that you need special tools for as well as a bunch of shims. This job would be very difficult with the transmission in the car, however it can be done.
When I did mine I had the transmission out of the car on a bench, made life pretty easy. Still took a bunch of hours though, and I was learning along the way.
- drain trans oil
- remove inner cv bolts both sides (easier if completely remove left axle, biggest pia will be axle center bolt)
- remove stub axles on both sides of trans (1 bolt in each)
- remove all the bolts circular left side tras cover
- work your way around and pry cover off (seal is o-ring on cover)
- once cover is off you just pull diff out (watch it's heavy)
I recall someone posting another test for diff... put one rear tire in a puddle, one on dry ground and try to do a jack rabbit start and see if you spin tire in puddle.
I am about to do this on my 993S. I went back to a factory LSD, I do not track/DE the car and I got good miles before the disks went bad.. so I can live with it. You can either buy the full unit or the disks and shims. Quicker if you just pull and replace.
other parts to remember:
1 o-ring on cover plate 999.701.743.40
2 inner bearings for new diff 999.059.027.00 and 999.059.064.00
2 CV Flange seals 999.113.454.40
12 diff bolts 928.332.276.05
These part numbers might have been updated, check with your supplier.
also while its up, have them check that nose bushing (gearbox mount)
That's what I had trouble finding, will try again.
From above, in this thread, it seems that tranny can stay in, so no need to coincide LSD rebuild with clutch replacement.
I don't drive hard enough to notice if LSD is worn. I only tried the test in Diego's video, but from what I read that doesn't always mean that LSD is shot. It still may be working under a load.
That's what I read also, but since my lack of knoweldge about the LSD type fitted in the 993 I guessed the test i did in the video might be useless because "it has to be under load" but once I took off the LSD, it's a simple LSD, even the old BMW LSD are whole better (more discs) than this LSD from the 993 which is poor.
A properly LSD working condition has to meet somehow the test I did in the video, it does show if at least it has some "grip" on it if both wheels turn the same direction. Now, how healthy is the LSD is another whole story, you will need to measure the breakaway.
- drain trans oil
- remove inner cv bolts both sides (easier if completely remove left axle, biggest pia will be axle center bolt)
- remove stub axles on both sides of trans (1 bolt in each)
- remove all the bolts circular left side tras cover
- work your way around and pry cover off (seal is o-ring on cover)
- once cover is off you just pull diff out (watch it's heavy)
I recall someone posting another test for diff... put one rear tire in a puddle, one on dry ground and try to do a jack rabbit start and see if you spin tire in puddle.
Thanks. Saved for the future.
That test with the puddle would not work imo as the ABD would kick in.
Just a mention here that if you replace the carrier (differential) bearings, the backlash should be checked and corrected with shims if necessary. This can be done by observing the engagement pattern or using the factory tools & fixtures.
Here is the transmission with the correct tools in place (you also need to have the input and output shafts at the nose of the transmission locked in place)
Not a difficult job with the right tools, just a little tedious.
While I do have most of the tools, and I have rebuilt a few transmissions, I prefer to leave diffs up to someone who has more experience than I.
There is a regear and an lsd coming up in my near future, but not until oil prices increase as my job depends on hinges on it. So far things look secure though.
Your LSD is shagged. It's not a low preload version like the gt3 got. It is easy to upgrade from 2 to 4 clutches. Read "LSD buster" in the 997 gt3 forum. You will find my opinion of the brass plates the dealer will sell you. You don't want a Cup clutch pack in a street car. 120lbsof breakaway torque is noisy and bothersome on the street.
01-29-2015, 12:14 PM
