Had an email exchange with Bill Ball on the question of LSD interchangeability and he has "been there, done that." Bill has installed a LSD out of an '83 in his '89.

As far as I've been able to determine, the change occurred with the '83 model year. So, the early LSD's are from '78 through '82. The later LSD's are from model years '83 through '89.

928 Int'l sold the the LSD I now have for installation in an '85. So, it should be a direct fit for model years '83 through '85. According to Bill, it will also fit model years '86 through '89. To fit an '83 through '85 LSD to an '86 through '89 tranny, however, you will also need the rear differential cover from an '83 through '85 because the location of the speedo sending unit is different on the '86 through '89 model years.

Apparently, the '83 on model year LSD will not work with the '78 through '82 tranny.

Bottom line is that I now have a LSD that should fit an '83 through '89, but won't work in my '82. So, if anyone is looking for a LSD for a '83 through '89, I've got one that is "excess to my needs."

Here is link to Bill's thread on installing the '83 LSD in his '89: https://rennlist.com/forums/928-foru...fferences.html

If anyone spots any errors in the above, please feel free to correct me....

James

 

Find the correct offset limited slip that fits your ring gear. That whole "spacer under the ring gear" thing is very, very crude.

DO NOT machine the stub axle (flange).....it will break! The flange is hard and getting the radius cut correctly so that there isn't a stress riser at the dimension change is almost impossible....unless it is ground by someone who knows how to grind a perfect radius. And even if that happens, the cross section of the flange gets too thin.

Don't be too concerned about if the limited slip has two friction discs (one on each side) or two friction discs (two on each side)......I'll guarantee that there isn't a single person here that could tell the difference driving the two or have it show up in their lap times.

 

James correctly quotes my understanding and experience. For some reason Carl appears to have the wrong MY change information. 78-82 LSD only fits a 78-82 case. 83-89 LSD fits any 83-89, with the only issue being the placement of the speedometer magnetic ring and sensor, which changed in 86. To my knowledge this latter information had not been previously documented.

https://rennlist.com/forums/928-foru...fferences.html

This can be resolved by getting the rear diff cover that matches the MY range (either 83-85 or 86-89) for the LSD.