The posi in my Roadmaster is a GM Auburn-style limited slip, which uses a conical surface on the back side of the spider gears to fit into the "cup" which is built into the carrier. There are no clutch packs or shims, and the unit is generally deemed "unrebuildable" once the cones and/or cup have worn too far.
In the spirit of the Challenge (and my pocketbook) I'd like to think some other crazy guy has figured out a fix. Shimming the springs for extra preload? Machining a conical "clutch" to slip between the cones and cup? Just weld the sucker? I'm open to the usual assortment of shade tree advice.
On the cone type mopar sure grips, you could machine one end of the cone and shim the springs.
May be something to look into. May also be completely irrelevant.
Yep, machine the small end of the cones then add shims on the other side. I did this on my Borg Warner 9-bolt.
The Auburn-type in my 96 Impala SS was trashed. No hope. No meat there to re-machine. I explored several options before taking it to the scrap yard and bought a Quaiffe type.
Let me know if you find a logical way to rebuild it, but thousands of us SS guys ask this question on forums daily, and the answer is always "chuck it."
Then again, they are not members of the GRM elite. If there is hope for that diff, it will come from a group like this.
Ive seen one done using the machine and shims but it didnt survive much before it was back to mostly open. 3 weekends of drag racing in an s10.
find an Eaton posi and swap it in. should be easy enough to find one for an 8.5 since GM put millions of them in cars and trucks for about a quarter of a century... or put an open diff in it and get one of those locker setups that replaces the spider gears...
The problem with the B-body's is the 30-spline axles. You can find 28-spline posis on craigslist all day, but the only 30-spline stuff is the gov-lock trash in the late model Chevy trucks.
The car actually has an open 2.56 (series II), but I just picked up this 2.93 (series III) from the yard last week. I'm not confident it will actually lock up, so I'm planning for the worst.
44Dwarf
UltraDork
11/2/15 11:53 a.m.
Why is no one making a Cupped shim to put in the cone area? If you build up the surface and grind it back in to spec it would work like new. but that takes time and a good welder / machine shop unless you're both it would be cheaper to replace. :(
maschinenbau wrote:
The problem with the B-body's is the 30-spline axles. You can find 28-spline posis on craigslist all day, but the only 30-spline stuff is the gov-lock trash in the late model Chevy trucks.
The car actually has an open 2.56 (series II), but I just picked up this 2.93 (series III) from the yard last week. I'm not confident it will actually lock up, so I'm planning for the worst.
i've put some serious abuse thru 28 spline 8.5's before. the 2 extra splines won't make or break the overall package. i believe axles from an 89 and older Caprice with the HD suspension (cop car, etc) use the same length axles with the same bolt pattern but with 28 splines instead of 30- if not, the whole housing bolts right in- so it might be a worthwhile swap to just go "backwards" to get a better differential design.
