Limited Slip/Posi Conversion

[The Lowly Genteman]

I managed to find an Auburn style posi out of a 90s Caprice cop car in the junkyard and it was a direct swap in my 8.5" 10 bolt. I kept my existing ring and pinion and was able to perform the whole swap on the cheap relatively. The downside is those units are not rebuildable so you just have to hope you find one that isn't too worn out.

 

[Schurkey]

What do you think of the gov-lock itself? I had one in my Yukon with correct lube and it only worked when it felt like it, never when I really needed it, and I was always scared it was going to explode. Is that mainly an 8.5" thing?

I'm not "thrilled" with the 9.5 Gov-Lock. It was abrupt when it engaged, even just going around corners. It softened-up some as I put miles on it. It had been parked for some unknown amount of time before I bought it.

Are you aware if the 2018 Silverado LT featured the g80 govlock for the limited slip differential? Those seem to work pretty well when they are new.

Don't know a thing about them.

However mechanically locking differentials, such as the automatic G80 locker are better off-road in slippery terrain IMO.
I reckon a swap to a G80 axle would satisfy in this situation.

The Gov-Lock is a clutch-type, but with a speed-governed control mechanism.

I managed to find an Auburn style posi out of a 90s Caprice cop car in the junkyard and it was a direct swap in my 8.5" 10 bolt. I kept my existing ring and pinion and was able to perform the whole swap on the cheap relatively.

Beware of the number of axle splines vs. spider gear splines. GM made the 8.5" ring gear pickup truck axles bigger (from 28 spline to 30 spline???) in or around 1989.

Perhaps they did the same thing with the car axles. I don't know.

 

[Hipster]

I managed to find an Auburn style posi out of a 90s Caprice cop car in the junkyard and it was a direct swap in my 8.5" 10 bolt. I kept my existing ring and pinion and was able to perform the whole swap on the cheap relatively. The downside is those units are not rebuildable so you just have to hope you find one that isn't too worn out.

The Auburn cone-type style can be freshened but you need to think outside the box because service parts are not available. When they go bad it's because the face of the cones have bottomed out in the case and the sides of the cones no longer grip. Disassemble, machine .050-.060 off the outboard side of the cones, shim the gear side correspondingly with what is a non-rollerized cam thrust washer as they are hardened material(My Mopar literature is packed away for the time being or I might be able to provide a part#). Some guys will put the cones on lathes, or mill, and others have ghetto grinded them. It's not a critical surface you just need to make some room so the cone is not bottomed out in the case. The trick is upon reassembly. You need an axle in both sides to line up the up the inner and outer splines on each side as you're putting the case halves back together.

You won't find this information in any service manual anywhere but the Mopar guys have figured out the supposedly non-rebuildable Auburn limited slip a couple of decades ago. They call them Sure-Grips but it's an Auburn unit none the less. You're not going to rebuild the same one 5 times this way but it will extend it's useable lifespan at least one more time for the cost of a few shims and some minor machine work.

 

[Anubis]

I agree with the comment made earlier regarding street manners and that a clutch style limited slip carrier would suit the OP well. A few of you have mentioned Auburn which in the drag racing world have a bad reputation. I however have two Auburn units that have worked flawlessly but if I had to buy a new carrier would go with an Eaton. If you’re keeping the same gear ratio, installing a posi carrier yourself isn’t a big job. you can do it for well under $700.

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[Schurkey]

If you’re keeping the same gears, so that you don't replace or disturb the pinion gear, installing a posi carrier yourself isn’t a big job.

FIFY.

 

[TechNova]

my 89 has the carrier out of my 09 truck. A few speclal bearings made it fit.
A few of my cars have the Eaton unit and have been great.