Determine Posi / Limited Slip

[Low_Bridge]

I'm looking at a 1996 Chevrolet Silverado 1500 6.5, 4l80e & 2 wheel drive.

Besides jacking the vehicle up what's the best way to determine if it's posi or limited slip.

Thanks! This purchase may put me back on board the page....

As always thanks

[JohnC]

(All from memory...) If it's stock, it will be neither. Look for the G80 option code, which is the Eaton locking differential. It will present as an open differential until the wheel speeds between the two rear wheels is sufficient to cause it to lock. The easiest way to confirm is to put one rear wheel on loose gravel and the other on dry pavement and stomp on it. If you get a chirp and some rubber off the one on dry pavement it's a locker.

I recall you can make it lock by jacking the rear and spinning one wheel (backwards?) while holding the other one, but I could be wrong.

[Low_Bridge]

G80 in vin or? are they sometimes tagged? (the dif?)

[a5150nut]

G80 in vin or? are they sometimes tagged? (the dif?)

Look on the door to the glove box. If its still there will be a build list of how the truck came from factory. Or find site or dealer that will run the vin for you.

[Low_Bridge]

well I bit the bullet & back on board

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[arveetek]

Nice looking truck! Welcome back!

Casey

[More Power]

... The easiest way to confirm is to put one rear wheel on loose gravel and the other on dry pavement and stomp on it. If you get a chirp and some rubber off the one on dry pavement it's a locker....

I know it's possible that a G80 equipped GM pickup - when stuck in snow/ice, and when an impatient driver spins the tires to an excess - that the resulting significant differential wheelspin can cause the G80 to lock with such force that it shatters the G80's friction disks and other components inside the differential. There is a governor of sorts on the G80 locking mechanism that is supposed to prevent locking when the vehicle is traveling above about 20-mph. This automatic feature isn't perfect and can allow locking in situations like what is described here (i.e. stuck, vehicle not moving).

My advice, be gentle... Try to avoid the expense of replacing the rear differential, along with a new ring & pinion set, carrier bearings, wheel bearings, and all seals - as well as having the truck laid up for weeks. It's amazing how quickly the insides of a rear axle can be turned into mush.

As a sidebar. My Lil Red truck's 9-½" semi-float rear axle is equipped with an Eaton posi, which is similar to the G80 locker (friction plates). This rear differential has taken >630hp/1200tq without complaint many times, but I always powerbraked the truck to gently ease the diff into lockup before applying the full load. Jim

[JohnC]

Yeah, I suppose "stomp on it" was bad advice... I've heard stories like that, too. Never had a problem with the three trucks I had that had the G80 option, though.

I did once get stuck with the C2500. Figured it wasn't locking. I actually got out and walked around the truck and observed both rear wheels slowly turning in the muck.

[arveetek]

I've got 370K on my G80. I'm pretty sure the axle is all original other than brakes and seals. I have changed the diff fluid multiple times, though, and never romp on it. I think the G80 gets an undeserved bad rap from folks who abuse it.

Casey