Hey,

My car has limited slip rear. Today, a friend of mine really seriously pissed me off so as I was leaving, I nailed the gas the hardest I've ever done. It actually lit up the tires for a good 20 feet. However, there is only one friggin black mark. I cannot find the second one either because it is marked too light and it's too dark outside or its not there at all...

Can posi every once in a while slip and let one wheel spin. Or did I just lose it? My tires are somewhat low, but no where near bald. They have reached the low-tread mark.

I think I'll test it tommorow by doing a short break stand and seeing if they both turn. Just wanted some info though...

Humvee

 

Yes a posi can wear out and start letting one wheel loose. The factory posi works by clutches that keep the 2 axles from slipping too much relative to each other. Over time, those clutches wear down and the wheels can slip more, with the other not moving.

 

I see... so that means my rear end is starting to wear down. Do you think rebuilding it would be a good idea or just get a new rear end? Keep in mind I do not have thousands of dollars to blow away... And when the posi does finally quit, is it still okay to drive around like that or further damage may result?

 

It's possible, if the clutches get worn really bad, for the c clips to fall out and let an axle come out of the housing. You can check how badly they are worn by jacking up a rear tire and pushing the axle in and out. Normal play is 0 to 1/4 inch. Around 1/2 inch or more is getting dangerous.

 

i did the same thing you did about 5 months ago and the car still drives fine. now i ordered a new posi unit and i just have to install it.

 

i think our 7.5 inch rears have the gov-loc posi. this is different from the older clutch setup, it senses wheel spin and slams a little "pin" which locks the wheels. they are crap and break because one wheel has to spin before it locks, meaning that "pin" gets a lot of stress. i'm pretty sure this is correct for the 7.5 at least.

 

Funny you mention the locker rear, thats what i have in mine (for now)

Actually, the factory posi in most thirdgens was an auburn clutch style. There was a period in the 84-85 span that they ran low on those so they substituted the eaton gov-loks from the S10 pickups (that also run the same rear and 3-series gears.)

This is what it looks like: http://home1.gte.net/res0t8sj/misc/eatonlocker.jpg

Anyhow, these things have a serious reputation for shattering, do a search on this forum for 'eaton locker'. Thats why mine is temporary. I have a torsen to go in w/ my old 28 spline axles.

ps. the auburn clutch style posis are non-rebuildable, you just replace it. 9 bolts posis can be rebuilt though.

 

Man i used to have an '86 Cutlass & dropped in a 3.73 & carrier from an S10 truck. I have the carrier here.....its split right in half.

It was only a mild 355 too!

 

if it is a limited slip as you say it is, then from the gm training book that i got while in school in 2001-02 this is what it says
"If the drive pinion-to-ring gear torque is too high, the forces compressing the clutch packs will be overcome. In this situation, the clutch packs slip." in other words if you were torquing the hell out(obviously you were) then yes its normal for this slip to occur.