[Born Too Loose]

I've got a 10-bolt GM with 4:10 gears and an Eaton posi unit. It has 35 spline axles. All supposedly in good condition. I have a receipt for a total rebuild (all the parts mentioned) from a reputable shop but they're no help. It has the additive specifically for posi units.

I just got the car on the road about a month ago. What's happening is that when I take it out, it starts off fine, but after driving around for a while I can hear loud snapping or grabbing and releasing sounds coming from the rear end. It's loud and nothing like the sounds some posi's make when turning.

It starts after about 45 minutes of easy city driving and sounds like it's not going to hold together much longer. It's very noticeable. I can hear it best when backing up or turning. But it only does it after driving it a bit. Even with the noises, it seems to run fine.

If it's worn out or broken why doesn't it make noises from the very get go. I can't see the gear oil breaking down but....heck, I don't know. Money's short right now and I don't want to take it in to a shop. I want to sell the car but I can't sell it like this. New posi in my future?

But shouldn't mine make noise all the time and have some symptoms of not working well? Somebody please school this boy.............

[gearheadslife]

eaton posi with 35 spline?

[Born Too Loose]

Well why not just tell me. I don't know. I know many things you don't. Tell me the problem so I can fix it. Sheesh.

[poncho62]

Probably is the posi unit making noise...Take the cover off and have a look at it.......I would change the gear oil, put a good quality posi fluid in it.....If it still makes noise, then off to a shop

[prostreet6t9]

Grab ya a couple bottles of the ford motorsports additive Part#43161.

Sounds like the posi is chattering.

Your posi is a 28 or 30 spline. But either way put some additive in it and do some figure eight's to get it worked in.

[big gear head]

You don't have 35 spline axles. At most you have 30 splines. You can get 35 spline axles with a spool, but the 8.5 10 bolt Eaton Posi is either 28 or 30 spline.

Change the oil. Use a good brand name 80W90 gear oil and a bottle of GM or Ford limited slip oil additive. Drive it around for a while and it should get better as you drive. While you have the cover off check for anything that doesn't look right, especially pieces in the bottom of the housing.

[gearheadslife]

Originally Posted by Born Too Loose

Well why not just tell me. I don't know. I know many things you don't. Tell me the problem so I can fix it. Sheesh.

Sir, we need correct info, to be able to HELP you..

[prostreet6t9]

Originally Posted by gearheadslife

Sir, we need correct info, to be able to HELP you..

Really don't matter what the spline count is. All the Eaton posi's are built the same but just have different side gears.

[vinniekq2]

when my 12 bolt chattered real bad,we took out the clutches and shims and shuffled them and putit back together without the rat trap.We used 2 bottles of additive. if you take it apart,take a real close look at the spider gears

[prostreet6t9]

[QUOTE=Born Too Loose;1615745].

I just got the car on the road about a month ago. What's happening is that when I take it out, it starts off fine, but after driving around for a while I can hear loud snapping or grabbing and releasing sounds coming from the rear end. It's loud and nothing like the sounds some posi's make when turning.

That statement is a common complaint with a new posi and chattering.

What brand of oil and additive did you use?

[Born Too Loose]

OK thanks guys. I bought the gear oil and additive at a NAPA store. Can't remember the names. I'll pull the cover and see what shakes then refill it and do some figure 8's. Been riding stroker Harleys most of my life (I'm 66). Them, I know. Cages? Not so much. Thanks again and Peace.

[gearheadslife]

Originally Posted by prostreet6t9

Really don't matter what the spline count is. All the Eaton posi's are built the same but just have different side gears.

ya it does... 35 spline could be a locker or spool.. giving info "thinking its a eaton posi" won't help much..

[big gear head]

If you bought the oil additive at a auto parts store then that is where your problem is. Only the GM and Ford (possibly Chrysler too) additives work. The junk that the auto parts stores sell is no good.

[prostreet6t9]

Originally Posted by gearheadslife

ya it does... 35 spline could be a locker or spool.. giving info "thinking its a eaton posi" won't help much..

"I've got a 10-bolt GM with 4:10 gears and an Eaton posi unit. It has 35 spline axles.

I don't see the word "thinking" lol

Needless to say I'm sure it will fix the Op's problem with the info he gave.