ReactiveSS

Here are the details, car now has 80,000 miles. The first upgrade I made to it was to install 4:10 gears at only 4,000 miles. Never really had any issues except the pinion seal did leak but very little. Recently started making a loud crunching noise, with car upon jack stands the noise is persistent while in any gear. Slide it into neutral or press the clutch and the noise stops. Also (still on jacks) with car in gear I can stop one tire or the other and you can feel the crunch, I also held a hollow rod up against the rear end and you clearly hear the crunching. By the way the fluid smelled sour, car has never been in any deep water and is shopped when not driven.

When I rotate one wheel the other wheel rotates in the opposite direction, what type of rear end do I have and any additional information on a rebuild will be appreciated.

2MuchRiceMakesMeSick

Thats a POSI differential.
The spider gears cause the other wheel to rotate in the other direction.
Rear end oil smells really bad so thats pretty normal.

The best advice I can give you is to save up for a 9" and try not to sink a lot into the stocker.

blue01ta

iTrader: (4)

^ that's right. You made it a long ways with 4:10s in there. A lot of 10 bolts running those gears don't last that long.

ReactiveSS

Thanks for the replies, my real question is with the wheels rotating in opposite direction is this an auburn or torsen unit. Because this issue just started I feel I have caught it very early so I plan to repair the thing if rebuildable. It sounds like a bearing has gone but I'll break it down as soon as I can. What are my options if all looks good to go and all I need to do install new bearings and seals?

ReactiveSS

Update, I pulled the rear end cover and laying there was two teeth from the ring gear. On the end of the pinion gear I could read these numbers 26014589-10-41 GM 7-5/8. The 7-5/8 may be an error it wasn’t stamped as deep as the other numbers. The teeth wear on the ring and what I could see of pinion looked great and there was very little sludge buildup on the magnet.

I’ve been running the 4:10 for sometime now but I still have the stock 3:42 with maybe 4,000 miles on them. What will I need to rebuild this on a budget, what bearings would need to be replaced if not all of them? Thought I would use the solid crush ring if this won’t cause any issues.

BTW: I have access to a new set of 4:30, I really loved the 4:10 and I don’t plan to do much if any track runs but on the street would the 4:30 be advisable? Car is a M6 with DR’s now and the motor is a bolt on only, maybe 350 hp.

Thanks again

JasonWW

iTrader: (2)

I want to know, too.

FUN LS1

You need at least the kit with the extra carrier bearings and pinion bearing, plus lots of shims for when you can't get the stock spacers back in on both sides. If the carriers bearings are bad, the hardest part about replacing them is getting them off the differential. We used a torch to heat 'em.

[EDIT] pic of removing carrier bearing

ReactiveSS

Update: I've bought one of the 10 bolt gear packages from one of the site sponsors. Choose to go back with the 4:10's, the package comes with pinion bearings, seals and carrier bearing, seals and shims needed. also has the TA gridle with stud kit. I plan to replace the wheel bearing seals but not the wheel bearings as thier appear to be good.
I purchased the crush sleeve shim kit too, but I'm not really sure how to set up this crush shim spacer. Any help would be great, I'm sure I can figure it out but I'll take any help.
I think I'm going to order the Ploy Urethane Bushing kits and replace all the old rubber bushing. I have been looking at the LCR's and Torque Arm and I feel that I can box these in and beef up the suspension. I've been working with metal and pipe fabrication for years so I have the experience to do a very clean job, might add just a bit of weight but if it stops the wheel hop it will be worth it. I feel like wheel hop ids what got the rear end to start with.

FUN LS1

The LCRs and TA will help with the wheel hop... See if you can find some hybrid rubber bushings (instead of just going with all polyu.) if you want to keep the ride smooth and quiet...