What the hell is this crap?!? (10-bolt problem)

**jcws6** · 05-15-2009, 05:00 AM

Alright, guys. Here's the deal:

Last summer/fall, I had my rear rebuilt with Motive Performance 4.10s. I did half of it, ended up hurting my hand, got frustrated, and had a performance shop finish the rest of the build. Everything was fine.

A couple days later, it started leaking fluid from the pinion seal (I used the one in the Ratech rebuild kit). I took it to a mechanic, because I didn't want to F with it. They tried two different seals before saying they didn't know how to stop it from leaking (awesome mechanics, here). I told them to put an OEM seal in. Didn't leak a drop after.

The Trans Am was in storage all winter. I brought it out and started driving it. A week or two later, the rear started making an absolutely horrible sound, and it would tend to lock up a bit at low speeds. Pretty scary shit. It also seemed to be leaking fluid again.

So, I assumed the worst and just put a used rear in the car. 11 hours of fun, right there. The pinion yoke had a LOT of play, so the nut must've backed off or something. After taking the cover off the used rear, I found this: http://i42.tinypic.com/uptub.jpg

So, here are my questions:

1. What the hell happened here? How did the marks get on the carrier? Any theories welcome.

2. Is this rear salvageable? Everything inside looked perfectly fine - even the pinion gear. Aside from the play in the yoke and the marks on the carrier, I couldn't tell anything was wrong.

3. Right now, I have the tendency to blame the dipshit mechanics who put in the last pinion seal, for not tightening the nut well enough. I have a solid pinion spacer, so I told them the exact torque to tighen the nut to. Am I justified here?

Any thoughts/comments/answers are appreciated.

**1998 T/A** · 05-15-2009, 12:34 PM

posi unit blew up?? thats what happened to me, loud as banging noise and then opened the rear end up and sure enough a bunch of shit fell out

**jcws6** · 05-15-2009, 02:55 PM

Definitely wasn't the posi unit. I drained the fluid & tipped the assembly over - nothing came out. I also spun the axles a bit, to make sure nothing was loose or rattling. When the carrier was rotating, all of the innards looked completely fine.

**Smittro** · 05-15-2009, 03:06 PM

Wow that's about the stangest thing I ever saw. Let us know what you find out. I never saw anything like that. Very curious. I was thinking these were for moveing the gear oil around. Nut hell if I know man. Wow! Never saw one machined in that way. At least it looks like they are machined in to it. again WOW.

**Th3unwant3d1** · 05-15-2009, 03:13 PM

your pinion gear is hitting the carrier. same thing that was happening to mine. Mine isnt nearly as bad as yours but you may need to replace the pinion gear. The carrier should be ok...looks like that happened because the crush sleeve was tightened waaaaay to much. or was put on wrong for that matter lol. I hope that helps.

Im in the same boat you are, had my rearend rebuilt going on 4 now.....

**Z28Thunder** · 05-15-2009, 04:50 PM

Originally Posted by Th3unwant3d1

your pinion gear is hitting the carrier. same thing that was happening to mine. Mine isnt nearly as bad as yours but you may need to replace the pinion gear. The carrier should be ok...looks like that happened because the crush sleeve was tightened waaaaay to much. or was put on wrong for that matter lol. I hope that helps.

Im in the same boat you are, had my rearend rebuilt going on 4 now.....

It is the pinion hitting the carrier. The carrier might be fine but I would not use it. Why not go 12 bolt or 9 inch.. I know alot here say go 9 and be done with it. I have a 12 bolt and no issues...

**1998 T/A** · 05-15-2009, 04:51 PM

M6 or A4?? My posi unit blew the fuck up and my ring and pinion shattered and we pushed it about a block with no trouble, axles spun fine; strange as fuck

**jcws6** · 05-15-2009, 05:29 PM

The car's a M6, and the pinion had a solid spacer (i.e. no crush sleeve). Everything was spec'ed by the book, since I'm a stickler for details. Either way, thanks for confirming my suspicions, guys.

I hoped to put a 9-inch in the car this fall, but I needed it streetable ASAP. Some dumbass blew a stop sign and totaled my Blazer, so the T/A is my only vehicle for the time being. I still plan on going back to the mechanic who changed the seal & asking how they're going to correct this problem.

Anyway, since I'm left with the old 10-bolt, I'll probably throw it up on the classifieds here as a "rebuild or for parts" unit.

Thanks again, fellas.

**Firebirdjones** · 05-15-2009, 06:01 PM

When ever the pinion seal needs changed it extremely important to get the proper crush again on the pinion bearings. If not,,either the pinion will move around and the seal cannot do it's job,,,or the pinion bearing will eat itself up and take the seal with it.
I'm not a fan at all of the solid pinion spacers. Prefer the crush sleeve all the way. You need roughly 25-35 inch pounds of rotational torque on new pinion bearings,,,and about 10-15 inch pounds on used bearings. Something you cannot check for unless the carrier is removed from the housing. So you have to do it a little differently on a completely assembled rear.

To get the proper crush on the bearing again, utilizing the crush sleeve, you have to start by marking where the nut is in relation to the pinion before it is removed. A simple chisel mark or scribe will do.

When putting it back together not only does the seal control the leaking, but you also need to install sealant on the pinion splines before you slide the yoke on. Those splines will also seep gear oil and you will see the nut getting wet eventually. Then when you tighten the nut, going until all play is removed from the pinion,,,then line up the marks you made with the nut and pinion,,,from there tighten the nut about 1/8 inch past your mark to keep proper preload on the pinion bearings.
The last thing to do,,,especially if re-using the old nut,,,is to peen the head of the nut with a punch into the pinion gear so it cannot spin easily.
These pinion nuts are crush type locking nuts,,,after running them on and off 1-2 times they just don't have the holding power they once had. So it's necessary to peen the nut for extra safety measure.
I generally just prefer to use a new nut anytime that has to come off.

Now as for that posi unit,,,I would NOT re-use that at all. All those ground marks are from the pinion gear. Those sharp edges create stress risers and eventually cracks,,,and you will find that posi unit will come apart with some extreme use. I've broken perfect 7.5 inch posi units into 3 huge pieces. They are not strong.

A good Eaton unit will set ya back $400 at least, another ring and pinion and setup kit is another $300 or so. I guess you have to ask yourself if it's worth the expense or put the money toward something stronger.

**1998 T/A** · 05-15-2009, 08:44 PM

Cleveland-Pick-A-Part man im getting a rear end off them with a 3 month warranty with 3.73's for 250 bucks, pickin it up on monday...better than buying a posi unit, 500 from summit, and ring and pinion 300 from summit. i'll get my car back on the road and when shes in the garage this winter i'll save towards a 12 bolt

**jcws6** · 05-15-2009, 09:01 PM

Originally Posted by Firebirdjones

When ever the pinion seal needs changed it extremely important to get the proper crush again on the pinion bearings. If not,,either the pinion will move around and the seal cannot do it's job,,,or the pinion bearing will eat itself up and take the seal with it.
I'm not a fan at all of the solid pinion spacers. Prefer the crush sleeve all the way. You need roughly 25-35 inch pounds of rotational torque on new pinion bearings,,,and about 10-15 inch pounds on used bearings. Something you cannot check for unless the carrier is removed from the housing. So you have to do it a little differently on a completely assembled rear.

To get the proper crush on the bearing again, utilizing the crush sleeve, you have to start by marking where the nut is in relation to the pinion before it is removed. A simple chisel mark or scribe will do.

When putting it back together not only does the seal control the leaking, but you also need to install sealant on the pinion splines before you slide the yoke on. Those splines will also seep gear oil and you will see the nut getting wet eventually. Then when you tighten the nut, going until all play is removed from the pinion,,,then line up the marks you made with the nut and pinion,,,from there tighten the nut about 1/8 inch past your mark to keep proper preload on the pinion bearings.
The last thing to do,,,especially if re-using the old nut,,,is to peen the head of the nut with a punch into the pinion gear so it cannot spin easily.
These pinion nuts are crush type locking nuts,,,after running them on and off 1-2 times they just don't have the holding power they once had. So it's necessary to peen the nut for extra safety measure.
I generally just prefer to use a new nut anytime that has to come off.

Now as for that posi unit,,,I would NOT re-use that at all. All those ground marks are from the pinion gear. Those sharp edges create stress risers and eventually cracks,,,and you will find that posi unit will come apart with some extreme use. I've broken perfect 7.5 inch posi units into 3 huge pieces. They are not strong.

A good Eaton unit will set ya back $400 at least, another ring and pinion and setup kit is another $300 or so. I guess you have to ask yourself if it's worth the expense or put the money toward something stronger.

Yeah, I know how to do it. This wasn't my first rebuild. However, the aforementioned mechanics who replaced the seal apparently didn't.

**jcws6** · 05-15-2009, 09:05 PM

Originally Posted by 1998 T/A

Cleveland-Pick-A-Part man im getting a rear end off them with a 3 month warranty with 3.73's for 250 bucks, pickin it up on monday...better than buying a posi unit, 500 from summit, and ring and pinion 300 from summit. i'll get my car back on the road and when shes in the garage this winter i'll save towards a 12 bolt

You lucky SOB! I paid about $265 for the 3.43 rear I ended up putting in. Great place, though.

**thearborbarber** · 05-16-2009, 12:21 AM

Originally Posted by 1998 T/A

Cleveland-Pick-A-Part man im getting a rear end off them with a 3 month warranty with 3.73's for 250 bucks, pickin it up on monday...better than buying a posi unit, 500 from summit, and ring and pinion 300 from summit. i'll get my car back on the road and when shes in the garage this winter i'll save towards a 12 bolt

I bought one from these folks as well. Top notch.

**Th3unwant3d1** · 05-18-2009, 03:23 PM

yea, after my rearend problems im saving for a s60, like the specs on them

**jcws6** · 05-19-2009, 08:38 PM

Originally Posted by Th3unwant3d1

yea, after my rearend problems im saving for a s60, like the specs on them

Whether it's a 12-bolt, 9-inch, or S60, I CANNOT stress upgrading the rear on this car enough. In the past 8 years or so, I've broken FIVE GM 10-bolts (2 in my Trans Am, 2 in a GMC Jimmy, 1 in a 3rd gen Formula).

The only reason I rebuilt the damn rear of the T/A was because I thought I could do it fairly cheaply (it only needed new gears) & get another year out of it, so I could spend the rear end money on some other mods. Complications and the mechanic who apparently ended up fucking up the rear made this a pretty worthless investment in time and money.