Fweasel

iTrader: (6)

Is that the one on craigslist in Logan Square? He's had that listed for quite a while now, would imagine there's room to negotiate, but I didn't know it was a whiner.

voodoochikin04

iTrader: (3)

I picked up a brand new 1st gen diff for $250 shipped. To replace my medium noise 1st gen diff when it fails. I hear you about not wanting to spend the dollars and doing things yourself when you can. That's what I do too! Also our local hardware and farm stores sell those clamshell bearing separaters. Maybe check thatdirection.

Gus_Mahn

iTrader: (1)

Yes that's the one. He said there was whining but that he had bushings, so he wasn't sure if it was the diff or the us bushings causing the noise. At this point, it's not worth the gamble to me.

AAIIIC

iTrader: (19)

So, I stand corrected - I finally remembered to look at the Service Manual and there is a procedure to rebuild the diff. I swear I had looked before and didn't find anything.

As Gus said, there are a bunch of special tools called out. I didn't look at the procedure all that closely to see if a shop could get by without all the special tools. It's definitely different than a "typical" diff rebuild (like for the 8.8" in my Mustang or the R160 in my Subaru). Makes me wonder if the reason Cadillac says they're not serviceable is that over time they decided the cost of all of the tools (at every dealership) + the hours of labor required to properly set up the diff just wasn't worth it, that it was more economical for them to just swap out the whole diff. I dunno.

I've looked all over here and on cf.com and haven't found this mythical rebuild thread. I found one thread on cf.com that mentioned another thread, but haven't been able to find that other thread. I even had the username of the guy who had started the thread, and still couldn't find it. If you can find it and share with the rest of us who don't have the benefit of your enlightenment, please do.

As for ordering the parts from the dealer...


According to parts.nalleygmc.com, the pinion shims (#6 in the diagram) are 89048209 (1.30mm) - 89048221 (1.90mm) in 0.05mm increments. The carrier bearing shims (#16) are 89058621 (1.30mm) - 89058643 (2.40mm) in 0.05mm increments.

It's not like people just randomly decided the diff was unserviceable. I've been on the forums for years and have seen ****-tons of threads about diff replacements; up until very recently I had never seen one about a diff rebuild (and even the one I saw recently wasn't an actual rebuild - it was just a guy taking the guts out of one housing and putting them into another. No shim measurements, no backlash checks, just bolt it in and hope it's good). When I had my diff replaced at Lindsay Cadillac, probably the most mod-friendly dealership on the East Coast, Luke the parts guy said he could only order the entire diff assembly. I've gotten a lot of parts from Luke and he's never steered me wrong. I talked to a race shop that built a diff for a SCCA T2 race effort and they said they had to buy parts (at great expense) directly from Getrag, that they couldn't get the parts from the dealer.

I would think the obvious answer is that you can do a proper rebuild of the stock diff for hundreds of dollars vs spending hundreds on a used diff and just hoping that it isn't as noisy as the one you're replacing vs spending thousands on an 8.8" swap. Of course, if you don't have the skills or tools to rebuild the stock diff (as is the case for me), then that's all a moot point.

voodoochikin04

iTrader: (3)

I recently helped another member get all the parts he needed to fix his stock diff. The carrier bearings, thrust washers, LSD clutch disks....all available. My dealer could order any of the part numbers. I don't see why it would be any different setting it up than ANY other diff... Use gear marker to figure your tooth engagement and set your back lash. Measure the stock preload shims and determine if you wanna stick with that or adjust. Its not some magical rrear end. Damn

voodoochikin04

iTrader: (3)

How do you figure hundreds of dollars to purchase some $8 shims, $20 bearings, some seals and elbow power. Cmon.

54inches

iTrader: (4)

so much fail.....

Whitten

iTrader: (1)

I purchased my 04 last December as well as an aftermarket warranty to go with it and within a month of owning the car and not driving it hard one time it was in the shop for a few smaller items. While in the shop the maintenance super came to me and asked me to take a ride with him in my car. He asked me if I had been hearing my rear end whine and pointed out the sound to me. To be honest I had totally missed the sound but at his pointing it out I realized that the rear-end was giving me the signs that it was on its way to needing some help. The supervisor told me that he was going to submit it to my warranty company to be replaced since it was covered. The warranty company responded by telling me that they would pay to have it rebuilt but not replaced. The Cadillac dealership I had it at responded that they would rebuild it and charge full book labor to do it. The warranty company responded by finding a used diff out of a junk yard car and sending it to the dealership to swap. I received a call from the supervisor the day the junk yard diff arrived and was met by him laughing his *** off because they had sent a diff out of a 03 v6 cts. He called the warranty company and told them they could either pay the price to rebuild my original or buy a brand new diff. I have a brand new diff, drive shafts, and bushings now... I guess the new diff is cheaper than what is on the shop manuals for rebuild or service.

voodoochikin04

iTrader: (3)

Sure if youre paying for labor....


54... What's your deal. Always some worthless piece of **** remark from you on my posts.

54inches

iTrader: (4)

aaaaaannnnnnndddd Scene....can we close this thread now or am I going to have to start calling people names and get banned for 7 days? lol

voodoochikin04

iTrader: (3)

You guys can replace your diff's all you want... And blindly state how its more cost effective for this or that...

But the fact remains you can adjust the gear mesh, the backlash, and the preload on these diff's without spending hundreds of dollars. You can also replace internals that maybe break for minimal costs. Like replacing a differential carrier bearing for $20 and your own labor.... Even the extent of jeph54's diff damage it was WAY cheaper than buying even a used diff.

54inches

iTrader: (4)

lol.....all the water in the ocean will never wash away the pride of this one......

AAIIIC

iTrader: (19)

Which is great to hear, but that was not possible for a number of years.

Don't see why it would be different? Have you looked at how the diff is assembled? Yes, the goal is to set the tooth engagement and backlash, just the same as any other diff. But the procedure is very different than it is for a "typical" diff that goes together from the rear instead of from one side. I don't have the tools to do it, nor am I confident that I could do the procedure correctly, so yeah, it would cost hundreds of dollars because I would be paying a shop to do it.

isis

iTrader: (1)

Not an expert on differentials but that exploded diagram makes it look like you would need to completely disassemble every damn piece to adjust any shims. Seems like it would be a lot of time just to disassemble and organize, and then put it together once let alone 2-3 times. Plus unless you buy quite a few shims upfront, it may take a few trips to the dealer. Or if you're like me and work when they are open, you have to wait and order online. It sounds like a pain in the ***. I thought they were like 1200 online tho? Am I imagining that? That's the mental budget I made for whenever it happens to me, so I must've seen it somewhere.

Crap. http://www.gmpartsdirect.com 1484+ shipping.

Gus_Mahn

iTrader: (1)

The car is together and drives fine, but one ring gear tooth had a little damage on the coast side of the tooth. I cookied it out the best I could, but there is a slight thump on coast between 20-40mph. I'll live with it until I can assemble a 3.91 assembly. I made it almost 100,000 miles on a generation 1 diff. I don't do burnouts or speed shift 1-2, or dragrace the car, so I'm not too worried about durability.

Really it's a pretty simple differential. No gaskets, it's all o-rings. Reuse the pinion bearing preload shim that came with the pinion assembly. The pinion assembly is easy to remove to change the shim that sets pinion depth. The only hangup is the carrier shims are behind the races in the housing, and a special tool is required to pull the races to adjust the backlash/carrier bearing preload, which I'd just set by feel.

There're none listed right now, but there were new OE surplus diff assemblies on eBay, and I was offered one for $260 shipped after putting it on my watch list. The 3.91 will create a 4.6% speedo error which is easy to live with or tune out.

voodoochikin04

iTrader: (3)

See it wasn't that bad. Yet all these guys tell you its a waste of time. Ha.

stratass

Good job!

bmylez

iTrader: (3)

I thought the speed sensors were part of the ABS sensors and therefore are unaffected by rear end changes?

handyandy496

iTrader: (9)

Wow this club has a lot of whining members

Gus_Mahn

iTrader: (1)

I guess that might be the way it works, and I hope so. I never really considered it working off of wheel speed sensors. I come from a time when everything had speedometer cables.