help! rear end question!

**1999transam** · 01-25-2011, 05:30 PM

im purchasing a 1999 trans am and it has rear end noise, ive found a few others for sale that have the same thing, is this a common problem? does that mean there is something wrong or is it charachteristic of them to do that after a certain amount of time? it has 149k miles on it and i just want to know if i should replace it or not worry about it, thanks!!!

**Cutlass** · 01-25-2011, 05:35 PM

Technically the rearend should be quiet. A tiny bit of noise is ok. But noise usually means that something needs to be fixed.
There's a fine line between ok noise and bad noise.

**INMY01TA** · 01-25-2011, 06:38 PM

My 12 bolt screams pretty loud. Doesn't bother me and doesn't wanna break. I ignore it. I could rebuild it but after a few trips to the track it'd start whining again.

**oldmanZ28** · 01-26-2011, 04:14 AM

bad noises could include axle bearing,carrier bearing,pinion bearing,and on 99+up worn Torsen posi gearset.

**hippiespace** · 01-26-2011, 04:30 AM

A little clicking at low speed around corners is normal. When I put all polyurethane suspension bushings on my '02 the the clicking seemed to stop.

**pajeff02** · 01-26-2011, 06:35 AM

Originally Posted by INMY01TA

My 12 bolt screams pretty loud. Doesn't bother me and doesn't wanna break. I ignore it. I could rebuild it but after a few trips to the track it'd start whining again.

Any idea what your backlash is set at? Mine is kind of loose at .011" and whines at certain rpm under light cruise. Just looking to compare notes.

**hippiespace** · 01-26-2011, 08:13 AM

I'm not sure. But when my 96 Z28 started making that whining noise the rear end was replaced shortly after it started

**35th-ANV-SS** · 01-26-2011, 09:43 AM

A properly set-up rear end will NOT be loud...I don't care what manufacture it is.

Some gears are a little louder than others, yes...but it should NOT be THAT loud.

My Moser 9" with 4.11 gears is pretty damn quiet. I noticed a slight increase in noise at all over the stock 10-bolt.

OP - Worst case scenario is the rear end will grenade on you and you will have to replace it. You can find a working 10-bolt, used, anywhere in the price range of $100-$400 dollars. That would be for the entire rear-end assembly.

**Firebirdjones** · 01-26-2011, 11:07 AM

Originally Posted by pajeff02

Any idea what your backlash is set at? Mine is kind of loose at .011" and whines at certain rpm under light cruise. Just looking to compare notes.

That's a bit on the big side. Some may call that acceptable but I prefer .006-.008 at the most.
I just setup a 9 inch and a 61 chevy rear for a neighbor, I used motive gears in the 9 inch and US gear in the 61 chevy. Both wanted a pretty tight .006 backlash per manufacture specs. That tends to loosen up a bit after some miles due to side bearings wearing in, gears wearing in etc.... I keep an eye on it, and if it gets in the range you are describing, I usually will tighten it back up just a tad, especially if it's a stick car.

**pajeff02** · 01-26-2011, 11:14 AM

Originally Posted by Firebirdjones

That's a bit on the big side. Some may call that acceptable but I prefer .006-.008 at the most.
I just setup a 9 inch and a 61 chevy rear for a neighbor, I used motive gears in the 9 inch and US gear in the 61 chevy. Both wanted a pretty tight .006 backlash per manufacture specs. That tends to loosen up a bit after some miles due to side bearings wearing in, gears wearing in etc.... I keep an eye on it, and if it gets in the range you are describing, I usually will tighten it back up just a tad, especially if it's a stick car.

Any harm in tightening it up now that it has about 3,000 miles on it? The car is down for the winter, so it's not a big deal to do.

**Firebirdjones** · 01-26-2011, 11:21 AM

Originally Posted by pajeff02

Any harm in tightening it up now that it has about 3,000 miles on it? The car is down for the winter, so it's not a big deal to do.

That's what I do, and I've never had an issue doing it. I'll go back and check the neighbors mustang and vette later this summer after he logs some miles. I set them up snug, so chances are good I won't have to do anything.

I've even done this on used cars I bought that had 70-100,000 miles on them. As a matter of fact, my 72 blazer had accessive backlash with 71,000 on the clock. Never been apart, so I tightened it up a tad. It never made any gear whine noise before, I just didn't want it that loose, it would sometimes clunk when putting it in gear.

**pajeff02** · 01-26-2011, 11:28 AM

I know that no one on here has anything good to say about Moser, but why the heck would they set it up that loose to begin with?

**Firebirdjones** · 01-26-2011, 11:36 AM

Originally Posted by pajeff02

I know that no one on here has anything good to say about Moser, but why the heck would they set it up that loose to begin with?

In a hurry?? I don't know. Is it a 12 bolt or 9 inch?

I ask because there really is no excuse for a 9 inch to be setup like that, they are the easiest to do. Simply use a spaner wrench and dial in the backlash and bearing preload specified, I call them "dial-a-shims"

It's like using a jack screw.

The 12 bolt is more involved, you have to pull the unit out, pack more shims and/or remove shims accordingly, reinstall, torque the caps, check the backlash. And repeat the procedure until it's right, it can get time consuming. In which case if they get it to what they consider "close enough" they probably just let it fly.

**pajeff02** · 01-26-2011, 11:38 AM

12 bolt.

**Firebirdjones** · 01-26-2011, 11:56 AM

Originally Posted by pajeff02

12 bolt.

That would explain it most likely. Got it close and called it good. With 3,000 miles on it, I would assume it may have loosened up a tad. I'd guess they got it at ~.009 and buttoned it up.

**INMY01TA** · 01-27-2011, 05:41 AM

Mine was set up by Strange and WAS dead quiet when new. 9 inch rears tend to stay quieter after abuse than 12 bolts.

**Firebirdjones** · 01-27-2011, 06:53 AM

I'm a fan of strange, always had good quality parts, good customer service.

I've never had issues of 12 bolts making noise after years of abuse.

Not sure what's going on there.

**bberretta** · 01-31-2011, 08:52 PM

OP- the stock rear in these car is WEAK, as you can tell by the number of people who've upgraded their rears. My suggestion would be if you do get the car the go ahead and start saving for a new rear. If you drive it gently, it might last. If you're not going to give it too much Hell, then you might get away with a rebuild, but I wouldn't waste the money. I had mine rebuilt, grenaded the posi unit and ended up upgrading to a 9". No more rear problems and it's smooth as silk.

**texasnas** · 09-02-2012, 04:44 AM

my 1999 Tras am is making noise. My cars has 63 k miles. Noise has beenthere for 10 years. I think it started when I upgrade to a larger size rims and tires. I replaced with royal purple lube and it drives great. A little noiSe will nit hurt. I can spent 2 k to rebuild the rear and was told that the noise could come back. moser complete rear end upgrade is 3.000 not including labor. I do nit race, so not sure it is worth for the money.