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Discussion Starter · #1 ·
01 Trans Am. Pretty bad bearing noise coming from rear driver side. Had it checked out and the prognosis was bad wheel bearing, driver side axle seal leak, passenger side axle noise, pinion bearing noise inside the differential.

So with all of this said, I think it's time to replace parts and do a partial rebuild.

Gonna replace both rear wheel bearings, replace pinion bearings inside differential, replace axles if necessary. Anyone have any other suggestions for me?

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1994 Firebird Formula 381ci LT1 / TH400+GV O/D
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Do you have all the tools required for a rearend rebuild - magnetic dial indicator, pinion depth checker, in-lb torque wrench, gear indicator paste?
 

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That makes the situation a bit confusing. A quality gear install would have included a rebuild kit. Here's an example of what gets replaced with Richmond's Mega Ring & Pinion install kit:

* Pinion and carrier bearings
* Carrier shims and bearings
* Crush sleeve
* Pinion seal and nut
* Marking compound with brush
* Ring gear bolts
* Thread locking compound
* Silicone sealer
* Cover gasket
* Wheel bearings
* Axle seals

They could have cut corners on the axle bearings and seals. But if you have pinion bearing noise, the person who installed the ring and pinion should warranty their work. They should have noticed the problem with the axle seal leak {(or sloppy work caused it). To replace the pinion bearings, you are are looking at a total disassembly - pull the axles, pull the carrier, drive the pinion out of the housing. The reinstall is the equivalent of rebuilding the rear, and requires at least checking the accuracy of the install with regard to backlash and pinion depth. The slightest error can produce a horrible whine and damaged gears.

I've been wrenching cars for more than 50 years, have done most of the work on my 94, but I wouldn't attempt to rebuild a rear axle assembly.
 

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Discussion Starter · #5 ·
The only 'real' noise that I hear is the rear driver side wheel bearing. It makes the normal bearing noise as I drive. It's really bad when I turn the car to the right for some reason. The shop claims there is noise inside the differential but I hear nothing coming from there. Although they did tell me about the axle leaking. Perhaps I should just redo the wheel bearings and check the axles for scarring.

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Would make sense to do that, before assuming you have a differential problem. I would still ask the mechanic that installed the gears whether he replaced the axle bearings and seals, and get his input on the noise.
 

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Discussion Starter · #7 ·
Hopefully someone can help regarding axles. I was told my axles may be scarred from the bearings or just scarred in general and that's why I may still be getting this bearing noise in my rear. My question is regarding the 'axle shafts'. Can I just get new axle shafts? It looks like they come complete with bearings already on them and the studs for wheels as well, leading me to believe they are just one whole piece. Just swap the new for the old and won't have to worry about dealing with changing the wheel bearings. See pic below. Thanks.
Metal Nickel Titanium

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I believe what is shown on the axle, right behind the hub, is the reluctor wheel for the 4-channel ABS+TCS rear wheel speed sensor. Does your car have traction control (RPO "NW9")? If not, you don't need the reluctor.

It would seem to me that the only way the axle would be "scarred" would be if the bearing seized, or was getting so bad that the inner race started to spin on the axle surface. I would examine the axle before assuming you need new axles.
 

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Discussion Starter · #9 ·
So I'm trying to understand...
Once I change the wheel bearings, and there may be scarring on the axle, what exactly needs to be changed? The axle shaft? Or the axle itself.

Just trying to get understand the proper way to move forward.

Which one of the pics below would I need?
Tire Wheel Motor vehicle Automotive tire Vehicle Automotive tire Auto part Audio equipment Cable Coil spring

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I replaced the rear end in my 00 in order to gain posi. The donor was from a 94 Z28 and I was disappointed that it had smaller brakes and rotors so I was hoping to take the axle shafts from my 00 and reinstall them on the 94 rear end in order to gain larger brakes. I was unable to find info on how to do this, so for right now I am sticking with the 94.

2KBirdban, you would need parts from the picture on the left. It really wasn't too bad switching out the entire unit, but if you don't know what it is coming from it may or may not be an improvement.
 

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He's not swapping rears. He is trying do diagnose and repair an axle bearing noise and seal leakage in his existing unit, in which he just had a new set of 3.73:1 gears installed.

The "axle" is the common name given to the axle shaft. The entire unit is a rear axle assembly. You showed a pic in post #9 of the entire big 'ol rusty rear axle assembly. You don't need that.

The second picture you posted is an axle from a vehicle with an independent rear suspension rear wheel drive, with two constant velocity joints. Or it could be from a front wheel drive vehicle. Your car has a "solid" rear axle assembly. You don't need the part you pictured in post #9.

If you have to replace an axle you would get one like you showed in post #7. You would only need one with the reluctor gear if you have traction control (RPO option "NW9"). If you don't have traction control, it would look just like the one you posted in post #7, except you would not need that "gear" that is up against the hub. I pointed this out in my post #8, but you appear to have ignored it.

I am completely puzzled about why you are not addressing this with the "professional" who just changed your gears. You appear too focused on the possibility of "scarring of the axle shaft".
 

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Discussion Starter · #12 ·
Well had the rear checked. Differential parts are all good, wheel bearings all good. Found that tires were rubbing the inside of the wheel well. I have 285/45/18 on the rear. So we banged out the wheel wells.

Noise has quieted down, but not completely gone. And it's both sides, not just the drivers side. I've changed tires on both sides. There is still a slight to moderate noise.

One mechanic said it could be he weights on the inside of the rim making the noise, or I can get small spacers. Or it could the larger wheels themselves with the lower profile tires as well.

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Do you mean the inside edge of the tire was rubbing on the inner fender? Sound like your wheels may have an incorrect offset, placing them too close to the inner fenders. That, plus running a 28" tire......why? Now I understand why you need the 3.73 gears.

What is the width and offset of the wheels. I run 315's in the back (street tires) and huge 28x10.5-15W (13.1" wide full slicks for the track) and the hammering was minimal, because of the correct offset/backspace. 285's should not be a problem.
 

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Ive built many rear ends. From dana 60s to GM 12/14 bolts, ford 9"- 8.8's, and even some Japanese types. Its pretty common once the pinion bearings get broke in after a lot of miles, they make noise. Make sure the yoke nut is tight. if it backs off (common issue even with locktite) and your pre-load on the pinion bearings is gone and the by product is noise.

I can say, unless it was a huge gear swap(2.50s to 4.56's) that even the crush sleeve can be re-used. Place it on the old pinion and where it has bulged out, give it a few whacks with a shop hammer to let it grow in length(.010-.020"). Unless you have some means of locking the yoke, it takes a $hit ton of torque to get the new crush sleeve to start to compress....that's mainly why Ive reused them. Never had one fail yet.
 

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18" wheels not 28"

Offsets are only 9.5" all the way around.Sent from AutoGuide.com Free App
I didn't say 28" wheels.... If you are actually running 285/45-18 tires, the tires are 28.1" diameter. That is 2" larger than the stock tires for the car. When it left the factory it had either 245/50-16 tires (25.7" diameter), or 235/55-16 tires, (26.1" diameter). Using a tire with larger diameter throws the speedometer/odometer off..... in this case causing the speedo to read at least 7% lower than actual speed, unless you have had the new tire diameter programmed into the PCM. The larger diameter slows the car way down. Less torque at the rear wheels, and more power consumed accelerating the greater mass of the wheels, and the larger radius of gyration.

Or maybe you actually have 285/35-18 tires. That would make more sense.

Because of the large diameter tires, your new 3.73 gears feel the same as if you had 3.46 gears (if there was such a ratio) with the stock tire diameter. And now you need the PCM programmed for the tire diameter and the gears, if you haven't done so already.

And, your wheels do not have 9.5" offset. I'll bet they are 9.5" wide... not the same as "offset", which determines how deep the wheel/tire sits in the wheel well. Typical offset for a 9.5" wide wheel that locates the tire correctly side-to-side is 35-56mm (1.38-2.21").
 
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