midias

I am using the OEM 1984 Trans am 10 bolt rear, 3.73 rear ratio with Richmond locker a T5 trans and a aluminum GM drive shaft.

Don't know if the ring and pinion are original or have been replaced (say with a noisy Richmond gear setup) but it is using the factory ratio.

So here the deal - no rear end whine while accelerating, no rear end whine while decelerating. No rear end whine while coasting in neutral.

However, there is a significant whine between 40 and 50mph then above it becomes much quieter only with a very light load on the gas pedal as if to maintain constant speed.

There is not a lot of sound insulation in my car. Therefore the noise sounds pretty pronounced to me I think it is coming from the rear end.

About a month ago I drained and refilled the rear diff with fresh lube till it ran out the fill hole. Noise is the same and the fluid was clean with no visible metal. I was told it was fresh when I bought the car about a year ago. There are no leaks around the pinion and I am fairly sure the rear was rebuilt when the locker was put in.

One side note when I had a steel drive shaft the noise seemed to be about 55mph at least that's what I remember now with aluminum I hear it mostly at 45mph.
Any other suggestions?

///DAN///

iTrader: (1)

i have a 84 z28 that i bought from my gran mother that does the same thing and she took it to the dealer a couple times when new for this and they said it was how they all were . Don't know if that is 100% true but it's done it since new and has never had a problem aside from that noise .

Ozz1967

iTrader: (4)

It's not how they all were. Sounds like you've got a problem that will eventually get worse. I tried installing a richmond set in mine, couldn't get a good lash setting on it, whenever they'd blue the gears to mesh them, they'd never match up right. Got a set out of a junked car, ran quiet, just like my originals. I'd definitely have it looked at before it goes.

midias

Interesting


Well i think I have the factory gears. I was told they are 3.73 and I have the RPO codes for the L69 with the 3.73 rear end.

The other thing it might be is the poly bushings I should probably lube them again. I remember in the last car I had all rear poly stuff it squeaked a lot. I guess I will have to pull the rear diff cover and take a look this winter.

joeblue83

iTrader: (8)

do you have any aftermarket rear suspension mods?? I have a crossmember torque arm, and from that day I have had a little whine around 45-50 mph. I have swapped the gears, and same noise. Called the company, and they told me that they transfer vibration much easier than the stock torque arm with rubber bushing and attached to the transmission

midias

Yea I do I have box rear control arms with poly bushings. I also have poly everything (engine mounts tire rod end links ect). Also a poly trans mount and the car is lowered with kyb shocks and intrax springs.

midias

Winter is here I may be able to get on a lift so I thought I would bump this for more opinions.

So to review

lowered 2 inches intrax springs
poly bushings on rear control arms
poly engine and trans mount
Gen 4 aluminum drive shaft or steel both make sound
10 bolt 3.73 GT4 with Richmond locker

Ozz1967

iTrader: (4)

Ok, this may be my opinion, however, my rear started whining, I mean "howling", when driving, there is no mistaking it. It was doing pretty much everything you've described. I took mine to a shop and they found a bad pinion bearing. Ran me $700.00 for the parts and rebuild labor. So, based on what you describe, I really think you've got a bad bearing in the rear that's going out. IF you wait too long and the bearing goes "shells out", the rear will grind to a halt and you'll lose your diff as metals shards go through it from the shelled out bearings. Better to have it looked at now than later. Unless you want to try and do it yourself, then just get a rebuild kit and do a search on the boards here for how to do it and the tools you'll need. Best of luck!

midias

^ do you remember what it cost to have it replaced?

Ozz1967

iTrader: (4)

Yeah, parts and labor was right around $700, but I'm here in England and prices are retarded high. When I just had the pinion replaced back in 2005 in Texas, I want to say it was around $400-$500 for parts and labor. That $80-$90.00 per hour labor rate really catches up quick.

TTOP350

iTrader: (8)

Wow thats pricey 4 rearend work.
I charge 250$ labor for a complete rebuild with or without gear/ diff swap.

Cosmik Debris

Did you remove your grandmother from the backseat? That is probably where the whining was coming from.

midias

I was thinking I am lowered 2 inches with the factory panhard bar. So you think the rear being misaligned could cause some noise? Maybe pushing on something poly?

Ozz1967

iTrader: (4)

The wine will have nothing to do with poly bushings. My car is lowered as well and it is possible that this is causing the issue. You'll need to get the lower control arm relocation brackets to fix this. I still believe your rear is bad and needs to be rebuilt. Get the relocations brackets, the company that repairs the rear should be able to mount those for you as well. I know Spohn, Hawks and I think UMI sells them for our cars.