97z28k&N

My rear end has recently started making horrible whining and grinding sounds. The grinding is only evident when turning right. I had my pinion seal replaced within the last 1,000 miles.

The whining is absolutely horrendous and came up out of nowhere. Im considering changing the whole rear because it leaks like hell anyways. The noise is not coming from the brakes either.

My question is, would you recommend looking more into it before swapping or should I just do it? I have a good deal on a low mileage rear end.

My rear has 142,XXX miles, stock.

Kevin Blown 95 TA

Interesting that you had your pinion seal replaced and now you got a problem. I would almost say that they didn't retorque it correctly after replacing the seal and now the pinion is loose. Maybe get under there and give the yoke a shake and see if there is any laterial movement. You might already have damage, though.

Swapping the rear end is pretty easy, but you have to worry about putting in one that isn't much better than what you already have. Rebuilding your is possible as well, but that would cost more... I'd say get it in writing that the one you are buying isn't defective or you can return it and get a refund if it is noisy, if that is possible.

97z28k&N

Thanks for the reply. I think the damage may be done because it gets louder and vibrates more every day. I have owned the car car for a year and i have only put 3,000 miles on it.

I can't really afford a rebuild or getting bearings pressed, for I am 17 and saving for college.

My buddy owns a junkyard and he gets totaled 4th gens frequently and said I could buy a rear for about $150. I like your idea about getting almost a contract to return it if it is noisy.

I just need some peace of mind, because the last thing I want is being stranded or losing a wheel due to a bad bearing.

FirstYrLS1Z

in getting a complete replacemant rearend,you gotta make sure you get one that's compatable.
3 channel ABS or 4 channel ABS & TC,it has to match the car.
You didn't state which one your car is.

97z28k&N

How do I know which one I have? I have a '97 with ASR and antilock brakes....but I have no idea what channel it is...

Injuneer

"ASR" is traction control (RPO "NW9"). You indicate you have both ABS and TC (4-channel), which means you need a rear axle assembly with a wheel speed sensor on each end of the axle housing, rather than a single sensor on the top of the differential housing.

97z28k&N

Ok thanks!

So to clarify, I need to look at 4th gen fbodies that are a 4-channel from '96-'97, correct?

I was just reading on an LS1 thread that the brake system on a 98-02 fbody are different and won't bolt up correctly on my '97, is this correct as well?

Thanks again.

Injuneer

The e-brake is different on the LS1 cars, but it can be adapted. That way you could look for a 95-02 rear axle assembly, with the correct wheel speed sensors. Traction control was not available in 93/94. In addition to the speed sensor differences, the ABS + TC cars have an individual brake line for each brake, when the ABS only cars have a single hydraulic brake line serving both rear wheels, with a "tee" on top of the differential housing.

You also need to consider the rear axle ratio. If you change the ratio from what you have now, you need to have the PCM reprogrammed for the new ratio, or your speedo/odometer will be off - the PCM needs the correct vehicle speed to control things like shift points and decel fuel cutoff. The A4 cars have either a 2.73 (RPO "GU2") or a 3.23 (GU5) rear axle ratio. The M6 cars from 95-02 all have a 3.42 (GU6) rear axle ratio.

97z28k&N

Wow, all this information is great! I'm glad I made a thread!

How do I know what ratio I have now? Is there a code on my differential housing or something?

Oh and if the car I take from is a '97, cam I just use it's pcm if the car is stock? Assuming that the gear ratio is different...

Injuneer

Look in the glove box for the service parts code tag. It will have one of the codes I posed above. GU2 = 2.73 GU5 = 3.23

Or go to this site and enter you VIN:

Comprehensive Chevrolet VIN Decoder

Just don't get excited when it tells you your car is "1 of 1" of all the 97's produced. It seems to tell everyone that.

Swapping PCM's gets messy. Your car will only run with a 96 or 97 PCM. Can't use 95, or 98-02. Then it has to EXACTLY match your car, except for the rear axle ratio. Different programs for A4 and M6 cars.

97z28k&N

Alrighty thanks again! I'm traveling across the country right now so i'll check my code when I'm back home.

I think I will just have my PCM reprogrammed if the gear ratio is different, seems easier.

Injuneer

If you have 2.73 gears now, the 3.42 gears will really wake it up. It will feel like you added 25% more torque at the rear wheels, at least off the line.

97z28k&N

Sounds great, I'm now hoping to find 3.42's!

97z28k&N

Just thought of another question... how can I tell what gear ratio the car I'm pulling from has if I cannot access the glovebox (I.e. front end collision)?

97z28k&N

My car doesn't have 1st in the gear selector so I guess I have 2.73!