'02 T/A WhinerI recently installed my first set of gears in an '02 Trans Am, upgrading the factory 3.23 gears with a set of Motive 3.73s. When I did my pattern, it looked good with the proper amount of play. It may be important to note that I reused all the bearings except the bearing that has to be pressed onto the pinion; that one was new. So in all, I put in the ring, pinion, and pinion bearing. Now there is a whining during acceleration and coasting, but no whining in reverse. Given that I took my time and all my measurements looked good, I can't help but wonder if I missed something.
Searching the Web, I have found a few possible diagnoses: a bearing is bad or I need to replace all the bearings to match the new stuff, the whine is normal because of the gears I have chosen, or it's a "breaking in" stage.ChadVia Internet
Ray T. Bohacz Responds:Gear noise after a swap is often a complaint in hot rodding and is something that is not only found with Pontiacs.
There are a number of additional reasons why the rear could be whining. You state that you ran a pattern on the ring-and-pinion and that it looked good. To those who have never done this before, what this means is the gears were coated with something (chalk, grease, paint, etc.) and the differential was spun a number of times. Where the gears mesh will then wear off the coating so the path can be viewed. Though running a pattern is the proper procedure while performing a gear swap, it is not all-inclusive. The backlash needs to be set to a specification with a dial indicator and the pinion depth needs to be measured and set to the manufacturer's recommendation. A pattern alone will not provide this information. It would be similar to checking spark plug gap by eye instead of using a feeler gauge. Any drastic difference will be seen, but the exact dimensions will be unknown.
The other issue is that many aftermarket gear sets are not made to the same tolerance standards as the factory-installed ring-and-pinion. This does not mean that the product is defective, it's just accepting a higher level of tolerance. As an example, Ford Motorsports gears are the slightly out-of-specification units that were rejected from the production line due to the potential for increased noise. This logic is accepted by the industry since an individual who is changing gears usually has a vehicle with a louder exhaust and is either unaware of the whine or does not care. I do not know if this is the case with your Motive gears as I do not have specific experience with that company's products.
I am sure my response will bring a good number of letters disputing what I said, but from my years in the business, all I can tell you is that gear noise will be a crapshoot. If you set the backlash and pinion depth properly, you will probably eliminate most, if not all, of the whine. But in some cases, the gears will be noisy, even with everything set to specification.
One Twisted FormulaI have a problem with my '89 5.7L Firebird Formula that I have owned since it was new, and has never been in an accident. The other day I decided to change the fluid in the rear axle. I put the back wheels up on ramps, and to level the car, I supported the front of it with jackstands under the lower control arms.
The floor jack would not fit under the car because of the low air dam on the front, so to get the body up a bit, I used the factory jack on the driver's side. Once the body was up enough, I used my floor jack under the crossmember and raised the car up further.
My fluid swap went well and I lowered the car back down. I put the front down first, but since my jack would not clear the air dam once the car was back down, I used a block under the driver's side front to keep the body up so I could get my jack out. I let the back down and then removed the block under the driver's front.