sakhara291

I have searched. Found nothing remotely close.

Let me start by being flat out honest- it's an 88 gxl, and it is a pile, but it is my pile, and it is fun. When I initially bought the car, the engine was blown and has been replaced, and I'm dealing with the rest of the issues as I find them. This one, however, has me somewhat stumped.

When I first began driving it regularly, the shim and bolt for the tranny mount were missing and the front diff mount was shot. The latter was replaced in about a thousand miles, the parts for the tranny mount took longer to find and only went in this afternoon (I've been driving it since the beginning of december.) I had noticed a.... I wouldn't call it a vibration, but a low growling noise coming from the rear of the car at highway speeds- typically 50+ mph- non-gear specific, when I was on the throttle. This has been occuring pretty much ever since the diff mount was replaced. I had the alignment double checked, and it lessened the noise somewhat. Having had a similar problem with my truck a few years ago, I figured it was the side bearings for the differential carrier, or possibly an axle. I shoved the car on a lift and checked the play in the axles and they both seem fine, so I figured I'd sit on it till I replaced the clutch- this month or next, depending on time.

It was about this time I heard the ujoints begin to go out. Those are on order.

So I tightened down the tranny mount this afternoon, and the noise has actually turned into a full blown vibration. It has changed in intensity, pitch, and time. I've reverted my opinion and am currently placing blame on a mount somewhere. I've not hit the freeway to test that, as it is LOUD, and I don't want to destroy more than I have to. The vibration still feels like it's coming from the back end of the car, and occurs consistantly (moving or not) at any point when the engine is reving over 2k, getting increasingly bad as it goes faster. Could the tranny mount have gone bad over this timeframe, or could I possibly not have it tightened down enough?

Tournapart

iTrader: (4)

well im not so sure on the noise so i dont want to give wrong/bad advice/suggestions

but you know on the stock driveshaft the ujoints are close to impossable to change, its easier and less frustrating to just buy a sotck drive shaft or mazdatrix.com sells a very competitively priced after market driveshaft with replaceable ujoints around 2-300 bucks


good luck

SureShot

When you remove the drive shaft, check for damage or anything that might unbalance it.

The U-joints can be changed.
The bearing caps are staked in the yoke bore.
You need a pencil air or electric grinder like a Dremmel to smooth off the staked metal to drive out the old bearings.
The new bearings are retained by clips on the inside.

sakhara291

Great. Thanks. I know about the ujoints. That's not what I'm asking.

RoughRex

By "moving or not" I assume you mean that:

When you are reving the engine with the clutch pressed in the symptoms still occur. So, if the clutch is in (assuming your clutch is working correctly) none of the drivetrain at the rear of the car is moving. The only thing available to make noise at the rear is the exhaust. The only thing left to shake around in the front is the clutch and the engine/engine components. While I hate to answer a question with a question....even if the motor mounts are bad, shouldn't that only cause a jerk when you punch the gas...unless they are like totally gone? Sounds like the engine is misfiring or is off balance to me(again assuming the clutch works).

aka_rocket

i've had the same problem for 3 months now and i haven't found the problem yet. searched but no help yet. if anyone else has this and finds out what the problem is, please share.

*how can the engine get unbalanced? how would you really know and would a rebuild be needed to fix it if it was the problem?