RxFred

My 1985 gsl-se started making a noise coming from the left rear corner last week. I lifted the car and diagnosed it as a rear axle bearing failure. I ordered the replacement bearing and bearing blocker ( sorry I forgot the name in english) directly from mazda and started the work. Not wanting to damage anything, i took my axle to a machine shop where they installed the new hardware. I have to say I was disapointed with the work they did. it took one hour, they charged me 70$ canadian and they cut a little thru the spacer to remove the bearing. They did what I did not want to do, the reason i paid professionnals... The machine shop owner also told me the new bearing seemed stiff for a bew bearing....

Fast forward a week, i reinstall everything and take the car for a road test (yesterday)... My wife and I imediatly notice a new noise, which starts to be earable in 3rd gear... It comes from the rear, but hard to say if from one side or the other.... I lift the rear of the car and go thru gears in my garage... The noise is actually a bad vibration. Since i changed the brake pads as well as the wheels at the same time as the bearings, i took the wheels out, as well as the brake disk and calipers... Did the same test, same result... Very bad vibration...

I inspected both axle, the one i worked on as a very little play when I pull and push on it. By little play i mean barely noticeable, but the passenger side does not do that.


So.... Did i installed a bad bearing or... Do the cut in the spacer is enough to put the axle out of balance at high rotation speed or... did the machine shop badly installed the bearing... I am confused as to what to do next. The car is still lifted and i intend to have my wife go thru the gears while i am under the car to locate the vibration more precisly

I also think the driveshaft may be going but to go bad so suddenly would be weird

Please feel free to give your input on this subject as I am a little discouraged on what to do next

Thank you

NCross

iTrader: (18)

The bearing could have been pressed in at an angle causing vibration. Or they didnt tighten something up.

RxFred

Back from the garage...

The noise/vibration clearly comes from the center of the car. This rules out the bearing problem... Looks like a universal joint on the driveshaft. I've been wanting to overhaul it for 2 years now... Looks like this is my opportunity. Could be the differential as well but it has been rebuilt 2 years ago... So i hope that´s not it.

Still is strange that such a vobration would appear while working on the car...

rwatson5651

iTrader: (5)

I have noticed that sometimes when I fix one noise, it makes it quiet enough to hear another that was covered by the first.

RxFred

I know what you mean... But it is not the case here... That vibration is scary!

StormBeforeDawn

There should be zero, and I mean ZERO play in the axles in the axial (side to side) direction unless I have a terrible misunderstanding of the system.

Also, cutting the bearings off is pretty common practice, but you can **** up the axle if you gouge it. Hard to tell what you mean w/o pictures.

My $.02? Really spend some time finding the vibration source. Don't just replace things thinking that they must be the problem. If you can hear it when you are in the cabin, you should be able to feel/hear it if you poke around under the car while its running.

DivinDriver

iTrader: (15)

I don't have the 85 manual handy, but according to the 80 FSM, rear wheel bearing end play limit is 0.1mm (.004in).

I recall after changing my axle bearings I had to discard the gaskets originally installed between the axle and the brake backing plates to get the end play zeroed - used a thing smear of gear-lube-safe silicone instead. Made me wonder if the newer bearings were slightly under-spec with regard to thickness of the outer race.

StormBeforeDawn

Humh, 4 thou is the spec? That seems about right to me. Thanks for having some real numbers handy.

DivinDriver

iTrader: (15)

That's the spec for an SA.

'85 FSM shows 0.1mm/0.0039in, so essentially the same.

RxFred

Update:

It ended up being the pinion gear in fth diff which broke 2 theets. Had my diff rebuilt with a slightly lower end radio (from a gs I think). Was told it was repacked with one more clutch disc.
Observation: i barely notice a difference in acceleration and my revs at highway speeds are about 200rpm lower. It is in fact perfect as I race with smaller ratio wheels and was always hitting the rev buzzer too soon on many occasions.

LongDuck

Is this to suggest that you drove it for a year and a half on a broken pinion? The taller rear gears should help with fuel mileage slightly if that matters to anyone anymore.

Glad to hear it's not the axle bearing whoch you paid to have swapped on the axle. The FSM specifies cutting through the retention collar with a grinding wheel, the chipping the last little web with a cold chisel, taking care not to whack the axle steel. At any rate, glad you got it worked out,