So I Destroy My Indestructible 9" Rear....

[Roscoe]

Well late last year I was out for a ride and the rear started making weird noises. I went to make a U to come back and on the exit ramp the rear actually locked up; as if I put the brakes on. Good thing nobody rearended me.

I had to muscle the car to move again and on the way back it was making a variety of terrible sounds. I winced all the way back. When I got back the rear was actually sizzling with smoke coming out of the vent. It stunk too.

I finally got around to pulling the center section. The paint on the casing was discolored from heat. The pinion bearing was completely destroyed.

Took it to a trans shop and the guy said the only servicable parts were the casing and the yoke. The pinion housing was toast too.

I just had it rebuilt and put it in yesterday. Bruce's Speed Shop in Rockaway, NJ did it. Car runs like a top.

The rear was one of the very few parts that was used. Came with my rolling chassis and I put about 25k on it.

Roscoe

[spl310]

Roscoe,

What was the reason for the failure? Sounds like it ran dry if the heat was that high.

[Roscoe]

It looks like the rear might have run dry; although there was never a puddle under the car nor were the inside of the wheels oily. Just don't know. But it cost me nearly a grand to set it right.

Roscoe

[Cobrabill]

That's $111.11 per inch.Rearends seem to be overlooked quite ferquently.

[427sharpe]

The lack of fluid is burn out from the rear end running so hot. Will boil the gear oil into sludge and burn the rubber on all the seals as well. From what I have seen in the shops, this usually happens when the pinion nut is WAY over torqued, binding the crush sleeve and dragging the pinion too high on the ring gear. I doubt it was low or empty of gear oil from the get go because you would have heard and felt it. Had anyone replaced the pinion seal for some reason? If not is was an assembly error. Just to be safe, I would run a high quality full synthetic gear oil (redline, Mobil1, etc) along the lines of a 75W90.

[Roscoe]

Bob,

Thanks for the reply and info

The gear oil that came out of it was not sludgy, just black; and not alot of it. About 8 years ago I had a racing shop put a solid spacer in it. Other than that I did not touch it.

New one seems to be fine now.

Thanks again,
Roscoe

[trularin]

Roscoe, good thing you were not run into while you were having this event.

Did you go with the same setup, or did you do any upgrades or changes?

[Roscoe]

I went with the same setup. No changes.

Roscoe

[CowtownCobra]

I think running it dry is the only way to kill a 9", the damn things are pretty indestructible

[Curt C.]

Originally Posted by Roscoe

Bob,

Thanks for the reply and info

The gear oil that came out of it was not sludgy, just black; and not alot of it. About 8 years ago I had a racing shop put a solid spacer in it. Other than that I did not touch it.

New one seems to be fine now.

Thanks again,
Roscoe

Hey Roscoe. Sorry to hear about the failure. Does the above quote mean that you did not change the fluid for 8 years? I know you track you car. I burned up a 9 inch diff (Auburn Pro) and gears several years ago due to puking fluid out the breather. Replaced the gears and diff (True Trac) and fixed the puking breather. I try to change the fluid every other season now. I think that when I blow up this one I will go with an 8.8. I love the 9 but it is so damn heavy. Most of the axle folk say that aftermarket 8.8's (31 spline) are as tough as the 9.

[Roscoe]

You're supposed to change the oil????? I'll have to be more attentive to that. I'll put it on my maintenance sheet....really. I guess I should check the level every so often also.

Thanks,
Roscoe