Clunking in rear when pulling in powerband.

[graphikg]

I was driving my car and heard a weird grinding noise coming from around the diff area. To test it further, I was in the powerband in third and punched on the gas a couple times. I ended up hearing a clunking noise on each pull. I think our cars should be able to handle punching the gas in third without clunking. Do you think my diff is going out or my axle is trying to come off? The week I have been having, I tell you.

[rThor432]

Meh my S52 car did that for a while. It was because my H&R Sport springs werent stiff enough to keep the rear from compressing the quarter arches into the 225's. I rolled the lips and had no more grinding in the powerband.

If the noise is only when you initially punch it, it could be the diff shifting. That would be a clunk.

As far as losing an axle, the CV's dont make that sort of noise, and if it is bad enough to make the noise you describe, you need to get it on a jack and check it out. Something should be easily noticable with the suspension unloaded. Axle wont make a clunking noise though.

A wheel bearing could sound like a grinding noise to some.

But you said clunking at first and then mentioned grinding. Which is it, or is it both?

Good luck.

[318isbmw]

Check your diff bushing, that would be my first guess.

[daniel]

Check your diff bushing, that would be my first guess.

i agree that this is a good guess.

[graphikg]

Meh my S52 car did that for a while. It was because my H&R Sport springs werent stiff enough to keep the rear from compressing the quarter arches into the 225's. I rolled the lips and had no more grinding in the powerband. Good luck.

Soon to be my S52 right :). Ya, thanks guys. I will check the diff bushing... Didnt think of that. Well to be more specific, my car was on some gravel and I took off kinda fast to create wheel spin and it sounded like grinding. To test further, that is when I did the 3rd gear pulling thing and heard the clunking. One day when I was pulling my rear sway, my left rear axle came out of my lowered diff and I had to pop it back in (no bolts necessary to take off or put back in). Could it be that issue haunting me, or is that just how the axles come out?

[E30Nova]

Soon to be my S52 right :). Ya, thanks guys. I will check the diff bushing... Didnt think of that. Well to be more specific, my car was on some gravel and I took off kinda fast to create wheel spin and it sounded like grinding. To test further, that is when I did the 3rd gear pulling thing and heard the clunking. One day when I was pulling my rear sway, my left rear axle came out of my lowered diff and I had to pop it back in (no bolts necessary to take off or put back in). Could it be that issue haunting me, or is that just how the axles come out?

Um, what?

The axle is supposed to be bolted to the diff. If it popped right out and you didn't bolt it up, that's a pretty major problem. :eeek:

Matt

[Unearth078]

+1 on diff bushing, had the same dealy going on, was it. wasnt really a clunk more like a metallic kling, tho.

[graphikg]

Um, what?

The axle is supposed to be bolted to the diff. If it popped right out and you didn't bolt it up, that's a pretty major problem. :eeek:

Matt

Why did it just pop out then? Thats wierd. I am going to have to check it out tomorrow.

[E30SPDFRK]

No, that was just the axle flange coming out of the diff. That shouldn't be your problem.

Will it clunk in every gear and whenever you hit the gas, or only in 3rd at certain times?

[graphikg]

It is every gear when i'm hitting the gas hard; when the engine is transfering a lot of torque. Under a lot of acceleration i hear grinding.

[E30SPDFRK]

Have you done anything to the drivetrain recently?

The clunk could be a bad tranny, a horrible guibo, a bad diff, loose diff bolts or a bad diff mount. The grinding could be from a CSB, the u joints, axles or wheel bearings. There are other things it could be, but none of us can tell you what it is without hearing it.

Get under the car and start searching.

[graphikg]

I got under the car and found that the 2 top differential mounting bolts are completely missing. 1 of the bottom diff mounting bolts was almost out, so only one was in completely. That may have been the source of clunking. As far as the grinding, it will still occur under mid to high torque initiation. I dont know if there is a problem with the differential or the axles, or either of them at all. Under grandma driving applications theres no grinding at all. But I'm still uneasy about the missing bolts.

[graphikg]

I had it checked. First of all, I am missing a tranny mount (completely gone). But the source of the grinding is the Ujoint on the diff. Time for the junkyard. Man I hate driveline work.