noise when accelerating

**79Firebird_99TA** · 06-20-2011, 02:34 PM

I am hearing a metalic rattle noise when accelerating on the highway - R rear. It's more pronounced there than on the streets... but I can still hear it. I thought it was brakes or axle shaft bearing so I swapped them both. Axle looked good too.

If it does end up being the diff, the shop quoted me 900.00 for eaton gears and bearings and a 3.73 gear..... it is a 10 bolt ....

**79Firebird_99TA** · 06-24-2011, 06:58 AM

No one? That's ok ... I just spoke with the race shop that overhauled my 10 bolt 50k ago. He doesn't even suspect the rear but possible u-joints. He said that the 10 bolts are fine for non-race driving; they take a hit when the power exceeds what they can handle. But with the harder hitting tranny and as many times as that drive shaft has been out in the last 6 months ...... afterall the car has 216k on the clock.

**35th-ANV-SS** · 06-24-2011, 07:03 AM

Sounds like your exhaust is hitting the upper pan hard bar support. It gets close in that area where it goes over the axle.

I would start there.

You can pick up a used 10-bolt for $200-$300 btw.

**79Firebird_99TA** · 06-29-2011, 05:39 AM

Originally Posted by 35th-ANV-SS

Sounds like your exhaust is hitting the upper pan hard bar support. It gets close in that area where it goes over the axle.

I would start there.

You can pick up a used 10-bolt for $200-$300 btw.

It wasn't the exhaust. Unless my ears are playing tricks on me, I swear I hear it from the R Rear wheel and it's loudest on the highway under a load while accelerating. If I decelerate, it's practically gone. I just put a Timkin bearing in .... and the axle looked good.

**0rion** · 06-29-2011, 06:11 AM

did you physically get under there and look at that heat shield? There's a shield that comes really close to everything on the right rear where it crosses over the axle. Might be worth looking at more closely.

**79Firebird_99TA** · 06-29-2011, 08:37 PM

Originally Posted by 0rion

did you physically get under there and look at that heat shield? There's a shield that comes really close to everything on the right rear where it crosses over the axle. Might be worth looking at more closely.

Yeah .... I didn't see anything close to the exhaust. I'm going to go back under and I'll do a double check and make sure that I didn't miss it. Thanks. While I'm under there, I think I'll swap my poly transmission mount with a rubber one. I do feel some vibration from time to time.

**0rion** · 06-30-2011, 04:42 AM

look for marks instead of something touching.....what happens is as you accelerate the suspension compresses and that's when you'll get rattles and stuff like that. You could be correct and there could be more going on there but 99% of the time a rattle will end up being something stupid like a heat shield. Grab those shields and wiggle them too in case one is just loose or something. Rule out all this simple free stuff first.....a lot of times that's what it ends up being. Good luck and keep us updated.