camaro_junkie

Alright, so just recently I have noticed a noise when I hit about 90 km/h (55 mi/h) in fourth gear. It sounds like something to do with the drive shaft or differential. The funny thing is that when I shift up to fifth the sound dies down a little. So it's only at high speed (above 55 mi/h) and at higher rpms (maybe above 3000 rpm). Any ideas?

camaro_junkie

bump

TraviZ

iTrader: (2)

its called a sonic boom.

camaro_junkie

Is that supposed to mean something or are you just messing with me?

llvll4l2c91350

what does the noise sound like

camaro_junkie

Well, my parents' old minivan had some teeth missing from the differential (ring gear) for a lot of years. It sounds something like that, except on the minivan the noise wasn't quite as loud and it only depended on speed. On my car it depends on speed and rpm and it seems to hit a resonance at higher rpms.

Pheonix542

B4 you go into the rear end check the coil spring isolators,(round rubber donuts) at the top of the springs by the body. Age and hard driving tend to cause them to rub through and start vibrating against the body a little.

camaro_junkie

Thanks for the tip. I do have new springs and shocks that have been waiting to go in in the back for a long time, so I'll check that out for sure.

No5.0

Here's what I have done to isolate sounds in the rear end. First jack the rear end up, and chock the front end. Drive the car up to speed in the gear you want to try and recreate the problem. If their is no sound then it is in the front end. If you get the vibration take your rear tires off and put the lugs back the hub/drum/calipher. This eliminates bad balance in the rear tires.
If you still have a problem I would try to either balance the driveshaft or just swap it out with a good one or change out the U joints. If you still have the noise then it is in the rear end which could be bearings in the carrier or at the wheel. Do forget to check play and movement everywhere you can think.

Noises are very trial and error.

camaro_junkie

Sounds like a good plan to narrow it down, although I'm not too sure about going 55mph in 4th gear with the rear tires off the ground. But thanks for the tips.

No5.0

It might sound risky but remember to lift the car under the rearend and use two jack stands to support it. Even the weight out among the three and keep the tires at least 4 inches off the ground.

Have you ever seen a pro stock car adjust a clutch like this at 150 mph!

camaro_junkie

I'll be sure to point it away from the house.

camaro_junkie

Now that I've fixed my exhaust leak, I can hear the noise better. It actually seems to happen over all the speed range and now it sounds like it is coming from the front of the car. I'm fairly certain that it is not the engine or transmission because I cruised downhill with the clutch in and it got noisier as the speed increased.

The first thing I'm going to do is get all the wheels balanced (I checked all the lugnuts tonight and they are fine). I'm also going to inspect the front bearings as soon as I get a chance. Any other ideas/suggestions?

camaro_junkie

Come on, a little help here.

camaro_junkie

Anyone?

camaro_junkie

As I thought, it was the bearings on the front passenger side rotor. It was actually only the outer bearing. The outer race on that bearing had some galling and the rollers in the bearing were pretty chewed up too.

Problem solved.

mrbulman19

cool, i have the same problem and i'm about to replace the front right bearing and ujoints as well. thanks.

i agree with pointing it away from the house!