Howling noise comming from rearend/driveshaft area

[UpRise_5.0]

Hey,

I just grabed a 1994 Mustang GT, that was built up a bit.

When I'm driving WITHOUT my foot on the gas, I hear a loud howling noise that sounds like its comming from the rearend or possibly around the driveshaft.

As soon as I touch the gas peddle the noise goes away, only happens when I take my foot off the gas.

The car had a bunch of engine, suspension, and rearend workdone a couple months ago. One of the installs was 3.55 FMS gears. Is it the gears or the driveshaft? Or something else?

Now if it is the gears how bad is it to be driving around the car like that? Don't get me wrong Im going to fix it ASAP, but wont be able to until Monday. And I was supposed to go to the Street Legal Drag Races tonight.

Thanks for any help.

 

[BlownFiveLiter]

It's probably the backlash set incorrectly in the rear end. Could also be u-joints, but I'd put my money on the rear end install being bad.

 

[Roland69]

could be gear noise....sounds like it could be pinion bearing also....maby even just axle bearings

 

[RYC CUKR]

Sounds like the gears weren't set up correctly. I am not sure what a bad pinion bearing sounds like but I know that when I had an axle bearing going out it made noise all the time if the car was moving. It wasn't really a howl but rather a rumbling noise.

Easiest thing to do is pull the diff cover, clean everything and put some marking compound on the gears and spin the tires. I don't have any pics of what the wear pattern should look like but if you do a search you should be able to find some. If the wear pattern looks good then you can start to look at the bearing. If the wear pattern doesn't look good then have the gears checked and get the backlash and pinon depth set properly.

 

[Roland69]

axle noise is there most of the time but gets worse when you go lane to lane...

 

[twistedwankel]

It's probably the backlash set incorrectly in the rear end. Could also be u-joints, but I'd put my money on the rear end install being bad.

I agree with gears out of adjustment. It takes a person with skill to shim them right. U joints and pumpkin bearings usually clunk when bad on deceleration or acceleration not howl.

I wouldn't go racing with this condition. You could ruin a perfectly good posi or stick your driveshaft into the tarmack making car pogo...all bad and expensive.

Solve the problem first. Depends alot on how "loud" the howl is. Balls in a vise loud? Or just a halloween ghostie? You sure you have lube in the pumpkin?