rikhemi

I believe I may have a bad diff. I first thought it was possibly my tires but Ive checked them and I cant find any type of nail in them. I hear a clunk or you can say a thump as I increase my speed while driving. I cant even hear my engine at 4k will Im going 50 with this thumping. It kinda sounds like a flat tire but the tires are all ok. Coming home now I do hear occasionally a clunk of some sort like something is kinda rattling. I haven't launched my car for months, I raced a couple weeks ago but t was from a roll. I'm going to have this checked tomorrow to see if they can determine if it a tire or the diff. But if it is the diff, i have a couple of questions..

Is there any way I can tell its the diff thats bad instead of the tires. I was thinking of lifting the car up by the rear and then turning the car on and accelerating to see if I could determine if the noise is coming from the diff. (will prob have a mechanic do it if thats the only way)

Can it be something else other than the diff or the tires.

If there is low fluid for some reason, and I put in more, would the sound possibly stop or is the diff damaged since there was a leak or low fluid and would this cause the gears inside the diff to start falling apart.

If the diff is possibly bad, how long can I go driving the diff.

If the diff breaks, whill the car just stop moving... or will I keep on hearing more clunks..

Thanks for any help

afwfjustin

If the diff is going, you'll hear a whining noise that varies loudness with the speed of the car. Are you hearing whining or clicking or lound bangs?

You can drive it until it breaks. If the diff or gears actually break, the car will not move. This can be dangerous though, for obvious reasons. I wouldn't rule out another possibility, but it may be a good idea to start looking for used diffs in the FS section.

You may also want to look into CV joints and axles - and check the tightness of your lug nuts too. You might have a loose wheel!

rikhemi

Its not really a whine, but a thump. It really sound like i got a flat but there is no flat tire. The noise increases in speed and the sound aswell. At lower speeds, I might hear a small clunk of some sort but its occasional and only at lower speeds.. Might happen at higher speeds but the car gets too loud. Other than that, can it be the wheel bearings? I just dont know why my diff would break if it is that.

negcamber

As I learned weekend before last...the carrier caps on the ap1 can break with enough hard miles. Mine finally let go after 72k miles of autox, track days, Dragons. Not many clutch drops...maybe 6 in 6 years.

The sound my car was making was a feint "whap whap whap"...could only be heard at low speed and while coasting. My guess is that the cap was cracked and allowing the assembly to shift/vibrate causing the noise. The whole thing let go within 100miles of Dragon driving later.

Save yourself some money and get with Jeff Hardtop Guy now about a replacement diff (with upgraded gears if you choose). If yours has not let go entirely, then you may have a decent core, which is worth some money.

rikhemi

I currently have 4.77 installed which were done about 8-10 months ago. I never have auto x the car, and have probably raced it lets say 30-50 times. Clutch drops may be 10 but the last time I did that was 6 months ago at the drag strip.

But i cant imgaine its the diff. there is no whine noise. Hopefully i can take it to firestone tomorrow to lift the rear and then test out to see if the noise is coming from within. Should i change the fluid in case of anything.

SheDrivesIt

Firestone? Maybe you can just have my mom take a look, she knows how to drive a car.

Ed_Grant

Sounds more like CV joints. Had the rear CV joints go out in a VW van once. Made a thump, thump, thump noise. Actually more like a clicking sound.

gomarlins3

I think this should be in UTH.