Scary sound coming from the rear

[Burntz]

Iv been having a serious sound coming from the rear of the car. It does this all the time over ~ 5 mph. Accell, decel, whatever. Its a grinding, thump thump thump noise.

I knew the brakes were garbage so I just put on entirely new rotors and pads, properly lubed the slide pins, all caliper pistons moved freely.

The 18" rx7 wheels were slightly rubbing, I "clearanced" that area a bit. When the car was in the air I spun the rear wheels and it didn't feel overly rough or hard to turn.

My main candidates are a wheel bearing? Or could it be the diff? I didnt see any obvious suspension issues (IE: broken).

Help?

 

[importracr317]

You can check the bearing play by jacking up the rear end and shaking the rear wheels from side to side. If there is a lot of play, it's a good indicators of worn bearings....the only real way to tell though is disassembling the hubs. Worn wheel bearigns don't typically make a grinding noise though...it's typically just a dull droning sound that is present all the time, regardless of speed.

Could be the diff. Drain and inspect the fluid and the plug for metal flakes or chips.

Good luck.

 

[Burntz]

I did give the wheels a shake when it was up in the air, no play.

I think I might have to do that. What fluid is recommended for the rear?

 

[importracr317]

I did give the wheels a shake when it was up in the air, no play.

I think I might have to do that. What fluid is recommended for the rear?

I'd start looking at the drive train components then.....

You'll get a ton of opinions on which diff fluid to use. I'm a fan of Royal Purple, the 75W90 stuff....other people use Redline, Mobil 1, etc, etc. Gear oil is gear oil IMHO.

 

[Burntz]

The weird thing is that a week or so ago, it was a weird steady noise, accompanied by a steady "vibration.. nothing.. vibration..nothing.. vibration". Now Im hearing so popping / scarier noises. Blah, suspension is not my forte.

 

[98zx23369]

it could be the drive shaft support bearing. they make the sound your describing when they are realllly gone. or have you checked your transfercase fluid?

 

[eli96talon]

My friends gsx 2g would make a thumping noise in the rear also..one day he brought it to me to check and it turned out that the bolts that hold the diff. In place had came loose so it would move around and hit surrounding objects causing the thumping sound.

 

[Burntz]

I didnt really think about it, but rear cv shafts? Trying to do some research. Hope its not, because they seem to be impossible to find.
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its raining, but I said to hell with it and jacked up the rear. All the boots look intact and grease free.

I went to grab the drivers rear and it felt rock solid.

I went to grab the passenger rear..... and almost a 1/2" of play in and out.

my attempt to video the problem

bbbc8d72.mp4 video by xBurntzx - Photobucket