Diff making grinding noise.

[SrBigbutt]

Ever since I got my Supra running I could hear some grinding coming from the rear of the car. First I thought it was the brakes, but I got the master cylinder fixed and they are not sticking. I put the rear on jacks and put it in drive and its definately coming from the Differential. I can hear it more on the passanger side.

So I decided to drain and replace fluid. It did not smell to bad. I used Royal Purple for LSD and i'm still getting the same grinding noise. I've read a lot about Ford fluid and friction modifier for high mileage diffs. Do you think this will make a difference? Or are my bearings shot?

 

[grimreaper]

not likely that ford fluid will help if your already hearing noise... gear whine maybe, but not grinding.

 

[mk3sons]

my differential grids too but only when i turn and my mechanic said it was fine. i think he full of bs

 

[SrBigbutt]

Mine pretty much grinds all the time. I'm thinking it may be the bearings. It seems to still work fine. I still get 2 wheel burnouts. I don't know about on turns though.

 

[OfnaRcR4]

would that ford additive help the LSD grab though?

 

[Poodles]

Nope, the friction modifier actually makes it more slick. SO add it until the chatter goes away.

Grinding could be any number of things in the back (lots of joints/bearings), are you sure it's the diff?

 

[SrBigbutt]

Nope, the friction modifier actually makes it more slick. SO add it until the chatter goes away.

Grinding could be any number of things in the back (lots of joints/bearings), are you sure it's the diff?

No, i'm not 100% sure its the diff. It doesn't sound like its coming from the wheels. Definately around the diff area. I have to jack it up again and test it again. What should I look for?

 

[Poodles]

Well, you have the bearings in the spindles, the half shafts, and the diff.

Bearings in the spindle are the most likely to go out. The half shafts last damn near forever if they stay sealed, so check for tears in the boots. The diff could be a number of things, but check play in the pinion (cost cutting design in how they set bearing preload on the pinion with a crush sleeve, it sucks). An automotive stethascope will help.

 

[SrBigbutt]

Finally had some time to jack up the rear of the car and try to find where the noise is coming from. Its definately not coming from the wheel bearings. I have no play in the wheel and everything seems normal there. I do hear a little coming from the CV Joint on the half shafts when I'm turning it by hand. There is no play, but I can hear and feel a little bit of vibration under the boot. I can hear it on both sides. A little more on the passanger side. Drive shaft doesn't make any noise and doesn't seem to have to much play. I don't hear anything from the diff itself.

When I turn it on and let the wheels spin freely i just get loud whirring noise and can't tell where its coming from. Sounds like gear whine maybe. I don't hear the grinding noise as much anymore.

I'm confused now. Could be worn diff. Car has 153K miles. Could be half shafts. I feel some vibrations over 60mph as well. But that could be because of the tires. They are brand new, but 10 years old. haha.