Diff just started whining!
 

Hi all.
I have a Cusco LSD with 4.08 gearing and had it all rebuilt with new bearings, etc, a couple of years ago including new Whiteline bushes that support it. It has been well serviced as far as oil changes go and when it had just been done there was a little bit of whining which went away after a few months as it "ran in" I guess. It has been nice and quiet till now. I very recently did a (long) bit of wheel spinning in the wet over a fairly long distance under quite a few revs and it has now suddenly started whining pretty loudly, much more than it ever has. Could something have moved or failed with it's internals? :mad:
Regards.

Check for diff fluid leaks, may be running dry?

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Thanks for your reply and I will check that.

No problem, my Titan had that problem, but the diff didn't have a bolt, just plugged with sealant from factory. I'm sure the Z has a drain bolt but maybe it came loose or is gone.

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God I don't think so and hope NOT!
No leaks !

Has anyone got any proper input? :wtf2:

Change the fluid with a good synthetic oil. Check the magnetic drain plug for debris. When you drain the fluid starin it and look for chunks of metal. There should be some metal on the plug but if there is a lot then there is probably something wrong. If you were doing a long standing burnout then you might have over heated it. If the whine is there after then take it in.

Thanks for that and yes I've taken the car to my mechanic to have it checked out.

Did you do a roll-back ??

eg: reverse back, car moving backwards, select first and dump the clutch for a spec'cy launch ??

Shock loads might have chipped a tooth on the ring-gear.

Check for something more than just filings against the oil drain plug.

Alternative is to stick a bore-scope inside the diff and check the teeth faces ....

Sudden change in noise in the diff is rarely good news (but you might create history).

LOL, no roll back, although I did some great ones in my Mum's Datsun 180B many years ago and broke nothing.;)
I dropped the car off at Revzone (who do all my work) this morning and they have just rung me to say the noise occurs in neutral as well so they will be dropping the diff for a proper inspection. I'm sure it's not leaked any oil and is running dry. Perhaps a bearing has failed? :shakes head:
Thanks for the feedback BGTV8 as it's all still very interesting to me. :tiphat:

as mentioned,i'd change oil & inspect fluid that comes out.(for metal or shiny look) can even send off & get an oil analysis.
Be sure & use an oil that has the friction modifier in it for the clutches...

Sooo .... your's was the grey rocket at Molan Street today ......... I was in there checking on my engine build around lunchtime ........ still sorting all the details of dummy assembly ..........

Be interested in the diagnosis in the end ..........

Why yes it was! The filthy one that needs a wash.:eek:
Yes I will post here on what the diagnosis is.

Update on diff whine diagnosis:
 

A few days before the whining started I drove over what turned out to be a piece of square steel tube about a foot long that I thought I would clear! Big FAIL!!! I went over it right in the middle of the car and there was a couple of big horrific bangs! The car kept driving normally and there were no new noises. I has a look underneath and saw that the rear tunnel brace was a little damaged and a small dent in one of the exhaust pipes. After an inspection by my mechanic I'm told that it appears that the end of the tail shaft/front of diff was hit by it. This has somehow damaged the front diff bearing which is now causing the whining noise after a few days. A small camera was poked into the diff and the crown wheel and pinion appear ok, but the diff will have to be taken apart to fully check, have the bearing replaced and anything else that may be damaged and then all rebuilt again. The drive shaft itself will also need to be checked and possibly rebalanced.
I would have never called this! :shakes head:

Good you got to the bottom of it ............