differential or lsd issue?
 

Morning Pelican's,
I have an 89 3.2 and have noticed a humm coming from what I believe to be the differential. It increases in volume as the MPH increases but is not sensitive to engine RPM. I can put the clutch in, rev the motor, and it stays the same. At freeway speeds you can hardly hear it but I believe its still there. Any ideas what this might be?
thank you

Have you checked the fluid level? And how are you sure it’s the differential but not the rear axles/bearings?

diff or lsd
 

Yes, the fluid level looks great as does the fluid itself. The axles are both about a year old...
thanks

Diff and gear noises should change, when on and off throttle. How about a wheel bearing?

I have seen worn rear tires make that noise.

Tires?

Hard to suggest anything specific without hearing the noise, but the fact that it persists with clutch engaged and disengaged is somewhat interesting.

I know an individual with a shop up in Santa Rosa:

de Jung Motorsport

I have not engaged that shop, but I know the proprietor and have seen his work. Very detail oriented, experienced and accomplished.

Does it change if you turn slightly left or right while at speed? If it does I'd be looking at the wheel bearings.

diff or lsd
 

thanks to all. it has one new wheel bearing and i'll check the other side. I do know Steve DeJung.
cheers

Good luck!

diff or lsd
 

No it doesnt change sound turning right or left..
thanks

Tyres on mine!

tires
 

The tires are not that old, maybe a year. They are Toyo's R888's. Great stick!
thanks

those tires have a reputation for being loud...

Toyos....

Mr. DeJung has some experience with some Toyo models used in racing settings.

I will never forget following his son, a very talented, experienced and accomplished racing driver, as he tried to use 100% of his Toyos in a race in which I participated. If I recall correctly, I was in no man's land with no cars around in my class so I just hung back to let him race with cars in his class. He was magical dealing with those tires.

We had some challenges with one model of Toyos when it was for a time the spec tire for our PRC Spec 911 class. Caused quite some challenges.

My only experience with Toyos was in around 1997 when I got a set of RA1's free and used them on my hopped up 951 in AX and on track.

In any case, I again wish you good luck!

diff or lsd
 

Thanks Pelican's
i have another set of wheels and tires and will give that a try.
cheers