Coup D E'Tat

iTrader: (2)

I have a T56 from an '02 in the Miata, and under load only in 5th and 6th, it whines pretty good. If I let off the throttle, it goes away entirely. Is this normal? It's loud enough that I could imagine it being quite an annoyance on a trip. I was told it may be the rear end (Ford 8.8" from an '03 IRS car,) but it really doesn't sound as if it's coming from there, and as I said, it's only doing it in 5th and 6th it seems.

~3.5 quarts of Synchromesh are in it, and I believe it only has about 42k on it. Shifts fine.

thesource

iTrader: (60)

Sounds like the diff to me . The IRS units are well known for making noise and Ford has had alot of issues with the Explorer IRS units . Their solution is to change the ring and pinion but the noise is still there . I believe that diff in that configuration is just noisy . The aluminum housing does not help anything either .

Coup D E'Tat

iTrader: (2)

Hm. Any reason why it would do it in 5th and 6th only though? I'll have to take it out again tonight and triple check this, since perhaps in the lower gears (slightly higher RPM,) I just can't hear the whine over the exhaust.

If it is the diff, has anyone tried wrapping it in sound deadening material? Because I sure as heck will be The whine is definitely annoying!

thesource

iTrader: (60)

Well 5th and 6th gears are spinning the diff at a much higher speed than the lower gears for one . Typically , a transmission will not stop whining when you let off the gas and most of the time they make noise in 1st-3rd , gets quiet in 4th and then makes noise in 5th-6th . The only time a modern 5 or 6 speed makes noise in 4th gear is if the rear output shaft bearing is bad or maybe the front bearing is toast . That noise is more of a growl and not a whine .

snketr

iTrader: (3)

What you are hearing is prob the normal minimal whine. It's just magnified in your car b/c it's a cramped space and you prob don't have any sound deadener to suppress the sounds.

thesource

iTrader: (60)

That probably has some to do with it . I would also check the pinion angle on the diff as well and make sure its where you expect it to be . With a shorter drivetrain , you have less margin for error .