Xentrix

I just finished up my TII drivetrain conversion in my 89 gxl. I've put about 50 miles on the car but I've got to get a new starter. My thing is this... while driving the car there is this spinning sound, a whirrrrr that is noticable. It is obviously coming from the back of the car. My TII rearend came off a car with about 90k on it, but the car has always had redline in it. During my install I drained the lsd and refilled with redline. The lsd has been sitting for a couple years though, but sitting in a barn would be better than being driven wouldn't it?

Is the whirring sound normal for a lsd that has brand new redline fluid?

ViperKillerWannabe

It's a clutch-type right? If it is, the clutches could be going bad, but I think they'd last longer than 90k... Maybe it was abused?

Rotary Racer

Correct me if I am wrong but I thought the 1989-1991 TII were Viscous L.S.D's? I know my GTUs is a 4.30 Viscous L.S.D.

When you hear the sound do you feel any vibration?

Xentrix

ok... the lsd and tranny are from a series 4 tII car.

No there is no vibration from the rear, just a whirring sound. The faster I go, the more I hear it, when I slow down the whirr slows down.

Hot_Dog

Sounds like the classic symptoms of rear wheel bearings going bad. How many miles are on the RWB's? I've found that the RWB's usually have an average lifetime of about 100K miles. Of course, some may go longer than others.

I've had bad experiences with Mazda rear ends. I had to replace the original rear end in my 90 GXL after only 140K miles. Problem was excessive backlash and severe vibration that would intensify with speed. I replaced it with a low mileage (about 60K miles) LSD out of an 86 GXL. At about 220K miles later -- that's 140K miles on the LSD -- I changed the rear end again. The problem was noise and a mild vibration. I repalced this LSD with another new S4 LSD that I managed to pickup at a reasonable price. The new LSD was from an AT car since it had a 3.909 gear set. I have a 90 GXL with MT which uses a 4.100 gear set. I decided to replace the 3.909 with a 4.300 gear set. Having started with a brand new rear end, I've come to the conclusion that Mazda doesn't know how to setup their rear ends. Upon pulling the new rear end apart, I've found that both the backlash and the pinion depth weren't set correctly at the factory. There was too much backlash, and the pinion wasn't set deep enough, according to my measurements. Now, the pinion depth setting will determine how noisey the rear end runs. The rear end that I put in rides really quiet compared to all the factory assembled Mazda rear ends that I've had experience with.

Aside from that, a high-pitched whirring sound usually indicates that the noise may be coming from the drive pinion bearing. A bad ring gear bearing will usually make a low pitch rumbling sound since the ring gear turns much slower than the drive pinion. I would suggest first checking your RWB's as a possible cause of the vibration.

Hot_Dog
90 RX7 GXL
02 RSX-S

Xentrix

I doubt it is the bearings, the car didn't make any noise until the new rearend went in. There is no vibration, just a whirrrr sound.

Spawn VII

maybe a fluid problem? needed lsd additive or low on fluid or somehting?

slow87turbo

my car does the same thing... the winning sound like a school bus rear end. my car has 150k on it.


ej