Help Identifying Drivetrain Noise?

[fawcett]

I'm almost 100% positive its comming from the rear end. I get this pretty loud noise comming from my drivetrain. It sounds like a (lightly vibrating) whining noise which gets louder as the engine's RPM's either wind up or down (read on or off throttle while in gear). It gets quieter as the drivetrain's RPM's match the engines. Its still there when the clutch is depressed but much much quieter.

The reason I think its comming from the rear end is because I changed my diff. cover and put 2-3 times the amount of fluid needed and ran the crap out of the car for a couple weeks before realizing the mistake I made. Its got the right amount of fluid in it now buuuut its also got that noise.

I'm going to take it to a shop this week but not knowing how to identify the noise and problem is killing me.
Any ideas?

Fawcett

 

[toyman]

I'm almost 100% positive its comming from the rear end. I get this pretty loud noise comming from my drivetrain. It sounds like a (lightly vibrating) whining noise which gets louder as the engine's RPM's either wind up or down (read on or off throttle while in gear). It gets quieter as the drivetrain's RPM's match the engines. Its still there when the clutch is depressed but much much quieter.

The reason I think its comming from the rear end is because I changed my diff. cover and put 2-3 times the amount of fluid needed and ran the crap out of the car for a couple weeks before realizing the mistake I made. Its got the right amount of fluid in it now buuuut its also got that noise.

I'm going to take it to a shop this week but not knowing how to identify the noise and problem is killing me.
Any ideas?

Fawcett

I doubt if it's related to overfilling the diff. Not sure that you can really do that, especially in the amount you indicate. It's more likely that you may have chipped a tooth on the pinion or ring gear.

 

[fawcett]

Oh it is possible to overfill the diff.
I got a T/A cover and used the wrong filler hole.
The directions said to fill the diff. until fluid comes out of the hole.
I used a hole at/near the top of the diff.
I think I used like 4 bottles of Royal Purple diff. fluid. Doh!
Then I ran the car real hard on the highway on the way to the track-raced it-then drove it home.
Driving it home was when the noise started up.

 

[True 5.0]

Does that TA cover have the preload screws? Did you overtighten them?

 

[TrueBlue95GT]

If its dependant on engine speed, its definitely not the rear end. That sounds more like transmission. Check for leaks, especially where the driveshaft enters the rear of transmission. There's a seal back there that commonly goes first.

 

[fawcett]

Hmmm, I hope my trany didn't drain itself. What would need to be replaced if the trany was ran without fluid in it? I've never checked its fluid level so now I'm concerned about it. Its the best mod on the whole car!

So the noise I hear definatly sounds like gears meshing together. If the clutch is depressed will the drivetrain assembly continue rotating? I ask because the noise is still there when the clutch is depressed, although it is much quieter.

 

[TrueBlue95GT]

If you're standing still and the clutch pedal is pressed, nothing inside the transmission will move. If your in neutral, stopped, and the pedal is not pressed, the input shaft will turn with the engine. If your driving, with the pedal pressed, the output shaft will be spinning at the same speed as the driveshaft and everything after. If the clutch is not pressed and you're driving, the input shaft will match engine speed and the output shaft will be multiplied by the transmission gear ratio in everything other than neutral.

 

[fawcett]

So I may have an input or output shaft bearing which went bad?
I'm going to get it into a shop very soon.
This is a bummer, I thought these D&D T-56 tranys were bullet proof?

 

[TrueBlue95GT]

If the sound changes with engine speed and not vehicle speed its something before the output shaft. If the sound doesn't change with different gears, I would bet the input shaft bearing is the culprit. Check the fluid before you take it to a shop though. It might just need fluid and no damage was done.

 

[94 Black GT]

CHECK YOUR DRIVESHAFT BOLTS..last time i changed the fluid in my diff i happened to look up and see that 3 of my driveshaft bolts were loose and once i tightened them that noise that i had been hearing for a while was not there anymore..just another thing to check..process of elimination..hope it helps

 

[fawcett]

After letting the car sit for a while in distaste, I've started driving and working on it again.

I've just gutted the interior and I can hear the noise more clearly. It's comming from the transmission. I changed the fluid last night with Royal Purple. The shifts are nicer but the noise is still there. My Haynes manual has a trouble shooting section and it suggests to check the trany fluid levels, u-joint bearings and it also suggests input/output bearings on the trany.

Looking at the trany, I dont think its lined up right. While under the car, I used D&D's t56 brace as a visual guide and the trany seems to be twisted to the passanger side. From inside the car, the shifter in the transmission tunnel is cocked to the passanger side so much that I can't put a 13mm socket on the front right corner of my shifter. To get to it I'd have to clearance the hole for the shifter.

When my motor was put in, the stock motor mounts were used. I fear one or two of the mounts went bad and started the misallignment.

D&D told me to take the trany out and send it to them but do I really have to? Its going to cost hundreds to ship and I don't even know where to find a suitable container. Are local speed shops not good enough?

I'm going to have the u-joint checked out but I think this is going to be expensive.