drive train noises

[dusterbd]

so i did a 300 mile trip on Saturday with my 4 speed 70 duster.

car is equipped with a stock, higher mileage, higher abuse 23 spline 4 speed.

also a 8.75, used 489 case (3.55 sure-grip), moser axles, green bearings.

the car has always had a slight whine at light throttle a normal cruise speeds (before and after the gear swap, and normal being 45-65 MPH)

also always had a roar that sounds much like the blades on a helicopter on TV when you push in the clutch and coast.

well, on this trip, both got worse. on the 150 out, the whine all but went away at 70+. the helicopter noises did too, but i think they were cancelled out by road noise and mufflers.

on the way back, it was like riding with a very pissed off, very loud router buzzing right next to my head. all speeds above 35, all gears, and it changed tone with throttle changes. heavy throttle it got deeper, light it got higher. faster got louder. the helicopter noises also got much worse when the clutch was pushed in to give my ears a rest on the downhill stretches.

upon inspection, i have found some debris in the fluid, but no metal like i would expect of a catastrophic failure.

what I'm thinking is this, and i would like confirmation before spending lots and lots of money.

i think that the bearings have gone bad in my hogshead and or axles, causing a bit of odd loading on the ring and pinion, causing them to wear, thereby making the whine.

does that sound right given the description? i really don't know much about rear axles, so I'm asking for help. any other info you need, let me know.

michael

[JVMopar]

First thing I would do if it were mine. Would be to jack it up put it on stands run it in high gear at the speeds where you can hear the noise. Then using a mechanic's stethoscope listen to the rear axle and transmission to determine which is making the noise. Sometimes the noise is transmitted through the driveshaft. Of course with loud exhaust it makes it harder to determine so you may have to adjust the speed in order to hear.

Kinda sounds like you may have 2 noises. With the clutch pushed in kinda sounds like a bad throw out bearing. And the other noise kinda sounds like bad pinion or carrier bearings.

[cudabob496]

The 8 and 3/4 3.91 rearend in my Cuda has been noisy for 15 years. Went from Mopar gears to Richmond gears and nothing changed. Gotten a little quieter over time, but not much.

Fluid levels correct?

Different lubricating fluids or additives can change noise levels.

[Ray Bell]

Originally posted by cudabob496
The 8 and 3/4 3.91 rearend in my Cuda has been noisy for 15 years. Went from Mopar gears to Richmond gears and nothing changed. Gotten a little quieter over time, but not much.....

Or you've started to suffer hearing loss?

You blokes are lucky, you should try driving a Nissan Skyline as assembled in Australia using a Borg-Warner 78 rear axle!

[cudabob496]

Originally Posted by Ray Bell

Or you've started to suffer hearing loss?

You blokes are lucky, you should try driving a Nissan Skyline as assembled in Australia using a Borg-Warner 78 rear axle!

Nope, always use earplugs. Now that I have a 3 inch exhaust, can't hear the rearend at all! Had car for 20 years. If had not used earplugs, would be deaf now!!
You guys down under are coming up on summer! Lucky! You guys got some nasty snakes down there!!

[Ray Bell]

Snakes?

Yeah, I've heard about them, rarely see them. Someone told me they saw one a few weeks ago, I recall.

And the way the weather's been battering us the past weeks I'd be thinking summer's a long way off!

Have you checked my place on Google Earth?

[Dart 360]

I agree that putting foot on clutch it could be the throw out bearing, to eliminate that with car stationary and motor running put your foot on clutch, if noisey then that bearing is faulty. If you have a noise when stationary and you put foot on clutch and it goes away then the gearbox bearing may need attention, this doesn't test the rear gearbox bearing though. What are the axle bearings like?

[dusterbd]

well, i should have said neutral for the helicopter nioise, as it does it with the clutch in or out in neutral.

and ive been hearing it over my 3 inch, so you know its bad.

the axle bearings have no play in them that i can detect at the wheel. they probebly only have about 15K on them though.

Michael

[Ray Bell]

The 'all gears' bit is a bit of a curiosity...

Presumably this is an overdrive A833? If that's the case, a lot of noise should disappear in third (direct) gear.

I'm thinking that perhaps the bearings in the back of the input shaft might be at fault here, though I've no experience with what noises the cluster shaft bearings might cause.

[dusterbd]

its a non od trans. the whine is worse in direct than any other gear, though.

ive actually got a t5 lined up fr this car if the trans is going south.

[Ray Bell]

I'd be betting on you having a cratered shaft for the countershaft... bearings knackered in that part of the gearbox...

When the countershaft is 'loaded', ie. in the indirect gears, the slop is taken up to some extent. But then it's all 'loose' when you put the power straight through the gearbox.

Just guessing, but an educated guess.