High-pitch noise from transmission Options

[rjames]

After installing a new clutch which included installing a new flywheel, a new pilot bearing and a new throwout bearing, I am getting a high pitch whining noise in 5th gear @ 2900-3500 RPMs. It also happens a little in 4th at higher RPMs, but it's in 5th gear where it's really noticable. It goes away immediately when I depress the clutch pedal. It's not the same noise that the old throwout bearing made which caused me to replace the clutch in the first place.

It's not crazy loud, but loud enough to be slightly annoying.I never heard the sound before I replaced the clutch. But then again, I had a bad rear wheel bearing that I replaced with the clutch that might have been drowning it out before.

I was thinking it might be some sort of sympathetic vibration, but then I would expect the noise to happen at the same RPMs regardless of what gear I'm in, but it doesn't happen in 1st, 2nd or 3rd and barely in 4th.

Car drives and shifts fine. (no better or worse than it has for the 7 years I've owned it)

Thoughts?

[pcar916]

It goes away immediately when I depress the clutch pedal.
... it doesn't happen in 1st, 2nd or 3rd and barely in 4th.

Silly preliminary question: You did put fluid in it right? Now that that question is out of the way...

1. If you don't depress the clutch and simply decelerate while in 4th, and especially in 5th gear, does it go away or change in any way?

2. When you shift from 4th to 5th does the whine restart and just get louder as you go faster?

3. Is it the same pitch (frequency) the whole time or does it get higher?

4. While in 5th gear, is it the same volume all the time, or does the volume increase with higher speed?

5. While in either 5th and going at a constant speed, will it increase in volume with more acceleration?

Good luck

[rnellums]

I had something like this but it would only manifest under load. It turned out to be excessive wear on the gear on the mainshaft that interfaces with the ring gear on the differential. Dr. Evil told me it was not repairable and would grow worse with time but wasn't catastrophic.

[IronHillRestorations]

If it's the pinion gear, it's going to be pricey to fix that transmission.

[Jeffs9146]

I had the same noise on mine before I rebuilt it and it was the bearing above the pinion gear!!

It fell apart in my hands when I took the trany apart!

[Jakeodoule]

I also had the same problem and it was the same bearing Jeffs9146 is talking about.
Just above the pinion.

[rjames]

The weather was finally dry enough the other day where I could take the car out to answer the questions that were asked a while back:


Silly preliminary question: You did put fluid in it right? Now that that question is out of the way...
Checked fluid level was full

1. If you don't depress the clutch and simply decelerate while in 4th, and especially in 5th gear, does it go away or change in any way?
Noise goes away

2. When you shift from 4th to 5th does the whine restart and just get louder as you go faster?
Yes up to ~ 70mph then above 70 it goes away.

3. Is it the same pitch (frequency) the whole time or does it get higher?
Gets higher

4. While in 5th gear, is it the same volume all the time, or does the volume increase with higher speed?
Pitch egs higher, volume doesn't change too much. Happens only in the ~55mh-70mpg range.

5. While in either 5th and going at a constant speed, will it increase in volume with more acceleration?
Mostly just increases in pitch

So if it's the bearing is this something that I have to address any time soon? I don't to trash my transmission for lack of replacing a bearing, but I can live with the noise for a while if it's not going to hurt anything.

[Dr Evil]

So:

- the noise is present when the pinion is moving the fastest; 4 and 5.
- Increases with pinion speed
- It worsens under load = putting power to the pinion gear.

Looking like a bearing like Jake pictured. This can lead to badness if left alone.

Replacing the R/P is not that expensive as I sell good set for $50, then the labor to install them. BUT, rebuilding a used core is more economical and you usually get some good parts in the core to save $. If I can help, let me know. I wish I had better news, but based on what you are describing it is not so.

[Jakeodoule]

(IMG:style_emoticons/default/agree.gif) You described my symptoms perfectly.
When I drained the gear oil it looked like gold flake paint. With pretty metallic colors.
I would drain the oil and see what it looks like.
If it looks ok put fresh in and drive it for a while.
If it gets louder then drain/check the oil again.
Oil's cheap and you can kinda see the condition of that bearing that way. If you see any metallic flake in it you better think about pulling the gear stack and having a look.

If it were me, I'd just pull it now and fix it.

[John]

Just in case you did not get the clear picture of what seems to be going on, you have wear between your ring/pinion.

In my humble opinion, you would be best served if you were to find a lower mileage 901 side shift transmission to start with.


I have made many comments to my own nephew along the same lines, and even offered to provide a rebuilt box free of charge without response. GreatPumpkin, you know who you are, and I have driven your car. (and I may be able to do two..... Erik, Alex... Bueller... Bueller... Bueller come on, I feel like Ben Stein here.....)

I am your uncle after all....

[pcar916]

Yup. It's gotta be pulled apart. The bearing above... now THAT was makin' some racket. When the pinion bearing gets loose it compromises the R&P contact pattern as the pinion is forced away from the ring. Bad carrier bearings can do the same thing by allowing the ring to wobble and be forced away from the pinion.

Good luck

[Jeffs9146]

Yup. It's gotta be pulled apart. The bearing above... now THAT was makin' some racket. When the pinion bearing gets loose it compromises the R&P contact pattern as the pinion is forced away from the ring. Bad carrier bearings can do the same thing by allowing the ring to wobble and be forced away from the pinion.

Good luck

(IMG:style_emoticons/default/agree.gif)

Just my $.02 but this sounds like what mine was doing with one of the ones I rebuilt and it turned out to be the bearing!

[rjames]

So:

- the noise is present when the pinion is moving the fastest; 4 and 5.
- Increases with pinion speed
- It worsens under load = putting power to the pinion gear.

Looking like a bearing like Jake pictured. This can lead to badness if left alone.

Replacing the R/P is not that expensive as I sell good set for $50, then the labor to install them. BUT, rebuilding a used core is more economical and you usually get some good parts in the core to save $. If I can help, let me know. I wish I had better news, but based on what you are describing it is not so.

Thanks for the quick responses, everyone.

So, any special tools needed for this job? (besides your dvd?)

I don't relish the idea of making room in the garage to take a part two transmissions and hoping that an advertised 'low miles' transmission when combined with mine for parts will = one good transmission.

Are you still doing rebuilds for $500 + parts?

[Dr Evil]

Robert, PM me. I owe you for computer support way back when and can make you a deal (IMG:style_emoticons/default/smile.gif)