4 speed experts: Diagnose noise
Thread Starter
Safety Car
Joined: Mar 1999
Posts: 3,715
Likes: 1
From: VASS, NC, USA
4 speed experts: Diagnose noise
4 speed:
I have a whining noise I have isolated as being the tranny, not the clutch engine, u joints, or rear end.
It only comes when the engine is in gear, and under a load. In other words, I'm in gear, and pressing the gas. As I go faster with the gas down and in gear, the whining gets louder. But if let off the gas, or coast IN gear, or if I push down the clutch while driving, the whining goes away
It doesnt occur at idle, wether in gear or not. Only when applying the gas
So the whining is only when the tranny is under a load, with the gas pedal down.
Its fairly loud
I beleive its the input shaft bearings in the tranny about to go.
any ideas?
I have a whining noise I have isolated as being the tranny, not the clutch engine, u joints, or rear end.
It only comes when the engine is in gear, and under a load. In other words, I'm in gear, and pressing the gas. As I go faster with the gas down and in gear, the whining gets louder. But if let off the gas, or coast IN gear, or if I push down the clutch while driving, the whining goes away
It doesnt occur at idle, wether in gear or not. Only when applying the gas
So the whining is only when the tranny is under a load, with the gas pedal down.
Its fairly loud
I beleive its the input shaft bearings in the tranny about to go.
any ideas?
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
Melvin, I thought you had the trans out of the car. Is it back in? Did you figure out if it is M-21 or M-20? I have an easy method to tell which it is, but you have to be driving the car.
Race Director
Joined: Nov 2006
Posts: 13,258
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From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
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Cruise-In VIII Veteran
4-speed whine
You can talk about this for years. just pull the thing out and tear it down. we can keep guessing but you know you have a bad bearing in there. I pulled out the 4-speed in my 77 last year at home with the car on jack stands. NO FUN. Good luck!
Le Mans Master
Joined: Aug 2000
Posts: 6,362
Likes: 7
From: Brazos TX
Cruise-In IV Veteran
Cruise-In V Veteran
I concur with rotgirl and either way the mid bearing may be going as well. It sounds like it may be time for a rebuild. Make sure the 4 bolts connecting the transmission to the bell housing are tight. If they are loose it may cause that noise and it will destroy the input shaft and cluster gear...I have experience with that little scenario.
4-vettes, what are you talking about? It takes maybe an hour to pull the transmission with the car on jack stands. It's no problem. Air tools help.
4-vettes, what are you talking about? It takes maybe an hour to pull the transmission with the car on jack stands. It's no problem. Air tools help.
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 439
From: Wellington, FL
St. Jude Donor '11 thru '25
Without actually listening to the whine, it's very difficult to determine the problem, if there really is one. I had a '67 that had what I considered a bad whine, so I took it out and tore it apart and had a knowledgable friend look at it. He pointed out a slight problem with the input shaft bearing and a couple of other problems. I then took it to widely respected tranny builder/rebuilder who went thru everything and made the following comments:
This tranny is almost 40 years old and while naturally having some wear, it is in overall good condition. Keep in mind that these trannys do have a tendency to be noisy. You could replace all the bearings and the whine may end up still being there.
Well, since I had it apart, I replaced all the bearings and a few other items; the end result...the whine was still there. Hope this helps and good luck with it.
This tranny is almost 40 years old and while naturally having some wear, it is in overall good condition. Keep in mind that these trannys do have a tendency to be noisy. You could replace all the bearings and the whine may end up still being there.
Well, since I had it apart, I replaced all the bearings and a few other items; the end result...the whine was still there. Hope this helps and good luck with it.
Last edited by Jud Chapin; Dec 15, 2006 at 09:17 AM.
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Racer
Joined: Jan 2004
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From: Everfrost Second Life
Bearings when bad, don't whine, they growl erratically. Check your fluid level. The oil level if low in a ST10 or Muncie will usually scuff up the main drive gears, and the 2nd and 3rd sections.
Paul
Paul
Race Director
Joined: Dec 1999
Posts: 16,945
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I agree, check the easy stuff first, just as an example, the tranny in my DD started whining, I looked at the fluid level and there was less tan a pint of oil in it (case is leaking because the shop messed up a sealing surface when they worked on the tranny at some point), added oil, no more whine.
