# 4 speed noise



## MAP53 (Nov 10, 2013)

As I get to know my new to me GTO I seem to keep finding out things that I have to learn. First of all this is my first GM in a bunch of years so I am not familiar too much.

My transmission is a 4 speed and works flawlessly except there is a noise in first gear. The only way I know how to describe it is a sound like a old truck with a granny gear makes in 1st, kind of a waa waa waa thing. If you start out slowly and don't apply much torque it is quiet, all other gears are quiet and it up and downshifts real nice. 

The last GM 4speed I had was in a 79 Corvette about 25 years ago and I don't remember it making any noise at all.

My car has the standard engine with 3.55 rear gears.

I suspect there is a bearing or something not quite right. I have checked the fluid and it's full with no leaks.

Any advice would be appreciated. 

Thanks
Mark


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## allpawl66 (May 9, 2008)

Pull it before something breaks , could be a bearing . Easily detected upon inspection .


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## MAP53 (Nov 10, 2013)

That is my thought, boy there are a bunch of monkey motion linkage down there, my reverse lock out is still hooked up. I guess I got spoiled by the new transmissions with the shifter that sticks out the top.


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## SCG Pontiac (Feb 23, 2014)

you didn't mention which transmission you have . The m 22 " rock crusher" close ratio trans can sound like a school bus in first especially hooked to a low geared posi.


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## leeklm (Mar 11, 2012)

as mentioned, the m22 with straighter cut gears will make more noise. My first guess is not a bearing if only making the noise in one gear. You only have two main bearings in a Muncie, and they are both spinning at all times. Other than that, you have a few roller/needle bearing sets, but again, they are always spinning as well. 

I am not a tranny pro, but have had mine tore down a couple of times. I had a "whine" in 3rd gear only, and was nothing obviously wrong. I found a receipt from previous owner where a tranny shop replaced the 3rd gear, likely because of the noise. However noise was still there. I ended up replacing the counter gear while upgrading to a 1" counter shaft. Noise gone.

My first guess is something going on with the 1st gear and/or counter gear cluster.

On edit... the M20/21/22 are relatively simple transmissions. With a book, basic hand tools, and a press for removing the speedo worm/drive gear, most backyard mechanics can perform a basic rebuild with ease. In addition, there are great parts resources online to obtain any and every part you will need. Places like Riverside Gear will even provide you with a little phone assistance if you buy your parts from them.


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## geeteeohguy (Feb 2, 2008)

A whine in only one gear is probably a gear tooth wear issue or a possible replacement gear. A bearing issue would affect all gears except 4th, which is direct. You can pull the side cover with the trans in the car and inspect the gears visually. My bet is you will find nothing obvious. If it were me, I wouldn't worry about it. If it bugs you, pull the trans and overhaul it with new bearings and syncros, and have a pro inspect the cluster gear and remaining gears.


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## MAP53 (Nov 10, 2013)

I have a M20. I did some research and communicated with Paul Cangialosi of 5speeds.com who is a authority on Muncie transmissions. He says my noise is not uncommon. It apparently is caused by first gear going back a tad too far and rubbing on the face of the reverse idler gear. This is due probably from a worn 1/2 shift fork that lets the 1st gear go too much to the rear. He says a rebuild is not necessary and a new 1/2 shift fork should fix the noise. He also says it won't hurt to drive it that way. I am going to order a fork and the necessary gasket and give it a try. 

When I drove it today I did make the noise lessen by pulling on the shifter while driving, so the worn fork theory seems plausible.

Mark


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