Vet76te

Hey Guys, my stock M21 4spd is noisy. It makes a “whirling” sound in the first 3 gears....but it’s quite in 4th gear. It does NOT grind, does NOT jump out of gear, does NOT show any problems other than a circular sounding whirling sound as I run through 1st, 2nd and 3rd gears.

Anyone have any idea what this could be?

PainfullySlow

Any kind of whirling sound would have to be a bearing however the M21 is famous for being a noisy transmission. Is this a new sound? Or are you just new to owning/using this trans?

Vet76te

I’m definitely not new to C3 Corvettes nor M21 4spd transmissions.....but I’m new to THIS Corvette. I just bought it today.

I have another C3 with the same engine and transmission, but it is very quite through all the gears.

keithl1967

Could be the pilot bushing/bearing, or the throwout bearing...

Have you messed with it to see if the clutchfork is properly adjusted?

forman

maybe its a m 22

CanadaGrant

A whirring or whining noise that changes pitch with RPM in 1st, 2nd and 3rd but quiet in 4th is an indication of worn gears due to lack of oil. With a low oil condition under acceleration it all runs to the back of the transmission and starves the main drive section of lubrication. This causes extreme wear on the faces of all the gear teeth except 4th gear.

forman

not if its a m-22 lol i had some drinks

derekderek

that is the bearings in the cluster gear. once in fourth they spin free instead of being loaded. pilot bearing or throwout bearing make noise when shifting or standing still with foot on clutch. check gear oil level. out of oil will make this noise. don't drive again til you are sure there is gear oil in there. if it has enough oil, don't drive it hard or much. get it in 4th as much as possible.

NeverTooOld

A whining noise in first through third gears is normal for a four speed because the first three gears use the counter shaft with fourth gear being a direct drive that locks the input shaft to the output shaft.

JoeMinnesota

I love the whine of the Muncie, and that characteristic brought back memories when I got my C3 early last year. If you're concerned, check or change out the fluid with fresh stuff. After that, if it's working perfectly and shifts smoothly, drive it.

gg521

There are two places you can call that are EXPERTS on Muncie transmissions. One is 5speeds.com and the other is Auto Gear.

derekderek

the whirring noise gets bad as trans goes bad or dry. I think OP is mentioning it cuz it got louder than before...

jim-81

Mine does the same thing and always has. Hasn’t gotten any worse and runs great.

CanadaGrant

If 4th gear was also noisy it would be from wear/mileage. With 1st, 2nd, and 3rd noisy but 4th not, it's not bearings or anything other than being run low on oil for a lengthy period of time somewhere in the past. There is no front seal on a Muncie. If it's overfilled it will leak through the front bearing and out the front of the case. It runs down the inside of the bell housing, drips out the bottom and will do the same with normal oil level if parked on a down hill slope for a length of time. Too much oil in a Muncie and it will let you know by the drops on the garage floor and too little oil will also let you know soon enough by gear noise in every gear except 4th. Too much oil corrects itself. Too little oil doesn't and wears the first 3 gear faces which requires gear replacement. I have the same with mine but it isn't overly noisy. It's a nice smooth gear noise in all but 4th and sounds fine to me. Since it's the original trans in a 69 numbers matching 427 car I have just left it alone but if it gets bothersome a new gear set will be in order.

Highlander1732

David’s 4 Speeds in Wisconsin rebuilt my tired M-21 a few years ago. It was in my ‘60 Biscayne with 455hp and easily handled everything thrown at it. Fairly inexpensive ($1300ish if I remember correctly)...

sparky77

It might be the PO put synthetic gear lube ,the older transmissions need the older type gear lube.