66ragtop owner

I just installed a rebuilt M-20 in may car. The trans makes a loud whining noise in 1st, 2nd, and 3rd gear. It is also noisey during shifting those gears. The noises are worse the lower the vehicle speed.

The trans was rebuilt by a guy who "specializes in vettes and 4 speeds". I swapped out a M-21 so this trans is new to my car. I had the side cover off prior to installation and didn't see anything that looked wrong.

Does anybody have any ideas what could be wrong? I will be calling the rebuilder up on Monday to see what he will do. This bites, it's no fun doing a trans install a second time.

magicv8

Lots of questions may get you an answer-

Did you replace the pilot bearing? Is it brass or roller?

Does the trans have a new bearing inside the input shaft - between it and the tailshaft?

When you say it's noisy shifting, is the noise a whine or grinding gears?

Do you have 80-90 lube in it?

66ragtop owner

Pilot bearing has 5000 miles on it and was quiet with the old M-21 trans.
The rebuilder says all the beraings are new.
The noise during shifting doesn't sound like gear grind. It sounds like the syncros?
Gear oil is 80-90.
thanks
Brian

396 RAT

Pilot bearing? or bushing?
I found out the hard way yrs ago to lube the bushing so it can wear in properly. Mine made an un-godly noise without proper lube and had to be replaced.
Best solution is a pilot roller bearing.
Not saying this is your problem, just trying to prevent someone from going through the same nightmare as I did.

RGGregory

How many miles have you put on the car since the rebuild? I swapped out my original M21 for a rebuilt M21, and it took about 400 miles for the new gears to quiet down. That may be the case with yours.

v/r
Bob

magicv8

IMO possibilities are:

(slight) worn pilot bushing (not roller) with hole offset due to noncentered transmission input shaft.

(probable) Shift fork/collar noise.

(probable) cluster gear not matched to teeth on 1,2,or 3 gear (as noted above - it may wear in a matching pattern and go away)

(slight) new bearing or thrust washer defective.

66ragtop owner

I like the theory of the gear set not being matched. It really sounds like a gear noise, almost like a m-22 rock crusher gear noise.

I'd be willing to try and break in the gear set, I've only drivin it 40 miles since installation, however there is now gear oil leaking down the front of the trans. This really bites.

I'll try to look at the bright side, I'll be really good at trans installation.

I will let you know how I make out with the rebuilder.

Hitch

Ah just bite the bullet and get the 5spd :lol: :lol: Dave..

magicv8

The gear oil leaking down the front tells the story. The cluster gear shaft is loose in the case at the front - probably the source of the noise too.

TheOman

Yup...If the counter shaft is loose in the case the gears are not traveling on centerlines that are parallel. Never EVER gonna get better if that is the problem. I just FREAKIN LOVE IT..............ANOTHER EXAMPLE OF "A GUY WHO SPECIALIZES IN VETTE STUFF" doing half baked work. Muncie cases are NOTORIOUS for being worn where the counter shaft rides in the case. Better to just stepping up for a NEW SUPER CASE. Whoops can't do that not original shame on me.

As for swapping individual used gears into other used transmissions with other used gears. A buddy of mine passed away and left PILES I MEAN PILES on Muncie transmissions accumulated over the years. A rebuilder came out to bid the "lot' and he did not want to touch ANY separated gears or un assembeled transmissions. All he wanted were fully assembeled COMPLETE cores. His reasoning was "I don't wanna match and mix used gears outta cases that have bad countershafts. When ya do that the funny running pattern worn into the teeth cause nosies later. It is like mixing one ring gear with a pinion out of another rear when NEITHER gera set was set up right in the first place"

On the wall of my work shop:

I Anit in in for the Money
I aint in it for my HEALTH
I anit in in for the glory or anything at all
And I sure aint in it for the WEALTH
But I am in it till is over and I just won't stop
If ya WANT IT DONE RIGHT, you gotta do it YOURSELF


[Modified by TheOman, 10:38 AM 11/3/2003]


[Modified by TheOman, 10:39 AM 11/3/2003]

JoesC5

When I installed a rebuilt Muncie(not a made up Muncie) in my 56 I had gear noise in 1st through 3rd and some in fourth on de-acceleration. When I installed the trans I also filled it with GL-5 oil which was all I could locate. I thought that with a little driving it would be okay. While in O'rielly's getting something else, I discovered they had a couple of bottle of Sta-Lube GL-4 which is better for transmissions(do not use in rear ends) so I replaced the GL-5 with GL-4 and 70-80% of the noise went away(using my calibrated ear) and the transmission shifted easier. Plus, after a rebuild, it's better to replace the gear oil after a short period of time to drain any metal shavings, etc left over from the rebuild.

muncieman

The gear oil leak can be fixed by bushing the case. If it's a numbers deal than it's worth the trouble. The counter shaft is a press fit in the front of the case so it it is leaking it means the hole is over size. As for the noise, it may or may not go away. Mixed gears will be noisy as can matched gears after a rebuild. For my money, it's not worth putting 30 year old plus gears back in the case when complete new sets can be had for $475 for M-20 and M-21 and $550 for M-22 and the new M-22W sets.

In a non numbers deal, replace the case with a Super case. There is no comparison between the stock junk and one of the new cases. You can now buy every piece of a Muncie new and the parts are much higher quality.

Kid_Again

....forget the locals and call ed hartnett @610.623.9381 (lansdowne pa)

.....he is THE best in the business....expect to pay about $100 for the bushing work and god knows how much to fix what bubba did

good luck

muncieman

Rebuilding a Muncie is not real difficult, most guys with the proper hand tools, a way to clean parts and the good sense to ask questions can do it themselves. The case that needs to be bushed gets sent out with the new counter shaft, a no brainer. I've seen plenty of units built by the masters, they don't do anything that I can't do.

I wonder what an average rebuild from one of these guys cost?

Kid_Again

...yeah, i can rebuild anything i set my mind to but just don't want to get in over my head with a tranny...set aside about $500 for a rebuild when all you do is replace the "soft parts"...i take theOman's point about all the alleged experts out there...ed is great, has quick turnaround and an EXCELLENT reputation

...ANYTHING with that many itsy-bitsy little roller bearings is something that is sent OUT from my garage in one piece :yesnod: ...to be RETURNED in one piece (he did both of my M22s, no problems whatsoever)

muncieman

I'm way to cheap :eek:

I only get about $300 for the same job, just a complete kit with new counter shaft. Been doing them for 30 years, had to so I could keep racing a Z/28 that ate them for lunch. 8K off the starting line is hard on parts. Never had one come back in all that time, must be dumb luck :thumbs:

65tripleblack

The pilot bearing/bushing will only make noise when the clutch is disengaged....when engaged the crankshaft turns with the input shaft. If it is gear whine (that was also my first thought, like M22 straight cut gears), then the mesh between the mainshaft and cluster shaft is improper. It sounds like your rebuilder mucked up somewhere, especially if he didn't bush the hole where the cluster shaft is pressed into the case.
When I rebuilt my 1965 M20, close ratio, I replaced the 7/8" cluster shaft with a 1" shaft ang gearset from a 1972 unit. The machine shop bored the cluster shaft hole from a sloppy, leaky 7/8" to a nice tight 1". We also moved the centerline of the cluster shaft CLOSER to that of the mainshaft, for a deeper gear mesh. The trans is absolutely quiet, and shifts smooth as silk. :thumbs:

Joe

Kid_Again

that's a great idea, thanks

magicv8

The only reason I asked whether there was a brass bushing is that an imbalance or misalignment will wear the bushing hole into a slot - alowing misalignment of the input shaft and noise as the cluster gear is driven by a misaligned gear.

In that way - I have actually SEEN (the damage) and heard bushings that can cause noise that the clutch clamped under the plate. Some times the noise is intermittent - depending on the level of misalignment when the clutch pedal is released. Thats why I prefer the stronger roller bearings originally prescribed for diesel 350s.

66ragtop owner

I drove the car last night and I think the noise is getting worse. When the car is running in neutral you can hear a rattle type noise coming fromt the trans. It sounds like something is coming apart. The gear whine sounds way too loud to be a gear macthing problem. It also makes a strange noise when shifting 1st to 2nd and 2nd to 3rd.

I called the "rebuilder"and he is going to build another trans for me. He thinks it could be a bad input bearingor shaft. He said the pin was a tight fit in the case and doubts that is the cause. He said the gear set is a matched set. At this point I don't care what the cause is just so the next trans is quiet and works. He says he has rebuilt over 300 Muncies and will stand behind his work.

I had a M-20 I bought in peices and was going to rebuild myself but had second thoughts. I figured if I bought one from a professional I would have a trouble free operation.

Thanks for all your input. I will let you know how the next trnas works.