My brother in-law has a Muncie with the counter shaft leaving a witness mark on the bellhousing where it's been hitting or possibly turning. He recently pulled the engine out and the shaft is about a 1/4 inch deep in the case so obviously the shaft is moving back and forth. It also leaks pretty badly. He's thinking about cutting a 1/4" off an old shaft and tapping it in along with some type of rtv to seal it up. Will this work or what's the best fix without taking the trans apart? Thanks for any help.

There really is no good fix without taking the trans apart. It is one of the most critical area's of case strength and gear survivability.

If the shaft is moving, that means at the very least the case is stretched at the press-fit hole the shaft fits at each end, which is generally bad because the holes in the case stretch down more than in any other direction, making gear mesh tolerances between the main input and main speed gears to the cluster gear worse....and that is what breaks the gear teeth.

Even worse is it the bearings in the cluster are so bad the cluster gear is actually trying to turn the counter shaft, and if the case is so loose that it allows that to happen....you're running deeply on borrowed time .

Best to pull it and fix it before he really ruins it.

Stuffing a cut off piece of old shaft in the front means that there is now 1/4" less support between the case and the shaft...and at the end that see's the most force trying to drive the cluster and input shaft gears apart when power is applied. Not a smart move to butcher this together.

it needs to come out of the car, tore down and either replace the case and the countershaft(and anything else bad) or at the very least the case reworked with the original shaftholes bored oversize on the correct centerline and press fit bushings installed to hold the shaft tight.

^^^^^ X2 per Eric above. If you do afro-engineer it chose your RTV with care. Gear lube is especially hard on regular RTV. Permatex use to make a specific formula for gear lube. Aside from that ultra-gray or the right-stuff. Good luck.

Ron, actually the best fix is to sell the car.

The RV "Fix" won't work and neither will cutting off a second shaft and stuffing it in the case to stop the leak. By now the case is junk and the end is near.

This is a hand grenade with 98% of the pin removed. Get it out of the car before something serious happens. Parts for that Muncie are not cheap. If you are determined to replace it get one with a 1 inch shaft. There is a boss on the lower right side of the case, drill a h0le in the boss and install a 1/8 drain plug so you can change the gear lube from time to time.

Bob

If push comes to shove
I have been sleeving the counter shaft holes for some companies that build/update/rebuild the Muncies.
You will need a new shaft.
I only need the bare and CLEANED case.

Chances are that once you tear it down you will find other things that need updated.

Muncies may be old and crude by today's standards but they still need some experience to get right. If you don't have the experience you may want to seek a specialist.
I am not it BTW. I just do the special repair/machining.

Thank you all for the comments and advice. He's having a 327-300 sbc machined to go in this Vette so now's the time to pull the trans and do it right. I will pass along all the comments.

Yea got to save that muncie.Kind of like moment that are being torn down its part of history and a cool part.