66RBS

Gents
Re 66 with M20 and undercar exhaust

I recently had my rear transmission seal replaced and the mechanic advised I have a leak at the countershaft. I have searched the archives and understand the countershaft repair. However I am contemplating if this is above my pay grade to move the transmission back an inch to access the countershaft. I don't like working under a car on jackstands.

Assume I only need to disconnect the front universal joint, clutch linkage, trans mounting bolts and lastly the trans to bellhousing bolts.

Can the shifter linkage stay attached to trans? I have an early 66 and the linkage is attached to the tranny. later cars had a bracket on crossmember

When moving the trans back an inch should I get longer bolts to put in the bellhousing to support the weight of the transmission?

Will the transmission input spline come out of the disc at 1"?


Assume before removing transmission to bellhousing bolts I need to support the bellhousing to keep pressure off the input shaft

Regarding the countershaft repair, I plan on using Permatex Ultra Black RTV and a gasket and not driving the car for a day to allow the RTV to set.

Randy

Powershift

You CAN DO THIS JOB.............but from what you say in your post, I would take it to a trans shop that has a lift and a skilled manual trans tech that is familiar with Corvettes.

The only good way to permanently make this repair is to remove and tear down the trans. You interim solution should work and has worked for others.

Good luck.

Larry

Frankie the Fink

On my '63 I just loosened the tranny mounting bolts and the crossmember bolts and took a wooden block and a pry bar and forced the tranny back a couple of inches - that's all...none of the other stuff you mention.

I then made an RTV sandwich with a piece of rubber (toolbox drawer liner) in the middle. I slathered RTV on the counter shaft hole -- applied the rubber Bubba seal and more RTV on top of that then snugged everything together and let it all sit overnight. IIRC that was like two years ago - still no leak.

Here is that thread: https://www.corvetteforum.com/forums...-leak-fix.html

wmf62

a long bolts in one or two of transmission-to-bellhousing holes will help keep the alignment, but is not necessary.

also, clean the area around the countershaft hole to remove the oil, etc before applying the 'patch'.


Bill

Plasticman

I recommed Permatex Ultra Black RTV (available at just about any auto parts store, Walmart, etc.) with no rubber patch required or desired. But clean the area well as Bill stated, and leave sit for a day or so. Clean both the trans cluster shaft hole area and the opposing bell housing area, apply the RTV, and reseat the trans before the RTV begins to set.

The Ultra Black RTV is a superior RTV than most other types, but you pay the price at removal time........

Not a permament fix, but should last a few years, depending on how badly the main case is worn "egg" shaped at the cluster shaft hole.

plasticman

wmf62

a small (maybe an inch wider around the hole, can be square...) piece of thin metal (could be out of the side of a coke can (or beer if you prefer...)) over the rtv & hole will provide a separation media between the transmission and the bellhousing so that the rtv doesn't stick to the bellhousing.


Bill

66RBS

FTF
That's good news. I did not think there was that much "slip" in the slip yoke to allow it to move back that much. In the picture it looks like you got about 3/4".

RE your RTV rubber sandwich was it the diameter of the counter shaft hole or did you use a larger 2" x 2" piece? I think a larger piece will disturb the alignment of the transmission to bellhousing. I was thinking of RTV and a full face gasket approx. 4" x 6" like the one shown in your post and archives. Kinda belt and suspenders approach.

wmf62

if you are using the full aluminum bellhousing, your bellhousing should be smooth and flat in the area o the countershaft. if so, I suggest you use a "thin' piece of metal for the reasons I stated in my in my post; a 4x6 gasket material is gross overkill...

but, do whatever you please....

Bill

Frankie the Fink

I used the black RTV and cleaned the location thoroughly with lacquer thinner; the THIN rubber was just slightly larger than the countershaft opening. Some advised me against the rubber because of alignment but its been a non-issue for 2-1/2 years

wmf62

my concern would not be with alignment but, if the gasket material is too thick, stressing the transmission mounting ear.


Bill

65specialk

It is a grey color . You see it on all Kubota tractors sealing the trans and final drive cases.Used it in my 62 7 years ago and not a drip. Dave

GTOguy

No need to unbolt everything, as stated. You should be able to leave the bellhousing in place, and just loosen the 6 transmission bolts: flanges and cross-member, and slide it back enough to apply some RTV after you use brake cleaner or whatever to clean off the oil. You can do the job with a lot less than an inch of gap, simply by applying RTV wit a putty knife. There is no 'oil pressure' where the countershaft runs in the case....just splash lube, and as the aluminum wears over the years, oil wicks out. A dab of RTV will keep it inside the gearbox. The CORRECT repair is to remove and re-bush the trans case, but an RTV patch will probably outlast most of us.

Frankie the Fink

Precisely....

I used the thin rubber piece on a whim and it worked - prob not necessary

Chuck72

That's how I do it. A quarter inch space, a putty knife, lacquer thinner or brake cleaner, some silicone, are all you need. If it leaks bad, drain it, allow the lube to stop seeping, then clean it and apply goop. An air hose sometimes helps.

Roger the, "RTV patch will probably outlast most of us," comment.

GCD1962

Plugging the end with goo only stops the leak. The wear will continue until corrected resulting in a more costly fix

Frankie the Fink

Wear will continue - but by the time my lil ole 250hp motor stresses that wallowed out hole enough to leak again I will be getting around on L-88 angel's wings...

If I'm a very good boy that is...

66RBS

I understand this. The correct fix is to remove the transmission and have the countershaft rebushed. Tranny rebuild probably around $600 plus cost to R&R the transmission. To fix a drip on a car driven 1000 miles a year I'm OK with Bubba this time.

Randy

wmf62

there is only one true 'fix' and that is bushing the hole and is costly no matter what the amount of leakage'

it took years and miles to create that leakage and it will take more years and mileage to make it worse; more than most of us will be around...

'goo' it up and drive on...

Bill

GTOguy

The seep in the front of the Muncie in my '65 GTO is no worse now that it was 30 years ago. In another 30 years, it won't matter to me....(and it won't be any worse unless I put 300,000 miles on it!)

GCD1962

Or one could purchase a new case from Autogear which corrected the problem.