The Stovebolt Site Forums The Shop Area Driveline 1946 3 speed Transmission bracket bolt

I have a 46 1/2 ton truck. 216 engine and 3 speed on the floor. I was looking for a transmission oil leak. Haven’t really found the leak yet but I noticed this bracket on bottom of tranny below the speedometer cable is missing a bolt. Would anyone know what size bolt it should be. I was also wondering if this hole goes into case and is the major place of transmission fluid leaking. I can put weed eater line in the hole. It’s a hard place to view without taking bracket off. Thank you for the help. Glen

I don’t recall seeing that feature on my ‘46. I have a spare 3 speed transmission and will try to get out to the shop tomorrow to check this out for you.

Glen - Here's a diagram from a 1942-47 Chevy Car and truck Shop Manual (1st pic below) that shows there shouldn't be any kind of "bracket" like yours on the underside of the truck 3 speed on the floor transmission.

The spot where the open bolt hole in the bracket lines up to the main case appears to be the same as were the counter gear shaft should reside in the transmission. It looks to be a modification someone did to perhaps keep the counter gear shaft in place??? There isn't any kind of seal indicated in the Master Parts Book diagram at the rear of the case where the counter gear shaft is, so just a WAG on my part but I think the shaft may be worn badly which will allow for oil leakage at that spot.

When I bought the truck last year the tranny was dry. I added fluid drove it a bit but fluid was on the floor after drive. So I drove it short trips last fall. Added more fluid this summer and after a drive and park there was quite a bit of fluid on the floor. Didn’t notice any excessive leakage on the floor till the drive. I will add more fluid and see if it drains out the mysterious hole!

What is case casting number on your transmission?

The Chevrolet Mater Parts Catalog 1929-1950, page 183 shows the 1941-1947 All commercial 3 -speed transmissions should be #591194 or #591195. Note: prior year versions of the MPC only list #591194. The later version shows both numbers.

I checked the spare transmission I have. It shows the #591195 cast number. A couple of photos of this one are attached. Note, it does not have the “bracket” shown in your photo.

Looks like 590874. The serial number on my block looks to be a 1949 so maybe that’s what year it is.

That code is a 37-39 tranny

It looks to me like that bracket may be to retain the cluster gear shaft in place. Is the end of the shaft itself drilled and threaded? Maybe some non-hardening gasket sealer would work to stem the leak. You'd have to clean the area with brake clean before applying to get anything to stick.

I'd pull that bracket off and inspect. It may even be an add-on that someone did (not factory.)

Thanks, I decided I will remove the other bolt and see if it goes into the case and then I will have a better view of the missing bolt. I’m hoping it just fell out and there are threads. The tranny works fine other than fluid leaking. Hopefully that’s the case that bolt fell out.

So I was able to remove bolt on bottom and tranny fluid does come out. Moved bracket a bit to get a better view at other hole. Looks like a hole with jb weld or similar in the hole. Will try some more and hope that seals the leak for now but looks like a new case is in order. It would be good if I could temporarily seal it though for now.

Looks like a crack in case also😢

Ouch, it does look like a crack. Your first pic was pretty fuzzy. I assume you had oil come out of the hole for the bolt that went in vertically. Did that bolt have a flat boss where the hole was or just the rough casting. If the latter, that would kind of reinforce my idea that someone drilled and tapped for the bracket for some reason. It almost looks like someone tried welding the cluster shaft to the case. If you want to save the tranny, I think you'll have to take it and have someone braze the crack and likely re-machine the bore for the cluster shaft.

Ponchogl - Your transmission code 590874, as you mentioned above is confirmed as a 1937-39 Commercial Truck 3 speed. I will try and dig in to an early 1929-46 Chevy Master Parts book to see if I can find anything related to this transmission, the odd bracket and leak issue tomorrow.

Hard to say if that is a crack in the case or not as that's where the normal casting mold part line is.

BTW - Your engine serial number beginning "GAA" indicates its from a 1949 Chevy passenger car per the 1949 Chevrolet data PDF.

Thanks for clarifying engine origination. Looks like the case would have the hole but hole was repurposed for my truck. This pic is from eBay for 37-39 case. I will be able to add fluid on Monday and check if that is the major leak or if there are more places. Then fill and see if “crack” is from the casting or leaking also.

So the ?crack is actually from the casting, so no leak there. Thanks for that. The bracket who knows what that was for. The hole in the case is a hole for removing internal shafts for transmission repair. Instead of putting the correct plug in the hole they put JB weld or something in there to seal. It is leaking there so I put gasket seal caulking on there. Have to wait to see if it holds if I have it clean enough. Give it 24 hours to cure and fill. Also where the torque tube ball screws on is leaking there. Would caulking hold there or would it fly off? It needs a gasket there. But before I get new gaskets I want to make sure the plug hole doesn’t leak. I guess if all worked out I would like a 4 speed tranny which may be a challenge or just a different case. Switching tranny’s may need to be a different thread! Thanks

I’m curious about the patched hole. Was finding and using an appropriately sized tapered plug not possible?

As for the torque tube leak, my guess is an Oakie bushing would fix that?

Curious also. I’m guessing they couldn’t and didn’t get one one or maybe buggered up and filled the hole. I think the oakie bushing is ok. Nothing leaking into rear differential. I was thinking the small cork gasket that comes with gasket kit?

If you look at the cross section diagrams I posted above, that counter gear shaft rearward end should be almost flush with the case and there is no seal or "plug" to prevent leakage. I thinks it's unlikely that you will find anything that will stick to that small gap/space to prevent leakage in its present state. Unless you tear the transmission down, thoroughly clean and during reassembly apply some sort of sealant it's unlikely to stay put.

The difficulty with that is if you read the counter gear installation instructions in the shop manual, there is supposed to be a dowel like tool that is pushed into the case to capture the gear, needle bearings and counter gear trust washers (fore and aft) and hold in alignment for the counter ger shaft to be installed. Then that tool gets pushed out the rear case hole as the counter gear shaft is installed until seated fully at the front of the case.

Perhaps if when you reassemble you put a good coat of heavy grease in that hole, when the shaft settles into its appointed place the grease will reduce the amount of leakage/seepage of oil?

I’m pretty much thinking it won’t hold, thought for a few bucks it may work just to allow me to drive a bit and have fun with it. Looks like a good winter project. Hoping to find out what 4 speed may work with what I have I think is ultimate goal. Just lacking time at the moment. There is a case on eBay like the one I have. Not sure how readily available they are. But like I mentioned I would like to go to a 4 speed if not a lot of work to swap it out. Thanks

Be aware that the 4 speed transmission (GKT-134) that fits your truck is not synchronized. I love mine but not everyone is a fan of double clutching.

Kent

Thanks Kent,

Would the 4 spd (GKT-134) fit with my bell housing along with a 1/2ton 4 spd ujoint? My engine is a 49 216. New at this. I’m just going to seal up mine till I find a 4 spd transmission. I have a guy with a 4 spd and he is checking if he has the ujoint. Don’t mind double shifting, used to drive semi!

Glen

The GKT-134 will bolt up to the bell housing but you will need a different pedal bracket. This is because the 4 speed transmission is wider than the 3 speed. I believe the part numbers are 477083 (4spd) and 475811 (3spd).
Kent

Thanks

I have a 4 speed that I took out of a 46 chevy. I only drove the truck a couple times before it got pulled. It's a double clutcher for sure. I will check the numbers on it if your interested. You can have it if it will work for you.

Yes you could check numbers. Would you also have the u joint and pedal bracket? Shifter also. Thanks