The Stovebolt Site Forums The Shop Area Engine Shop transmission input shaft and surrounding collar

When I changed from a 207 to a 235 I kept the original '34 three speed but have a clutch from a '56 chevy. The input shaft collar that the throwout bearing rides on is non existant on this old tranmission because they had a different centering system. Can I get a collar from a '56 three speed for this tranny and have it fit or must I machine something? Right now everything is fine but the T.out bearing is going to rub on the input shaft. And probably be off center when clutch is depressed. Any insight appreciated.

I don't have a real answer on what parts interchange, but any reason not to update to a newer 3, 4, or 5 speed while you're at it?

If you keep the old transmission looks like you'll be looking for or making a front bearing retainer with a snout for the throwout bearing.

Well it semms it is neccessary to have the old tranny to hookup to the old torque tube system. I think next time I will go all stock. Thanks---dave

why not use the original throwout bearing and clutch arm. I take it you changed bellhousings with the engine change.

I know later on the bearing retainer was used to index the transmission to the bellhousing. On gm trucks from about 48-67 the bearing retainer eas 4.686 inches in diameter, and the snout that the throwout bearing rode on was 1.373 inches. My 1940 GMC transmission is indexed to the bellhousing, but I am not sure of the size.

Food for thought... When a later transmission like the A833 or the SM465 is put in an older truck, an adapter plate is used or the bellhousing is bored out for the 5.125 bearing retainer. If you go the other way, lets say put a sm420 in a truck that had a sm465, the bearing retainer is too small. To remedy this, a "donut" is used. The donut presses into the bellhousing and then indexes the bearing retainer.

In your application, using the later bellhousing, you can probably have a donut machined out of aluminum to index your transmission. Once you have the donut in place, you can redrill and tap the mounting bolt holes. You might have to roll the transmission slightly to the left or right to get a clean spot to drill. Since you are using the stock transmission, the stock throwout bearing should work. The Monkey wrench in this scenario is the newer bellhousing and clutchfork. I am not sure about the new geometry invvolved here.

John

P.S. I'm also in Northern Cal

Thanks for that info--probably take me awhile to digest it. But I can tell it is useful! What i did was go with a '56 235 eng then a '46 bell housing and inside that a '56 clutch--and then that has the '34 tranny. The original fork and thout bearingis made to mate up with the speacial '34 clutch--way different--but something might be made to work there. I am not sure about the donut idea--is that something that the t.out bearing rides inside of? right now i was thinking of just getting a snout as they call it machined on to a bearing retainer--or just make another basicly. With that snout on it---dave