'46 Chevy transmission swap

I'm building a '46 Chevy Coupe w/ 235 6cyl, headers, & original closed drivetrain. With headers installed, I cannot shift to 2nd or 3rd. I've been told a '38-'47 Chevy truck 3spd tranny will work nicelyand be an easay swap putting the shifter in the floor which would be good as I am building a retro rod. Any info would be greatly appreciated. thanks

 

haven't done it, but that sounds correct. You could also just convert what you have to a floor shift, if it's not vacuum shift.
Not sure if the trans mount is in the same spot on the trucks and cars, but you can figure that out once you see the transmission for yourself.
Might want to switch out the torque tube section for one from a '50-54 powerglide car so you can get the more highway friendly 3:55 gears.

 

I don't think it has to be a truck tranny to work. I have a 38 and a 46. The 38 was in a car and has the top mount shifter. No levers on the side.

 

it is the original vacuum shift unfortunately

 

thanks Rogueman, I'll look in to that

 

I believe '38 was the last year for a trans mounted shifter in the cars? They continued to use it through '47 in the trucks.

A 3spd from a '53-54 car is going to be the strongest, but the trans mount is in a different spot, so a little fab work would be needed. You would also need to get a floor shifter for it.

There were floor shifters made back in the day for these trans, but they can be hard to find. National Chevy Asociation sells one also, but the shifter is not a good quality shifter. If it was me, I'd find a decent used Hurst off Ebay, and just make my own mounting bracket for it.

 

Thanks Snarl but the later three speed trannys are longer than the ones from the '40s as they have a tailpiece for the rear bearings which I don't believe can be removed

 

any other helpful advice?

 

What part is hitting the exhaust and where is it hitting? There are thousands of these cars with a 235 running Fentons. Do you have pics of the area that's interferering?

 

Well, and this sounds crazy, but I have a 1948 Gibson Garden Tractor. It has a CHEVROLET 3-speed trans with reverse, and a top mounted shifter; the trans to bellhousing bolt pattern looks to be the same as that of a 51 Chevrolet passenger car 3-speed (49-54 years actually) I gave away. The number on the trans is 590685 GM14. I don't know what year trans Gibson used, but it is a top shifter trans. The rest of the tractor consists of a MOPAR 8 3/4 inch narrowed rear end with separate manual brakes, for brake steering, and is bolted directly to the trans. The trans input shaft is shortened and has a chain sprocket bolted on, with the chain run to a jackshaft. A pulley and belt system (3 belts) has an engagement/disengagement system/clutch. It's powered by a 9 HP Wisconsin engine. And, it has "tiller" steering, no steering wheel (that was an option though)............Maybe I could swap to a six or a flathead V-8, and run it as a HAMB dragster. Whatever trans they used would solve your problem. Butch/56sedandelivery.

 

I don't have pics, but the shifter levers on the column themselves are hitting the headers. I'm not worried about that. I'm wanting to know the simplest way to do a floor sift without changing the torquetube drivetrain.

 

What about something like this?

My Dad had one of these on an old Nova he had long ago. Hurst Indy.

http://www.summitracing.com/parts/HUU-5010016/

You might have to get a shop to fab up some linkage rods, but that's not too hard.

There's also this POS on eBay.

http://www.ebay.com/itm/3-speed-shifter-CAR-TRUCK-FLOOR-CONVERT-COLUMN-GM-FORD-/270261455452

 

Have you actually verified this, or is someone just telling you this?

There is a cast iron section on the tail end of the case that has the mount as part of it, but it can be removed, at least on '49-54 car 3spds.

Also remember that the driveshaft attachment is able to change in length (up to a point).


I have a couple of these transmissions that I can take measurements on if you need to.


They did use non-vac shift in the 40's, you just need to look for one, and then make a bracket and mount a good Hurst shifter to it. Are you able to fab up a bracket, or does it all need to be a bolt-on as bought?

 

thanks Snarl, I do have a spare '50 tranny I could use if the tailpiece can be removed without compromising the rear bearing. I was unsure as to whether that was an option. Also I can purchase a prefab from Natonal Chevy or use a Hurst three speed

 

Ansen also made a nice 3-speed floor conversion back in the day. You might be able to find one on e-pay or Craigs.

 

thanks for the tip Waldo53

 

Another question concerning the '46 tranny, could I just swap the '46 shiter side plate and shifting components with ones from a '50 tranny that I have on hand. That seems to be the easiest way to go if it'll work. Then I could install a 3spd shifter for the floor.Thanks for any tips guys.

 

I think I've heard of guys modifying them, but I don't know anything about it, so I can't really offer any help there, but it would seem to me that if you just measure the two transmissions, and if the '50 is in good shape and the length and mount are going to work, then just swapping them around would be a better/easier solution.

 

48 back trans are shorter than the 49-54 boxes.

 

What he said

 

no-one have any more tips?