I am considering replacing the stock 4 speed in my 48 F1 with the much more quiet, 3 speed. Aside from actually locating a transmission, I'm not familiar with what challenges or options I may have. While I'd like to remain as stock as possible, I am not sure if I can simply locate a 3 speed transmission and bolt it directly to my flathead 8. Is there a range of years or models which are appropriate? Is there a difference between a 3 speed transmission for a 6 cylinder and an 8 cylinder flathead? I do, in fact have a floor shift and intend to keep it that way. Also, I have read where I'd need a different driveshaft. Could the existing driveshaft be modified to accommodate length and/or spline?

Would like to learn from someone who has done this. Thanks for any insights!

 

I think you will need a driveshaft stretcher. Easier to shorten than lenghten. 6 and 8 bell housings are the same, should bolt right up, and mounts are the same. 48-52 should work. Good luck.

 

The half-bell attached to the trannies is the same, the part bolted to the engine is not the same from 6 to 8. So any trans from either a 6 or 8 will work if you just keep the "flywheel cover".

The ideal swap would be to a heavy-duty 3-sp, which is also floor shift, works with the same clutch (11"), and has the same type of driveshaft. Unfpotunately, they aren't easy to find.

The light duty 3-sp from a 48-50 will also be floor shift, while a LD from a 51-52 will be column shift. Driveshaft replacement would be required, costs about $200. You may also need to go to a 10" clutch, I can't remember other than there have been problems with certain swaps. A search on here will turn up several threads about it.

 

Ross, i forgot about the column shift, and I should have said that the transmission for a 6 and an 8 will bolt up the same. The bell housing is not the same. You could find a wonderfull sparkomatic conversion shifter.