I'm getting everything together to install a C4 in my 55 and am starting to think, or maybe over-think the driveshaft. I know the difference in the rear u-joint. but the front is different also. Is there a difference in the u-joint size between a 55 and 56? A quick measurement near the differential showed the driveshaft to be 2 in. in diameter which seems small and I was wondering if the 56 was larger.

I guess the short version is there a great enough advantage to updating the differential yoke, or just take my existing driveshaft and a C4 yoke into the machine shop and have them put every thing together when I get it lengthened. I'm not planning on any real racing, but might continue to warm up the existing 312 just a little with headers and a mild cam.



Thanks,

Don

As I recall you should be able to use the C4 yolk on the T-Bird driveshaft with the proper u joint. The T-Bird shafts were all on the skinny side. Not aware of this ever being a problem.

Asking for advice here is good, but ultimately you will be taking the shaft to the driveline shop along with the front yoke and rear U joint requirements, the length measurement, and let them handle it.  No need to overthink it at this point.

John - "The Hoosier Hurricane"

Have them balance it too.

       A  L  A  N   F  R  A  K  E  S   ~  Tulsa, OK    

I put a C4 in my 56 Bird. As far as I know, the shafts for the 55 are basically the same as a 56 - about 2 inches in diameter (I was surprised that the 56 shaft was so small in diameter). I just took the C4 yoke and my old shaft to the driveshaft shop and had him make up the shaft (bought the u-joints from him) with the measurement I had.



Paul



Based on one of the catalogs for TBird parts, the 55 u-joints are different than the 56 (56 and 57 were the same) and it shows the 55 front and back were different.





54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

Back in the 60's, I pulled an air cooled fordo out of my 'bird, and put in a T-85 o/d. The car drive shaft came with the deal. I had it shortend (didn't want to cut the bird shaft), and after I put the 4.27 wagon gears in the car, the shaft hit the tunnel on a hard departure in low. Might be the reason the shaft is smaller. Had a little problem with the ujoints too, as I remember. And broke the right main leaf spring, among other things.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

I've run a larger driveshaft in my 56 Tbird for years and never a problem. It came factory with a T-85 od and I converted the driveshaft from small to large then.

-Gary Burnette-