Drive shaft question

[bmerkley58]

I will be installing a T-85N Warner 3 speed overdrive transmission in a 67 F-100 short bed two wheel drive truck with an FE engine. Does anyone know what the tube length is on the driveshaft?


bmerkley58

[FORDification]

I can't give you the measurement you need, but once the engine and transmission are installed, it's easy enough to measure it yourself. (Of course, I'm assuming that it'll have to be shortened...but I'm not 100% sure on that...but isn't that tranny a little longer than a standard 3-spd?).

Load vehicle with total operational weight. The car must be at operational height. DO NOT measure with wheels hanging down from hoist or jack stands. Rear suspension must be at normal ride height to insure proper driveshaft length!!! Measure on the floor. Install a test yoke into the back of transmission, push all the way in, pull back 1". With the help of a friend measure the center to center measurement of the front u-joint to the rear u-joint on the differential. TIP: It is sometimes difficult to guess where the centerline of a u-joint is. By moving to the rear of the slip yoke u-joint cap instead of centerline and measuring to the rear of the differential u-joint cap it is the same as measuring center to center. You have just adjusted for the radius of the cap diameter and have a solid surface to measure on instead of an air gap in the center of the cap. You can then provide this measurement to the machine shop or driveshaft shop who will shorten the shaft.

Good luck!

[flyboy2610]

[bmerkley58]

Thanks for the info, Keith. The T85N overdrive transmission measures 23 1/4 inches from the bellhousing mounting surface to the rear of the bolt on yoke. I don't have a regular three speed to measure but I believe the overdrive is longer also. Do you know if the regular three speed for the 67-72 F100 has a bolt on yoke?

[FORDification]

That would depend on whether the tranny was originally installed in a SWB or a LWB truck. The trannies in SWB trucks had a slip-yoke, like a car. The trannies in LWB trucks had a bolt-on yoke with a two-piece driveshaft and a slip-joint in the back section of the driveshaft.

Does the tranny you're planning on installing have a slip-yoke or bolt-on yoke?

[bmerkley58]

It has a bolt on yoke.

Bob

[FORDification]

Hmmm....this might become a problem. I know that with automatics, you need to find one set up for a slip yoke to work in a SWB truck, since it's more involved with converting it over than just finding a different tranny. However, I'm not entirely sure on how difficult it would be to convert a manual 3-spd to a slip yoke....or if it's possible. Hopefully someone with more experience with this can chime in. Otherwise, you might pose this question over at the Ford Tranny Talk messageboard and see what the tranny gurus over there have to say about it. Good luck!

[willowbilly3]

The driveline shop should be able to make you a drive line with the slip yoke in it, just like all the 4x4s used.