Heavy Duty 3-Speed T87 Conversion

[dmgirardeau]

I have a 1949 Ford F-1 sporting the heavy duty 4-speed (spur gear) transmission. As I prefer synchronizers in my transmission, I looked around and found a T-87D-1 (heavy duty 3-speed). The rear bearing retainer on this "new" transmission has the integrated emergency brake with rear retainer that is incompatible with cross member on the '49 F-1 frame. The main shaft is the 11.97" 10-10-10 straight spline 8J-7061 which is incompatible with my current drive shaft. In order to use the horseshoe style rear retainer and associated driveshaft bracket (with speedo gear), I was wondering if anyone could clarify the following:

- Would a 8D-7061 main shaft 10-10-6 spline work with the driveshaft bracket currently on the 4-speed transmission?
- Can the existing rear bearing retainer from the 4-speed be reused? The bolt pattern for the 4-speed rear bearing retainer matches the one on the 3-speed case.

Basically, I would like to have the ability to swap out the 4-speed with the 3-speed, but I need to make sure the parts will work. Mac VanPelt suggested I reach out to a forum to see if anyone else has tried to do a similar swap.

 

[Bob C]

I looked in the Ford parts book and for the F1 it shows
8D-7085 Retainer, 8D-7061 Bearing and 8D-7065 Shaft
9 47/64 long 10 & 10 spline

 

[JHFORD51]

The half ton four speed driveshaft is unique to that application far as I know; in my southeast area not a lot of T87s around in F-1s, F-2s, or F-3s. I didn't know the T-87 was even an option in an F-1.

I know the F-2s/F-3 all use a deeper drawn cross member and its relatively easy to swap between three and four speeds.

No clue about interchangeability between rear bearing retainers and yokes from the two transmissions you have. Its just bolts, so give it a go! its simple to swap those parts around on the various four speed applications.

I think you are fighting three obstacles and need to narrow down--if you can't swap parts between your two transmissions. I suggest sourcing an F-2/F-3 driveshaft and having the front section shortend PLUS cutting a deeper middle portion of your crossmember (with some suitable reinforcement) or removing the F-1 crossmemeber in favor of a F-2/F-3 crossmember. That'll get you cruising. You can just remove the band and handle and leave the brake drum on the back of your T-87; won't hurt anything if you get the crossmember sorted correctly.

For all that effort, its going to be way easier to just install the half ton light duty three speed and associated driveshaft while selling the T-87 to larger truck person.

 

[GB SISSON]

And if you find you will need to deal with driveshaft and crossmember modifications, you might want to look into a Borg Warner T-5. I just converted my '47 1/2 ton and while not a 'bolt in', it was relatively easy. I had no idea I was gonna love it as much as I do, and I feel the effort was well worth it. Back to your 3 speed, have you asked about the HD 3 speed swap on 'Ford Truck Enthusist' forums. They have a huge group on the '49-'53 pickup segment. Someone might even have a driveshaft or other parts.