So I got a call today from a friend who is helping another friend finish the build on an F1. I went to look at it tonight and from what I can tell its an 48-52 F1 chassis with a 51-52 front clip and a 48-50 cab. A rebuilt 239 flathead is installed and they are having transmission problems. When he went to install the 4 speed spur/ crash box the trans mount is WAY different then what the trans cross member looks like it needs. Doing some quick googooing it looks to me like the truck was "born" with a three speed trans. The rear mount type that looks like "wings" coming off the side. The crashbox 4 sp has the bottom mount and of course has the tail of the trans way to high. So the question is can a 4 sp go in this truck with some changes or a different mount? different cross member or do they need to source a 3 speed. I'm not very well versed in F1s so thanks in advance for any help and comments. It seems odd to me that Ford would have used different cross members for different transmissions but maybe they did?

 

The F1 used its own trans crossmember. F2 and up used a different one with a larger opening, and different mounts, trans tailshafts and everything. From your description it sounds like the 4 speed they have may be from a F2/3, which won't work so well in an F1 without surgery.

 

Easiest swap would be either the 4 spd spur, the 3 spd light duty or 3 spd heavy duty (T87D) that came from an F1 originally. Otherwise search for a rear trans mount for the F1 - once in awhile I see them on the auction site.

 

Someone will correct me soon as in say this but can't you swap the rear mount of the 4 speed to the rear mount off a 4 speed that came in an f1?
sounds like 4 speed he has is from an f2 f3 truck with the rear mount to match the f2 3 crossmember?

Maybe I'm just confused again, need to compare them side by side I guess? I think ive got a f1 rear mount off what I though was a 4 speed. (It was in an f1) Its all wrapped up at the moment but will have to pull it out for a look.

 

Thanks for the information guys. Now I know the f1 is a different set up all together. I will pass along the info. Josh...if you could find that mount and send me a pic of it that would be great. If not no worries. At least we know what we are looking for now. Thanks again!

 

Here is the crossmember/mount for that trans on my F2.

 

And here is a picture of the mount/bearing carrier that goes on the back of a transmission on an F2/F3. This is what bolts to the frame cross-member in the red circled area of Pete's photo above.
Tom

 

 

Yep, looks like my friend needs a 8C-7085. Maybe Napa or Rock Auto tomorrow. Bahahaha. Thanks everyone. And I learned something along the way. That's always good.

 

Here is the 4 speed rear mount with the f1 mount.

If your friend needs this one let me know. Just need to remove it. Might be a little while before I can get it sent though?