The Ford Barn

Rob Paul · 03-07-2012, 08:57 AM

Ive got a three speed side shift open drive tranny from a 51 F-1 with an 8BA.

I wanted to turn it into a closed drive tranny to put in a 46 Ford car. I gutted the F-1 tranny and put all the guts from a 39 Ford tranny into it.
Cluster/mainshaft/reverse/early style 2.75" syncro. Everything fit great.

Now comes the shift forks. The sideshift shift forks are too wide. The opening on the front one is 3.125", and I didnt measure the rear one.

Im thinking I can close them up with some heat and a vise and make them work, but Im sure someone here has done the same thing so let me know what you think.

This is a low buck assembly using what I have laying in the parts stash. Probono work for a friend.

THX, Rob

Juergen · 03-07-2012, 11:37 AM

This won't work. The side shift trans uses the later hockey puck synchro which is bigger and has the fork slot toward the rear edge. It is about 1/4 inch behind the earlier donut synchro which has its slot in the center. So even if you narrowed the fork, it would be in the wrong location.

the cleanest solution is to use the gears from a real 39 up trans which has the hockey puck synchro. You might be better off mig welding .1 inches on to the big fork instead of trying to bend this hardened unit. The mig weld is a lot harder than a gas weld. The rear fork will be all right.

Either that or figure out a way to move the fork 1/4 inch forward, pehaps by welding the earlier narrower fork in front of the side shift fork cut down where it spreads out. Check to see if this moves the fork 1/4 inch forward.

Straightpipes · 03-07-2012, 01:14 PM

You have to use the later syncronizer that matches your shifter forks. It's really tough to alter the forks in any way and make them work properly. Good luck..

JM 35 Sedan · 03-07-2012, 01:55 PM

I don't think you even want to try what you are suggesting. Best thing you could do is contact either Mac VanPelt or Charlie ny and get them to advise you on how to accomplish what you are trying to do. There is a way but unfortunately you are presently heading in the wrong direction.

rotorwrench · 03-07-2012, 07:35 PM

There is a lot of interchangeability in the old Ford tranys but the main shafts are different between the open drive types and the closed drive types. The side shift closed drive transmissions are basically all the same from 1940 to 48. There are still a bunch of them out there. Mac VanPelt's book will answer any question you might have about the passenger car & commercial car transmission up to 51. They all changed gears after that.

Juergen · 03-08-2012, 09:06 AM

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It's really not that tough and what have you got to loose. Those side shift forks are scrap iron material and so are the smaller shift forks. If you grind the front hardened part of the side shift fork, it reduces to 1/4 inch so laying the smaller fork right on it will get you the proper dimensions and angles. Now cut the smaller fork down so it can lay in place against the larger fork and weld it on the side opposite the larger fork tines. Then cut off the larger fork tines and weld both sides. Keep the welds in the same area as the ribbing of the original forks.

I've done similar work modifying a 34 top forks to work with the later gear set with the later synchro.

03-07-2012, 08:57 AM	#1
Rob Paul Senior Member Join Date: May 2010 Location: Green Bay, WI Posts: 102	Early Ford three speed tranny question.... Ive got a three speed side shift open drive tranny from a 51 F-1 with an 8BA. I wanted to turn it into a closed drive tranny to put in a 46 Ford car. I gutted the F-1 tranny and put all the guts from a 39 Ford tranny into it. Cluster/mainshaft/reverse/early style 2.75" syncro. Everything fit great. Now comes the shift forks. The sideshift shift forks are too wide. The opening on the front one is 3.125", and I didnt measure the rear one. Im thinking I can close them up with some heat and a vise and make them work, but Im sure someone here has done the same thing so let me know what you think. This is a low buck assembly using what I have laying in the parts stash. Probono work for a friend. THX, Rob

03-07-2012, 11:37 AM	#2
Juergen Senior Member Join Date: May 2010 Posts: 500	Re: Early Ford three speed tranny question.... This won't work. The side shift trans uses the later hockey puck synchro which is bigger and has the fork slot toward the rear edge. It is about 1/4 inch behind the earlier donut synchro which has its slot in the center. So even if you narrowed the fork, it would be in the wrong location. the cleanest solution is to use the gears from a real 39 up trans which has the hockey puck synchro. You might be better off mig welding .1 inches on to the big fork instead of trying to bend this hardened unit. The mig weld is a lot harder than a gas weld. The rear fork will be all right. Either that or figure out a way to move the fork 1/4 inch forward, pehaps by welding the earlier narrower fork in front of the side shift fork cut down where it spreads out. Check to see if this moves the fork 1/4 inch forward.

03-07-2012, 01:14 PM	#3
Straightpipes Senior Member Join Date: May 2010 Location: Ballston Spa, NY Posts: 789	Re: Early Ford three speed tranny question.... You have to use the later syncronizer that matches your shifter forks. It's really tough to alter the forks in any way and make them work properly. Good luck..

03-07-2012, 01:55 PM	#4
JM 35 Sedan Senior Member Join Date: May 2010 Location: Near Rising Sun, Maryland Posts: 10,858	Re: Early Ford three speed tranny question.... I don't think you even want to try what you are suggesting. Best thing you could do is contact either Mac VanPelt or Charlie ny and get them to advise you on how to accomplish what you are trying to do. There is a way but unfortunately you are presently heading in the wrong direction. __________________ *John* *"Never give up on what you really want to do. The person with big dreams is more powerful than one with all the facts". Albert Einstein*

03-07-2012, 07:35 PM	#5
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,431	Re: Early Ford three speed tranny question.... There is a lot of interchangeability in the old Ford tranys but the main shafts are different between the open drive types and the closed drive types. The side shift closed drive transmissions are basically all the same from 1940 to 48. There are still a bunch of them out there. Mac VanPelt's book will answer any question you might have about the passenger car & commercial car transmission up to 51. They all changed gears after that. Last edited by rotorwrench; 03-08-2012 at 09:11 AM.

03-08-2012, 09:06 AM	#6
Juergen Senior Member Join Date: May 2010 Posts: 500	Re: Early Ford three speed tranny question.... Sponsored Links (Register now to hide all advertisements) It's really not that tough and what have you got to loose. Those side shift forks are scrap iron material and so are the smaller shift forks. If you grind the front hardened part of the side shift fork, it reduces to 1/4 inch so laying the smaller fork right on it will get you the proper dimensions and angles. Now cut the smaller fork down so it can lay in place against the larger fork and weld it on the side opposite the larger fork tines. Then cut off the larger fork tines and weld both sides. Keep the welds in the same area as the ribbing of the original forks. I've done similar work modifying a 34 top forks to work with the later gear set with the later synchro.