Rebuilding a 37 transmission with 47 donor
 

I have a 47 3 speed that I was hoping to keep for a future project but my 37 transmission is in need of some help.
I will have to rob the shift tower from my 52 light truck transmission for the wider shifter forks.
This will be a budget swap.
If I understand correctly all the internal parts from the 47 should fit the 37 case. I think I have to check for clearance in the bottom front of the 37 case where there might be a raise boss.
I have Vern Tardels Ford transmission service and repair. I went over Mac’s od transmission rebuild. I think I’m ready to tackle the swap.
I’m hoping some of you guys might remember earlier threads that will be helpful.


I’ll post some pictures later today.

Re: Rebuilding a 37 transmission with 47 donor
 

I did about the same thing, and it went exactly like VanPelt's book (I wouldn't rebuild one without it) described. Installing the input after the tight-fit cluster episode was the only thing from normal '39 style rebuild. I think my case is actually a '35-ish case, so your '37 could possibly have zero clearance issues.

Re: Rebuilding a 37 transmission with 47 donor
 

One of the more important things to note is the quality of the main shaft front bearing surface - it needs to be spot on (size) and not pitted or worn.

Also, if the caged roller bearings are good, use them (or find genuine Ford ones). Every recent re-pop that I've seen is junk (the cages are soft and frequently fail).

There are NO replacement cluster shafts that are worth a darn, so hopefully yours is not too worn. If it is worn on one side (which happens due to the forces pushing down), then rotate it 180 degrees when you reassemble the transmission. The re-pop ones are of inferior material, are about .001 undersize and are not correctly hardened. I've not found any NOS ones for quite some time (had to make my own from linear shafting).

There are different thickness thrust washers available for the main shaft stack up - you want the end-play to be on the LOW end of the scale. I usually try to get to about .003 to .004 max. If you can't achieve it with STD thrust washers and shims, then you may need want to have a machine shop "tune" the clearances with a surface grinder on the front of 2nd gear (you're talking about only removing a couple thousands at most). When buying parts, but a couple of different thrust washer thicknesses - so you have some selections to play with.

Tight clearances and quality parts are key to building these transmissions so that they don't pop out of 2nd gear. Another trick that I do is have Charlie NY rebush the 2nd gear (to my specific main shaft). Having a really close fitment on 2nd gear really helps keep the transmission in 2nd as well.

Best of luck! The job isn't that hard, just pay attention to the details.

Re: Rebuilding a 37 transmission with 47 donor
 

I would love to but Mac’s book but with the cheapest shipping to Canada plus the book 96.63 exchange to CAD at 116.69 I can’t justify that right now. ( I might regret not buying it if I blow the transmission up) I’ll have to stick to Vern Tardels book which I have and of course the ford barn.

Re: Rebuilding a 37 transmission with 47 donor
 

I thought I would use the guts from a 46 car into a 48 truck case. Works good BUT 1st gear is taller and with Weber flywheel can stall on launch. I plan on putting together another after researching my parts and swap it

Re: Rebuilding a 37 transmission with 47 donor
 

I use Mac VPs book. I haven't looked at Vern's yet. Mac VP has a thrust washer kit and a snap ring kit that are very good parts to have, The thrust washer for the 68 type cluster would be needed unless the later cluster is already in there. The retaining method for the thrust washers is different otherwise they are interchangeable.

Check the 2nd gear bushing for wear. It can affects function and prevent 2nd gear disengagements. It's as important as proper cluster thrust end play for this. Some new blocker rings aren't the right dimension and don't work right. The correct blocker to gear clearance is about the thickness of a quarter if I remember correctly

Check closely for cracks on the front of the counter shaft bore. It can crack all the way through to the main shaft bore if there is a catastrophic gear tooth failure is its history.

Some pickup gears are truck like ratios. Mac VP's book lists all the gears that are compatible with each other. A lot of Mercury cars have the 15/29 input set where the 16/28 sets are more common to passenger cars.