Late gears in 39 Transmission
 

What is the latest Ford transmission that you can take the insides out of and slip them into a 1939 transmission? That is without modifications.

Re: Late gears in 39 Transmission
 

I'm fairly certain it's 1948.

Re: Late gears in 39 Transmission
 

I have done a few 48 guts into the early cases. But also with a bit of machining I have fitted a mainline guts into an early case
Lawrie

Re: Late gears in 39 Transmission
 

I too have installed later gear sets in to early (a '34 and a '35) cases. I never found it necessary to do any machining.
I did make an installer for the front bearing as I was unable to install the entire input assembly as a unit.

Re: Late gears in 39 Transmission
 

The gears from a up to 50 or early 51 F1 pickup would still work less the main output shaft but they might not be a ratio a person would want. 1949 thru early 51 Mercury transmissions still used early type gears with some minor improvements but it's the same deal with the output shaft and especially if it has overdrive. 1951 was a change over to improved gear tooth design but the Ford & late 51 Mercury and up had the 1-inch 10-spline input shaft so they wouldn't be an ideal replacement. Lincoln had the close ratio gears for a long time but a person has to have a different rear axle ratio to really be able to appreciate them for highway driving.

The later 39 & up gears have to have the 91A type fork to get the positioning right and that complicates things if a person wants the original angled shift tower like the 32 thru 35 have. If they can live with the vertical tower, then it's not much of a problem. Early gearboxes may not fit the larger clusters in the case. Smaller clusters should work.

There is a lot of interchangeability with the light duty 3-speed. 78 & later pickup top shift cases will all work for a 39 type or later blocker style synchronized transmission. The ones from 40 through 48 cars are all a direct replacement including the main output shaft for car applications. You have to watch for Mercury cars. They sometimes have the 29/14 (see post #8 below) tooth ratio. I like that ratio with 3.54 rear gears on a light body car.

Re: Late gears in 39 Transmission
 

That's that one oddball "rule of 43" cluster gear. Most Ford clusters live by the "RULE of 44". DD

Re: Late gears in 39 Transmission
 

and the oddball 27 tooth on 51ish pickups too

Re: Late gears in 39 Transmission
 

I was looking at the wrong input gear. It's 29/15 for the set I was thinking about. They have the odd 022A prefix part numbers. Some of the Mercury transmission stuff was made specifically for the Mercury line in 1939. They even had their own case part number. They eventually changed for interchangability. They were also used on the V8 60 applications but they had a stump puller rear axle ratio.

Re: Late gears in 39 Transmission
 

When I had my 46 first was missing most of 2 teeth, this was in the 70 s, took apart several correct transmissions, all bad, then laying on the ground was a later transmission, partly disassembled,one with no bell housing, small fine splines for the clutch ,the cluster had loose needle bearings, and one less tooth on the driving gear, the teeth looked to have a slightly different shape, I was desperate and installed it, was quiet and survived many hard downshifts, wheel spinning starts---

Re: Late gears in 39 Transmission
 

The gears produced after mid 1951 all come nearly to a point on the teeth and are referred to as diamond teeth due to that shape. The early ones all have a noticeably more rectangular shaped blunt tip and they don't come to a point at all. I've never tried to fit any diamond tooth types outside of a set. The first/reverse gear is nearly the same for all the different sets that have the helical internal splines with the diamond tooth type being the exception since it has 28 gear teeth instead of 29. The 21C-7100 gear was used clear up to early 1951 for the Mercury cars. The 8M-7113 cluster was a replacement part for all the 39 & later standard "car type" transmissions with the late type synchro. Now days they reproduce the original 68-7113-A as a replacement cluster gear but it takes the early type four notch rear thrust washer instead of the oblong type of the later clusters. It uses the caged roller set like most of the early ones.

Re: Late gears in 39 Transmission
 

"Back in the day" when I had my 32, Olds powered w/39 tranny I would occasionally "need" new gears. Local fellow had pails of used gears. He would pull one out and count the teeth. Get a matched set after a few trys. Put them in and I"d be good to go til next time. I got where I could pull the engine in about an hour. :):D:cool:


Paul in CT

Re: Late gears in 39 Transmission
 

You didn't jack the torque tube back, with a bumber jack?

Re: Late gears in 39 Transmission
 

Tranny in a 32 mounts to the K-member, has to come out from the front.
Paul