39' trans question

flat-v8

flat-v8

Well-known member
I think I have a 39' original 3 speed transmission, but not sure of exact year. Since installing I have only drivin the truck once, and it shifted great! It should because it was rebuilt by an old flathead mechanic\rebuilder, who also rebuilt my 59A engine that ran great! All this was well over 20 years ago, I got broke, put the truck in a ragged dirt floor pole barn and never touched it again till now. I'm starting all over with the project, the motor was stuck, I got scared, but she freed up and runs great now. The thing that worries me is the 3 ball bearings that were stuck in the transmission drain plug. I drained the trans, rear-end, and steering box, to replace the gear oils, found some 600W but haven't installed yet. If the transmission hasn't moved in over 20 years, where could the ball bearings be from? They look like the type that would be in the main gear bearing. I am hoping they were just stuck in there since the rebuild, or the plug came from another trans case he had laying around. Any thoughts?
 
Save them I used them to fix the kids bike that someone had loss 2 of them. best you got them out of there.worst off it wouldn,t shift right.Drive it.
 
There are three detent balls in the syncros, under the sleeve- about 3/16" (memory). I would suspect that some one took the top off the trans and slid the sleeve too far one way or other (guess how I think that)... VERY hard to get back in place with trans in car... But can be done... Karl
 
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Flat,
What Karl said if they are 1/4 dia. You will go nuts trying to reinstall
with the trans in the truck. Remove the shift tower and carefully slide the
the syncro outer sleeve to the front...you will see at least one of the 3
keys appear...they are nested in the syncro hub. There should be a 1/4 dia
ball in the center of the key and a pretty stout spring behind each ball.
The balls and springs keep things centered. It's hard to believe but
if you have a real tight shift tower the transmission will actually work with
those balls and springs AWOL....you'd have to be real lucky but I've seen it.
If the balls and springs aren't where they should be don't gamble
yank the trans.
Charlie ny
 
Thanks for the info. I do not know much if anything about the trans, other than looking at pictures on the internet. The only thing around the transmission is the bare cab, this truck is not put together yet so removing the shifter top would be easy, I'm just not very knowledgeable on transmission's, but I'll check it out. The gear oil that came out was very thick, like molasses, the 600W is actually 250 weight and that is what I was told to use in all 3 units. 140 seems way to thin, but I dont really know anything, still newbie.
 
Ford recommendations vary, depending on the source, between 90 and 140. I use 140.
The 600 is a pre-special additives for extreme pressure (EP) stuff that was used because that was what existed...OK for straight cut gears (Model A trans), not the best for spiral cuts which would include the A rear axle.
Ford adopted the new SAE graded gear oil meant for modern gears in 1932 (weights available then were around 200) and then updated specs in the Service Bulletins as the new weights came along. You do not have straight cut gears and really should have EP.
 
flat-v8 said:
140 seems way to thin
Click to expand...

I use Synthetic Manual Transmission Oil in the transmissions of my old Fords. It is about like 20 Wt Engine Oil. It really makes the syncro clutches work a lot better. They do not have to push all that old thick oil out of the way to be able to grip onto the gear. HOWEVER, your trans has to be absolutely leak free of the stuff will run out on the floor.

A lot of people say there is no way this stuff will work, but I have been using it for more then 6 years now with excellent results. I have several "Customer" transmissions with the stuff in them and they really like the way they shift.

600 W is really way too thick especially for the '39 and later syncro assemblies.

My Experience.

Chris
 
It is not only too thick, it has no EP additives for the sort of sliding contact spiral cut gears have. It has been obsolete for pretty much any use at least since '32, when Ford moved on. It is simply a wrong lube for the job at hand.
 
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