38' truck 4 speed trans leak

[RBaker]

I have a leak at the rear of the trans where the drive shaft connects.....I have no service books on the trans but will be removing it from the truck in the next few days. This is a model BB trans from 1936

What kind of seal would be leaking and how hard is it to fix?

I have a 1940 3 speed trans as a backup.....not sure of the condition because its been sitting in a shed about 35 years.

I know the 4 speed works.

 

[Hoop]

Most folks will advise you to forget about the 4-speed, non-synchro clunker. I'm not sure which '40 3-speed you have, but it's a start in the right direction.

The optimum transmission is a floor-shift, closed-drive 3-speed with the late (1939 and newer) gears which include the more modern blocker synchros.

You'll get plenty of help on this choice.

 

[RBaker]

Most folks will advise you to forget about the 4-speed, non-synchro clunker. I'm not sure which '40 3-speed you have, but it's a start in the right direction.

The optimum transmission is a floor-shift, closed-drive 3-speed with the late (1939 and newer) gears which include the more modern blocker synchros.

You'll get plenty of help on this choice.

Yep I have had others give me the same advice so I guess I need to listen and install that 3 speed......

This is a photo of the 3 speed...serial number 18-5573305

 

[OLD...BILL]

Ron: You have yet to take the top of the (39) gear box. and show it to us.. It should be the one you use in your truck, not the rock crusher 4 speed, you will not like its shifting,..
The "39" is much better for your piccckup truck....and while we'er on things you don't need, the overload leaf springs, need to go away, I don't see your truck being used with heavy loads ?? MHO. ...P.S. The frame repair looks great... your doing a good job. There two places the trans can leak #1 rear mount to trans ..or #2 The two place clam shell at the drive shaft to rear mount. or the case its self. there are no grease seal in this area...there is cork seal in the clam shell, short of a wrap around ?? OLD...BILL

 

[Hoop]

Like Old...Bill says, look inside to make sure, BUT it appears you have the exact right transmission ... a prize.

Take the top off and simply measure the inside dimension of the larger fork. You want a full 3" to indicate the late gears/synchros.

 

[RBaker]

Ron: You have yet to take the top of the (39) gear box. and show it to us.. It should be the one you use in your truck, not the rock crusher 4 speed, you will not like its shifting,..
The "39" is much better for your piccckup truck....and while we'er on things you don't need, the overload leaf springs, need to go away, I don't see your truck being used with heavy loads ?? MHO. ...P.S. The frame repair looks great... your doing a good job. There two places the trans can leak #1 rear mount to trans ..or #2 The two place clam shell at the drive shaft to rear mount. or the case its self. there are no grease seal in this area...there is cork seal in the clam shell, short of a wrap around ?? OLD...BILL

I was one step ahead of you today on those overload springs.....removed them this morning along with the old farmers home built trailer hitch.

Thanks about the frame.....First thing in the morning I will remove the top of the gear box on the 3 speed and snap some photos. I have no idea what I will be looking at but I know you guys will.....this site is the best service manual EVER!

Will have the pics up before noon.

 

[41ford1]

For driveability you really want to use the the 3 speed unless you're real good at speed shifting an double cluching. The syncroed 2nd and 3rd will make life good. Check out and clean up that unit and use it. Use the 4 speed a back up.

 

[RBaker]

Like Old...Bill says, look inside to make sure, BUT it appears you have the exact right transmission ... a prize.

Take the top off and simply measure the inside dimension of the larger fork. You want a full 3" to indicate the late gears/synchros.

Ok, so the fork will be attached to the top of the gear box when I remove it? I will check for 3".

 

[RBaker]

For driveability you really want to use the the 3 speed unless you're real good at speed shifting an double cluching. The syncroed 2nd and 3rd will make life good. Check out and clean up that unit and use it. Use the 4 speed a back up.

I will use it.....no way can I pass up the advice of you guys. To be honest I've never driven either one of these Ford transmissions in my life.

 

[Mac VP]

Take a look at our website's pages on "39" transmissions. If you want to fix up the 3 speed, you can get our book and order parts to do it yourself. If you don't feel comfortable doing it, we and others around the country rebuild these regularly. If for some reason the 3 speed trans doesn't have the correct 3" wide shift fork, you can use the existing gearset inside or upgrade to the 1939-48 gears. Here is the link:

http://www.vanpeltsales.com/FH_web/flathead_transID_3speed.htm

 

[Hoop]

"Ok, so the fork will be attached to the top of the gear box when I remove it? I will check for 3"."

Yes, that's the easiest way for a novice to check. Again, like Old ... Bill, those who are familiar with the transmission have noted the "double detent" top, two aprox. 1" plugs that screw in horizontally just behind the shift tower. That is NOT a sure sign of the later gears, but a great indicator along with the ID number.

Edit: Mac VP is an excellent source for flathead transmission information/parts/service/etc. Should have mentioned his website ...

 

[RBaker]

Take a look at our website's pages on "39" transmissions. If you want to fix up the 3 speed, you can get our book and order parts to do it yourself. If you don't feel comfortable doing it, we and others around the country rebuild these regularly. If for some reason the 3 speed trans doesn't have the correct 3" wide shift fork, you can use the existing gearset inside or upgrade to the 1939-48 gears. Here is the link:

http://www.vanpeltsales.com/FH_web/flathead_transID_3speed.htm

Excellent link thank you.....I will find out in the morning what I have.

 

[RBaker]

Spent the morning cleaning the old 3 speed.....the dirt on the outside is hard as rock, had to use a hammer and chisel. On the top of the case is the number (26) above the numbers (81A-7222).

Top of the case came off easy....oil was still in bottom of trans case, inspected all gears and saw no broken teeth. Shifted the gears and turned the shaft by hand...seems to work just fine.

Measured the smaller shift fork it is 3 inches.....the larger fork is close to 4 inches.

 

[RBaker]

Headed back out to the garage.....thanks for the help! Pic of the frame with the overload springs and hitch removed.....its cleaning up nice.

 

[RBaker]

Oops...went out to measure the forks again just realized I should have measured from the inside.

 

[OLD...BILL]

Ron: Your trans is real prize: clean it up and run it. I know you will paint it to match the engine, get the book Van Pelt offers, just for reference, You did your distributor, and made it work you can deal with anything that transmission sends your way... down the road, Now back to your good neighbor, you need the instrument cluster on the shelf (wrong color gold ) the truck was gray... The best thing for the 4 speed, is gut it,. bolt plywood on each end and us it for wheel stand, also good place to put tools and nut/bolts while working under the truck, send all old parts out of it, the top and shifter, to the iron man.
One more thing " tooth count " count the big teeth on the input drive gear.
should be 16, not a big thing, just info. .....OLD...BILL

 

[Hoop]

It's hard to diagnose from your picture, but it would be a safe bet that the synchro rings should be replaced before you install the transmission. 2nd, the rear one, sure looks too tight. However, it's not a bad idea if you use quality parts.

The synchros rings are the small, brass, loose gears on either side of the slider that the 3" fork fits into.

 

[RBaker]

Thanks for the advice....Old Bill I like your ideas on the old 4 speed..haha

I plan to remove the 4 speed in the next couple of days....I'm going to Sams Town casino down in Mississippi today to a car show so today no work on the truck.

I do have a few more questions.....Will I need to remove the rear axle to remove the trans?

Take a look at this picture where I have the red arrows....will these two long bolts connected to the rear of the block & frame be enough to hold up the engine with the trans removed or will I need to support the rear of the engine below?

Hope you all have a great day.

 

[Hoop]

"Will I need to remove the rear axle to remove the trans?"

In your case, either unbolt the rear ... or unbolt and pull the engine forward/out. There doesn't seem to be much left in the way. Depends on what else you're planning on doing/detailing/replacing. Piece of cake working with a bare chassis.

" ... will these two long bolts connected to the rear of the block & frame be enough to hold up the engine with the trans removed or will I need to support the rear of the engine below?"

No. Put some sort of jack under rear of the engine (unless you decide to pull the engine.) It also helps to adjust/align the stuff when you reinstall.

 

[rotorwrench]

From the looks of your chassis so far, you could either pull the engine & trans as a unit or disconnect the rear axle from the frame & support the engine. Generally, when the cab & bed are mounted, you would support the rear frame then disconnect the rear axle and pull it back far enough to clear. Next would be support the rear of the engine then pull the trans out. Most of the 30s & 40s cars/trucks had trans access cover plates that can be removed in order to lift the trans out from the top or lower it down to the floor (which ever is more convenient). The load can be lightened by removing the shifter top.

Kerby