Making a Ford 3spd the best it can be.

[Henry Floored]

Hey gang I'm planning on pulling the '39 Ford trans out of my friend Don's '37 Coupe to probably replace the synchronizer assembly.

Don's car is a pretty hot, hot rod with a healthy 260" Flatty. I'd like to make the gearbox shift as slick as possible and hold up to the meaty torque band that the engine provides.

My question is basically what advice can you give me to make the "box" the best it can be. Are there any mods or special parts that would be beneficial.

I'm toying with the "Zephyr" gear set idea but those are pretty pricey. If you have tried those aftermarket gear sets do you think they are worth the money? Do they hold up well?

What would you suggest to help the tranny shift buttery smooth or as close to that as possible?

Are there certain tricks that will help seal the shafts better?

Any and all opinions and advice would be welcome.

Thank you in advance!

[Lawrie]

Get max vanpelts book, also look up rumbleseats old info ,These guys know how to make the box as good as it can be.
Lawrie

[fordcragar]

Originally Posted by Henry Floored

.........................Are there certain tricks that will help seal the shafts better?...............

You could machine the case and use o-rings.

[JSeery]

The idea with the zephyr gears is similar to what was later referred to as close ratio transmission gearing. The idea is to keep the engine within a fairly narrow band while shifting in something like a drag race situation. You are trying to say shift at maximum HP and have the engine drop to near maximum torque. I like close ratio transmissions and like the Ford T5z in part for that reason. Ok, a flathead has a lot broader rpm range for a torque curve than a lot of engines, so it is a little more forgiving in this area, but still fun to mess with if you are into the acceleration thing! It is going to depend somewhat on how the car is going to be driven, in town stoplight to stoplight favors this type of setup vs a highway cruiser, IMHO. I would want a low rear end gear, say a 4:11 and a light driveline. A 9 inch clutch would be good along with a lightweight flywheel if the car is light enough to use it. A 37 coupe may be too heavy to go too light on the flywheel. I second the VanPelt information and Rumbleseat has some outstanding information.

[flatheadmurre]

Originally Posted by fordcragar

You could machine the case and use o-rings.

And stay away from the aftermarket shafts sold by the company not to be mentioned by name...they are undersize not hard enough and barrelshaped from incorrect centerless grinding.
I got fed up and started making my own.

[pooch]

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I ground 1/8th off the ends of the long shaft and the reverse shaft, and fitted 3/4 welsh (freeze plugs ).

I ground the ends of the locatig pin hole flat and used a piece of 1/4 threaded bar with fibre and steel washers and nuts on either end.

Using synthetic GL4 and zero leaks .

[Lawrie]

I stripped the case,mounted it vertical on the mill,picked up the centre of the hole,bored it 3 mm oversize,with it still set up turned up the sleave a few thou undersize on the bore,pulled it in with a bolt ,then bored it to size ,done about 6 this way,no leaks ,and rescue an old case.
lawrie

[Fairlane500]

I shorten the retainer pin and tap the case and put grub screws in to retain the shafts and seal the retainer pin holes, the shortened pin is floating in between the grub screws. Bit of sealer on chamfered case hole bores = no leaks.

[pooch]

I shorten the retainer pin and tap the case and put grub screws in to retain the shafts and seal the holes, the shortened pin is floating in between the grub screws

Good idea too Fairlane500

Did Henry use the 600 sludge that was in the model A in the V8 boxes back then ?

I guess synchro boxes needed something a bit thinner .

[JSeery]

Originally Posted by pooch

did henry use the 600 sludge that was in the model a in the v8 boxes back then ?

no!

[JM 35 Sedan]

I would definately use the later 39-48 syncos and '39 style wide fork, double detent top shifter. Set all internal gear spacing correctly, and seal the rear of cluster and reverse idler shafts. If you don't already own a copy of Mac VP's book, this would be a good time to pick one up.

[Seth Swoboda]

Originally Posted by JM 35 Sedan

I would definately use the later 39-48 syncos and '39 style wide fork, double detent top shifter. Set all internal gear spacing correctly, and seal the rear of cluster and reverse idler shafts. If you don't already own a copy of Mac VP's book, this would be a good time to pic one up.

What John said.

Also, I would forget the Zephyr gear idea. If it's gearing you're after then swap the cluster gear to the 29/15 combination with 3:54 rear end gearing. Better results.

[Bruce Lancaster]

Yes, LZ gears are inappropriate for a big car with 3 speeds unless you do as Lincoln did...use very low rear gears and an overdrive. The current torque tube type )D would be easiest route to that, the 4.44 gears or at least 4.11.

[Henry Floored]

Guys thanks for all the responses. I am loving this.

[Jason in TX]

I bought the VanPelt book and it's amazing. I used the 26 tooth LZ gears and love the Zephyr gears in my Model A coupe. Long first and second gears. In my runs at the beach at The Race of Gentlemen, I was able to stay in second gear most of the 1/8th mile run with winning results.

Video of my Question Mark Coupe drag racing.
https://scontent.cdninstagram.com/t5...51257344_n.mp4

Engine is 274 cu/in with McCulloch Supercharger. Merc Crank, 3 5/16 pistons, Cyclone heads, Schnider cam.

[Seth Swoboda]

Originally Posted by Jason in TX

I bought the VanPelt book and it's amazing. I used the 26 tooth LZ gears and love the Zephyr gears in my Model A coupe. Long first and second gears. In my runs at the beach at The Race of Gentlemen, I was able to stay in second gear most of the 1/8th mile run with winning results.

Video of my Question Mark Coupe drag racing.
https://scontent.cdninstagram.com/t5...51257344_n.mp4

Engine is 274 cu/in with McCulloch Supercharger. Merc Crank, 3 5/16 pistons, Cyclone heads, Schnider cam.

Do you use an air filter, how do you keep the dirt and sand out of the engine? Or is it not a problem?

[Jason in TX]

I do not use an air filter. Winfield carburetors traditionally didn't have air filters. The beach was sandy and I'm sure I sucked up a bunch of airborn sand. I should pull the tops and check the bowls, but haven't messed with the car much after racing two weeks ago.
Model A Fords also don't have air filters and I've put 30-40K miles on my 4 banger without a filter and everything still seems fine.

Driving around in the city with a hood on, I don't think I'm getting enough to cause a problem.

[Seth Swoboda]

Originally Posted by Jason in TX

I do not use an air filter. Winfield carburetors traditionally didn't have air filters. The beach was sandy and I'm sure I sucked up a bunch of airborn sand. I should pull the tops and check the bowls, but haven't messed with the car much after racing two weeks ago.
Model A Fords also don't have air filters and I've put 30-40K miles on my 4 banger without a filter and everything still seems fine.

Driving around in the city with a hood on, I don't think I'm getting enough to cause a problem.

I don't run an air filter on my model A either. I believe the small amount of anything sucked in is negligible.

[rotorwrench]

There isn't much in the way of beef ups for the Ford light duty top shift transmission with the late type gears. The best thing you can do is get it to the best possible tolerances & clearances at reassemby. Don't use questionable internals or case and definitely get MVP's book.

They are no super T-10 or anything close but for a small motor like the old flatties, they do OK. I'd be more worried about busting an axle in an old banjo rear.

[flatford39]

Get Vern Tardells "Let me help you" book on rebuilding a 39 box. That and Van Pelts book got me through it in about an hour. I put 46 48 gears in my 39 case and put in the newer syncros that Vern suggested. Van Pelts sell everything you need.

What Tardell does with the shafts is just countersink the surface and then apply a sealant after you are complete. I didn't bother with this step.