Transmission Book

[dkd35]

What's a good book to get 1939 transmission specifications? I have Mac Van Pelts would the service bulletin 38-40 work?

[Tim Ayers]

Not sure you'd find any better than Mac's book. What specs are are you looking for?

[petehoovie]

Originally Posted by Tim Ayers

Not sure you'd find any better than Mac's book. What specs are are you looking for?

http://www.vanpeltsales.com/FH_web/f...trans-book.htm

[dkd35]

[QUOTE=Tim Ayers;2202288]Not sure you'd find any better than Mac's book. What specs are are you looking for?[/QU. OTE] The spec on Gloster gear mac says it shouldn't move back and forth but spin. As the old cases stretch some spin freezer than others.

[Tim Ayers]

[QUOTE=dkd35;2202304]

Originally Posted by Tim Ayers

Not sure you'd find any better than Mac's book. What specs are are you looking for?[/QU. OTE] The spec on Gloster gear mac says it shouldn't move back and forth but spin. As the old cases stretch some spin freezer than others.

I am not a certified transmission expert, but the overall backlash of the cluster assembly is really your main concern. Mac's book clearly gives the specs and his advice on this.

When there is too much backlash, that is what causes the cluster to move around and downward under deceleration. That is what is popping the 2nd gear fork out of engagement I believe.

The backlash will give you the overall fitment of the all of the cluster components and that is why Mac sells spacers in different thicknesses to get this measurement within spec.

Checking backlash does mean the trans needs to be assembled with the rear bearing retainer installed before one can get an accurate backlash measurement.

I hope this helps.

[Bored&Stroked]

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There are lots of things to consider when you are trying to build one of these trans. The better the quality of the components, the tighter the clearances, the better chance you have of it not popping out of 2nd.

Here are some of the things I care about:

1) Mainshaft: If the snout/bearing surface of the mainshaft is worn, then this introduces a lot of 'flex' in the upper input shaft through mainshaft assembly. I do not use worn mainshafts.

2) Caged Roller Bearings: Unless Mac VanPelt says differently, I would not use the repop caged rollers. The cages are not correctly hardened and they wear out. Use original Ford stuff.

3) Main Shaft Stack Up: You have to tune the stack-up end-clearance. The closer you can be to .003, the better. I buy an assortment of thrust washers and fine-tune the clearances on my surface grinder.

4) Second Gear Bushing: I have this gear rebushed by Charlie NY for a tight fitment on the actual mainshaft I'm going to use. They then become a "matched set". Having a slight drag on the fitment is another key part of keeping the trans from popping out of second.

5) Main Cluster Shaft: The repops that I've seen are undersize and not hard enough. I try to use original cluster shafts (with no wear), or I make my own from linear shafting. If your shaft is worn on one side, then turn it over on the rebuild (putting the worn side down).

In the end, if you use parts that are not worn and setup the clearances on the tighter side of the specs, then they will usually stay in second gear.

If you ask any of the various transmission rebuilders if they "guarantee they won't pop out of 2nd" . . . you'll probably find you don't like their answers. LOL

Take your time, source high quality original parts and you'll be okay . . .

[hotcoupe]

Another source for early Ford transmission rebuilding information is a publication by Max Navarro (if you can find one). It is clear and concise, very well photographed (see images).
Tom

[Tim Ayers]

Originally Posted by hotcoupe

Another source for early Ford transmission rebuilding information is a publication by Max Navarro (if you can find one). It is clear and concise, very well photographed (see images).
Tom

That is a good one as well to use in tandem with Mac's book. I got my copy from Moon many years ago. Looks like they still sell it.

https://www.mooneyesusa.com/Book-How...-p/im39fdt.htm

Vern Tardell sells a "little" book on transmissions as part of his series of help books too.

[deuce5wndw]

Originally Posted by Bored&Stroked

There are lots of things to consider when you are trying to build one of these trans. The better the quality of the components, the tighter the clearances, the better chance you have of it not popping out of 2nd.

Here are some of the things I care about:

1) Mainshaft: If the snout/bearing surface of the mainshaft is worn, then this introduces a lot of 'flex' in the upper input shaft through mainshaft assembly. I do not use worn mainshafts.

2) Caged Roller Bearings: Unless Mac VanPelt says differently, I would not use the repop caged rollers. The cages are not correctly hardened and they wear out. Use original Ford stuff.

3) Main Shaft Stack Up: You have to tune the stack-up end-clearance. The closer you can be to .003, the better. I buy an assortment of thrust washers and fine-tune the clearances on my surface grinder.

4) Second Gear Bushing: I have this gear rebushed by Charlie NY for a tight fitment on the actual mainshaft I'm going to use. They then become a "matched set". Having a slight drag on the fitment is another key part of keeping the trans from popping out of second.

5) Main Cluster Shaft: The repops that I've seen are undersize and not hard enough. I try to use original cluster shafts (with no wear), or I make my own from linear shafting. If your shaft is worn on one side, then turn it over on the rebuild (putting the worn side down).

In the end, if you use parts that are not worn and setup the clearances on the tighter side of the specs, then they will usually stay in second gear.

If you ask any of the various transmission rebuilders if they "guarantee they won't pop out of 2nd" . . . you'll probably find you don't like their answers. LOL

Take your time, source high quality original parts and you'll be okay . . .

Excellent advice!!