Transmission Main Shaft ID Needed
 

I am trying to identify two different transmission main shafts shown below.

I think I got the first one correct as being 48-7017 after perusing Mac Van Pelt's book and the Green Bible.

The second main shaft photo has a different configuration. It's 8.27 in long, has 16 helical teeth and 30 synchronizer teeth at it's front end. However, the width of the shiny, tapered surface at the front (for the synchronizer) is much narrower than on #48-7017. It's only 2.280 in. wide.

QUESTIONS: What is the correct part number for the mainshaft in the 2nd
photo and
What year and model Ford transmission does it fit?
Thank you, Jim

Re: Transmission Main Shaft ID Needed
 

Hey Jim ..... Sorry but I don't have the answer you're looking for. Hopefully to help with your inquiry, those two shafts are "INPUT SHAFTS", or MAIN DRIVE gear. They are not "main shafts". The main shaft is the shaft that fits-in behind the input shaft, upon which the second gear and synchronizers fit and slide. The main shaft will also have the six splines for the U-joint at it's rear end.

Coop


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Re: Transmission Main Shaft ID Needed
 

Jim, The top one is 81A-7017, the bottom one is 48- 7017

Re: Transmission Main Shaft ID Needed
 

Thank you V-8 for "giving me the shaft" info.

Re: Transmission Main Shaft ID Needed
 

I would THINK that either of these would go with an accompanying 28-tooth cluster, and would have a 2.82 1st gear ratio.

Coop


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Re: Transmission Main Shaft ID Needed
 

As Brian alludes to, I believe your TOP shaft is mis-identified, and is actually the "81A-" shaft. "81A-" indicates 1938 FIRST YEAR usage, whereas a "48 "prefix indicates a 1935 FIRST YEAR of usage. That would stand to reason with the width of that synchronizer surface growing larger....PROGRESS!

Coop


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Re: Transmission Main Shaft ID Needed
 

Re: Transmission Main Shaft ID Needed
 

Just a word of caution when looking at a 16T main drive gear of unknown origin - it could be a 1C rather than an 81A. If 1C it must be paired with the later gears that come in the open drive transmissions from ‘51-52. Maybe Mac will chime in but I think 81A is around 2.35” and 1C is 2.45” when measuring the diameter of the gear teeth. You will also know when you try to bring up the cluster gear and everything gets tight

Re: Transmission Main Shaft ID Needed
 

Will, good to see you chime in here!!! Hope all is okay with you. I have enjoyed looking at your "side" hustle work.....Simply beautiful

Re: Transmission Main Shaft ID Needed
 

Thank you Mr. Kimble for jumping in and providing the gear measurement info.

Both 16 tooth helical gears on the parts I posted measure 2.35 inches OD.
(One measures 2.3540 in. The other measures 2.3555 in.)

Re: Transmission Main Shaft ID Needed
 

Sounds good, 81A (or 8M) it is!

Re: Transmission Main Shaft ID Needed
 

Don’t forget the possibility of this main drive gear being the B-7017 which is the 1932-34 version. The following links to our website pages will make this more clear to you.

http://www.vanpeltsales.com/FH_web/F...o-bulletin.jpg

http://www.vanpeltsales.com/FH_web/f..._mdg-types.htm

Lots of good technical information is buried in our website. These two webpages are in the Transmission Parts Drawings section. Enjoy!

Re: Transmission Main Shaft ID Needed
 

Both the parts I posted measure 8.27 in. long using my vernier caliper.

How critical is this .02 in. difference from 8.25 inches?

Re: Transmission Main Shaft ID Needed
 

I think you’re ok there. The MDG with the small cone is used with early synchronizer, stock applications from ‘32 to early ‘39. The other is stock for ‘39-50 - the traditional ‘39 style transmission.

Re: Transmission Main Shaft ID Needed
 

WOW!
THANK YOU ALL VERY MUCH for taking the time and effort to help me by sharing your knowledge and life experiences with transmissions.

There is so much valuable knowledge that is not written in a book or manual.