Diff. pinion cut down on threaded drive shaft
 

In fitting a Mitchell O/D to a members car, we found the pinion had no threaded portion and was retained on the drive shaft by smaller nuts on the driveshaft itself, which was threaded. See pics. attached.
Is this a "Farmer Fix", part of a different model Ford or what?
Anyway it slowed us down because the Mitchell stub shaft is much thicker, so I would have to turn it down to thread it if we wanted to use the old pinion. Plus the Ring gear ("crown wheel" if you report to Her Majesty The Queen, as we do) doesn't look too good anyway.
No questions, but thought this little setback might help other Barners fitting a Mitchell O/D, or has this been commonly found before?
Happy New Year to all.
SAJ in NZ

Re: Diff. pinion cut down on threaded drive shaft
 

No, it's not a farmer fix. What you have there is the early tailshaft commonly referred to as an Early AR. Sorry can't say when they stopped using them but I'm sure others will chime in here with additional info.
I have seen a couple of these over the years (mine included)
not sure what is required to fit to a Mitchell Overdrive.

Re: Diff. pinion cut down on threaded drive shaft
 

What you have is a very early 28 ring & pinion gear set. The ratio is 370:1. This set up is not compatible with a Mitchell overdrive installation. What you are going to have to do is tear the rear axle assembly apart and locate and install the later 378:1 ring & pinion gear set.

For more information on this early gear set up go to the web site of the Santa Anita A's of Arcadia, California at santaanitaas.org. On the home page put your cursor on "Technical Reference". My name will appear below, click on it and it will bring up a menu of technical articles. Scroll to the one of differential rebuild revised 2014. It is a pdf file end you are welcome to download and print out.


Tom Endy

Re: Diff. pinion cut down on threaded drive shaft
 

Thank you RUNNERBUN and TOM for your rapid replies. It comes back to me now. I will read your latest rebuild pages tomorrow. I followed your earlier publication 4 or 5 years ago to rebuild the diff. in my Roadster.
In the meantime, can I ask if we place a quick order to Snyders tonight (It is almost midnight here) for Ring, Pinion (3.78:1), cups, cones, shims gaskets, tab washer etc, will it all fit into the early diff housing I presume we have?
The car is a late 1930 Phaeton, but who knows what has gone on over the years. The axle housings have powder coat over very deep rust pits and it looks like the rear axle was rescued from under a hedge before it went into this car
Thanks again
SAJ in NZ
OK TOM, just read your article so I see we will be OK with all new parts

Re: Diff. pinion cut down on threaded drive shaft
 

SAJ replaced same unit in Dave Whites sedan some years ago here as destoyed it on some ruff road in the Molesworth , replaced d/shaft , ring & pinnion, i think that was all, Re your new parts required , why not support your local supplier, he will have in stock. & be open , Cheers Derek

Re: Diff. pinion cut down on threaded drive shaft
 

Derek. Ralph decided to do as you suggested. I sent him your post since he doesnt belong to Ford Barn. He tells me you are sending up a 3.78 and Errol is providing bearings etc. Will get straight onto it when the bits arrive.
Many thanks.
SAJ in NZ.

Re: Diff. pinion cut down on threaded drive shaft
 

No Problem . courier will collect today , might take few days being new year , Was talking to Ralph a couple of times , & look forward to catching up at the National meet in March. He will love his Mitchell, I have 4 arriving this week plus a transmission for custmer . one spare O/D if someone needs , Thanks Derek