39 PU/46 Merc rearend

malpais

malpais

Well-known member
Just read thru 14 pages of posts, and didn't find quite what I needed.

I would like to replace the 4.11 rearend in my 39 Ford PU.

The only "higher" rearend I've found on which the input splines are good, is from a 46 Merc.

Is it possible to use the banjo from the Merc, and the bells and the axles from the 39? (Merc complete rear axle is wider).

May be better to buy a new one (someday), but was just wondering....

Thanks, Gordon
 
Duece is correct. The commercials sometimes got the older parts, the 18 tooth ending in '38. No problem, you'll be using the spider from your '39 anyway, which of course does match your axles.
 
Gordon in reading your post I'm understanding you want to change your ring & pinion gear set like I did and not the complete rear diff assembly?

The fella who re-built my rear diff and changed the ring/pinion set (6 spline) sold me a later torque tube that was 6 spline and those tubes have a center bearing as well.

My 39 now has 3.54's hope this helps you, pm me if you have any other questions. Scott
 
I replaced my 4:11 ring a pinion with a 3:74. Everything else stayed the same. I believe that R & P gears are interchangable from 1935 to 1948.
 
Go the direction you are talking about.
The '39 pickup uses the same rear setup as a passenger car.
In fact I did what you're talking about. I installed a '42 Merc 3:54 center section & ring gear into a '38 pickup axle assembly. '38s & up use a six spline pinion.
Not a big deal.
 
Yes, the Merc axle assembly IS wider.......1-1/2" wider. That amounts to ONLY 3/4" per side. The difference on a pick-up is negligible, and more than likely moves the tires/wheels to a more-eye-appealing position in the fender well. DD
 
V8COOPMAN said:
Yes, the Merc axle assembly IS wider.......1-1/2" wider. That amounts to ONLY 3/4" per side. The difference on a pick-up is negligible, and more than likely moves the tires/wheels to a more-eye-appealing position in the fender well. DD
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Not talking about using the Merc axles & housings, just the Merc banjo with the pinion already in place plus the Merc ring gear.
Axles, axle housings, torque tube & drive shaft would stay '39.
 
V12Bill said:
I replaced my 4:11 ring a pinion with a 3:74. Everything else stayed the same. I believe that R & P gears are interchangable from 1935 to 1948.
Click to expand...
Good points here, however the truck spline is 10 not 6, 3.54 and 3.78 ring & pinion gear sets that were available when I had my 39 changed came 6 spline only.

Option one for our application is either buy a 6 x 10 spline adapter for the pinion gear or the route I took later 6 spline, center bearing torque tube. Got your pm Gordon, we'll get through this. Scott
 
Re: 39 PU/46 Merc rearend. I'm dangerous

Thanks everyone.

After 38 has 6 splines - correct?

But 39 trucks had 10 splines? Been together for a couple of years - don't remember.

V8Coopman - wondered if the wider assy would fit with shackles etc.
Sounds like a good way to go
 
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Re: 39 PU/46 Merc rearend. I'm dangerous

malpais said:
Thanks everyone.

After 38 has 6 splines - correct?

But 39 trucks had 10 splines? Been together for a couple of years - don't remember.

V8Coopman - wondered if the wider assy would fit with shackles etc.
Sounds like a good way to go
Click to expand...

To me, it sounded like a good way to go because you don't have to go through any of the motions of setting-up a new rear end. To potentially answer your question about shackles and width, the shackle hangers on a '39 rear measure 48-1/2" wide. A '46 has the hangers at 46-3/4" wide. BUT .......if I remember correctly, '46s had longer shackles that angled more or less straight down, instead of the shorter shackles that were angled-inboard on the '39. I can't answer whether or not the two springs were of the same length. However, if you utilized the '46 spring on the '46 rear end, it should certainly bolt into the '39 crossmember. Read thru the old STREET RODDER article in the link below to help re-familiarize yourself with a bunch of old Ford rear end info. Hope this helps a little. DD

http://www.flatheadv8.org/fordrear.htm
 
39portlander said:
Good points here, however the truck spline is 10 not 6, 3.54 and 3.78 ring & pinion gear sets that were available when I had my 39 changed came 6 spline only.

Option one for our application is either buy a 6 x 10 spline adapter for the pinion gear or the route I took later 6 spline, center bearing torque tube. Got your pm Gordon, we'll get through this. Scott
Click to expand...

I have not run across a '38 or later pickup with a 10 spline pinion.
In fact to satisfy my curiosity I went into my storage & removed the torque tube from a '39 truck rear axle assembly. Lo & Behold a 6 spline pinion.
'37s & very early '38s had a tubular drive shaft with a 10 spine pinion.
Later in service if a 6 spline setup failed they could have been replaced with a 10 spline setup. This is the reason Ford provided the 6 to10 spline drive shaft coupling. This allowed the service department to use left over production 10 spline ring & pinion sets.

If using the wider Merc rear & using the '39 torque tube, you'll have to fuss with the radius rods. The Merc axle being wider will make the radius rods some what shorter.
 
42merc said:
If using the wider Merc rear & using the '39 torque tube, you'll have to fuss with the radius rods. The Merc axle being wider will make the radius rods some what shorter.
Click to expand...

With regard to the radius rod situation, see the link below which addresses a dimensionally similar swap. Note in post #6 by Kube (I know he has done more than one of these swaps) that the radius rod situation is addressed by the use of simple spacers. DD

http://www.fordbarn.com/forum/showthread.php?p=976041#post976041
 
42merc said:
I have not run across a '38 or later pickup with a 10 spline pinion.
In fact to satisfy my curiosity I went into my storage & removed the torque tube from a '39 truck rear axle assembly. Lo & Behold a 6 spline pinion.

Well you know that old saying a picture is worth a thousand words, here you go lo & behold my 39 torque tube and old pinion. Were here to help each other out on the FordBarn so hey, you win:rolleyes:

I think in the previous post it did say "for our application" and I hope this does not turn into a competition to get into the Benson research center.

Got a call from Mr. ED today, he said it's time to leave him alone and lets all help get Gordon's 39 on the road:D. Scott
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This is one of those questions better answered by me puling stuff apart, comparing it to what have, and proceeding from there.

Sure do appreciate all your help - maybe we are not sure of the splines, but I'll certainly know what to look for.

Happy spring - supposed to be 70+ today in Northern Colorado, and officially, it's still winter!

Gordon
 
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