diff

Mr. Endy,

Your entire wonderful article on differential re-build is centered around sound mechanical engineering professional practice which is still used in modern times for accurately measuring & setting differential preloads & backlashes for modern vehicle differentials, as opposed to just "guessing" & "feeling" such intricate measurements of movement & "guessing" & "feeling" such resistance which can be measured accurately with a torque wrench in inch-pounds of torque.

In the not too distant past, because of mechanics guessing at & feeling these critical differential measurements, I remember quite a few Model A's traveling down the highway with the differential sounding like an amplified corn grinder.

In my humble opinion, the most time consuming part of differential rebuild is the removal & disassembly of the differential & mechanical brake system; cleaning of old caked 600W lubricant; preparing for painting, priming & painting; removing & re-installing internal parts; and re-assembly, & reinstalling the differential & brake system.

Then, the least time consuming part, but the very "most important" part of differential rebuild is the correct adjustment of backlash & the correct adjustment of preload.

Model A differential banjos were never designed to easily provide these adjustments & measurements; however, it cannot be overemphasized for one to follow "your" unique written recommendations on how to correctly & accurately provide these adjustments for a Model A differential.

There is no doubt that the valuable time given in your preparing these articles & other articles, is very much appreciated by "all" who rebuilt differentials & those who have gained knowledge from reading your articles.

On another lighter note, we know that you will continue to write very informative Model A articles in knowing that you will probably never be awarded the Nobel Peace Prize for your important works; but after seeing who they dished one out to recently, heck, I would never want one of these prizes either.
 
Tom,. very nice! I was thinking (watch out) wouldn't a pipe vice work as well?
Terry



Tom Endy said:
It is not absolutely necessary to build up the rear axle assembly in a verticle jig, it just makes it so much easier. I built this jig years ago. It is a bench vise that swivels that I picked up at a swap meet. I mounted it on some boards I laminated together and I clamp it in a wood vice I have attached to my work bench. The grabbers are made from a section of steel pipe I cut in half and had the two pieces welded to brackets I could bolt to the swivel vice.

I glued some pieces of carpet inside the grabbers to protect the axle housings.

Right above the bench I have an electrical hoist attached to ceiling rafters that I use to lift out the whole assembly when complete.

Tom Endy
Click to expand...
 
Humble Opinion:

The vertical differential jig described by Mr. Endy in my opinion can be most helpful for a "Do-it-yourself" differential rebuilder working all alone in his shop as follows:

1. For positioning the multiple ultra-thin gaskets so that they lay flat between the threaded rods which are threaded into the opposite faces of the banjo, as recommended by Mr. Endy.

2. For trimming the thin paper gaskets with an xacto knive mainly because not all gaskets from all vendors fit perfectly on the axle housing, & some can get compressed on the axle housing lip thus giving a slightly inaccurate reading after tightening said gaskets.

3. In some cases, one can experience that some former person(s) incorrectly used a bottle jack or something similar to push out the two pinion gear races; hence, the banjo was stressed causing it to be slightly out of round & slightly eliptical; therefore the protrudinrg perfectly round lip on the axle housing can snag the thin paper gasket during re-assembly if this gasket is not very slightly trimmed to exactly fit the slightly eliptical banjo.

4. After experiencing the following of Mr. Endy's instructions on differential re-build "to the letter", it was most obvious that:

A. His differential article was written after vast differential re-build experience as opposed to an article written about describing somebody's first differential rodeo; &.

B. These instructions could accomodate one (1) person accurately performing a differential re-build "all alone" as opposed to needing a helper; &,

C. His instruction were written in sequence like a very accurate verbal road map accompanied by his photos.

Also, I think Mr. K. R. Wilson, even though a fine gentleman, was providing mass produced jigs to sell to dealerships; whereas Mr. Endy in his article is describing how to do basically the same thing in one's own shop, all alone, by making a few tools without having to try to buy Mr. Wilson's tools, hence, whether working with differentials in a horizontal or vertical position, each to his own, both gentlemen deserve respect.
 
i adapted an old rim to use as a stand for the build. drilled one extra hole in it and bolted the axle tube down.
 

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Mitch//pa said:
i adapted an old rim to use as a stand for the build. drilled one extra hole in it and bolted the axle tube down.
Click to expand...

Nice job using the rim. I am just finishing my first diff rebuild and I tied the bottom axle housing to a bench leg then used 2x4s to shim the bottom and keep it tight. Next time (hopefully not) I'll do it your way.

Now, ta da, my 20 inlb preload measurement. I clamped a copper line to some all-thread through the center of the pinion. Weighed out a pound of water and slide it out to twenty inches. That's 20 in lbs the cheap way. :D
 

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Milton said:
Nice job using the rim. I am just finishing my first diff rebuild and I tied the bottom axle housing to a bench leg then used 2x4s to shim the bottom and keep it tight. Next time (hopefully not) I'll do it your way.

Now, ta da, my 20 inlb preload measurement. I clamped a copper line to some all-thread through the center of the pinion. Weighed out a pound of water and slide it out to twenty inches. That's 20 in lbs the cheap way. :D
Click to expand...

To be accurate you also need to factor in the weight of the pipe. If the pipe weights 4 pounds and is 30" long, then you have added another 60 inch pounds of torque, unless the pipe is balanced by having equal amounts on both sides.
 
I'm in the middle of putting one back together and I'm sure I'll have some questions. I made a holder from a 2ft long piece of 4x4 and two 2 1/2ft long 2x4s. Screwed them together (with the 2x4s longer in front), drop the bell down in the hole and have a 2x4 chunk to act as a cover boxing the bell in. The weight of the rear keeps it from moving and wedges itself into the wood...makes it a little tough popping it out. Then I "C" clamped the wood to a STURDY bench.

Also I just bought an old snap on inch pound gauge just for the banjo.
 

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One thing not mentioned by Tom. When Tom helped me install my Mitchell, we disconnected the spring from the rear end while in the car. Safety was the reason. As mentioned several times before in this forum, that rear spring could do some serious damage if it separated and not captured somehow.
Tom's fixture worked very well. The only improvement would be to have the rear fixture wheels behind the centerline of the rear end thus eliminating the need for 50 lbs of weight.

Good discussion here.

Dick Wyckoff
 
Tom Endy;60061 And there may come a day when AAA has to haul the car home on a flat bed truck with rusty chains wraped around the rear axle housing. Paint the rear axle assembly when it is all together like Henry did said:
Tom, Before my AAA driver put them BIG hooks on my rear axle housing, he CAREFULLY threaded some HEAVY LEATHER GLOVES on them---YEP! right into the MIDDLE finger!!!:eek: We almost choked from LAFFING!:D Bill W.

OH! & Buster T.:cool: asks, "Whut room in your COTTAGE do you use to overhaul rear ends & ur you MARRIED"?:confused:
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I use a variation of the rim idea. I use a wheel rim and put a piece of 2x2 ft 5/8 piece of plywood with a hole in the center of it. After putting the housing on the plywood.
I put the banjo with the driveshaft installed into the end of an engine stand where
the engine stand head would go. (Axle shaft clears the ground with this setup)
Works well and easy to make.
 
I picked up a few weight lifting stands..cut/bolt..en ya can come up with a nice piece of equipment to assist the assemble of the job..Charles..:o)..
 
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