Question for Tom Endy

[Big hammer]

Differential carrier bearings preload tool, if the spider is modified to test preload, would the threaded hole in the spider make it unusable for road use ? I don't have extra spiders to dedicate for tool use only.

[Tom Endy]

I can't really answer your question because I have never tried it.

It would appear that the threaded hole would have no affect on performance, the two flat sides of the yoke ride against the flat surface of the gear end of the axle.

Tom Endy

[Big hammer]

Thanks Tom, your tool and adjusting looked like the best way! I can adjust manually.

[racingrufus]

I used Toms instructions to build my differential.I got a used spider from a friend but I could not drill it to tap it so I welded a one half inch nut on to the spider that I screwed a all thread rod into to set my preload.

[Big hammer]

Now thats an idea, weld on a nut, when finished grind it off Thanks!

[Vonn Ditch]

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That spider is too hard to tap. I did manage to drill one using a masonry bit, actually two, but when it came to tapping it? Nope you just can't do it with a hand tap. Spiders are pretty easy to come by, so I just welded a rod to mine for a dedicated tool.

[Kurt in NJ]

When we did my brothers we just stuffed a piece of rope in the lock the gears---then just pull the rope out, no need disturb the assembly

[H. L. Chauvin]

Homemade Schedule 40 PVC Model A Ford Differential Preload Adjusting Tool To fit Over Spider Gear Tri-Axle:

1. Material Items; (under $10.00 without PVC Glue):

A. 3" Schedule 40 PVC MIPT Clean Out Plug, Model #C4818HD3 =
$2.30. (Refer to modifications below in Paragraph 2).

B. 1/8" thick x 1-15/16" wide x 3/4" deep, (top to bottom), aluminum flat
bar to fit diagonally in the square opening of above Item A after
clean out plug modifications specified in Paragraph 2. below.

C. 3/4" Schedule 40 PVC pipe, cut 2' - 6-3/8" long. (Cut pipe from a new
10 ft. long 3/4 in. PVC pipe = $2.87.) On bottom end of PVC pipe, drill
a 1/8" hole through both sides of pipe, 3/4" upwards from lower end of
pipe. With a hacksaw, provide a 1/8" wide x 3/4" long up & down
slot in both bottom sides of PVC pipe, from cut off end of the pipe to
the above 1/8" drilled holes.

D. Provide and glue a 3/4" PVC coupling on the top end of the above
Item C PVC pipe = $00.34.

E. Provide and glue a 3/4" x 1/2" Schedule 40 PVC reducer in top
end of Item the above formerly glued Item D. coupling = $1.11.

F. Provide and glue a 1/2" plug in the top end of the above Item E. PVC
reducer = $00.96.

G. Optional to help maintain 3/4" PVC pipe in a vertical position when
turning: Cut a 3/4" PVC coupling to 7/8" long, burnish inside of
PVC coupling with sandpaper so it slides easily over the above Item C.
3/4" PVC pipe. Position and glue this burnished coupling in place such
that the bottom end of this coupling is 2' - 2-1/2" from the slotted
bottom end of the above Item C. 3/4" PVC pipe.

2. Preparing above Item A Clean Out Plug:

a. With a hacksaw, cut off and remove the top, flat square part of the
above Item A PVC plug thus providing a square thru-hole in said
square part of the PVC plug.

b. With a hacksaw, if required, cut grooves in the inside corners of the
square open hole in the clean out plug for the above Item B. aluminum
plate to fit tightly.

c. Place the 3-1/2" PVC clean out PVC plug on a sheet of paper, and with a fine felt
tipped marker, scribe a circle around the outside threaded circumference of
the PVC clean out plug.

d. Using a grammar school cheap compass with a pencil, locate the
center of the drawn circle to determine the radius of this circle. Next,
place the metal point of the compass on the marked circle's
circumference and scribe (6) consecutive radius marks on the
circumference of the circle. (E.g., the circumference of a circle can be
divided into (6) equal segments using the radius of the circle.)

e. Chose any (3) marks which will fit directly over the (3) axles on a
Model A spider gear Tri-Axle and provide (3) 90 degree vertical marks on the
threaded sides of the PVC plug.

f. Clamp a 2x4 on edge, with one 1-1/2" side flush with the threaded
side of the PVC plug. With a 3/4" spade bit, next drill a hole in the
2x4 and also through the threaded side of the PVC plug, and repeat same
for providing (3) holes. With a round file, custom fit (3) recessed holes to fit snugly
over the (3) axles of the Model A spider gear Tri-Axle.

3. Adjusting Model A Differential Preload:

With Model A axle housing positioned in the vertical position, (per Mr. Tom Endy's instructions), after installing the Model A Tri-Axle, place the modified PVC plug over the Tri-Axle, insert the 3/4" PVC pipe slots over above Item B. flat aluminum bar, place socket wrench socket on above Item F. PVC plug, and turn PVC assembly and Tri-Axle with an inch-pound torque wrench to achieve the desired preload.

[Big hammer]

Thanks H L after reading three times and then looking at Tom's pictures of the carrier I finally saw that your tool fits inside the carrier in place of the axle/gear space. I liked that you painted your tool red and identified it so someone in the future would not throw it a way! At my work many of my homemade tools have been discarded when others just think the tools where just junk. Thanks to all for your ideas and help!

[H. L. Chauvin]

You are welcome.

Like many, because of not having a spare differential Tri-Axle, I went to Home Depot, and as usual a Home Depot salesman asked, "May I help you?" Told him I was looking for some Home Depot materials to invent and make a tool to adjust the preload on a 1930 Model A Ford differential. Like all salesmen ..... after their "Deer in Headlights Look", they always leave me alone to think.

I used this tool to adjust my new 3:27 ring & pinion (10) years ago -- it allows extremely accurate reading per Mr. Endy's specifications.

I still get a few Model A private technical email questions from time to time over the past (20) years. About (10) years ago, when I recommended that this gentleman in Oregon make a PVC tool like this, I dated it November 25, 2007 with a felt tip, painted this tool red with black highlighted edges so it would show more details as indicated in these (10) year old photos.

And yes, I paint most my tools "red" so my (4) kids do not take them & think they are scrap material for their projects. The plus side of using PVC for tools is after the mice wet it, it will never rust.

[Kurt in NJ]

From what I see of these tools they all require assembly of the diff case without axles, then once preload shimming is determined the diff case is dissassembled, the spyder gears and axles are put in----perhaps I didn't fully describe how I last did it--

With a fully assembled diff case---ring gear,axles, spyder gears all torqued up and safety wired a piece of rope is stuffed into one of the holes in the diff case with a screwdriver leaving one of the ends acessable---this will "lock" the diff----assemble the bells, put a nut on the axle with a pin(cotter pin. cut off nail) to keep it from turning---then a socket can be used to turn the assembly to check preload-----after the preload is correct just wiggle the axles and pull out the rope.

[john in illinois]

I had this company do their axle conversion on my roadster banjo rear end.

http://www.hotrodworks.com.

They told me a good way to set preload.

Set the pinion preload say15inlbs. Guess at ring gear preload shims. The pinion and ring gear preload add together. If you have say 31 when you turn the pinion,then ring gear is 16. Saves a lot of steps.

I would think there would be a gearing effect to the reading,but these guys do lots of banjos and even make new carriers for model As.

Check out there web site,it is interesting.

John