1914 Pathfinder driveshaft repairs

Started on sorting out the driveshaft.
The keyway being beaten out raised some metal on tapered part of the shaft.
I put the shaft in the lathe and skimmed the raised metal off of the taper. This also showed me that the taper was slightly worn in a couple places from the pinion rocking back and forth.
I took about 0.003" off to restore a proper taper, then used some lapping compound to fit the taper to the gear perfectly.
I'm going to take a little bit off the shoulder to ensure the pinion nut doesn't bottom on the shoulder before seating the gear tightly. Then I'm going to cut a new keyway.

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Oct 29, 2026

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Replies (22)

· 4d

Nice job saving that driveshaft. I’m assuming that you’ll need to add shims when you set up the gear mesh to account for the .003” you had to take off the taper, right? Or is there some other means of adjustment?

· 3d

Fortunately, the pinion bearing assembly is threaded and fully adjustable for depth so it should be easy to set up again. No shims needed.
These are just plain bevel gears so it's much simpler.

· 4d

What is the diameter of that shaft? Doesn't look large for a full size car?

· 3d

A bit over an inch diameter.

(edited)

· 3d

Shawn, do you know the final drive ratio and the outside diameter of the wheels? Also approx what the car weighs? 1" feels undersized to me but clearly it has lasted over a century so what do I know?

· 3d

I'd have to go count teeth but it's a pretty low ratio from my calibrated eyeball. Probably close to 4.10. The tires are 35 x 4.5 and if I had to guess, it's probably around 2800lbs.

-edit-
Just counted. 13 teeth on the pinion, 52 on the ring so 4:1.
Looks like the old eyecrometer works pretty good.

(edited)

· 3d

😂

Shaft does seem on the skinny side but clearly it worked all these years.

· 3d

@alsancle
That's what she said.

· 3d

@tbrow
Shaft is 1.25"

· 3d

Ahhh! I was gonna make some jokes and decided against it.

· 3d

Gear looks pretty good for 110 years old.

· 3d

If the odometer is to be believed, it's only got 19000 miles on it.

(edited)

· 3d

Keyway machined, key fitted, gear fits well but the nut bottoms out on the thread before it contacts the nut. I suspect this is why the pinion came loose in the first place. The metal I removed from the taper just increased the clearance.
Machined a spacer washer to go between the gear and the nut. I suspect this may have been missing as well.
Next step, new pinion bearings.

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· 3d

There may have been one there originally that got dropped on the floor at one point and rolled in to a drain before reassembly. My theory is that all of these cars are at least 1% lighter than when they left the factory based on parts that don't make it back on.

· 3d

The ole "where do these left over parts go?" scenario.

· 2d

Never happend to me! 😅

· 2d

One of the two pinion bearings is not available so I machined up a spacer to use a common, off-the-shelf bearing instead.
Hoping to assemble the driveshaft, pinion gear and pinion bearing assembly soon.

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· 2d

Nice work Shawn!

· 1d

How often do you discover a replacement bearing is not available and what do you usually do in that case?

· 1d

@DuesyGuy just ran into this problem of finding matching bearing. I don't know what he did.

· 1d

Thank you!

· 1d

@dj1970 Maybe 10-20% of the time I can't find an equivalent bearing but usually there's something close and I can machine up an adapter to handle it.