1940 Johnson DT-10 Lower Unit Seals

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Buccaneer
Posts: 1934
Joined: Mon Mar 09, 2015 9:34 pm

1940 Johnson DT-10 Lower Unit Seals

Postby Buccaneer » Sat Aug 12, 2017 2:09 pm

The drive shaft seal on the subject motor has a conventional, but very old
seal in it with a steel case, but appeared to have some kind of packing
under it. Not sure what originally was in there, but it looks like
I can replace is with a conventional 1/2" shaft x 1" OD seal.

The prop shaft seal on the other hand is one like I've never seen.
It's a brass hub that sticks out from the gear case cover. It may be
pressed on the end of the bronze bushing in the gear case cap.
It had "plier" marks on it and I gently tried the same with no
luck. I didn't want to destroy it. Only enough room under the seal case
to get a putty knife in, but I had no luck that way.
What ever type sealing material was in the brass case is long gone.
Packing perhaps?
If anyone is familiar with this type of seal,
How does it come off, and what in the world would I use to replace it?
Thanks!

UPDATE, later in the day-
I found a tiny chisel that I was able to use to pry off the brass "packing?" cap.
I think it had some old sealer helping it to stay on, but once I got
it moving it came off easy.
So........ now I know "how" to get it off, but am still at a loss what to do next.
The brass packing cap fits over a raised portion of the gear case cover.
The bore of this raised portion (where the packing would go) is tapered....
I suppose to compress the packing around the shaft as the brass cap is
tapped on?
Anyone know what kind of packing I would use, as well as where to get it,
or have a better fix all together?
Thanks!
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t2stroke
Posts: 753
Joined: Mon Mar 09, 2015 3:58 pm
Location: Smyrna, TN

Re: 1940 Johnson DT-10 Lower Unit Seals

Postby t2stroke » Sat Aug 12, 2017 11:46 pm

C/R used leather as a seal material way back hence Chicago Rawhide. I guess you could try to fashion something like that?

Dan in TN

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Buccaneer
Posts: 1934
Joined: Mon Mar 09, 2015 9:34 pm

Re: 1940 Johnson DT-10 Lower Unit Seals

Postby Buccaneer » Sun Aug 13, 2017 7:18 am

Dan, I ordered some 1/8" Flax Packing that's said to be for
prop shafts, stuffing boxes, etc., good for 1000 ft/min shaft speed.
Not sure If I should try multiple rings with the joints staggered
or just one piece wound around the shaft..... cant imagine
either will be too effective.

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Garry in Tampa
Posts: 1967
Joined: Mon Mar 09, 2015 2:32 pm
Location: Florida

Re: 1940 Johnson DT-10 Lower Unit Seals

Postby Garry in Tampa » Sun Aug 13, 2017 4:15 pm

The first seals used by Evinrude were cork. These were later "improved" by impregnating them with Graphite. During World War two rubber supplies were greatly restricted. In order to keep demand for rubber tires down, gasoline was rationed. It was during this time that our rubber tire dock bumpers disappeared, and my tire swing was stolen. The government poured a lot of money into research for rubber substitutes. Meanwhile Chicago Rawhide supplied seals for critical applications. So the first synthetic rubber oil seals appeared in 1946 on Evinrudes Weedless drive. By 1951 they were on the full line. . . :D
Image

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Buccaneer
Posts: 1934
Joined: Mon Mar 09, 2015 9:34 pm

Re: 1940 Johnson DT-10 Lower Unit Seals

Postby Buccaneer » Sun Aug 13, 2017 6:17 pm

Interesting History! Perhaps the lack of rubber was the start of
the "Baby Boom"? ;)


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