RD/Big twin drive shaft o-ring

[trex014]

The current PN# 339543 is the o-ring that goes just beneath the splines on the drive shaft. Has anyone found a substitute or McMaster’s equivalent? Figured I’ll make good use of the shipping $$ if I’m ordering supplies anyways.

Sierra specs list the ID: to be .501 and ring thickness to be .100

My measurements of a RD driveshaft ring groove shows .535 but I’m not sure my caliper is working right. I misplaced my last new OEM o-ring for this application so I don’t have one to measure.

[frankr]

I’m hesitating to answer because I’m not 100% sure, but I THINK it’s nominal 1/2″ x 11/16″ x 3/32″. Beat me up if I’m wrong.

[crosbyman]

is it overly crtical to have the exact size ?….it is there to keep water out I guess not for heavy duty sealing hardware/plumbing stores should have someting similar that fits…enough

but see chart ,,,,,,,,,,,,,,,F.R. was ….pretty darn close 🙂

Joining AOMCI has priviledges 🙂

• This reply was modified 4 years, 5 months ago by crosbyman.

[crosbyman]

full page

Joining AOMCI has priviledges 🙂

[Bob Wight]

On my RD18 I used an Oring with the dimensions Frank noted.

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1955 Johnson QD-16
1957 Evinrude Fastwin 18
1957 Evinrude 3022
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

[lindy46]

I usually select an appropriate o-ring from my assorted box from Harbor Freight.

• This reply was modified 4 years, 5 months ago by lindy46.

[outboardnut]

Plug in info on left side
I could not come up with anything good
Here are decimal equivalents if you need them
id 1/2 = .50
od 11/16 = .6875
w 3/32 = .09375
https://www.mcmaster.com/o-rings/cross-section-shape~round/

[olcah]

I have also used that size on RD18s. Got mine at Tractor Supply.

[Author]

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