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Drain Plug Seal

To: <mg-t@autox.team.net>
Subject: Drain Plug Seal
From: "Laura & Ben Prince" <blprince2@home.com>
Date: Thu, 19 Jul 2001 13:25:58 -0700
List Participants,

There were a number of excellent responses to my earlier inquiry regarding the
best way to seal the gearbox drain plug.  I would like to thank all those who
took the time to make suggestions.  Based on your comments, here is what I
came up with.

There is a groove at the bottom of the threads of the transmission drain plug.
I am told that originally there was a small rope in the groove, held in place
with a wire clip.  When the plug was tightened the rope was supposedly pushed
up into the threads.  The clip was intended to hold the rope into position.
My drain plug did not have a rope, but the metal clip was present.

In my opinion, John Seim has the best approach for a seal.  First, the clip
and any rope are removed from the plug.   John then uses two washers, one
nested inside the other.  The inside washer is an o-ring, 3/32" thick, that
fits in the groove.  The inside diameter of the o-ring is 1-1/16".  This
neoprene o-ring is readily available at auto parts stores.

The second washer is metal and fits around the o-ring, holding the o-ring in
position.  The metal washer is not nearly as thick as the o-ring.  The metal
washer's job is to cause the o-ring to squish into the threads rather than
outward.  Although a number of materials are possible, John feels that steel
washers are best for the outside washers.

It was a real trick finding the right size steel washers.  After exhausting
numerous possibilities at local hardware stores, specialty shops, and auto
parts stores, I found a company on the Internet that has the washers.  Their
name is McMaster-Carr, phone 404-346-7000, web site  www.mcmaster.com

Their washer is a shim washer with dimensions are 1-1/4" ID, 1/-3/4" OD, and
.062" thick, part number 98126A757 for stainless steel.  I have installed this
steel washer and the appropriate o-ring, and things seem to be sealed tight.
At some later date, I may experiment and try a steel washer that is a bit
thinner at .047", part number 98126A712.  The stainless washers come in
packages of ten for around $10.  Plain steel are a bit cheaper.

By the way, McMaster-Carr also sells a fiber washer that fits the gearbox
filler plug.  The part number is 95601A430.  Unfortunately, the minimum
package contains 100 washers.

Also, John Seim points out that the engine-oil drain-plug may be sealed the
same way with a steel washer and o-ring (different dimensions, since the
engine-oil plug is smaller).  I have not pursued this, however, since my oil
plug already seals well.  (It has a thick tight-fitting fiber washer that some
previous owner installed.)   Although I have not tried it, based on John's
figures, it looks like the McMaster-Carr stainless steel shim washer, part
number 98126A662 should work.  It measures 7/8" ID, 1-3/8"OD and .047" thick.

Ben
54 TF 1500

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