Subject: [Fot] Rear Main “Rope Seal”update

From: Phil Gott via Fot <[email-masked]>
Date: Tue, 15 Sep 2020 17:19:04 -0400

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A while back many of you were kind enough to share your methods of sealing t=
he felt or rope seal area of the rear main.
We have tried 2 of them should o far with mixed results and have arrived upo=
n a third method I think is best.
Using Kas=E2=80=99s method with Aviation Cement has been our tried and true a=
pproach. However, the oil we are using, Driven XP, turns out to be a solvent=
 for all but the most hardened of the Aviation Cement. And leaks develop ove=
r time.
We then tried diluting Hondabond HT with acetone and =E2=80=9Cmarinate=E2=80=
=9D the felt in it. Using the Kas method, as in the shop manual, successfull=
y packed the trapezoidal volume, and the Hondabond oozed out the sides. The a=
cetone did not significantly thin the Hondabond, and penetration into the fe=
lt was very limited. Nonetheless, we think this will hold up, but worry a bi=
t about the Hondabond not drying in the center of the Trapezoid, as contact w=
ith air (Moisture) is needed. It made a bloody mess as well.
So we looked further. Permatex has an Anaerobic version of rtv. Expensive at=
 about $15 for a small tube, but we tried it. Cut off the usual tapered plas=
tic nozzle to just fit into the trapezoid, fitted a 5/16 washer over the end=
 to seal the trapezoid (see picture), and squeezed the tube to fill the holl=
ow trapezoidal volume until the rtv came out the chamfered hole at the cap a=
nd block mating surface. The washer made a good seal, preventing the rtv fro=
m coming back out the end of the hole. For comparison, I did the same thing o=
n the other side with regular rtv (Blue just because it was handy).
After 5 days I removed the main cap from the block and found that the anaero=
bic rtv had fully cured, but the regular, air-drying (really moisture activa=
ted) rtv to be still very much in putty form, just as squeezed from the tube=
. See pictures. Note the anaerobic rtv oozed into the space between the side=
 of the cap and block much better than the blue regular rtv. I did not prep t=
he block or cap with the recommended activator for the anaerobic rtv, which i=
s said to improve the bond.=20
Will be using the Anaerobic in this area from now on, once I test it for res=
istance to Driven XP.
Thought this might be helpful.
(Yes, it is a rusty and cracked old block used for experiments, having donat=
ed its body for science....)
Phil Gott

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Sent from my iPhone
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