MTFCA Forum

I hear when installing any felt washers and other pieces you're supposed to put either gasket shellac or some rtv on them before instillation on all sides. my question is though if its an issue or not when it comes to the sides of the washers, for instance the seal on the front bearings, they rotate, so wouldn't the shellac sticking to the rod and hub be an issue?

My question for the gaskets is if its fine to use the same gasket shellac on gaskets in place of rtv because I heard shellac was the old way, but is it good enough at helping the gaskets seal?

Thanks.

Hi Lucas,
I'm thinking you are referring to axle felts? When I use axle felts I oil or grease them, same for the front crank felt. The hogshead felts are done
with sealer of some kind if you use the felt. ( I use a heavy bead of silicone between the block & hogshead with a thin layer of grease on one
side so it can be removed)
Craig.

The only felt I can think of that needs the help of gasket seal is over the “hump” on the transmission hogshead. Generally it’s best just to soak felt “seals” in oil and let them do their thing.

I haven’t seen gasket “shellac” forever !! But I wouldn’t recommend it. Everyone has their own favorite method, RTV sealants are popular, personally I prefer “old fashioned” Permatex #2 non-hardening gasket seal, it can be applied more sparingly and evenly without putting a lot of squeeze-out drops and strings into the works, and makes disassembling parts much easier. Beware of “gluing” the hogshead to the pan so firmly that removing it becomes difficult.

So I shouldn't shellac the Axel seals and similar? But won't oil and grease make it's way through still? I mean I guess that's what the modern neoprene ones are for.

Soaking felt in oil 'loads' them, and they compress and seal better. Don't really know why but it works.
All the best.

A Whiteman wrote: ↑

Mon Sep 29, 2025 3:08 pm

Soaking felt in oil 'loads' them, and they compress and seal better. Don't really know why but it works.
All the best.

what oil would you say I use? like a heavier gear oil or even a grease or should it be lighter?

The very few places old time felt is used, have rubbed the felt with axle grease. Compresses the felt, and helps retard oils from seeping.

For me the only felts are the rear wheel hub/drum recess and the hogshead felt circle seal.

Old school for me is to use varnish, dip the hogshead felt strip, let dry a bit, then install. The undried varnish will ooze out and make a nice seal, but won't be so stiff, as silicone sealers can be, to allow the hogshead to pull free easy. Add a good dab of black silicone at the corners of the hogshead and the block (where Ford service says to lay a candle wick!) to pack that leaky spot.

All the paper gaskets get a coat on gasket and metal surfaces with good ole Permatex #2., that brand has made the test of time!

Other seals are best done with modern seals at the front plate, a rope seal at the front plate/pan nose, seals at rear hub, inner Hyatt bearing seals, and modern dust seals in the front wheels.

Please allow me to put my little bit of advice drawn from some experience I obtained working in the aerospace industry for 30+ years.

I think the majority of people here on the forum recall the very early days of the Space Shuttle-Orbiter Program. You may also recall the serious problem that arose with the adherence of the heat-resistant ceramic tiles that were attached to the lower outer skin of the shuttle to prevent it from becoming a meteorite on re-entry. Unfortunately, they worked very well until the last Columbia mission. That tragedy did involve the loss of tiles, but the cause was very different from the original problem.

I started my employment with Boeing-North American, Downey Space Systems Division in 1997, long after the last shuttle was completed. This was the plant where the Space Shuttle Orbiter was born. While working there, I befriended a man who had a long history with this division. Also, another one of my co-workers there had a hire date of February, 1947. His father developed the high-altitude flight suit for Wiley Post. Not just a tall tale. He had the photos of his father and Post with the flight suit between them to prove it! It was a fantastic place never to be seen again.

Now, the reason for this too-long tale is, the man I befriended was the guy who solved the problem with the large amount of tile loss on re-entry. The tiles were made from layered different materials. There were no two tiles alike on the lower skin of the Shuttle, and there were hundreds of them!

The tiles were comprised of a layer of a thick, felt-like material that comprised of a rust-colored fiber. This was bonded to an extremely porous, white ceramic that was extremely lightweight. That porous ceramic material had an extremely hard, black glaze that was fired on. To attach the tiles to the lower side of the shuttle, the lower skin was primed with a special liquid to promote RTV silicone adhesion.

The rust-colored felt was coated with red, RTV (room temperature vulcanising) rubber, as well as the mating surface on the lower skin. The tile was placed on the skin, held in place and allowed to cure. When the shuttle returned from orbit and was allowed to cool, the tile loss was significant.

A study was launched to find the cause of the failure. The results of the study found that by applying the RTV directly to the rust-colored felt and to the lower, outer skin of the orbiter, the felt-like material was wicking away the silicone. The decision was made to pre-apply the adhesive to the back side of the tile and the receiving face of the orbiter and allowed to cure, thus preventing the wicking effect. More uncured RTV was then applied to the cured, mating surfaces thus halting the wicking effect.

Now, if you're all still awake, I would say that if you're using something like a product such as Ultra Black, it may greatly improve the sealing ability of the gasket sealant if you were to apply the sealant to the face of the felt seals first, allow them to cure, then apply more sealant to the surface to one, or both mating surfaces, then assemble, thus halting the wicking effect of the felt.

If it worked for the Space Shuttle, it just might work on a 100+ year old Ford. We now return you to your regularly scheduled forum.

Mike Spaziano.

Pretty sure it was Silane Ceramic Primer

not that it matters here

The guys I know that use felt & RTV, Work it in/on completely into the felt. It's a messy job, but seals well if the thing doesn't slip during installation. Put a thin coat of oil on the HH mating surface so it will release the next time you remove it.

Just did another like that, John - best in my opinion !

Boeing put me through a class while I was at Downey (they moved me to Huntington Beach when they shuttered the Downey plant) and taught me how to correctly apply RTV primer/silicone and make it stick.

To be honest, Scott, it was 28 years ago and I haven't done it since. I don't remember the name of the primer, but I do remember that the primer was a strange transparent, light pink colored liquid. When it dried it left a powdery-looking surface.

Probably carcinogenic. Thankfully I didn't use it as a sandwich spread. Since I was required to wear latex gloves when I was applying it, I'm probably ok there, too. Wait! Did I wear gloves? Oh, never mind.

Lucas

For the HH we in the Milwaukee club have had great results by using RTV on one side of the felt and placing it on the block. Let it sit overnite, and then apply RTV to the top of the felt and install the HH. If you try to install the HH at the same time you place the felt with RTV, it slides around on you and drives you nuts.