New Felt Baffle Seals (Continental C-85)

The original felt seals were about 3/16" - 1/4" thick strips of felt which lay over gaps to seal, just as we use rubber seal strips today. The Cessna 140 used 1/2" square strips of felt in a cloth cover to act as seals and rub strips for the cowl. I like the idea but it requires a flange on the edge of all the baffles to support the rub strips. After making new seals for the Cessna I realized I could use some of the 1/2" thick SAE F-26 felt, which I bought but didn't use one the Cessna, to create seals which act as rub strips without adding a support flange on the edge of the baffles. The piece of 1/2" aluminum angle on the rear baffle was the only support piece I needed to add.

For the seal along the bottom of the rear baffle I had to cut a piece of felt to fit snugly to the contour of the crank case and cover the holes I added for access to the mounting bolts. A card stock pattern was made and some blue chalk used to draw on the felt. The chalk is only on the scrap areas.

I used a band saw to cut all the felt as I did on the Cessna 140 seals. Some were just strips about 2" wide and some like this were cut to odd shapes needed to fit some spot.

Just like on the Cessna, the felt seals for these baffles were held on with staples about 1/2" wide made from 0.041" wire. I used stainless safety wire to make the staples.

The first step was to layout the spacing, with red dots, about 2" apart.

I made a little gauge from a scrap of aluminum angle. The notch allowed me to see the dot and the holes are to mark the staple holes. Clearly the factory just used a big stapler which I don't have and can't afford.

With the gauge in place the holes were center punched with a spring loaded prick punch, then drilled with a 1/16" drill.

The staples go from the back side through the felt and the ends get folded into the felt.

Making staples was easy. I cut lengths of safety wire and folded them with my duckbill pliers.

I found they fit more consistently if I gave them a light tap with a hammer to square the corners.

I made a wooden gauge block to control the length and cut the ends on a diagonal with the cutters against the block. Presto! Staples.

To hold the felt in position while installing the staples I stuck heavy duty fabric pins through from the staple side.

At first I added pieces of card stock to hold it all together. A few spring clamps will work as well and you don't poke your fingers as much.

I thought the staple would just slide through the pin holes, but they didn't. I needed to drill/ream the holes to easily get them through. At first I used a piece of the same safety wire. Then I realized the pins didn't bend so I ground the end square and gripped it with vise grip pliers. That worked great. You just wiggle and push. Some times it follows the pin hole and just slides through.

The staple gets pushed and wiggled through from the back so the ends stick out of the felt.

Using the duckbill pliers just bend the ends in like a staple, folding the sharp end slightly into the felt.

Th seals on the rear baffle.

The finished staples look like the factory did them.

You can just kind of see that the edge of the felt looks rounded. I trimmed the corners with some big scissors so it would ride nicely on the cowl and hopefully be less prone to folding over. I've tried to leave 1/4" to 1/2" sticking up for compression to seal against the cowl.