Bum Stop

Bum Stop

Making A Cafe Racer Seat

Ifiddled with the tailpiece in the past, but in the end, it justdidn’t fit right, so I went ahead and made one from scratch. Thisis not a super complicated process, just time consuming. Also it’sdirty. And not the fun kind.

Istarted off by cutting out some cardboard to fill in the gap of thesubframe. This should add some support for when we lay the glassdown the road.

Next I laid up a bunch of floral foam blocks where the tail piecewould be. I glued these together with spray adhesive… which onlybarely works as this stuff is too dusty. I Also made a cardboardstencil of the shape of the tailpiece.

Then you can just start carving the shape with a knife. The floralfoam is really easy to slice.

Once I get it down to the right shape, I go back with a razor andsmooth the thing down real nice and sexy. This wasactually Kate’s idea.

When you’re done, you should have a nice looking tail shape. Don’tpay any attention to the junk all over the place. We just movedinto this house and the garage became the place everything gotdumped until we find it’s new home (which will most likely be thetrash can).

So now that you’ve inhaled a few pounds of green dust particlesit’s time to bring out the big guns and get to the toxic fumes.

Take some of that aluminum duct tape and cover the area to befiberglassed. That means the subframe from side to side (across thegap that you cardboarded over) and the newly fashioned bum stop.You’re going to want to use smaller strips for the round part ofthe tail so it will lay flatter. Once it all looks like a bakedpotato, use car wax to slick up the surface. This will act as areleasing agent (sorta).

This next part is best done with two people. Skyler was kind enoughto give me a hand. Pre-cut your fiberglass into strips. You don’twant to lay giant pieces down as it won’t lay completely flat.Prepare a cup of acetone and your fiberglass resin. Using apaintbrush, apply the resin to the aluminum tape in one area andthen lay a strip of fiberglass on top. Then use the paintbrush topush it down flat and soak more resin in.

Once you’ve covered the whole thing, you can use fiberglass cloth(it’s more smooth and delicious than the chop stuff) as a finallayer to smooth it all out. Alternatively, you could probably justbuild the whole thing out of this, but I haven’t tried that.

After this I leave it to dry, and usually don’t touch it for atleast 24 hours.

As you can see, it has some imperfections. But these will besanded/bondo’d/cursed out.

So that’s where I’m at RIGHT NOW. I’ll update this post when I getin there and trim it, etc…

Tags: Airhead, BMW Cafe Racer, Bum Stop, Fiberglass, R65, Seat, Seat Pan, Tailpiece

Sunday, April 3rd, 2011 BMW Cafe Racer No comments