Can't Screw in the Hard Rubber Rear Tank Supports

[88bmwjeff]

The gas tank for my 1988 R100 RT has two hard rubber supports screwed into the frame at the rear of the tank (see photo). They were kind of worn, so I purchased new ones; however, I cannot get the new ones in. I cannot get the rubber bumper started. After just a little under a 1/4 turn, they pop out. Does anyone know a trick to getting these screwed in. I've tried a bit if silicon grease, wetting the new support, etc.

 

[20774]

Can you show a picture of your stop bumper and a slightly different angle of where it's supposed to go?

 

[88bmwjeff]

Here are some more photos from the other side.

 

[20774]

Strange that it is being difficult. The bumper has the spiral thread on it, so it suggests that lining that up with a lip on the frame, it should "just" spin on.

 

[Omega Man]

Is it left-hand by chance?
OM

 

[88bmwjeff]

Strange that it is being difficult. The bumper has the spiral thread on it, so it suggests that lining that up with a lip on the frame, it should "just" spin on.

Yes, one would think that.

 

[88bmwjeff]

Is it left-hand by chance?
OM

It's on the left-hand side of the bike, but i's thread is standard righty tighty, lefty loosy in case that's what you meant.

 

[179212]

Classic

If it’s not broke don’t fix it
If it’s partially broken
Maybe old hard rubber remember old hard rubbers can get you in trouble

 

[swall]

I would try chilling it before installation to shrink it down and take the resiliency out of it. Try putting it in the freezer overnight. If that doesn't work, try dry ice and acetone.

 

[69zeff65]

make it cleaner

Clean up the area around the hole, top and bottom. Then look real close at the bumpers and clean out the slag (bits left over from its molding at the factory) from the threads. Take a little bit of spray silicone and apply it to the first few threads on the bottom of the bumper and screw it in.

 

[88bmwjeff]

Thanks for everyone’s advice. I finally got them in. I tried chilling them the freezer over night as Swall suggested, but that did not help and may have made it a little harder. I did clean up all the slag from the new bumpers, but that alone did not really help.

Here’s what did work. I greased the top and bottom of the frame where the bumper screws into and on the bumper itself. I hope I can describe this well. The portion of the frame is a flat metal area where a portion was pressed lower than another area to make for the screw threads. I took a very small flat-bladed screwdriver and kept pushing the rubber portion down and through while turning. Eventually, I got it spun on about two turns, which is about where it needs to be. I can twist is a bit in either direction now for fine tuning once I put the tank back on. Once I figured this out, I got them on in about 5-10 min each. Not as quick as one would like, but not a terribly long time either.

 

[20774]

Sounds like you were working smarter!!