Rubbery Part Cracking

[vroomr]

On my '07 (it's getting old!) the black plasticky rings through which the chrome fork tubes slide are showing some cracks at the top where they are tapered. I'm pretty sure it's part number 31422311980, described as both a boot or a cup.
When I was in for service I asked about replacing them, but my dealer referred to them as dust seals and said that as long as no oil is leaking (none is) I can just leave them alone. Well and good, and they appear to be thick beefy pieces, but I'd hate to see them start flaking away. Any suggestions? I'm considering some judiciously applied rubber cement.

[deilenberger]

I'd suggest replacing them. The dealer is correct - the actual fork/oil seal is under the dust seal, but the dust seal wipes things like squished bugs off the fork tubes so they don't attack the actual oil seal.

On your '07 this isn't a big deal. You need a way to hold the front end up, or at least in place. Like a jack under the engine. The top of the fork tube is bolted into a ball-like joint in the top triple-plate. Take the bolt out (it's under the plastic cap) and the tube will drop down, allowing you to replace the seal. I'd suggest also getting the rubber seal that goes around the top of the fork tube near the triple-plate - if your slider dust seals are deteriorating - the other ones will be too - and will probably fall apart when you take them off to replace the dust seals.

And another spot to check - the ball-joint at the forward end of the telelever arm that goes into the bridge on the sliders - the rubber accordion like boot is probably starting to crack by now. The boot isn't available as a separate part from BMW, you'd have to buy the entire ball-joint ($$) and then replace it - which requires disassembly of the fork legs, mounting the bridge in a yuge vice, then using a yuge socket wrench to remove the old joint after applying heat. That's a PITA. I found a guy in Poland who made up a replacement boot - ordered one and installed it on my '07 by just removing the nut on top of the ball-joint, dropping the arm down and R&R of the boot. I thought it was a great idea (around $30) so I talked to Mike at Beemerboneyard and he ordered a bunch and has them in stock. I think he charges about the same for them, but shipping is gonna be much faster and cheaper.

These boots go bad on the R and the GS - not so much on the RT or ST since they were protected more from sunlight by the plastic on those bikes.

HTH,

[vroomr]

Thanks. One reason I addressed it on this service visit is that it was time for brake fluid replacement, and I figured that servicing these parts would require a brake line disconnect, so..... As for the ball joint boot, which is in good shape, I long ago wrapped some vinyl around it, a boot for the boot.

[Karamazov]

I'd suggest replacing them. The dealer is correct - the actual fork/oil seal is under the dust seal, but the dust seal wipes things like squished bugs off the fork tubes so they don't attack the actual oil seal.

On your '07 this isn't a big deal. You need a way to hold the front end up, or at least in place. Like a jack under the engine. The top of the fork tube is bolted into a ball-like joint in the top triple-plate. Take the bolt out (it's under the plastic cap) and the tube will drop down, allowing you to replace the seal. I'd suggest also getting the rubber seal that goes around the top of the fork tube near the triple-plate - if your slider dust seals are deteriorating - the other ones will be too - and will probably fall apart when you take them off to replace the dust seals.

And another spot to check - the ball-joint at the forward end of the telelever arm that goes into the bridge on the sliders - the rubber accordion like boot is probably starting to crack by now. The boot isn't available as a separate part from BMW, you'd have to buy the entire ball-joint ($$) and then replace it - which requires disassembly of the fork legs, mounting the bridge in a yuge vice, then using a yuge socket wrench to remove the old joint after applying heat. That's a PITA. I found a guy in Poland who made up a replacement boot - ordered one and installed it on my '07 by just removing the nut on top of the ball-joint, dropping the arm down and R&R of the boot. I thought it was a great idea (around $30) so I talked to Mike at Beemerboneyard and he ordered a bunch and has them in stock. I think he charges about the same for them, but shipping is gonna be much faster and cheaper.

These boots go bad on the R and the GS - not so much on the RT or ST since they were protected more from sunlight by the plastic on those bikes.

HTH,

It's a real shame this forum doesn't have a like button...

[vroomr]

I'd suggest also getting the rubber seal that goes around the top of the fork tube near the triple-plate

Those disintegrated years ago. This non-mechanic got new ones, cut them [!], put them in place, and neatly wrapped black vinyl electrical tape around them. No one knew until now.

[deilenberger]

Thanks. One reason I addressed it on this service visit is that it was time for brake fluid replacement, and I figured that servicing these parts would require a brake line disconnect, so..... As for the ball joint boot, which is in good shape, I long ago wrapped some vinyl around it, a boot for the boot.

No brake line disconnect needed - it's almost a trivial job on the R1200R..