replace timing chain tensioner rail?

[Bruce_C]

I ride a '85 K100RT that is reasonably well maintained. I purchased the bike from Cal BMW where it was maintained, with 37,250 mi. on the clock. One year later I have just went over 52.000mi. with no problems. I do all my own minor and major service including valve clearance check and the clutch spline lube. A couple of areas I have not gone into and need some advice on doing them as part of routine maintance.
(1) Does the cam chain tensioner rails need to be replaced every 36,000mi. even though the engine emits no odd noises at all?
(2) When do the front wheel bearings need servicing even though there is no loosness or rough spots when turning the bearings by hand when the wheel is off to replace the tire? I also noted in the manual that heat is required to remove the inner bearing. Doesn't this ruin the clearcoat on the wheel and not do the new grease you just put on your newly re-packed bearing any good?
(3) Same as above for the swing arm bearings.
(4) And lastly how often do you re-pack the steering head bearings? Here I have just been lazy because of all the work involved, the front forks turn very smooth through their full arc and have no loosness at all.

Thanks
Bruce C :)

[deilenberger]

I ride a '85 K100RT that is reasonably well maintained. I purchased the bike from Cal BMW where it was maintained, with 37,250 mi. on the clock. One year later I have just went over 52.000mi. with no problems. I do all my own minor and major service including valve clearance check and the clutch spline lube. A couple of areas I have not gone into and need some advice on doing them as part of routine maintance.
(1) Does the cam chain tensioner rails need to be replaced every 36,000mi. even though the engine emits no odd noises at all?
(2) When do the front wheel bearings need servicing even though there is no loosness or rough spots when turning the bearings by hand when the wheel is off to replace the tire? I also noted in the manual that heat is required to remove the inner bearing. Doesn't this ruin the clearcoat on the wheel and not do the new grease you just put on your newly re-packed bearing any good?
(3) Same as above for the swing arm bearings.
(4) And lastly how often do you re-pack the steering head bearings? Here I have just been lazy because of all the work involved, the front forks turn very smooth through their full arc and have no loosness at all.

Thanks
Bruce C :)

Cool.. since Bruce used numbered paragraphs, I'll use numbers to reply!

1. No. The 36k recommendation must have been dreamed up by a very conservative engineer at BMW. I know of K bike engines with 250,000+ miles on them that have never had the tensioner rail or the chain replaced.

2. I used to think the wheelbearings were forever. I'm now convinced they're not - but this may be more specific to certain models (although I don't know why), and there is one additional symptom to look for.

Roughness can ONLY be really found with the wheels off the bike and a very delicate touch with your fingers.. but a symptom that is really interesting is a shudder in braking. I was clued into the relation of the bearings to braking shudder by a well-respected BMW wrench. Before I discovered this - I had replaced 3 sets of rotors on my K75S. It is now still on the 3rd set - but not shuddering since I replaced the bearings. For some reason the K75S seems most prone to this symptom - but other K bikes (pre-telelever) are not immune to it.

As far as heating - the heat required is probably just below that where your clearcoat would be bothered. One manual suggests using boiling water to heat the center hub on the rim hot enough to remove (and install) the bearings. Since my rim is polished and I didn't have any clearcoat to worry about - I used a propane plumbers torch (home-handyman type) - to heat the rim. I kept the flame moving continuously and had the bearing puller pre-tensioned on the bearing. When the hub got hot enough - the bearing broke loose with an audible "crack" sort of noise. Kroil[tm] used generously before trying to pull the bearings would also likely help. Installing the new bearings is helped by putting the new ones in a freezer overnight - this shinks them, and they almost fall into a pre-heated hub (a tool IS required for the final seating.)

Since the bearings are sealed bearings - there is no new grease to worry about, and the temperature you're heating the hub to should not effect the grease in the bearings.

3. Whenever you feel roughness or notchiness in the bearings. This will be very much dependent on where/how you ride (riding fast in NJ with our pothole farms is going to be more damaging to the bearings than riding slowly on Florida's smooth straight roads..)

4. When they need it. I think you answered your own question here. If the front end feels OK - then it most likely IS OK. Symptoms of bad steering head bearings, besides roughness or notches in them can also include any wobbles in the front end. More important than regreasing the bearings IMHO - is proper adjustment of them once they have fully seated/bedded in. Loose bearings self-destruct due to impact forces. Properly adjusted bearings are vital to long bearing life.

HTH,