F800GS steering stem bearing replacement

Inspired by CycleRob, this section is devoted to all flavors of the F800.

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CycleRob
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F800GS steering stem bearing replacement

Post by CycleRob »

Those commonly occurring F800GS and F650 steering neck bearing failures are suspicious. The bearings are German made and at over $50 EACH should be of lifetime premium quality. I did NOT see weather proof seals protecting either bearing, only bent over metal washer air gapped dust seals, obviously unable to exclude dirty water. All M/C shops have the expensive bearing race removal/install tools because they WILL be used more than once! Even if you've never seen, tinkerers can get creative in making their own devices.

I just "helped" Boxer replace his F800GS's steering neck bearings yesterday in my garage. His bearings had a very noticeable heavy detent in the straight ahead position, indicative of damaged steering stem bearing races. It was a 3 hour job, including garden tomato BLT sandwich lunch and modifying a (too short by 3/4") Craftsman drift pin driver tool. In my toolbox also was a modified (hardened) chisel, decades ago hand made into a M/C wheel and steering stem bearing remover:

Image

It made it possible to remove those interference fit roller bearing outer races from the frame. A good quality hardened steel tool is necessary because only a thin portion of the bottom bearing outer race's ID is visible/accessible, enabling you to drive it out. We used a heat gun on High to warm the frame to 80degC (176degF) around the outer races, confirmed with an LCD IR thermometer. This is where driving out the pressed on lower inner race also required a hardened steel 1/8th inch diameter drift, pushing out the race thru the 2 factory drilled removal holes in the lower tree. My drift pin was too short so it was ground down in a electric drill spinning full speed oppositely against the running bench grinder stone. Prior to that, I sacrificed a good drill bit as a driver, only to have it shatter on the 2nd hit, then literally EXPLODE as flying shrapnel with the final hit . . . . only to discover the bearing race did not even move at all!

At the start of the job just after Boxer arrived, both bearing outer races went into our kitchen refrigerator's lower freezer to minutely shrink their size, making the installation easier. I used a sawed off 15 inch straight section of a crashed front fork tube to drive on the lower inner race as it was the just right diameter. It is important that you do not use the roller bearing race surfaces to drive on any of the races. The mating OD/ID surfaces were clean and then greased to ease installation. Driving in both of the frozen outer races was made almost easy with a 36mm 1/2" drive socket, cautiously tapped with a big steel welders hammer. Having an assistant also help check even axial alignment after each hit helps. It tends to want to jam sideways, off axiality, unless you use a carefully aligned steering stem bearing installer tool. Go slowly and hit the high side with just enough force to see movement. Once it is flush with the frame, hit the center of the socket and it will move straight in. The dramatic change in impact sound will confirm the race has bottomed out where it belongs. From there the roller bearing cages were greased with wheel bearing grease (clean hands!) and rotated on it's own outer race to fully distribute the grease on all of the rolling surfaces. Then it's put the steering stem in and the top bearing, dust shield and top tree on, all held in place by the free-play adjusting retaining collar. After installing the fork tubes at the correct height, tightening the lower tree pinch bolts and leaving the top tree pinch bolts loose, setting the free play was next. I was really troubled by the overly tight high rotational drag feeling generated by the factory specified final torque adjustment. That can't be right, especially in light of the unusual premature bearing failures. I even made it a little looser, yet still with the usual rotational steering drag remaining, typical of every Japanese bike with the same type of bearings. From there the fork brace, plastic tree shield, front fender, front wheel and brake caliper went on quickly.

Finally, his test ride confirmed with a smile that the bike was new again, going straight ahead without requiring constant corrections. Like my F800ST, the sound that bike makes with the stock muffler is surprisingly loud (for BMW) and I would say pleasant. No money wasted for muffler mods or replacements. More bearing race and other pics in Boxer's write-up to follow after Phil's return from the Hungry Mother camp-out-n-ride weekend . . . starting today, Aug 8th.

EDIT: To change photo provider and add additional text info.
Last edited by CycleRob on Sat Jul 06, 2019 4:02 pm, edited 1 time in total.
`09 F800ST

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Re: F800GS steering stem bearing replacement

Post by Mollygrubber »

I've had to replace my steering head bearings twice, once at 38000km - and again at 48000km :? . (2010 F800GS)

I don't know what the issue is, but the second one was free, as I was pretty choked.

Seems like there should be a replacement bearing and /or weather seal issued by BMW, that kind of "longevity" is unacceptable IMHO.
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2010 F800GS
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