Head shake

[PineGreen]

Recently bought a 92 R100RT with 31000 mi. It has a head shake whenever I deaccelerate. It is most noticable in lower gears. It lasts only for a second or two then settles down . Otherwise, the bike is very stable while speeding up or cruising along. Any suggestions

 

[20774]

With the weight shifting forward during deceleration, I'd first check the steering stem bearings. Probably way too loose. Put the bike on the centerstand with the front wheel off the ground. Position the bars in the center and then push them off to one side or the other. Do they quickly fall to the side and hit the stop and bounce? If so, that's too loose. They should slowly to go one side, maybe with a little nudging. If they stay wherever you put them, then they're probably too tight.

You could also straddle the front tire and try pushing and pulling on the tire. There should be discernible movement of the front forks.

After that, I'd check that the wheel bearings are not loose or have insufficient preload. Grab the front wheel from the side at the 12 and 6 o'clock positions. Push with the top hand and pull with the bottom hand. There should be no movement w.r.t. the axle. Repeat at 3 and 9 o'clock.

 

[jforgo]

There are good threads on the steering head bearings.
Like someone said "out of sight, out of mind"

 

[PineGreen]

Followed 20774s advice and the thing is too tight.. The front end will not fall to either side by itself when pushed. It requires constant pressure on bars to move front end Otherwise the front end stops immediately when pressure on handlebar is released. Time to get out the service manual Thanks a lot. George

 

[BRICKRIDER]

Kurt is correct. A head shake upon deceleration means adjustment is too loose; i.e. not enough preload on the bearings. The fact that the handlebars do not move per instructions means that the bearings are likely notched, frozen, rusted, full of old grease, etc.

This steering head appears to me to require disassembly. It seems to have problems for which no easy adjustment fix are available.

Check this forum for threads on the subject, as advised by Jforgo.

Ride Safely,
BrickRider

 

[rvbeemer]

What Kurt said. Also check your tires for wear, age etc.
Ronnie

 

[grumpyone]

Tires age should be checked by the code but the steering is like brickrider said probally needing to come apart and see what is going on. He is very versed on the steering head bearings, he helped us put ours right where it belonged and with the least amount of problems gettting there.
Steering head bearings can cause u a lot of grief if not tended to proper and imediate.
Ride safe and good luck
Jim and Esther
Make sure the top bearing is not a press fit on the stem also.

 

[PineGreen]

Thanks for the info ., Looks like a winter project to me. Also developed an oil leak around the left jug also. Ah , the joys of BMW opwnership.

 

[moose738]

One other thing to check is the axle nut. The nut on my /7 was loose last spring; it also caused a shake when deaccerating. Good luck.......

 

[88bmwjeff]

The 92 RT has sealed front wheel bearings and don't require the same preload that the older bearings need. At least that's what I've been told. Of course I could have been given misinformation-it certainly wouldn't be the first, and unfortunately not the last. That being said, it is recommended that the front wheel bearings be replaced about every 30K.

I would also check your forks for stiction. I'm not saying that could cause your problem, but if the head bearings need that attention, there's a good probability the forks need attention as well.

 

[ABE456]

I just replaced the steering head bearings on my 95 RT. I have adjusted the bearings several times, still get the head shake from 35- 50 mph. I have tightened the adjustment nut to the point I'm afraid it will strip the threads if I go any further. Regardless, the steering doesnt reach a point where it is too tight and binds.

Anybody got an idea what's going on with this? I should be able to tighten the adjustment nut to the point of binding, right? Could the upper bearing be binding on the shaft and not seating?

 

[20774]

Shouldn't the lower yoke pinch bolts on each tube be loose when you do this kind of tightening? Seems like you're squeezing things and the top plate has to bend due to the tightening.

 

[BRICKRIDER]

I just replaced the steering head bearings on my 95 RT. I have adjusted the bearings several times, still get the head shake from 35- 50 mph. I have tightened the adjustment nut to the point I'm afraid it will strip the threads if I go any further. Regardless, the steering doesnt reach a point where it is too tight and binds.

Anybody got an idea what's going on with this? I should be able to tighten the adjustment nut to the point of binding, right? Could the upper bearing be binding on the shaft and not seating?

Yup, sure do know what's going on.

Yours is yet another one for which the steering stem surface for the top bearing is oversize, wrongly cut from the factory supplier.

There is only one fix, and it's a lot of work. You must completely remove the triple tree from the bike. Since you have tightened that adjuster nut so tight in the attempt to correct the problem (not blaming you here, it's a common occurrance), do not be surprised if the top bearing will resist removal. In that case, you must have someone hold pressure on it, pulling downwards from the bottom, while you use a block of wood and a hammer to whack on the top of the steering stem until it lets loose.

I have written extensively on this problem, as it is distressingly common among Airheads. Please use the Search to find some of them. Recently I gave numerous long-winded responses to Kbasa regarding the same trouble.

The I.D of the bearing must be measured. Then measure the O.D. of the hardened spot on the steering stem where the bearing rides. There should be .002" clearance between the two. Yours currently has no clearance, or the steering stem O.D is larger than the I.D. of the bearing. If you do not have the tools to fix this problem, you need to find a good machinist who has a lathe in order to cut down the steering stem surface.

You might also contact grumpyone, who has a post in this thread. I just coached him through the exact same problem, and his result is most satisfactory.

Ride Safely,
BrickRider

 

[bikerfish1100]

I should be able to tighten the adjustment nut to the point of binding, right? Could the upper bearing be binding on the shaft and not seating?

yes. and very likely.

 

[ABE456]

Come to think of it, I tried to slide the upper bearing down the steering stem while I had it all apart. It wouldnt slide down, but I didnt realize what was happening. I read the posts on this issue, but didnt realize what the real problem was.

Now I guess I will have to tear the whole damn thing apart again and find somebody with a lathe. Not a single machine shop in my town.

Would emery cloth work?

 

[dennisdarrow]

abe...........This topic was discussed in depth not so very long ago. Brick Rider made some very valid points and some other folks discussed other cures....

perhaps check it out:

http://forums.bmwmoa.org/showthread.php?t=28550

 

[aaaaaa]

Seems like I always had head shake on my '92 (teal) and my '93 (metallic black) R100R's Picked up a trick from a fellow owner at the Chief Joseph pally in '98. Tossed the front Metzeler and switched to Macadam 50. Always ran 880's on the rear. Worked like a charm. Never had a problem on those bikes again.
robert

 

[ABE456]

Brickrider was right. I removed the stem, used emery cloth on the shaft until the bearing would slide (reluctantly) down the shaft and seat. There was just enough interference that the adjuster nut could not tighten the bearing.

I reassembled the fork, set the preload, and she's rock solid stable.

Thanks a bunch for all your help!

 

[ABE456]

Ok, one more question. The head shake has returned, worse than ever. Bearings are new, seated per Brickrider's reccommendations. Just to recap, tires brand new, no wheel bearing loseness. The head shake can be dampened with one hand, but I dare not let go of the bars even for a second or the bike would prolly wind up in the ditch. (Called my BMW tech; his response: dont let go of the bars)

I'm beginning to suspect bent or misaligned forks/steering stem. Hence my question: does the 95 RT require fork alignment? Isnt the steering tree sturdy enough to prevent misalignment? Will Obama win? And what happended to my 401K?

Anyway, you guys have been most helpful so far, and, once again, need help figuring out what to try next.

 

[BRICKRIDER]

Brickrider was right. I removed the stem, used emery cloth on the shaft until the bearing would slide (reluctantly) down the shaft and seat.

The evidence points to the steering stem still being oversized, or more likely now, no longer being round - instead it's probably oblong, and there is metal-to-metal contact where it ain't supposed to be.

I know you don't want to hear that.

Maybe I should have been more forceful preemptively about the emery cloth, as you asked first if emery would work. I don't know. But I specifically stated a good machinist with a lathe was needed for this job. The reason is, the stem part that you tried to emery down is hardened to around Rockwell 60. It's simply not like sanding off surface rust on metal before painting. The metal needs to be cut off with a lathe.

When I first ran into this problem, I took my 83 R100RT triple tree off no less than 3 times. I tried the emery route, too, and failed to get it right. That's when I took the tree and new bearings to my now deceased friend Sam the Machinist, if you read some of my other posts. You should have seen the metal fly as he cut off the necessary amount to create the needed .002" clearance! Some of these stems aren't so bad, as a lot of folks manage to get back on the road with some emery cloth. I wasn't so lucky, and it looks like you aren't, either. Again, if you read my posts, and consider how much work it is to take the tree out of the bike, PLUS I had no one to guide me on what to expect, you may get a sense of my passion about this issue.

The clue is in the quote above. The bearing is NOT supposed slide 'reluctantly' down the shaft. There is supposed to be a minimum .002" clearance the entire circumference between the shaft and the ID of the bearing. This means that the top bearing should easily slide DRY from the top where the threads are, all the way down to the bottom bearing without catching metal anywhere; i.e. past that raised part on the stem where the ID of the top bearing rides against.

There was just enough interference that the adjuster nut could not tighten the bearing.

I don't quite understand exactly what you are trying to say here. But I get a sense that you worked it just enough to get the bike back together. That's not what is needed here. That .002" clearance is important! I know you said that a good machinist is not to be found in your city. I feel your pain, there, too as I have had to travel some 80-to-100-mile trips in order to get decent machine work done. For that I guess you can thank the socialistic tendencies in government (i.e. high taxes and 'redistributing the wealth' to buy votes from select groups) for making it so hard for the small businessman to stay in business.

(Called my BMW tech; his response: dont let go of the bars)

I couldn't help but laugh at this one! That is EXACTLY what I was told by THREE different dealerships back in the 80s when I went through the learning curve on this issue! But I kept trying until the problem was solved, and that's what I recommend for you, too.

You might be tempted to look elsewhere for the source of this problem, but I fully believe the steering stem problem is yet unsolved on your bike.

Ride Safely,
BrickRider

p.s. Your 401K is now a 201K or a 101K.