Author Topic: Nearly a tank-slapper!  (Read 7578 times)

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Offline coffee_brake

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Nearly a tank-slapper!
« on: July 20, 2011, 05:50:59 pm »

I had a little stiction in my front end. The front tire was also badly cupped, the worst I've ever had. With the neck bearings freshly adjusted a couple thousand miles ago, I decided to put the handlebars back to stock and put on a different front tire. This tire is not new, it was leftover from a set change, but it is not cupped at all and has plenty of wear to go to this year's National and back. It's not too old, either.

I found about an ounce of different fork oil level, so I fixed that with the Motion Pro tool that sucks out the fluid till it's at the right level. While the tire, fender and bars were off, I did the bearing test again. Yep, just like it should be: forks move smoothly to the stop and bounce once, softly, when given a little push from center.

I put everything back together according to torque values. I mounted and balanced the tire myself. The speedo cable housing is in right. The spacer is in right. I replaced the fork brace exactly like the directions say, it fit perfectly with no binding or forcing needed.

I went for a ride and I have never been so scared on a motorcycle. Not one I was operating, anyway. The darn thing is nearly impossible to turn, the bars are shaking side to side so much. Usually if a tire is badly cupped or a bearing super-sloppy, the bars will begin to oscillate somewhere at 45 mph or below if you relax your grip a whole lot.

This bike is doing it at all speeds including parking lot turn speeds, and if I let go with one hand at speed, it takes all my strength to stop the instant, violent side-to-side movement of the bars.
And it hurts my hands up into my elbows after 5 minutes.

At least the stiction is gone.

I can't countersteer this bike. I can't safely navigate it. I'm not getting back on it, that was a helluva scary ride.

I don't see what I've done wrong. I didn't mess with the bearing, it was adjusted right with the other tire on there, and I only re-checked it because I had everything unbolted off the forks. The tire is good and balanced. The spacers are on the axle.

Anybody else been here? I know I've done something wrong but I can't find it....

Jenn in "Chaahlston, y'all...."

Offline conando

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Re: Nearly a tank-slapper!
« Reply #1 on: July 20, 2011, 07:02:27 pm »
I'm going to take a go at this.

Your steering bearings shouldn't be so loose that they bounce off the steering stops. There should be an ever so slight smooth drag in the adjustment. If you can't get it that tight or tighter by trying, then the steering stem is broken and the bike is unsafe to ride.

Check your wheel bearings as well for damage.

Simpler things could be loose nuts and bolts like the axle, axle pinch bolts, tree pinch bolts, steering stem top nut.

You might also want to check your rear wheel for side play. No side play should be evident even if checking forcefully.
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Offline Victor Salisbury

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Re: Nearly a tank-slapper!
« Reply #2 on: July 20, 2011, 10:30:36 pm »
I'm going to take a go at this.

Your steering bearings shouldn't be so loose that they bounce off the steering stops. There should be an ever so slight smooth drag in the adjustment. If you can't get it that tight or tighter by trying, then the steering stem is broken and the bike is unsafe to ride.

Check your wheel bearings as well for damage.

Simpler things could be loose nuts and bolts like the axle, axle pinch bolts, tree pinch bolts, steering stem top nut.

You might also want to check your rear wheel for side play. No side play should be evident even if checking forcefully.

+1 and right off the bat, I'd say the steering head bearing is too loose. It is practiced feel to get it right, even with the wheel installed, there should be no "bounce". 5" inch pounds of force to get it off of center, but again, it's a practiced science.  Make sure the bead is seated all the way around, and nothing is hanging up in the fork area, loose cables, bolts for the brake line splitter aren't backed out (if you still have it). Fenda extender? don't have a light bar across the front of the radiator do you? If you have both of those, I've heard of those interfering with each other.
Throttle cables routed good?
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Offline Steve in Sunny Fla

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Re: Nearly a tank-slapper!
« Reply #3 on: July 21, 2011, 12:02:27 am »
sounds like a core separation to me. Steve
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Offline coffee_brake

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Re: Nearly a tank-slapper!
« Reply #4 on: July 21, 2011, 08:10:31 am »
Thanks for advice.
Bead is seated both sides all around, cables routed freely, none of the above add ons installed.

I don't see how the bearings were OK before and now are causing this, if I didn't adjust them further. But it won't be hard to tighten them up more.

I've ridden some pretty poorly maintained bikes with super sloppy front ends, and none of them behaved this badly. I truly can barely keep the machine on the road.

I checked the tire over, would core separation be obvious?
I guess first I'll tighten the front end again, and then if that doesn't help I'm yanking that tire....
Jenn in "Chaahlston, y'all...."

Offline Victor Salisbury

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Re: Nearly a tank-slapper!
« Reply #5 on: July 21, 2011, 10:28:44 am »
I checked the tire over, would core separation be obvious?
I guess first I'll tighten the front end again, and then if that doesn't help I'm yanking that tire....

I would think so, look for a bump in the tire tread or sidewall, or a ridge in the tire that goes from one bead to the other, just something that doesn't look right. Might be helpful to centerstand the bike and spin the tire. Might see something obvious that way.
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Offline conando

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Re: Nearly a tank-slapper!
« Reply #6 on: July 21, 2011, 08:23:14 pm »
I just want to add to my previous comment on the steering bearing adjustment.

When you check, adjust them to a very tight drag to ensure everything is bottomed out and settled in. Then loosen the adjustment until there is a slight drag.

If any roughness or notching is felt at the final torque, your bearings are no good.

Hopefully, it's just your tire but.........

Also, inspect the fork tubes and wheels for cracks and bends. Tug on everything in all directions very forcefully. Nothing should feel noticeably loose.

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Offline Cap'n Bob

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Re: Nearly a tank-slapper!
« Reply #7 on: July 21, 2011, 08:53:10 pm »
A broken belt may not be obvious at all. And a broken belt in a larger tire for example can give the exact tank slapper feeling of the tire slapping back and forth at times under motion. Other times it acts totally normal. But I have never experienced it on a motorcycle tire. I have on truck tires before. And that was frightening!

Offline coffee_brake

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Re: Nearly a tank-slapper!
« Reply #8 on: July 21, 2011, 09:25:21 pm »
Thanks for the how-tos and tips, that helps. Lots I don't know, I'm listening...

I tightened the steering head bearings considerably. The bike is much more stable than before but still goes into a violent head-shake if I let go with one hand, anywhere above 30.

How darn tight do I do that bearing?! I can't put a torque wrench on the spanner wrench, and I have it so tight I am wondering if it will damage the new bearings, installed 10k ago.

I have re-tightened those bearings a half dozen times since I put them in last Sping. Enough miles that by now, they should have seated, right?

I had a heckuva time getting the old bearings out, it seriously took me about a week with a dremmel before even the special tool could budge them. Maybe the neck has been wrong from the factory. Maybe the new bearings are crap. Maybe I'm not tightening them enough?

I'm glad if it's something I've done wrong, but I think I might not know well enough how to adjust the bearings.

I've examined the tire closely, I see no damage at all. The fact that the old tire cupped so badly might mean that the "wrong-ness" of the neck bearings is causing the cupping....

Any more ideas? And thanks....

Jenn in "Chaahlston, y'all...."

Offline conando

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Re: Nearly a tank-slapper!
« Reply #9 on: July 21, 2011, 10:11:21 pm »
If you have re-tightened those bearings a half dozen times, then you didn't do it right in the first place, and now those bearings could be damaged as a result. I'd say three times max to get it right. Just using the regular tool to tighten the bearing to a tight drag should be enough, then loosen off as needed.

If you used a dremmel tool and cut into the frame tube by mistake, then tube may have split, not likely, but still another thing to check.

One more thing. Are all four of the engine mount bolts in place and tight?
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Re: Nearly a tank-slapper!
« Reply #10 on: July 22, 2011, 03:39:08 pm »
Check rear end.  Many times unusual front end problems are caused in the back.  Shock got air in it, good bearings, swing arm right?
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Offline coffee_brake

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Re: Nearly a tank-slapper!
« Reply #11 on: July 23, 2011, 08:51:19 pm »
Did check rear end, seems all good. New shock bearings recently, didn't see any play in the swingarm. New wheel bearings at 30k, probably time to order a new set and have it on hand.

I tightened the steering head yet some more, much more than I thought I should at first, and got even better results. Now it is stable at speed (at least on the 55 mph test ride), but it does still kick back and forth when leaned over. While that is still very unsettling, I can at least use the bike again.

I'll play with air pressure and then tighten the bearings again.

I'm really glad it was my mistake on the bearing tightness. That's new for me, and thanks for all the help.
Jenn in "Chaahlston, y'all...."

Offline conando

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Re: Nearly a tank-slapper!
« Reply #12 on: July 23, 2011, 09:21:40 pm »
Did you tighten the steering bearing till it was hard to turn the bars? If not, you need to, then loosen till there is a slight drag.

It's good things are working better already, keep at it.
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Offline WillyP

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Re: Nearly a tank-slapper!
« Reply #13 on: July 23, 2011, 10:29:14 pm »
Probably the outer races, or maybe the lower inner race, were not fully seated in the head tube, and they are now working themselves in a bit at a time.
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Offline coffee_brake

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Re: Nearly a tank-slapper!
« Reply #14 on: July 24, 2011, 05:21:40 am »
The English language, while amazingly versatile, is still limited in expressing the originator's meanings in such phrases as "hard to turn."

Please, I'm trying very hard but need more details about what you mean, Conando. You've already made a world of difference as I turned the adjustor far, far past the place I thought it should be, and yet got better results from it.

What do you mean by hard to turn? I turned it until the front end was "sticking." I mean, when I moved it, it would stay in the place of its arc of motion where my hand left it. I did not have to exert more than 5 -ish pounds of force when pushing the front end from side to side, but there was no further movement from momentum left in it. That's the best way I know to express how tight it was. I'll take a video on my crappy camera and post it if that will help...

I truly appreciate the  help. I'm so much more as ease now that I know I can at least use this motorcycle again. I'd like to make it even better, as it does kick back pretty violently when keeled over even a little. But at least it can take me on grocery runs again without scaring the daylights out of me...


Willy's probably right, I must not have seated the races right to begin with. I thought it was pretty simple but likely I missed something...
Jenn in "Chaahlston, y'all...."

Offline WillyP

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Re: Nearly a tank-slapper!
« Reply #15 on: July 24, 2011, 12:33:28 pm »
Normally I would say that is a little too tight, but in this case I think I would ride it that way, a short ride or two to see if it loosens up.

If it does loosen up, then either tighten it down again and repeat, or take it apart and see if the races are seated. Tough call. ;)

When you get to the point where they don't loosen up on there own, then adjust them correctly. The forks should fall to either side (with the front wheel off the ground) with a little nudge. But, not so loose that they bounce when hitting the stops. I think a lot of people have gone just a little tighter to act as a steering damper. Too the point where the forks do not fall on there own to the stops. 5 pounds I would guess is too much, but I think just a light fingertip push is fine.
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Offline conando

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Re: Nearly a tank-slapper!
« Reply #16 on: July 24, 2011, 12:50:44 pm »
English is my first language but I'll never write a book.

Anyways, "hard to turn" means it is sticking to one position and will not move freely side to side. By applying even more force with the adjustment wrench, the bearings can be made to seat further into position. Off course we have to back off from the tight position to make the bike rideable , or else the rear end will sway through the curves.

If after all this, it doesn't require anymore tightening from being too loose, and it still doesn't behave properly, then you have other issues.

I do think you have ridden too far on loose bearings and damaged them, but that's not likely if the handle bars swing very smoothly through their arc like butter, without feeling like the bearings are notched or gritty under slight drag pressure.

Willy is right about the seating problem, that is your problem from the beginning, but can it be resolved without replacing the bearings again...........?

You say the bike kicks back violently in a curve. To me that is just plain dangerous. That should absolutely not happen if you have the bearings fully seated. Since I can't come and see the bike, I would feel best if you brought the bike to a good mechanic to get a professional opinion. I don't want to hear about you getting into an accident!

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Offline coffee_brake

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Re: Nearly a tank-slapper!
« Reply #17 on: July 24, 2011, 02:55:58 pm »
Ah, thanks for explaining that. I really appreciate you taking the time to describe it better, now I know the latest adjustment is very close to what you both are describing.

I had let quite a bit of air out of the front tire  during that first test ride, because I really was scared of how it was moving and wanted more traction just to get home.

I'm airing up the tire to proper specs and taking it out again, to see if it's still shaking when keeled over.

If I didn't seat the races, I'm not surprised. I generally screw up most things I do the first time I do them, and this was my first Concours neck bearing replacement, even though I'd done several other bikes. The Concours was the most difficult set of bearings to remove I ever saw. Good chance I screwed up the install as well.

I feel lots better about it now, things are moving in the right direction, and as usual I'm learning a lot!
Jenn in "Chaahlston, y'all...."

Offline coffee_brake

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Re: Nearly a tank-slapper!
« Reply #18 on: July 25, 2011, 07:07:05 pm »


Nope, nothing doing.

I tightened the front end a whole lot till it was truly hard to turn, then backed off a bit.

Still can't let go of the bars with one hand at speed without the front end jumping around.

I'm truly at a loss.
The old tire had cupped with very few miles on it, but the bike was still at least rideable.

What did I change? The tire and the handlebars.
I don't know what to do now. This wasn't supposed to be a big deal before the National but at this point I can't even consider taking my Connie anywhere.

Swap out the tire next?
Jenn in "Chaahlston, y'all...."

Offline JPavlis_CA

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Re: Nearly a tank-slapper!
« Reply #19 on: July 25, 2011, 07:58:53 pm »
Jenn - two thoughts come to mind....

You've replaced the front tire with a used one. It is possible some cord damage occurred during the removal - reinstall process. I've seen tires with cord damage and yes, they are unrideable. Jack up the front, spread the brake pads so the wheel can spin free and give it a good whirl.

Ditch the fork brace until you sort this out. Unless perfectly installed, they can cause similar problems, or just contribute to the actual problem. Ya won't know till you take it out of the question.

Good luck.
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Offline WillyP

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Re: Nearly a tank-slapper!
« Reply #20 on: July 25, 2011, 08:04:02 pm »
Yikes! Maybe someone near with a tire on a wheel you could borrow to try out?

Dan Bergman posted this a while back, try it: sit on the bike, off the stands, and hold the front brake. Put your left hand between the top of the head tube and the upper triple. now, push the bike back and forth, against the front brake. If there is any looseness of the bearing, you will be able to feel a movement between the triple and the head. I am thinking maybe for some reason you have the nut tightened but the bearings are still loose, and the binding is somewhere else.

There are a couple of things along this line that come to mind, one is the disc at the top, under the top triple. perhaps that is rubbing on the top of the head, giving you the impression the bearing are tight when they are not.

Another is that the front end may not be tightened up correctly, or out of line. Are you loosening the top triple fork tube clamps before you before you tighten the bearing nut? And tightening them down again, after the triple nut (the hex nut on top of the triple) is tightened? For that matter, good idea to check the lower triple fork clamps to be sure those are tight. And while I am thinking of it, how about the axle, loosen the pinch bolts for the axle, tighten the axle, then re tighten the pinch bolts.
If all that checks out but doesn't help. before ditching the tire I would loosen up all four fork clamps (put a jack under the motor so the forks don't slide up the triples), the upper triple hex nut, and the axle pinch bolts. And remove the fork brace.

Now tighten the axle pinch bolts first, then lower triple clamps. Then the bearings. Then the hex locknut on top of the triple, and finally the upper triple fork tube clamps. Try it riding without the fork brace and then with.

Oh, and what JPalvis said about a used tire, good point!
« Last Edit: July 25, 2011, 08:05:41 pm by WillyP »
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Offline conando

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Re: Nearly a tank-slapper!
« Reply #21 on: July 25, 2011, 08:28:43 pm »
I hadn't thought about cord damage during tire removal like JPalvis said. Good point! I assumed, that since the tire was good previously, it would still be good.

Seems like a few issues have added up to a bigger issue.
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Offline wild man

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Re: Nearly a tank-slapper!
« Reply #22 on: July 25, 2011, 09:40:35 pm »
Wow Jen sorry to see you go through this yet again.

If you had to adjust the s/h bearings 5 -6 times in 10K miles something is just not right.  Once or twice maybe if the races are not seated correctly but you've already read that.  I've usually been lucky enough to get them seated the first time and Connie hasn't been an exception  I suppose its possible for the the s/h bearings to be shot at 10k miles, my replacements went bad with just 25K on them. I made one adjustment at 25K, then another at 1K and noticed the clunk in my steering wouldn't go away.  I feel the emulator had a lot to do with this.  I installed it as received; with yellow springs, one hole in the blow out plate and two turns preload.  The stiff metzeler 880's probably didn't help much either.  I learned a couple of weeks ago that a softer blue spring for the emulators existed so I ordered those along with new s/h bearings.  So Friday night I installed the parts along with 4 holes on the blow out plate (two turns preload) and I got to say things are much nicer now especially on the square edge bumps that used to jar the front end.  I also dropped the front tire pressure to 38 PSI.     
« Last Edit: July 26, 2011, 12:33:36 am by wild man »
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Offline wild man

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Re: Nearly a tank-slapper!
« Reply #23 on: July 25, 2011, 09:51:16 pm »
Continued..

Now that you've got the s/h bearings super tight does the front end now clunk (felt through the handle bars)over bumps on the road or has the clunking got stronger?  If the races were properly installed the initial s/h bearing torque to me would feel like about 15ft/lbs.  What is the sizes of the two front tires? Are the identical?  If the tire you have on now is a smaller size that would decrease the rake making the wobble more pronounced.

If you decide on changing the bearings you can use my tool again, just ping me off line..

I hope you solve this gremlin!! 
Bill
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Offline coffee_brake

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Re: Nearly a tank-slapper!
« Reply #24 on: July 26, 2011, 12:46:52 am »

I read and re-read it all, I'm sure I torqued everything down in the right order.
I think I have more than 15 pounds on the adjuster, feels like maybe even 25...but I'm not a real good judge of that, I live by the torque wrench.

I swapped the tires after dinner, hubby usually has to help me get the new tire on the rim.
This tire is a bit taller.

On the test ride up to 50, it feels better, I cannot detect a wobble except at decel down to 45 mph, at which time it begins to wobble and then corrects itself.

In the morning I'll yank the fork brace and see if it makes a difference.

Ya'll think I ruined the new bearings and that's the remainder of my problem?
Jenn in "Chaahlston, y'all...."