Steering stem bearings replaced - won't track straight - Wrist Twisters
 
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post #1 of 20 Old 08-29-2017, 05:38 PM Thread Starter
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Steering stem bearings replaced - won't track straight

I just wrapped up replacing my original steering stem bearings, and I must have screwed something up because the damn thing wanders back and forth while trying to go in a straight line. It handles like absolute shit. I've torqued the piss out of the steering stem nut thinking it must be a loose nut causing this behavior, but the behavior persists. What the hell did I do wrong?

2002 919 40,000 miles
"racing is life...everything else is just waiting"
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post #2 of 20 Old 08-29-2017, 06:11 PM
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If it's still meandering like that then that means the bearings are still getting caught in ruts in the actual steering head or the races, if i'm not mistaken. Did you feel them as well when you removed the bearings? if you haven't you should check out delboy's steering head video, goes pretty in depth into how to remove those burs and ridges (provided no cracks exist)


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post #3 of 20 Old 08-29-2017, 06:54 PM
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I was going to suggest the fork alignment. I didn't know about fork alignment before, but there's a specific way of doing it. However, I don't know if that applies to what you've done as you didn't loosen up the forks.

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post #4 of 20 Old 08-29-2017, 07:21 PM Thread Starter
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I can take a look at fork alignment, but I went through the same process I always do when removing and reinstalling the front wheel. As for the races, they've been replaced as part of the bearing change since I went to tapered bearings from the stock roller bearings.

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post #5 of 20 Old 08-29-2017, 08:05 PM
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I didn't know about this when I did my fork seals:


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post #6 of 20 Old 08-29-2017, 09:49 PM
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Quote:
Originally Posted by BockHawk View Post
I can take a look at fork alignment, but I went through the same process I always do when removing and reinstalling the front wheel. As for the races, they've been replaced as part of the bearing change since I went to tapered bearings from the stock roller bearings.
My guess is that fork alignment per se is not the primary issue and may not even be involved as a secondary issue.
My suspicion is that it is all bearing related.
Maybe not everything was truly seated, and has since walked a bit, either all the way to register, or just part way.
(This applies to EVERY snug to press fit of the inner and outer races of both bearings, so imagine the potential cummulative stack height and squareness errors.)
In other words, too much slop.
But, maybe excessive preload is involved.
A steering head set up too tight is akin to a steering dampener set too stiff.
It can cause weave, not wobble, but weave.
Ultimately, it all needs to be stripped down and checked.
You'll find the problem, or problems.

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post #7 of 20 Old 08-30-2017, 06:58 AM
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I didn't know about this when I did my fork seals:

https://www.youtube.com/watch?v=pNEmOqY02EU
Hmm. I've never heard about this either. So basically, he's saying that when you put the forks back on, they can have minute misalignments between the top and bottom yokes, and by pumping down on the front with the bottom yokes loosened, those minute misalignments are eased away since the yokes are machine-bored to be a parallel fit.

Did you go back and do this after you learned about it? curious to know if you felt a difference.

2002 Honda 919
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post #8 of 20 Old 08-30-2017, 06:59 AM
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You'll need to set the torque by feel. I found the spec did not work for me when I put tapered bearings on the SV; at spec the steering was notchy.

It took some trial and error for me to get it right, because torquing the top triple nut affected the bearings as well.

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post #9 of 20 Old 08-30-2017, 09:54 AM
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Hmm. I've never heard about this either. So basically, he's saying that when you put the forks back on, they can have minute misalignments between the top and bottom yokes, and by pumping down on the front with the bottom yokes loosened, those minute misalignments are eased away since the yokes are machine-bored to be a parallel fit.

Did you go back and do this after you learned about it? curious to know if you felt a difference.
I would NEVER set up a front end that way.
Front ends should be done unweighted.

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post #10 of 20 Old 08-30-2017, 10:05 AM
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Originally Posted by Superdog View Post
You'll need to set the torque by feel. I found the spec did not work for me when I put tapered bearings on the SV; at spec the steering was notchy.

It took some trial and error for me to get it right, because torquing the top triple nut affected the bearings as well.

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Setting up a steering head is critical.
I go by feel as well.
Sometimes many checks and tweaks are needed to get it "just so".
I found the factory specs for the 919 and the GSXR to be excessive for what I want as a setting - which is the least amount of even drag across the full sweep, but with no detectable bearing clearance.
If the bearings are worn, crap, not perfectly installed, you simply can't get the least amount of even drag across the full sweep, with no detectable bearing clearance.
Yes, the top nut affects the setting, because it is altering the male/female thread engagement thrust resultant which creates some axial displacement below that the thread engagement clearances will allow.

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post #11 of 20 Old 08-30-2017, 10:07 AM
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Tapered roller bearings have greater bearing stiffness than ball bearings.
Tapered roller bearings have their greatest life if they are preloaded.
BUT steering head bearings preloaded to any degree are a very bad idea as there will be too much friction.
So, when using tapered roller bearings in a steering head, take up the clearance but go light on the preload.

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post #12 of 20 Old 08-30-2017, 10:09 AM
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Quote:
Originally Posted by Superdog View Post
I found the spec did not work for me when I put tapered bearings on the SV; at spec the steering was notchy.
I'm curious as to what the spec was.
Would you please kindly post it.

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post #13 of 20 Old 08-30-2017, 12:14 PM
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Originally Posted by mcromo44 View Post
I would NEVER set up a front end that way.
Front ends should be done unweighted.
I've had hundreds of people recommend the bounce method for fork alignment... although never with the center nut.. hmm
******
edit:

actually maybe that's the difference. I think where i've had it recommended is just with getting the axle and fork lowers all lined up. Not the triple clamps... seems to line up the triple clamps you should unweight the front. and putt he forks in and tighten clamps to spec. I'm sure there's a procedure in the manual with more steps, but something like that.
I wouldn't try to line up the clamps that way either.

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post #14 of 20 Old 08-30-2017, 12:40 PM
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Originally Posted by CKutz_GO View Post
I've had hundreds of people recommend the bounce method for fork alignment... although never with the center nut.. hmm
******
edit:

actually maybe that's the difference. I think where i've had it recommended is just with getting the axle and fork lowers all lined up. Not the triple clamps... seems to line up the triple clamps you should unweight the front. and putt he forks in and tighten clamps to spec. I'm sure there's a procedure in the manual with more steps, but something like that.
I wouldn't try to line up the clamps that way either.
Mounting Front Forks by McTavish McRomo in 2011

Here are a few links if you want to get a little more info on the technical side of your forks.
http://www.trackdaymag.com/Articles/...rks-Work-.aspx
http://www.gostar-racing.com/informa...ion_set-up.htm
http://en.wikipedia.org/wiki/Suspension_(motorcycle)


Voodoo?
How about Nodoo, as in not doing everything that needs to be done.

Keep in mind how critical it is to properly align the forks and front axle, noting I'm not aware of a factory manual that tells you how to properly align the forks on the front axle. Proper mounting of forks is as crucial as any work inside them or setup adjustments made.

Do a trial fit with both forks in place, bare axle fitted and lightly clamped on the side with the bearing preload end bolt, and very carefully nip up the lower clamps with upper sitting in place.
Then nip up the upper triple.
Then torque the lower triple.
Then torque the upper triple.
Then remove the axle.
Then release the triples on no bearing preload end bolt side, just enough so it can be be slid in the clamps with a hand tug, let it slide down, then back up to see if it nicely indexes in the upper hole.
Usually it does and that is what you are looking for. (If it doesn't, you have a misalignment problem.)
Then put the axle in, and move the released fork up and down to a position where the axle easily indexes into and smoothly slides through the other side.
With good forks, you should end with both sides fairly even in terms of projection distance about the top triple.
The carefully go about buttoning up the lower and upper clamps.
When it's all back together, loosen the axle clamp on the side without the bearing preload end bolt, and with the bike on the wheels and front brake on, Jounce as much as you can, thus letting the free fork leg find where it wants to be on the front axle, then torque it up the axle clamping bolts.
(the axle needs light oil on it for this to work properly - there is too much friction with a dry install for this to work).
This way:
Your forks are square and equalized to each other.
The axle will be easier to install with the weight of the wheel on it.
The axle bores won't get scored over time from repeated R & Rs.
Your fork legs should be reasonably centred on the fork tubes - noting how much slop they have in them.
Your fork bushings should be more evenly loaded with greater bushing area actually being utilized.
Your forks should end with less Stiction and less Friction.
Others may have a different approach for the initial squaring of the legs in the tubes.
Ideally, and hoping you won't be removing forks very often, the best way is to remove the springs, and do all the initial set up work with the forks fully compressed. (Particularly so for old skinny tubed conventionals, e.g. 36 mm.)
Some might suggest doing the fitting work mid stroke. Doing the work with the forks fully extended is not the best, but it's much better than just slapping it together.

Of course, all of this is wasted unless the steering head bearings are in excellent condition and have been properly setup, the triples are true, the forks are true, and the axle is true.

One last thing.
The bearing preload end bolt (that threads into the end of the axle) should not be torqued with that side's fork axle clamp pinch bolts also torqued. Loose or barely loaded pinch bolts is all you want. Use the axle clamp pinch bolts on the other fork leg to hold the axle whole you torque the nut. Otherwise, the axle is not free to load up on it's shoulder, and your bolt torquing will not be the indication of bearing load that it is intended to be.

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post #15 of 20 Old 08-30-2017, 12:41 PM
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Quote:
Originally Posted by CKutz_GO View Post
I've had hundreds of people recommend the bounce method for fork alignment... although never with the center nut.. hmm
******
edit:

actually maybe that's the difference. I think where i've had it recommended is just with getting the axle and fork lowers all lined up. Not the triple clamps... seems to line up the triple clamps you should unweight the front. and putt he forks in and tighten clamps to spec. I'm sure there's a procedure in the manual with more steps, but something like that.
I wouldn't try to line up the clamps that way either.
Proper Front Axle Fitment Instructions by McTavish McRomo @ March 2012

For 919s, or 919s retrofitted with F4i forks.

Clean the axle and fork leg axle bores.
Lightly oil, not grease, the axle with a light oil, a 5W30 or 0W20 engine oil being ideal.
Lightly oil the fork leg bores.
Fit up the wheel.
Only tighten and torque the (rider on) left fork leg clamp on the axle.
Leave the right hand fork leg clamp free upon the axle.
Torque up the axle’s end bolt to spec. (Do not oil the bolt threads, they should be dry, as should all of the fork leg axle clamp fasteners.)
Torque up the right fork leg clamp on the axle.
Fully release the left fork leg clamp from the axle.
Straddle the bike.
Apply the front brake.
Jounce the front end as energetically as you can.
This lets the left fork leg float about and find it's natural happy spot.
Torque up the left hand fork leg clamp on the axle.

919s fit up quite well.
If the triples have been properly squared by correct sequencing, the marker ring on the axle will show near or at where it should be.
And normally the jouncing does not result in much movement.

A key point within the sequence is the proper preloading of the axial stack through the front wheel.
This seems to always get missed in concept, and it is never properly addressed in the manuals.
The end bolt on the axle is there to ensure that inner bearing races are hard seated and retained against the between bearing spacer.
The bearings are NOT preloaded by this, instead, they actually float upon their internal clearances as referenced against their outer races.
Hence the call to have the right fork leg clamp free on the axle during the end bolt tightening.
One must be sure the axle’s right locating shoulder is very free in order to properly allow the axle to float axially within the bore, which is key in ensuring that the distance washer will properly face up and load up against the inside face of the right fork leg.

END

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post #16 of 20 Old 08-30-2017, 01:28 PM
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Hmm. I've never heard about this either. So basically, he's saying that when you put the forks back on, they can have minute misalignments between the top and bottom yokes, and by pumping down on the front with the bottom yokes loosened, those minute misalignments are eased away since the yokes are machine-bored to be a parallel fit.

Did you go back and do this after you learned about it? curious to know if you felt a difference.
I didn't, my bike was in a hellish condition and I should be punished for allowing it to happen. My forks had a slush mix of water and oil and the damn thing would barely stay on the road.

I did a tear-down, clean up, reseal, fresh oil and she was working 200% better. However, I still need new tires and to adjust the suspension. I don't have the knowledge to properly setup the suspension, so that's on the list of things to learn.

It's not #1 on the list, but I'm hoping I can get all these things worked out soon.

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post #17 of 20 Old 08-30-2017, 02:23 PM
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Quote:
Originally Posted by BockHawk View Post
I just wrapped up replacing my original steering stem bearings, and I must have screwed something up because the damn thing wanders back and forth while trying to go in a straight line. It handles like absolute shit. I've torqued the piss out of the steering stem nut thinking it must be a loose nut causing this behavior, but the behavior persists. What the hell did I do wrong?
How are you making out so far?

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post #18 of 20 Old 08-30-2017, 05:48 PM Thread Starter
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Your suggestion on the nut torque was spot on. I pulled it back apart and backed the stem nut off a ton and moved the lower triple around to get a feel for the movement. Once I put it back together it steered much better. It still feels a nut off, but I think I'm going to ride it a little to let it bed in before I go nuts and pull it apart again. Thanks for the help!

2002 919 40,000 miles
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post #19 of 20 Old 08-30-2017, 06:00 PM
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Quote:
Originally Posted by BockHawk View Post
Your suggestion on the nut torque was spot on. I pulled it back apart and backed the stem nut off a ton and moved the lower triple around to get a feel for the movement. Once I put it back together it steered much better. It still feels a nut off, but I think I'm going to ride it a little to let it bed in before I go nuts and pull it apart again. Thanks for the help!
On behalf of all that helped, you are most welcome!

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post #20 of 20 Old 08-31-2017, 08:04 AM
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Quote:
Originally Posted by mcromo44 View Post
I'm curious as to what the spec was.
Would you please kindly post it.
I looked and cannot find it (did this over 3 years ago). I think it was in the instructions that came with the bearings I'd bought.

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