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jcramin

Steering Stem and Head Bearings

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jcramin
I assume the CAP NUT, which in the torque specs says SEE TIP is the same as the steering stem nut on most bikes ?????  First what us TIP ? That is what it says instead of giving a torque number.
 
I am trying to find the proper procedure for tightening that steering stem nut/cap  I have never seen a steering stem nut like the one we have on out FZ-07.
 
When I tighten it so the handlebars turn freely then I tighten the pinch bolt over the cap all of a sudden my steering is tight and I can hardly turn the bars.
 
Can anyone help me with the proper procedure for tightening the steering stem cap and pinch bolts.  It is obviously a procedural problem I am having since tightneing the pinch bolt on the cap tightens my steering.
 
Thanks,
J
 
 
 
 
 

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mjh937
The service manual says to first torque it to 38 ft.lbs then loosen it completely and retorque to 13 ft.lbs. I hope this helps.

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bmwpowere36m3
There's a spec in the service manual, but essentially you want it just tight-enough so there is no play in the bearing... And not too tight so there's extra drag.

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rick
I've looked at that set-up and scratched my head as well. Now I'm curious. Will have a look at the manual tonight and see if I can understand better
 
These days, many bikes have a torque spec for the bearing adjuster - the castellated thing under the top bridge. That 38 ft-lbs is a preload to set the bearings. 13 ft-lbs sounds about right for the adjuster - maybe not the nut (or whatever that is )
 
Of course, there's likely a special tool to apply that torque to the adjuster

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rick
OK, I've had a look at the manual. I believe what I speculated above is true. In order to do this by the book, there's a factory tool that's basically a hook spanner that has a square hole attachment point for a torque wrench - this puppy http://www.ebay.com/itm/Yamaha-Super-Tenere-Steering-Head-Ring-Nut-Wrench-/321770739708?_trksid=p2141725.m3641.l6368 Works on the same principal as a crows foot wrench, so you have to factor in the extra length to figure out the torque applied
 
Then you tighten this so-called cap nut to 38 ft-lbs, to set everything (maybe even squeeze some extra grease out) and then torque to a final 13 ft-lbs.
 
The upper bridge then slides over top of that cap nut and the center pinch clamp gets 15 ft-lbs.
 
Unless you are putting downward force on the upper bridge, there's no reason why the stem should get tighter just by clamping down the pinch bolt. The pinch bolts for the fork legs must be loose at this point
 
Short of having, or making that tool, do what bmwpowere suggested, just snug up that castellated top nut until the play in the bearing is gone and no tighter

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rick
One more thought. As the slot for that pinch clamp is off-center and not radial, i guess it's possible that as you tighten the clamp, that adjuster is also getting turned. it won't take much to make he bearing too tight.
 
If that's what's happening, then you'll need a hook spanner that can reach in under the bridge and grab the adjuster cap nut in the loosening direction. With just enough pressure on the nut to keep it still, then tighten the clamp.
 
this is really a set-up that's a bit too simple for its own good. There's usually some mechanism for locking that adjuster in place before the bridge is re-installed.
 
And keep in mind, because the top bridge is basically clamped to the adjuster, the fork legs must be in place before that pinch clamp is tightened.

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jcramin
Well I think what happened is my cap was torqued way too tight from the factory. When I took it off it was not even close to 13 ft/lbs it was closer to about 40 ft/lbs.
 
I am thinking after being so tight for 3000 miles it may have ruined my bearings and that is why I can not get it right.

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rick
Well I think what happened is my cap was torqued way too tight from the factory. When I took it off it was not even close to 13 ft/lbs it was closer to about 40 ft/lbs. 
I am thinking after being so tight for 3000 miles it may have ruined my bearings and that is why I can not get it right.
You will feel an over-tight stem bearing in a big way while you're riding along in a straight line. Having that bearing tight results in the bike responding slowly to your counter-steer inputs. It results in a bike that's almost impossible to hold a straight line. It's really an annoying, frustrating experience as you fight to keep the bike going straight. From behind, you might look a bit drunk from the weaving. From day one, you'd be asking WTF is the matter with this thing and have taken it back to the dealer.  
I'm assuming you've loosened it with a hook spanner of some sort - if it's only 6" long, then applying 13 ft lbs will require 26 pounds of force. Loosening will always require more - this is why using a torque wrench to undo something is always a mistake. 
 
Having it too tight will cause the bearing and races to wear prematurely. But the brinelling (where the races get dinged) that happens when the bearing is loose, shouldn't happen by making it too tight.
 
Tightening that pinch clamp should not change the adjustment ( that cap nut). So if the stem feels OK, before that clamp is tightened, it really should feel OK after it's tightened - unless it's turning somehow.
 
Have you removed the top bridge? At this point, it might not hurt to have a look at the upper race inside the stem.
 
 
 
 

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bmwpowere36m3
Agree with everything @rick has said… tightening the top triple clamp (center) pinch bolt shouldn't change the "tightness" in the steering stem bearings, UNLESS in the process of tightening that pinch bolt the adjuster (i.e., Yamaha calls cap nut) is rotating as well. You tighten the center pinch bolt, THEN tighten the fork upper pinch bolts.
 
On other bikes, where there is a nut sandwiching the upper triple clamp/adjuster/bearing… tightening it does usually tighten up the bearing. Thus you set the adjuster so there's a good amount of play in the bearing and then when you tighten the top nut, it tightens everything up. The DRZ-400 is like this, but it has tapered roller bearings instead. The spec calls for tightening the adjuster first to 32 ft-lbs, turning the stem 5-6 times back-forth to set the bearing and finally loosen the adjuster a 1/4 to 1/2 a turn. However I found I needed to loosen it more and my steering still has a little friction (bars don't flop side to side). I like the slightly added friction and the wheel doesn't flop when riding rough trails. I'd estimate it takes about 5 lbs at the end of the bar to get it to start rotating/turning.

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rick
My Aprilia uses 3 nuts. the 1st is set with a preload and then torqued to something pretty light. A tabbed washer goes on next and then the lock washer is turned onto the stem until it just touches and then it's turned no more than 90 degrees to line up one of the notches in it with a tab on that washer. Both of those nuts have notches - I cut a socket with a dremel to make the tool. The tabs are bent down into the adjuster and up into the lock nut. The bridge then goes on and then it's locked down pretty tight with another nut.
 
A bit complicated, but a pretty nice set-up - no worries for the adjustment changing by clamping down the bridge.
 
.
 
 

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rick
jcramin, if I might ask. Why did you get into this at only 3k miles?

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rick
I'm trying to get my head around the physics of torquing that stem bearing properly. The question that's in my mind is this.
 
Can this be done properly with the wheel on the ground and the weight of the bike on that bottom bearing?
 
I'm having this psycho-argument in my head that it shouldn't matter, but something tells me this needs to be done with the wheel off and the weight of the bike supported somewhere else (obviously not a stem stand) so that no other forces are applied to that stem nut.
 
If that's the case and it becomes mechanically difficult to lifting the front w/o a stem lift ( I can hoist the entire bike up off the ground, but not everyone has my toys), then I would go old school and adjust/tighten, go for a ride, adjust/tighten go for another ride and repeat until it felt right and there was still, absolutely, no play in the bearing.
 
Tapered roller stem bearings require a fair amount of drag to get rid of free play. But caged ball bearings (what's likely in this stem) will have very little drag when they are adjusted properly. With the wheel on the ground, loosen that adjuster until you can pull on the forks and feel the bearing thunk. Tighten the adjuster in small increments until the play is gone. Torque that pinch blot and see how it feels. If still too tight, loosen the adjuster a touch, tighten the pinch clamp and see if the play is still gone. Repeat until it's right.

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bmwpowere36m3
My Aprilia uses 3 nuts. the 1st is set with a preload and then torqued to something pretty light. A tabbed washer goes on next and then the lock washer is turned onto the stem until it just touches and then it's turned no more than 90 degrees to line up one of the notches in it with a tab on that washer. Both of those nuts have notches - I cut a socket with a dremel to make the tool. The tabs are bent down into the adjuster and up into the lock nut. The bridge then goes on and then it's locked down pretty tight with another nut. 
A bit complicated, but a pretty nice set-up - no worries for the adjustment changing by clamping down the bridge.
 
.
 

Maybe a little complicated, but seems like a nice setup. 

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bmwpowere36m3
I'm trying to get my head around the physics of torquing that stem bearing properly. The question that's in my mind is this. 
Can this be done properly with the wheel on the ground and the weight of the bike on that bottom bearing?
 
I'm having this psycho-argument in my head that it shouldn't matter, but something tells me this needs to be done with the wheel off and the weight of the bike supported somewhere else (obviously not a stem stand) so that no other forces are applied to that stem nut.
 
If that's the case and it becomes mechanically difficult to lifting the front w/o a stem lift ( I can hoist the entire bike up off the ground, but not everyone has my toys), then I would go old school and adjust/tighten, go for a ride, adjust/tighten go for another ride and repeat until it felt right and there was still, absolutely, no play in the bearing.
 
Tapered roller stem bearings require a fair amount of drag to get rid of free play. But caged ball bearings (what's likely in this stem) will have very little drag when they are adjusted properly. With the wheel on the ground, loosen that adjuster until you can pull on the forks and feel the bearing thunk. Tighten the adjuster in small increments until the play is gone. Torque that pinch blot and see how it feels. If still too tight, loosen the adjuster a touch, tighten the pinch clamp and see if the play is still gone. Repeat until it's right.
I'd assume along with adjusting the stem bearings, you'd take them out and re-grease them (factory is notorious for using barely any).  So any front-end stand wouldn't work... Either you support under the front of the engine or use some kind of strap method/hoist around the frame to hold it up.

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jcramin
Our stems do have ball bearings and not tapered.
 
I was dealing with this because I installed my GPR steering stabilizer and haven't been able to get the steering right since.
 
Last night I finally fixed it. I got my factory service manual in the mail yesterday and fallowed what it said about greasing the bearings.
 
That was the mail problem, needed to grease the bearings then I tightened the center pinch bolt first then the fork pinch bolts.
 
Everything works great now. YEP the factory put hardly any grease in them.

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