Juddering under medium-hard brakes

[2622]

Thanks Cam thats handy, I have the same problem

Me too but I just ride around it as dont trust anyone these days... had one set f'd up by a "brake pro" but hmm might try this guy as Cam has recommended.. trouble is am running out of rotors for them to fix or f'up.
Where's Malcolm ??

 

[CLEMTOG]

maybe incorrect front wheel spindle tightening technique, and or fork brace woes (chuck it in bin, regardless of who made it)
assemble wheel and spindle on to bike, tighten the spindle nut ensuring the speedo gearbox is correctly orientated and held so as  to not rotate on tightening, tighten pinch clamp on  left hand fork leg, roll bike up against something like a wall, and WITHOUT applying brake, pump the forks up and down a few times, and then (still without applying brake) tighten RHS fork pinch clamp, a gap between speedo drive gearbox and fork leg is normal and correct.

CLEM
PS if callipers are behind fork legs then left and right sides are reversed

 

[T.C]

Me too but I just ride around it as dont trust anyone these days... had one set f'd up by a "brake pro" but hmm might try this guy as Cam has recommended.. trouble is am running out of rotors for them to fix or f'up.
Where's Malcolm ??

Tried that number it is not connected any more so if anyone has another recommendation that would be great, also Clem thats great advice , will save this thread for latter.
Tom

 

[cbertozz]

maybe incorrect front wheel spindle tightening technique, and or fork brace woes (chuck it in bin, regardless of who made it)
assemble wheel and spindle on to bike, tighten the spindle nut ensuring the speedo gearbox is correctly orientated and held so as  to not rotate on tightening, tighten pinch clamp on  left hand fork leg, roll bike up against something like a wall, and WITHOUT applying brake, pump the forks up and down a few times, and then (still without applying brake) tighten RHS fork pinch clamp, a gap between speedo drive gearbox and fork leg is normal and correct.

CLEM
PS if callipers are behind fork legs then left and right sides are reversed

More sound advice, and you raise something that I'm unsure about - the Speedo cable, what's the correct position? Also, what TQ settings for the axle?

 

[Grant]

Correct speedo cable/drive position is the line of least resistance.
Nice smooth curve up into the speedo unit.
All too easy to tighten up the spindle leaving the speedo cable exiting the drive housing at an acute angle leading to premature inner cable failure.

 

[cbertozz]

Going to bin the fork brace, it feels like theres too much potential for binding and it definitely has an impact.

Will take the wheel off, do the steering head adjustment and then follow the procedure which a couple have mentioned for reassembly. (Same approach that Dave Moss suggested for the Aprilia, works beautifully everytime.)

 

[Legs]

Try to set the speedo cable up with the suspension loaded, might need somebody to eye-ball it. After all, that's when the cable is spinning, not when the bikes on the centre-stand with the forks fully extended.
Just my two bobs worth.

 

[Dellortoman]

While you're farting about with the front end, check the disks for run-out. You'll need to take the calipers off to allow the wheel to spin without the brakes binding anywhere. If you don't have a dial gauge, make a pointer out of a bit of wire, bolt it to a caliper mount and bend it so it just touches the disk. With a bit of fiddling, you'll be able to detect whether the disks are running true.

 

[Davo]

That juddering under brakes is exactly what mine did until the steering head was correctly tightened. Have you put the spacer between the adjustment nut and the top bearing. It will continually loosen unless that is in place.

 

[cbertozz]

That juddering under brakes is exactly what mine did until the steering head was correctly tightened. Have you put the spacer between the adjustment nut and the top bearing. It will continually loosen unless that is in place.

There's the bearing cover, and there's another washer, which from memory is in between the adjustment nut with the long collar that is on the actual stem - is that what you are referring to? I think it's possibly just that fact that the bearings are new and they have bedded in, will have a crack at it at the weekend.

Actually now I see what you mean, and no I don't think I have this installed BUT I did buy one, just forgot to install it.

This one:

 

[Davo]

Yep, inverse shallow cup shape that sits on top of the steering stem tube and stops the adjustment nut from pressing directly on the bearing.

And if I remember rightly this is exactly the reason you bought it and installed it in the first place.

 

[Simonr501]

Carlo! When you fit new taper roller bearings you don't have to 'bed them in', you do that on installation by torquing them up to 40ft/lb first, then releasing and doing back up to gnats fart tightness after!

 

[cbertozz]

Sorted by tightening the head and removing fork brace. Thanks everyone

 

[cbertozz]

maybe incorrect front wheel spindle tightening technique, and or fork brace woes (chuck it in bin, regardless of who made it)
assemble wheel and spindle on to bike, tighten the spindle nut ensuring the speedo gearbox is correctly orientated and held so as  to not rotate on tightening, tighten pinch clamp on  left hand fork leg, roll bike up against something like a wall, and WITHOUT applying brake, pump the forks up and down a few times, and then (still without applying brake) tighten RHS fork pinch clamp, a gap between speedo drive gearbox and fork leg is normal and correct.

CLEM
PS if callipers are behind fork legs then left and right sides are reversed

Just exhuming this thread for something Clem said above:

How do you orientate the Speedo gearbox so it is not spinning when you tighten the wheel nut?

I'm experiencing hi judder again but I'm also not sure that I'm tightening the setup correctly.

There is a cover that sits over the top bearing and then a washer between that and the nut with the collar that goes over the steering spindle below the clamp, and then the top but with collar goes onto spindle through clamp.

I've been tightening the bottom but using a thin spanner against the base plate washer and then tightening the top nut down.

Shouls I perhaps being doing it differently? Is there an order?

 

[cbertozz]

Also given that a new bike shop had the front wheel off to do the tyre I am going to follow this excellent guide from Piet.

"To understand this fully, one must be aware how the wheel is fixed in the forks.  The axle has a step that bears on the RH hub cover/speedo drive/whatever.  Therefore, the axle is tightened with the axle nut, pulling the wheel assembly against the LH slider.  The LH axle clamp bolt can then be tightened.  Then the bike can be taken from the stand and the forks deflected a few times by pressing down on the handlebars, without using the brake!  The RH slider will find a position where it is "comfortable" and the RH pinch bolt can be tightened, easy as...  This procedure applies to ALL Ceriani and Marzocchi Laverda twin and triple forks with the brakes in standard configuration (reversing the sliders on disc brake bikes opens another can of worms )!

When the axle is being done up, it is advisary to centralise the brake plate.  Spin the wheel, slam on the brake and hold the lever tight while tightening the axle nut.  A third hand is quite handy here... pinch the axle slightly to prevent it turning, the nut thread is strong enough to pull the axle through, should it not already bear upon the wheel/bearing assembly."

 

[Dellortoman]

You don't need to worry about the brake plate part. That only applies to drum brakes.

It's always a risky business taking old bikes to bike shop for them to work on it. Most bike mechanics these days wouldn't know how to fix a real motorcycle. There's only one bike mechanic in my area that I have any respect for. The rest are a waste of space and I wouldn't trust them to fix a roller skate. 

I always take the wheels off myself to get tyres fitted. I just take the wheel to the tyre fitter, with an arrow marked on the rim or disk showing the direction of rotation so they can't fuck it up. Even then I've had rims damaged and tyres fitted backwards  :

 

[Ventodue]

<snip>  Even then I've had rims damaged and tyres fitted backwards  :

Which is why I eventually started doing my own tyre fitting.

Actually, it was the guy swapping the spacers round on my Corsa that finally did it for me.  I mean, how bloody careless do you have to be to do that?