Help Urgently required problem solving front end judder

[Storm Trooper]

Ok guys, I am seriously pissed off and not exactly oozing confidence after our 2 day Trip up the West of Scotland. The shudder issue that developed when I was in the Alps in June is still there, even after the following work which I did when I came back to try and resolve it :

Front end was stripped and the following done:

I stripped and rebuilt the forks (as I previously done about 2 years ago when I changed the springs and did the rod mod.) They were rebuilt with new seals, new bushes, new O-rings and new oil. All reassembled correctly.

I checked and re- greased the Steering head bearings (which were also replaced 2 years ago during the front end rebuild)

New wheel bearings and dust seals.

New Tyres (Dunlop D209's)

Both Calipers were stripped and rebuilt. The seals and pistons were taken out and cleaned and were all good.

After I had done all this I reassembled, tested and it seemed ok, but coming back from getting its MOT (which it passed with flying colours), the same thing happened again. So last resort was to replace the discs and pads with new EBC ones.

Well it's still doing it. Pissed off is an understatement!!

It only happens under braking and not every time. It's totally random. Really heavy braking from high speed, or even just a slow corner coming to a stop it can still happen.

When trying to watch things as and when I brake, from what I can see it is the lower half of the forks that are vibrating/shuddering a lot. I have rebuild them and have also used another spare pair of younger lower fork stantions that I had, swapping them for my originals when it all started, so this is really bamboozling me

Can the upper tubes wear and cause the vibrations as the tolerance could allow for movement? It honestly feels when it happens that you are trying to brake while riding over corrugated iron. I am totally stumped on this one and its scary as sh1t!

I also have fitted a Sprint side mount steering damper, so the judder is not side way movement. It is like ABS kicking in, but I ain't got ABS!!!


Please, any advice would be much appreciated, as I am at a total loss with this.

Cheers

[fabiostar]

at a track day last year i had the same problem as you describe. iv also had the forks rebuilt with oil,seals,bushes the whole lot and it still happened. then discs ran free but in the end i changed them and got the front wheel balanced and that was it sorted.. the wheel was way outa balance and the discs ran ok until they got warm..

[sirch345]

I'm presuming you fitted taper roller bearings when you replaced them 2yrs ago. How did you go about tightening up the steering head bearings, you really need to be using a torque wrench to get the right tension. With the front wheel off the ground and looking straight ahead, with a little nudge of the bars, the front wheel should turn on it's own to the full lock position. There should be a slight resistance here, you don't want the steering to bang up against the stop after giving it a little nudge to start it moving, if it does then the bearings need tightening up,

Chris.

[Storm Trooper]

I'm presuming you fitted taper roller bearings when you replaced them 2yrs ago. How did you go about tightening up the steering head bearings, you really need to be using a torque wrench to get the right tension. With the front wheel off the ground and looking straight ahead, with a little nudge of the bars, the front wheel should turn on it's own to the full lock position. There should be a slight resistance here, you don't want the steering to bang up against the stop after giving it a little nudge to start it moving, if it does then the bearings need tightening up,

Chris.

I thought the standard ball bearing head bearings had torque settings. Didn't think tapered ones could be torqued. Went on feel and slight resistance as you have described. I may be wrong but what would the torque be for tapered rollers?

[AMCQ46]

You are correct, don't torque up the taper bearings or they will cause a weave, set them to the point they just start to cause some drag when the steering swings off center

[sirch345]

I'm presuming you fitted taper roller bearings when you replaced them 2yrs ago. How did you go about tightening up the steering head bearings, you really need to be using a torque wrench to get the right tension. With the front wheel off the ground and looking straight ahead, with a little nudge of the bars, the front wheel should turn on it's own to the full lock position. There should be a slight resistance here, you don't want the steering to bang up against the stop after giving it a little nudge to start it moving, if it does then the bearings need tightening up,

Chris.

I thought the standard ball bearing head bearings had torque settings. Didn't think tapered ones could be torqued. Went on feel and slight resistance as you have described. I may be wrong but what would the torque be for tapered rollers?

I should have said it's the steering stem nut (center top yoke nut) that still needs to be torqued up (torque value off the top of my head 103Nm, but please double check that). You're right (and as AMcQ pointed out) you can't torque up the steering head adjuster nut with tapered roller bearings as you would for an ordinary ball bearing head race, if you did they would be far to tight.

Personally I would get the front wheel up off the ground and check how the bars move left and right as I have described above if you haven't already, just to rule that out. In my experience taper roller head bearings take a few fine adjustments initially as the miles start to go on,

Chris.