headstock help please!

[ROD]

My forks are ,I think gsx750 or maybe 550.....OK... bear with me here!..................................................   
The headset bearings are different inner (and therefore outer )Diams. ,bottom larger.The top brg sits on a shoulder machined on to the pin that prevents it moving down the pin.Apparently this isnt a common setup?
      If the top bearing sits tight on to the shoulder ,and the bottom brg is sitting on the bottom yoke,there isnt any adjustment in the headset ! How much 'play do I leave under the top bearing before it bottoms on the shoulder of the pin?.So I presume the top yoke is loosened on the fork clamps to allow it to move up/down the forks a fraction,the large nut under the top yoke, atop the bearing is wound in /out,then yoke is replaced ,with a top (domed )nut locking it all in place?
  The large nut under the yoke,is very deep,and is shouldered ,with notches in the outside rim edge ,which Im told is for a locking tab? and there isnt room for a lock nut on it under the top yoke,due to lack of spindle length. When the top yoke is on ,there is a washer ontop of this,then a domed nut to finish off the top of the pin.
  I cocked up the length of my top tube and depth of seats for the bearings. If the bearing outers go right 'home' the thing is too short,being restricted by the pin shoulder,so I'll have to put a spacer under the bearing cups to allow the cup to sit on them ,and not go all the way to the bottom of the shoulder machined into the headstock..This means I'll have to proably muller the old outers to remove them.Due to the restrictive shoulder on the pin ,the distance between top and bottom bearing is critical.
  On other 'bikes is the top inner race just allowed to 'float 'up and down the pin?Should I just ignore the pin shoulder ,and set it up so that it 'floats' just above it?
   Comments please??
      Rod

[tbone]

Where and why do you want any adjustment in the headset mate? Rather than mess with spacers, as you have access to a lathe, cant you machine the top shoulder on the shaft and allow the top bearing to sit lower on the shaft?

[ROD]

Yes I cando that ,but I was worried about the steering pin being weakened by the bit of machining! Just been to a local bike shop ,and they reckon it will be ok to machine. It is about 6mm long by about .75mm deep .Therefore I think Ive solved it . Forks coming off today for transporting the frame,so will have a good look then.

[Manky Monkey]

Rod, the locking ring on top of the top bearing is designed to be turned using a C spanner in the notches, though more often than not you'll find owners have used a screw driver & hammer to tap it round instead. It takes up the play in the bearings as they wear, (I'm assuming you're using new taper roller bearings). On the last couple of Manky trikes, we had aluminium "slab" yokes specially made. We used a much cruder method of adjustment. The top & bottom of the steering pins are drilled & tapped & a large allen bolt screwed in, making sure it doesn't bottom out in the threaded hole. We then simply loosen the pinch bolts holding the fork tubes into the yokes, & wind the top & bottom bolts in a little more to pull the yokes together, taking up the free play in the bearings.
Trikes suffer a lot more stress on the bearings than a normal bike, but even so you shouldn't need to adjust them more than once or twice a year. To check for bearing wear, jack the front of the trike off the ground, stand in front of the wheel & hold the bottom of the fork legs. Try to pull the forks towards you. You won't normally be able to see the movement, but if you can feel it, the bearings need tightening up.   

[ROD]

Ok guys thanks for your wisdomic words!
           Rod

[ROD]

Just thought Id report back on the outcome of this........
  I stripped it down and after careful measuring I found I had about 2mm before the top brg bottomed out on the shoulder . Couldnt get the pin in the lathe with bottom yoke on ,so decided to file the shoulder off . After careful checking the bearing fit ,I gradually got the bearing to drop (if required at a later date for adjustment),by about another 3mm. This should give me enuf clearance when/if the bearing wears.
            Rod

[BikerGran]

the locking ring on top of the top bearing is designed to be turned using a C spanner in the notches, though more often than not you'll find owners have used a screw driver & hammer to tap it round instead.

I'm glad you said that Manky - it's what I always do and always think 'I should have a proper tool for this' - but never get one!

[Manky Monkey]

You 'n' me both Bobbi. 

[morrag]

Just as a matter of interest! tapered rollers are only meant to be adjusted to their correct clearance from new, and thereafter when removed should be returned to that origional setting, as if adjusted further, then the leading edge of the roller only rides up onto an unworn area of track, which gives an illusion of removing play, but in actual fact wear will quickly take place, so, at that point its time to renew the race, Morrag

[Manky Monkey]

Fair enough.

[ROD]

Good point Morrag!