Thursday, May 23, 2019

Handlebars, forks and leading links, headstock (steering) bearings


The forks on this bike clearly needed attention, there was a lot of play in the bearings and quite apart from the need to fix the rust and repaint, it was clear that there was also some play in the leading links akin to bush wear.  I removed the front wheel to start the investigation. The LHS was the worse with considerable up down and side side movement. . 


Front fork leading link in position, link retaining bolt towards rear, rubber limiter bolt at front. 
The leading link is held by one large bolt that passes through a bush at the rear, the second bolt towards the front holds the rubber limiter that restrains link movement both have to be removed to release the leading link arms and springs. Both forks are similar but on the Lhs both bolts were fixed by nuts, whereas on the right, the forward limiter bolt terminated in a welded fitting without a nut. I still dont know if this was original or not.
Two nuts internally on LHS

RHS only one nut, welded plate on rubber limiter. 
 All nuts were brushed off and released. The large nut is 14mm, the smaller 12mm
Remove the front limiter
 Remove the rearmost bolt and pull it out to release the link. I found the bolt was obviously rusty and had an obvious wear ridge.
Removing the rear link mounting bolt
 The link and it's spring can then be pulled out of the fork. The spring just pulls free, the rubber bump stop is retained inside it and has to be jarred out with a long probe.
Leading link removed
 The pivot point has a metal cover both sides. This is in two parts, the outer part just lifts off but the inner is retained by the link Bushing. The grease in this link was hard and congealed, clearly hadn't been renewed in a long time.
Lifting off the outer cover

 Once the covers are off the brass bushes and internal spacer is visible

The spacer pushes out
 A little wear is evident inside the Bush but most of what I'd initially thought was damage is actually a spiral groove machined inside the Bush to spread the grease.
 Stripping the LHS was identical, as expected it was in worse condition with solidified grease and an obvious wear ridge on the pivot bolt. although not as bad as expected. The reason for the link play became obvious though when the spring was examined. It had fractured in two places!
LHS leading link, broken spring


 Components of lhs link including rubber limiter and internal spacer Bush.  

Once more the internal spacer Bush just pulled out. Assessing the wear showed that the spacer was actually fairly snug in the brass bushings and the greatest amount of movement was between the pivot bolt and the inner bush. Accordingly I decided that replacing the brass bushes wasn't necessary and I opted to get two new bolts and new inner spacers/bushes. This will allow me to reuse the nuts and cover plates. 

Stripping the forks

Crack the steering head nut whilst the bars are still fitted. 


First remove the handlebars, two clamp bolts, note nuts and serrated washers to exterior


This releases the top nacelle mounting bracket to which the horn is attached.


There are spacer washers between the bars and the bracket but they were in very poor condition, one had disintegrated.

The second was removed.
The bars can be laid aside resting on their cables and the steering head nut removed completely. There is a thin thrust washer beneath. Its tabbed to locate into the bar support.


Next remove the top yoke 2 nuts and bolts
Lift the yoke away and store it with the two bolts.
This reveals a thick thrust washer covering the fork lock nut.

Removing the thicker thrust washer
The steering lock nut is a 36mm and needs a big socket. Support the forks as it is undone as the ball bearings will drop out.
Once unscrewed the bearing top cover is revealed

Lift off the bearing cap
The bearings are sandwiched between a cup and a cone, there was still grease in the top bearing although it was hard and dry
The top cone lifts off and the bearings remained stuck in the grease in the cup. The forks can then be lowered exposing the lower bearing. This was virtually dry and free of grease. The bearings dropped out.

I cleaned up all the bearing cones. The upper cup/cone pair was  slightly worn but not corroded. I will reuse these with new balls. 

The lower cup and cone were badly worn and corroded, presumably as any rain wat er ends up at the bottom of the head stock. I didn't think these can be reused and opted to replace them. Compare the two cones from the pics. 



This bike still has the original steering lock. Sadly, just like the paperwork and registration number, the key has long since been separated from the bike. New locks are available, although expensive, but before one could be fitted, the old one has to come out. The lock is a fairly primitive affair and unlike more modern locks that extend or retract a tang, in this case the whole lock moves. It can slide in and out of a special holder and can be locked in forward or back position by turning the key and engaging a pin in one of two holes. When pushed fully back the rear of the lock fits into a recess in the headstock on the frame and so locks the steering. When the key is turned again the lock body can be pulled forwards and  locked in that position by turning the key for instance before riding... Or if  the forks are stripped, the lock can be completely withdrawn. Of course I have no key and so removing it is a problem. The usual solution is to drill the lock out but that looked like a tricky job. The barrel locking pin is a pretty flimsy affair and I reasoned that it's likely to be weaker than the material of the lock mounting, so I just knocked it out using a punch alternately, each side of the steering stem. Once the lock has started to protrude it can be grabbed in a vice and pulled off the forks. 
Using a punch each side alternately to force the lock barrel forwards 


Lock barrel starting to emerge. 

The forks were rubbed down and repainted before changing the lower steering bearing and rebuilding the fork leading links

Rebuilding the fork leading links

I wanted to renew the The link grease nipples. These are a push fit but I foundit impossible to remove them by pulling or twisting. I found the best way was to Dremmel the top off, which exposed the central grease channel.



You can then drill down this channel and thin the nipple wall.

Drilling out the nipple 5mm drill.
Once drilled out the sides can be punched in with a drift and this breaks the seal. The nipple stump then just lifted out. Clean carefully and insert the new nipple. Support the link under the  centre of the arm not under the shields on each side.s
Line up the new nipple carefully so that its vertical.
Tap the new nipple home.

Nipple replaced.
Time now  to unpack my new goodies. I'm reusing the rubber stops, side covers  and swinging pin nut, but I've got new springs, swinging pin bolts and bushes. The fork bolt holes have been slightly narrowed with the new paint so they need to be cleaned out before reassembly or it will be awkward to slip the bolts in.
First thing is to insert the rubber bump stops into the springs, the springs can then be fed into the forks engaging with the moulding at the base.
I then prepared the leading links, these are not handed although they look like the should be. I greased the bushes and inserted the new bush, applying grease inside of that as well.
Grease the outer side covers
and stick them on the links with the grease.
You can then insert the links into the springs and tip them backwards to align the bolt holes. However the springs are too strong to depress the links enough to line up the holes perfectly so I refitted the stop rubber bolt (but not the stop rubber) so I could use this as a lever with a large screwdriver to force the links down and slip the bolts home.
The pivot bolt can then be slipped in.
I reused the rubber stops so once the pivot bolts were in I removed the rubber stop bolts used as levers above in order to fit the rubber stops themselves. These only go in one way and have a locating tab on the upper side.

Newly repainted forks with both leading links replaced.

I want the bike back on its front wheel before I remove the motor and eventually the rear, so before reattaching the forks I repainted the front section of the frame and the head stock. I'd already drifted out the lower ball cup so I fitted the new one and hammered it home.

Positioning the lower ball cup. Repainted head stock, masking tape over ID plate.
and hammered it home. I used the old ball cup inverted to apply force to the outside of the ball cone only, there was no hammering on the area in which the balls will run.

Lower ball cone in place
I could then remove the ball cone from the forks themselves. This is started by driving a wedge such as a screwdriver beneath the cone and then levering it up both sides with two screwdrivers.

Starting the lower ball cone
You only have to lever it off the taper, its then loose all the way up the steering stem.
 It was pretty cruddy beneath it so I cleaned it out and  applied rust stopper before fitting the new one. In an ideal world one would have a length of pipe wide enough to slip over the steering stem but narrow enough to contact the inner edge of the new ball cone. I used to have such a thing but have obviously used it since. I had to improvise so I used the old ball cone, inverted above the new . This made contact with the inner edge of the new cone and could be tapped down using a long drift on opposite sides in turn.

Fitting the old ball cone upside down above the new.

Tapped home
Fitting the forks to the head stock requires a little patience. I applied lots of grease inside the lower cup and then used this to stick 21 new ball bearings in place. It held them well against gravity.

21 balls inserted into the lower ball cup as seen from below.
I could then carefully introduce the steering stem and push it upwards through the headstock. I used an assembly of blocks to hold it in the raised position whilst I repeated the grease-and-balls process in the upper ball cup.


Steering stem inserted through the head stock and the forks kept there with blocks whist I sorted the bearings at the top.


21 balls stuck in grease in the top cup.

Finally,  I could add the top cone, the joint cover and large steering nut. I adjusted that to give free movement of the steering and fortunately now no play whatsoever! The large steering nut was then followed by the thicker thrust washer, locating tabbed washer, handlebar mount (engaging the tab) and finally the chromed steering top nut.

Head stock reassembled. Bar holder bolts yet to be inserted.
I re-inserted the bolts for the bar holder and fitted my old bars temporarily whilst I await the new! Now the forks were in place I masked them off and sprayed inside with grey stonechip for protection.
Stonechip applied inside forks.
The new steering lock arrived and just clicks into place. Nice simple fix.
Lock inserted, it works well despite the method of its removal



Rebuilding the handlebars and nacelle proved rather trying. Its always the things you didn't record that trip you up! I found the following hadn't been recorded
1. Bars are fitted behind the fork top mounting bracket.
2. Bars angle up and back 
3. I'd disassembled the  Horn/nacelle mounting bracket for painting and got it back together wrongly. It should angle slightly downwards at the sides  (ie, the nacelle fixings at the sides should point slightly downwards).

Refitted horn bracket with nacelle holding brackets facing forward and down.
4. The previous bar mounting bolts were inserted with their heads to the rear and visible, plain nuts being hidden beneath the nacelle. The new bar mounting bolts I received came with chromed dome cap nuts clearly meant to be seen and are inserted the opposite way round so the dome nuts are visible.

Bars refitted with dome nuts on the rear. At this point I'm still working out the wiring.

Test fitting bars and nacelle.

















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