Dismantling

Introduction

In my opinion, this year’s Bradford-on-Avon meet was the best I have experienced. Much credit is due to the organisers, who combined a fine balance of efficiency and friendliness, which pervaded the atmosphere of the weekend. I also sensed a more positive camaraderie from the crowd. Hopefully this is our club reflecting the subtle, healthier change in the national mood. It felt great to be there.

Some of you who attended the Bradford-on-Avon Weekend will have witnessed the Masterclasses held on Saturday afternoon. Judging from the appreciative crowds around our demonstrations they seemed a great success. Mike Hessey suggested that we serialise the Masterclasses in print for those who couldn’t attend, so here comes episode one.

Front Suspension Overhaul

At Bradford-on-Avon, Ian Hodgson and I demonstrated the dismantling and rebuilding of series one front forks. Our forks were ready-prepared; as anyone who has rebuilt an un-serviced set will know, they could take up to three hours to dismantle!

Dismantling

The original instructions state: ‘Remove forks from bike in conventional manner’. This doesn’t account for seized handlebars – especially alloy ones. Apply Plus Gas easing solution 24 hours prior to separation: it’s better than WD40. If this still fails, apply heat from a blowtorch, then, with the front wheel held between your feet, quickly jolt the handlebars left

to right, right to left (having loosened the stem expander bolt first of course). Under no circumstances saw off the bars – yes, people really do! – you lose your only workable lever. I should apologise here if some tips seem obvious, but some owners are far more experienced than others.

With the front brake cable released and wheel and mudguard removed, you can now remove the bars, loosen the headset race and lift the frame up and forks out of the frame. Expect some steering race balls to scatter round the room, likely to re-appear some years later.

Remove the long, rubber-filled spring from within the fork crown hole. This will be held in compression, so go with care.

Firstly, remove the brake. On the earliest Moultons a small alloy tube houses the brake bolt in the fork crown. Tap this out, taking care not to damage it as you won’t be able to pass the bolt back through it later. If this part is not fitted, the brake bolt passes directly into the crown, through a hole in the “spring abutment” – a cylindrical tube ½” to ¾” long. Abutment sizes vary; longer ones give harder suspension, but are trickier to assemble because of tighter spring loading. Once this abutment is released the spring should come out. On a healthy machine, it will shoot out and smear grease all over your carpet instantly. On a Friday-job Moulton built at Kirkby, where it was Friday 4 days of the week, it may shoot out, showering red rust round the room – because they forgot to grease it. A minority are so rusted that you will need to enter the brake hole with a screwdriver and prise the first coil of metal spring downwards. Again, use Plus Gas if it is stuck. In severe cases, drill up into the rubber spring, insert a long screw and, with a Mole Grip clamped onto the screw, pull down on the spring. It’s worth noting that as recently as summer ’97, APB front suspension springs were emerging from Pashley ungreased. On enquiry, Pashley said they weren’t supposed to be greased, but Bradford said they were. From experience, I would confirm Bradford as correct, and I would not wish to dismantle a 30 year old APB!

You can now get on with the main job of separating steerer tube from forks. Retaining screws were Phillips headed on all Moultons except the earliest (1962 – early 1963) and later Mk 3s, which had slot-head screws. For the job you need a tough screwdriver, at least 10″ long and narrow enough to enter the alloy steerer tube and engage a hidden screw inside a stool in the tube. There is no access for releasing the forks by entering the fork crown.

The retaining screw head will be covered in years of gunge. Feel your way with the screwdriver; gently tap the blade into the head to make good contact. Apply Plus Gas before deciding to remove the screw; apply shoulder pressure to the screwdriver and firmly turn the screw, stopping instantly if the screw resists. Failure to stop will fatally burr the head. If it sticks, soak it in Plus Gas for 24 hours, and when re-introducing the screwdriver, hammer it home prior to trying again. Don’t hammer too hard or you may damage the parts, or even the fork blade drop outs. If the screw head is damaged you can sometimes take a flat-blade screwdriver, “sharpen” the blade, hammer it into the old screw head to create a groove and then it will often turn. If all else fails, drilling out is the only process left. You will need a long drill bit, passing through a specially-made guide tube cylinder with a central hole for centring the drill. Use plenty of oil, as much friction is created with this method. I am lucky to have had these special tools made for me by Clive Fletcher. Without these, many forks would have remained seized up. This is one of the jobs that may best be carried out by Moulton Preservation if you run into difficulties.

Presuming that the screw has been persuaded to turn, you unscrew it for what seems an eternity, then suddenly the rebound spring retainer drops out of the fork crown, followed by the short spring. Watch out for this one – it will roll away into the 5th dimension or spring about like Zebedee on Ecstasy. If it was a Kirkby Friday job, it won’t emerge at all. Don’t worry: once the forks are apart, you can push it down the tube with a long screwdriver.

Spray Plus Gas on the base of the steerer tube to ease the release of the lower bearing retaining cup, which is best done in a vice. The cup must be unscrewed from the steerer tube base, and this is necessary before separating the tube from the forks.

Gently tap the cup using a hammer and screwdriver inserted into one of its two grooves, then unscrew with a C-spanner. It is alloy and will shatter if hit too hard. It is also easy to cross thread.

Once released, you can pull steerer and forks apart. Put the steerer tube aside. You are left with a pair of greasy forks, two nylon bearings, bearing retaining cup and bellows retaining ring. Slide off the bellows first. Above the top nylon bearing is a circlip, usually invisible under a layer of old grease. Clean it and try to find the split in it. It’s almost impossible, and when you eventually insert a tiny screwdriver in the split, it will jump out and puncture your thumb. Never attempt this bit in shark-infested waters. It’s best to hold the circlip still with one hand, and a good rag, and to prise the clip open and up with the other, using a fine screwdriver. Once released, you can lift off the bearings, retaining cup and ring, and clean all the parts.

Inspection and replacement of parts

At this point, check the base of the splined column at the brazed joint to the fork crown. A rogue batch of forks appeared between late 1963 and summer 1964, made by a subcontractor who insufficiently brazed the crown joint, resulting in fork failure. Most were recalled, and most that weren’t have usually failed by now. However, this is a grim fact to be aware of if you rescue a little-used Moulton built earlier than week 29 of 1964. Check the spline/crown joint, cleaning, then scratching in the grooves with a sharp blade, to expose a brassy colour, which shows through in places if the braze ran through correctly.

Now check whether the top bearing is worn. Were the forks rocking when braking? Does the nylon look worn? If not, clean and prepare for re-fitting. Similarly, was there steering play? The steering bearing need not be replaced if you remove and clean it, then refit using a different groove/spline relationship. This will take up any slack and produce a tighter fit that will last for years. Only order bearing replacements from Moulton Preservation if your originals are really worn out.

All parts should now be cleaned and de-greased. I use Dabitoff stain remover on kitchen roll to degrease everything – best used wearing rubber gloves as it dries out your fingers. Moulton artist and pedalling plumber, Kevin Hawkins, supplied me with wire, nylon bottle brushes for cleaning out the tubes. The coil springs should be treated with fine wire wool or rubbed with fine emery cloth if badly rusted. When all parts are clean, regrease with Molyslip grease, using this on fork splines, nylon bearings, liberally on the long rubber spring and rebound spring, lightly on rebound retainer, screw and abutment.

Re-assembly

Stand the fork blades upright. First replace the bellows retaining ring on the crown (unless already brazed on) followed by the bearing retaining cup, serrated nylon bearing, fitted with

the wider step uppermost, ensuring a tight, sliding position. Then put on the smooth, top bearing and replace the circlip. Cover in Molyslip. Refit the steerer tube over the forks and slide 4 nylon bearing steps into the steerer tube grooves. Then carefully screw up the bearing retaining cup – check for cross-threading. Push the steerer tube down to the fork crown. Insert the short rebound spring, well greased, followed by the spring retainer into the fork crown hole and follow these up with the long spring, to ensure the spring retainer reaches the top of the tube without twisting round. It must present itself centrally to accept the screw and it must also be turned to allow its small snib to engage in a slot in the steerer tube stool. To ensure this has occurred, hold the fork blades up, remove the long rubber spring and insert a flat ended screwdriver between the blades and up to engage the rebound spring retainer. This has a slot in its head for this purpose. Turn slightly and it will drop into the small groove and refuse to turn further. Keep that screwdriver in place. Prepare the other screwdriver, usually Phillips head, with a little Blu-Tack or plasticine, to keep the rebound stop retainer screw in place on the screwdriver tip. Hold the first screwdriver to steady the rebound stop, with one hand, whilst introducing the long screwdriver with screw attached, down the steerer tube, carefully feeling for the central hole in the steerer that enables the screw to meet the rebound spring retainer. Tightening the retaining screw takes a while but eventually the screw should bite and tighten. Time for a sigh of relief! Test by pulling steerer and forks apart. The gap should increase but stop abruptly indicating that the screw is holding. Check for no side play in steering or rocking between forks and steerer. If all is tight, fit the bellows over the steerer and down over the retaining ring, ensuring the bellows are the correct way up, inner, lipped ring downwards to hold on the retaining ring.

Extend the steerer/fork gap, insert the long rubber spring followed by the spring abutment. This should be fitted with the closed end against the rubber spring, open end outwards. Put a rag over its end and press with thumb, gripping the fork crown with fingers as levers. Once the abutment hole aligns with the fork crown bolt hole, stick a nail or small screwdriver blade through the rear of that hole to secure the abutment. Then introduce the brake bolt or bolt tube (on the earliest Moultons) through the abutment, releasing the screwdriver or nail once the brake is far enough in. Test the suspension like a pogo-stick. It should feel tight, not too bouncy and quite stiff at first. This simply means a good, tight fit that will wear in. Refit to the frame, having greased the steering races and filled with ball bearings of 1/8″ size. Believe it or not, people write asking how many balls are used in the races. The answer – fill them full and remove one ball.

Addendum – Problems with tight or loose bearings following replacement [2/4/2003]

Michael Woolf adds the following comments regarding the fit of the new bearing which he supplies through Moulton Preservation.

When I sell these bearings, I always warn that it will be a tight fit over the upper, less-worn splines but is usually easier further down where travel produces wear. Normally with a little molyslip grease and a little use, the bearings settle in well. Occasionally there are factors that conspire against us:

  • We made the mould to suit the majority of forks with average wear. Since not all the bikes have the same wear, and in fact Moulton components are notoriously non-standard (eg try fitting one pair of rear forks to a different frame!), we occasionally get a mis-match.
  • Imperfections on a few serrated splines (e.g. a small dent) can flatten the grooves and impede the bush. Check to see if you have that problem. If so, a small file can remedy the problem.
  • If the bearings were bought some time before fitting, and stored either in hot, dry or slightly damp conditions, they are liable to shrink slightly. On a tight spline, this would be enough to cause trouble.

If you can’t get a smooth ‘slide’, and you’ve checked the splines for damage, send the bearing to me. I’ll test it and return a slightly looser one till we get it right – as you’ll appreciate, we’re having to suit varying tolerances, but ultimately we can get it right.