Fork Bushes

Due to my phased approach to building my SQ4, I put the forks back together without re-bushing them, many moons ago. They weren't too bad at the time and since Amelia had arrived in a number of boxes, and I had no Ariel experience at the time, I needed to get it assembled to understand what I was dealing with.

Dashing about Norfolk's roads last year showed re-bushing was going to be necessary this winter, so off we go.

The first step was to truss her up with a bungee to stop her shaking her head about. I planned to leave the yokes in place to avoid unnecessary disruption to a running bike.

Then, we need to get the front wheel off the ground without the ever-useful front stand. A scissor jack comes into play here:

Next step is to remove the front wheel, mudguard stays on one side and remove the fork top bolt and clamping cap screw in the bottom yoke. Next, we use the fork puller tool to knock the stanchion out of the taper in the top yoke:

With the leg out, we can start disassembling. We put the leg in the vice using the cast lug on the bottom - we don't want to clamp around the thin slider. Having lifted off the spring, we can use the special tool to remove the seal holder.

With the seal holder undone, we can think about the next step. Lift the seal holder about six inches up the fork leg, and tape it out of the way. Don't try and pull it off upwards, as the leg is tapered and you will stretch the seal.

The top bush retains the leg in the slider, since the bottom bush is bolted to the leg, and the top bush is retained by a circlip under the seal. Here's the circlip in place:

You can see, at just past 12 o'clock, a semicircular groove. This gives you access to the full diameter of the circlip. Get a small flat bladed screwdriver into the groove and push the circlip out. Find the end of the circlip and maneuver the screwdriver, still holding the circlip clear of the groove, towards the end of the circlip. When the end of the circlip is free of its groove, get a scriber or another small screwdriver under the end of the circlip and maneuver it upwards, moving back along the circlip as you winkle it out.

You can then pull the leg out of the slider:

These two pairs oil holes ( the others are behind the leg) show this is a post 1953 leg, which gives more progressive rebound damping than the earlier legs (which only have one pair of holes). The long top bushes which go with these later legs are shown in the picture above; earlier legs use a top bush of about half this length.

Here are the new bushes in place.They were both oversize on the outside diameter and required some 'easing'; The lower bush is retained by the stanchion bottom nut.

The next job is to lubricate the buses with some SAE 30 and place the stanchion back in the slider. You can then maneuver the circlip back into place by aligning one end in it's groove, and pushing the clip away from the retained end with a small screwdriver until it snaps into place. Next, put a little more oil around the top bush and screw the seal holder back down with the factory tool; fit the spring and you are done:

This is a new H18-48 stanchion top adapter, courtesy of Mr. John Budgen. The previous one succumbed to an unfortunate incident involving a copper mallet and a lack of forethought. You can see how it used to look in the previous picture - they are not very strong and cannot tolerate much abuse.

Once you have it all back together, you will need to fill the forks up with some SAE 30 engine oil. This is simply accomplished by removing the top bolt and, with a small funnel, pouring sufficient oil into the leg such that the level is 17-18 inches (43 cm) from the top of the yoke.

For reference, here is a sectioned drawing of the fork from Mr Charles Weller's book.

Clutch

Having got the brake shoes back, I want to finish off a couple of cables that are cluttering up the workshop, before starting on the cylinder head. One of those is the clutch cable, and I would like to do a dry run of the clutch build. It's a dry run, beacause I want to spin the engine on the power drill using the crankshaft shock absorber nut, and I don't have the oil pump or any of the timing gear ready yet - because the head is not fitted.

So today I will fit the clutch temporarily, to have a look. First up is the basket, fitted over the cage & needle rollers. It's retained with new bolts and lock washer I bought from John Budgen.

Next up is the stack of plates and the clutch centre, preceeded by the final thrust washer. First problem appears - the new clutch centre nut is not happy on the gearbox mainshaft thread - though the old one still fits. This is the whole point of a dry build!

Push rod fitted!

The pressure plate comes next, followed by the cups, springs and the nuts. And the first outing for the clutch spring screwdriver I made a couple of years ago. Works fine!

The clutch operates very nicely using the arm on the other end of the gearbox, and the pushrod adjuster is screwed almost right in. Odd I think, the plates are in good shape but not wholly unworn. Most of them came from John Mitchell of the AOMCC. Maybe the pushrod is too short or there is a ball missing? The ball is certainly present in the adjuster cup...

Primary Drive

The next step is to fit up the primary case for the second time. First off, make sure all the engine bolts behind the case are good and tight.

Then, a dose of Threebond on the flange between the two halves of the case, and bolt them up. This immediately reveals that we are missing three bolts - we have the nice stainless screw in the top, that came from Acme, but I have not sourced the others. So we can get on, one comes from stock - it's the right bolt, but the wrong material.



The clutch sprocket bearing cage goes in next, well greased and followed by the twelve needle rollers, courtesty of John Budgen:

Then the chainwheel goes on:

A quick spin reveals a horrible grinding noise... But I know what that is - I've forgotten the ring behind the chainwheel. Primary chain goes on, courtesy of Draganfly, with the clip safely fitted in the right direction:

I found that the primary chain is much easier to adjust if you flip up the rear mudguard - the access to the adjuster is much better.

So, all done. I need a few parts:

• bolts for the two halves of the rear case
• the bolt for the lower chainguard to the rear primary case
• a spacer for the rear case to the frame
• a split pin for the shock absorber
• spring washers for the clutch dome screws.

But that's it for the moment. Here it is, all together:



Managing

I use this spreadsheet to manage my parts, track what I need, what I've ordered, what I paid or budgeted for the rebuild...

The parts are grouped by work package; can be filtered or grouped by vendor, order status, part number, or whatever you want.

Very useful. Here it is: http://pisl.co.uk//ArielAccounts.xlsx.zip

DIY Respite

So, a day came when there was no decorating or other householdy tasks, when the weather was not too wet, and there were no pressing domestic engagements. Amelia was mobile on her own (hitherto flat) tyres and we were able to face up to the beast that calls itself chain alignment.

My plan was to fully assemble the engine plates, gearbox and primary drive and determine once and for all whether I was going to have to modify, or replace the G107 gearbox.

The first job was to finally bolt up the engine plates with the correct studs - luckily I had enough of these and all of the special ones from the boxes of bits, plus the lower gearbox bolt from Acme Stainless. This was very straightforward, only needing a small amount of help from a jack to get the bottom front engine stud in and tie the bottom frame tubes to the down tube. All nuts on, and I was pleased to see the top & bottom gearbox lugs aligning perfectly within the plates.

Small problem - the bottom gearbox bold threads in the frame lug are caked in rust - must buy a 1/2" CEI tap to clear these. Previously when I had trial fitted the primary case I had realised that neither the special brake lever stop nor the side stand bolt would screw fully home, so I took the opportunity to clean the threads on those out - 5/16" CEI. Investment in tools pays of pretty quickly.

Here's the side stand trial fitted, to check it's function and to start to establish what spacer we need behind the inner primary case. Is the way that spring bears on the primary case as the designer intended, I wonder?

However, with the gearbox fitted we could take a look at the secondary chain alignment.  I wanted to use a toolmakers clamp to set a straight bar against the face of the  sprocket, and point it at the rear wheel sprocket. So I cleaned up the face of the sprocket in preparation. Of course, anyone who has  tried this will know there is no space to get a clamp in there!

So, it had to be hand held against the sprocket, which was a bit of a challenge when taking the picture! With the straight edge held against the gearbox sprocket, and the rear wheel roughly aligned, we appear to have a match. There is a small burr on the end of the straight edge, where it approaches the rear wheel sprocket which tends to confuse the eye a little but the exercise shows us that we have good alignment there.

So, onto the next task - building up the primary drive and the clutch.

This is pretty straightforward, since we have done it before - but never with the gearbox & engine fully bolted in!

The first small surprise was that when I had the inner primary case in, I fitted the top screw (the visible one) from the outside. I then found more screws (I don't have the original ones) for the lower positions and was confused when I found no thread - thinking I was in for a helicoiling session, I looked further and on the basis that both sides of these lugs are milled flat it looks like the lower three use hex bolts and nuts.

However, since the neither the Ariel parts book nor Drags list identify nuts for these maybe I'm wrong? But then, the Ariel list doesn't identify nuts for the engine plates either, so maybe it is a policy.

Any how, pressing on, we could then bolt up the inner case and re-fix the brake pedal stop at the bottom.




Next came the clutch race and it's thrust washers, which entailed making a special scraper to clear the gunge out of the clutch centre splines.

That all went fine.

Whilst I have new rollers for this bearing, there is no point in fitting them now - I will only risk losing them when I strip it again.

Getting around to fitting the clutch centre, here we can see the clutch sprocket has been fitted over the needle roller bearing. The  final thrust washer is in place as well, showing where the clutch centre will fit. I'm happy to see that the sprocket, bearing and thrust washers all fit and that everything is lining up for the centre to fit perfectly.

And here is the clutch centre in place, with a new tab washer. For some reason the new centre nut doesn't want to fit, thought the old one is OK. that proves the mainshaft thread is good which is the MAIN THING!

The moment of truth. Here is the straight edge again, this time across the two primary drive sprockets. the folded card is in there to hold the straight edge in place for the photograph  but the big news is that the sprockets align perfectly.

Two pictures here show the clutch basket in place with & without the clutch cover. Everything is running smoothly & freely, no sign of any misalignment here, so I think we can pronounce this potential problem, originally discussed in the Gearbox Woes post,  null & void.

Why we have a G107 gearbox number remains a mystery. Error in the factory? Curious that it has a J51 date code, which is November 1951, several months after the bike was shipped. Replacement part? warranty item? accident damage?

We'll probably never know.

Finishing the clutch

Easy job first - degrease and clean the clutch cover. Chrome plate as suspected, with a nice little ding at the front, presumable from someone's boot. Maybe we can beat that out with a handle planishing hammer and a sandbag... maybe not...

Clutch sprocket, plain and friction plates. All jolly nice; friction plates are worn but not burnt. Plate thickness is 1.6 mm/16 SWG, about 1/16". Cork protrudes anywhere between 1/32" & 1/16", so they will need relining. Since they are easily accessible from the outside, and i have 101 things to do, this job will get put aside for a dark winter night.

An additional plain plate, by the way, kindly provided by AOMCC member  & 'Cheval de Fer' magazine editor John Mitchell. Several other parts provided by John are stashed away to appear in later posts.

Next up, clutch basket, repainted by moi, cleaned original needle roller cage and thrust washer, and original pressure plate. John Budgen (John Budgen) provided a new set of rollers.

Here's the centre, which may need to be replaced. I've recut the threads, but as we've seen the splines are not good, inside or out. John Mitchell has provided another. Spring lengths vary 1.625 - 1.64", but since I'm not sure what the factory limits are we will have to see whether this is OK.

I nice set of new set screws for the basket to sprocket flange, with a tab washer - all from John Budgen.

Clutch, assembled and ready for testing. Clutch nuts all ok, spring cups ok, all assembled using my clutch screwdriver, pictured in an earlier post.