Model A - layshaft bush

 With the kickstart shaft nearly finished, we need to think about the bush for the lay shaft. This fits in a bore in the end of the kickstart shaft: 

The bush will be a top hat shape to accommodate the end of the layshaft and to determine the end float of the low gear pinion. It's going to be made from this piece of SAE660 bronze:

First job is to reduce the diameter to nominally 1” to pass into the shaft with a few thousandths clearance:

Next, we reduce the diameter such that we have a few thousandths interference fit in the 7/8" bore, and add a small chamfer to aid assembly. That done, we can bore it in steps up to 5/8" - our shaft is 11/16", but we will do that last bore in situ.

Parting off the bush. The hang out here is not ideal at all, and I believe I may have knocked the stock out of square in the chuck - it would have been far better to do this job with the revolving steady.

No matter though, this does not affect the working diameters and we can face off the end of the bush if necessary.

The top hat bush, mostly finished aside from the layshaft bore.

It's not as tight as I would have liked, so I have fitted it with Loctite 603 retainer. This won't be cured until tomorrow.

This is the last job for the lay shaft bush - it's been fixed in place and the Loctite has cured overnight so it is now being bored to 0.6875" for the layshaft. Notice that the shaft is in the fixed steady - it is essential that the shaft is bored concentric to the kickstart bush in the outer gearbox cover:

Some while back I had left a little excess material on the major diameter of the shaft thinking that I might need to play with the first gear pinion end float, and so it proved. As machined the shaft is a little overlength and I used this setup to remove around 0.020" from the end of the shaft which provided the necessary clearance. 

I'm pleased to say that assembly and testing of the gearbox proved that everything works as expected. The next step, and final step, is to machine the recess for the kickstart lever cotter pin.

SQ4 - bushing the saddle nose

Updated: First published June 2021

Since I've had it on the road, the Square Four has felt a bit wayward around the rear end. Since I had rebuilt the rear suspension and knew that it had no wear, I suspected the tyre and wheel though they were both new and rebuilt - until I realised the problem was closer to home. Literally much closer, to my backside.

The saddle nose bracket on an Ariel frame is quite small, giving little bearing area. Coupled with a bolt with an over-long thread, used as a bearing surface produces this effect after a few years:

This picture shows the saddle removed, but with the bolt in position. The red circle shows a portion of the thread used as a bearing - a very poor idea:

So, the first job is to make those worn holes round again. The bolt is 5/16" (0.312", or around 8mm), and they are both worn to over 0.350". I used an adjustable reamer on them to remove the ovality.

Ovality in the frame holes is not the only problem - the holes in the saddle frame are also very large. I have another problem in this area in that the fuel tank has very little clearance around the saddle nose bolt and I have solved both these problems in one go. In this picture, the original bolt has had it's head thickness reduced to produce a shoulder which fits in the saddle frame hole with very little clearance, and the full nut used at the other end has been reduced to the thickness of a half nut, again with a shoulder. This enabled the bolt length to be reduced, to get more clearance for the tank, and removed the whole assembly to the right to move the thread out of the bearing area.

Next job was to make two shouldered bushes to fit in the holes:

The bushes pass right through the fixed frame lugs, to provide maximum bearing area; there is a minimal shoulder to allow the bush to be retained in place (or removed).

This repair has removed virtually all the play from the saddle nose bearing.

Three years after I wrote this, I sorted out another problem - that of the bushes coming out of the frame lug and all play returning. I made a spacer on the lathe:

It's just a bit of 1/2" round bar with a clearance hole for the bolt; it's relieved slightly in the middle as the pivot bolt is very close to the frame lug.

Posterior stability has been restored.

FH - Swinging Arm bushes

A while ago, last May in fact I removed the SilentBloc swinging arm bearings and I wrote about it here. Since then, lots of things have got in the way - not only the Honda stuff, the QR50 and the CX500 but also the rear mudguard and the oil filter for the FH and of course the W/NG engine rebuild. Anyhow, as regular readers will know, the oil filter is done and I am on to the swinging arm. I'm doing this next as I want to check the oil filter will fit (and can be re-fitted) with the FERC in place and I can't do that without the swinging arm fitted, so here goes.

Before I start, the inspiration for this job, the details of the bushes and indeed the spindle (and it's machining) came from Steve Carter, who's done more miles on Huntmasters than probably anyone alive today and who is a stalwart member of the AOMCC and a daily contributor to the AOMCC forum.

Thanks Steve.

So, I have two oil filled bronze bushes measuring 22 mm ID x 32 mm OD x 50 mm long that I bought from Simply Bearings under the part number AM2232-50. The cleaned out journals for the old SilentBloc bushes measure exactly 1 1/4", which is 31.75 mm and we will want an interference fit of maybe 0.002" or 0.05 mm.

Well, you know what is coming next don't you. Charlie will start banging on about the virtues of his mini-lathe. What puzzled me for a while was how to hold the bushes to machine the outside diameters to size - I considered expanding mandrels, grub screws in a mandrel and Loctite. I was nervous of using Loctite as the these bushes are porous and I was worried about getting the bush off the mandrel.

As it happened, I just went for it and did it. This Ever Build cyanoacrylate is old and cold and may not work very well but I put a 1/4" wide ring of it around the 22 mm mandrel and slid the bush on - in a few minutes it was set.

I machined the bushes quickly and easily to size using the power feed and a carbide tipped left hand tool running at about 400 rpm. and it cut beautifully with no complaints from the glue. Actually, the cutting forces probably don't test the glue very much as this bronze is quite soft.

When considering fits, I had thought about cutting a clearance fit and using Loctite 603 Bearing Retainer, but discarded the idea as I should be able to machine a reasonable interference fit and not require a liquid retainer. As it turned out, this worked beautifully with the first bush which had a medium driving fit, but I cut the second one slightly undersize so I used some retainer with that. They both held up to the reaming forces.

The mandrel knocked out very easily and the bushes were pushed in flush with the end of the swinging arm tube, since I knew that there was minimal end float with the swinging arm in the frame:

The spindle material I got from Steve was 7/8", which is about 22.25 mm so we needed to ream the bushes. The spindle needs to carry the original stud through the middle, which created a problem - my lathe is not long enough to drill out a suitable round bar, nor does it have the capacity to pass such a bar through the lathe spindle. This is where Steve comes in again - he had a bit of bar long enough to provide spindles for two of his bikes, mine and another friend’s so he ended up making four. All I had to do was trim it to length to suit my frame, which I could do with a fixed steady. 

With the reaming done, I could oil and fit the spindle - fortunately it fitted both sides simultaneously with out any adjustment, so I was lucky - I had taken no precautions to align the bush I was reaming with the other bush.

The fit is great - there is no play that I can feel on the bench, though it may be a different story when the bike is on the ground.

Last thing I need to do is fit a grease nipple, though I want to assemble the arm back in the bike so I can see where to put the nipple for best access.

QR50 - Fork Bushes

As you know, I have decided to make a new set of telescopic forks for the QR50 since I can't find a new pair locally, or anywhere else for that matter, for a reasonable price. You've seen how I recovered the sliders and stanchions with new tube, and replaced the missing dust caps with machined parts.

Now it's time to machine the bushes and assemble the bits. I bought a 30 cm length of 30 mm white acetal, and cut off two 80 mm lengths, planning to make a complete leg-set of bushes in one setting. I wanted to make sure the set-up for the 22 mm bore was done without removing the material from the chuck.

I made a drawing to set my bush lengths against the existing design and the springs I had bought:

I set one of the 80 mm lengths up in the 3-jaw and centre drilled it, opening it up through 6, 10, 13  and 19 mm for the boring bar.

Here's the boring bar in action, taking out a 40-45 mm length to 22 mm or so to give a sliding fit on the stanchion.

From this bored part, I finished the top bush OD to 29 mm and parted off.

The top bushes fit in a 29 mm ID register in the slider, which is made from 32 mm OD seamless tube of 2 mm WT. The bush has a 0.5 x 0.5 mm register in one end to let it sit just below a circlip groove in the slider.

The circlips are wire type - I bought the sheet metal type initially before I realised there wasn't sufficient space in the leg to house them. Wire types are harder to get out but occupy much less space. The nominal 30 mm circlips need the ends trimming:

The clips fit in the end of the slider nicely - there is a 0.5 mm deep groove about 8 mm in, to let the clip retain the top bush:

The slider has a ground channel to allow you to get a scriber under the circlip:

It's very hard to see, but the circlip ends are ground flat to allow you to lift the ends out of the grooves:

The bottom bush is essentially a blind tube - bored 22 mm for the stanchion and finished to 28 mm OD for the slider, it has a 5 mm thick closed end to seat the spring. It's loosely retained to the stanchion with a small roll pin.

This shows the complete assembly, with the dust cap, main compression spring and the rebound spring. The springs were bought from ebay, selected for wire diameter and OD.

Here's the stanchion in paint:

The frame is also almost finished:

By the way. This interesting effect is called fisheye, and is what happens if you don't degrease the parts prior to painting...

Sticky Legs

You will remember from a recent post that the forks were stuck down again. After a long trip to Manchester (over three days - graduation ceremony) it's time to sort it out.

It was fairly obvious that the front end was going to come out, so that was all quite straightforward and nothing I haven't done many times before. Remembering that I had dented the front mudguard, that needed to come off too.

Oddly, the wheel spindle was not forthcoming and I started to suspect that one fork leg may be free while the other was stuck. Manoeuvring the mudguard out revealed the wheel cocked over at a strange angle and I realised that the brake side leg was stuck and the other side was free.

I thought that a luggage ratchet strap would do the job, allowing me to compress the free leg and extract the fork spindle. I looped it over the top yoke and down under the lug on the bottom of the fork slider.

This worked nicely and I was able to take the wheel out

Next, I shaped a piece of stout timber such that it would locate on the wheel spindle and tie-wrapped it to the fork leg. A sharp few taps on the end had the fork leg free again, until next time.

Ride like a veteran...

Out on a commuting run yesterday showed me that the fork bushes still have clearance issues. The forks are stuck again:

I rode it half way across Norfolk like that; now I know what the London to Brighton Run feels like; and the speedo is stuck again.

Looks nice in the rain though! Could have been taken 50 years ago, if it weren't for the wheelie bins.

Back in the workshop, my usual approach with the plywood caul, shown here, didn't work:

Unfortunately, it seems to be more firmly stuck this time and a bit more force dented the top of the mudguard:

It'll knock out.

Special tools

Special tools, those that are devised to make some unusual job that bit easier, come in all shapes and sizes.  Having no desire to pull the Square Four forks apart again (since I have the Huntmaster ones to do) I decided to see if the recalcitrant forks bushes would free themselves with a little brute force, tempered with at least a little intellect.

I thought I would be able to pull the stanchions out of the fork sliders without taking the forks apart again, by persuading the bottom yoke away from the wheel, thus pulling the stanchions away from the sliders.

The front mudguard is a serious piece of engineering (especially with all the welding wire I added to it) and it can take a bit of force. I devised a tool made from a block of 3/4" ply to spread a load into the mudguard:

Five minutes with a stout bit of bar saw the fork stanchions pop out of the sliders. Hopefully the next time I hit that pot hole the forks will have worn a little and won't get stuck again.

State of our Roads

There are some outrageous pot holes around here. There's one I always forget about on a hill nearby, which has been filled in but is now sunken again making a smooth but significant hole.

So sunken in fact that Amelia's forks haven't recovered yet:

I think we have a fork bush clearance problem!

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.