Britbike forum Forums Projects started by Britbike forum members Members bike projects New Year, New Project, New Imperial

Not a lot of progress of late but I did discover that the gear peddle was quite the wrong shape - too low down.



As It was it would be all but impossible to get your foot under the peddle to change gear.

Other members have told me that they have had similar problems. However the peddle responded to "thermal percussion adjustment" i.e getting it hot and hitting it with a big hammer.



Peddle in a much better place.

Not a lot of progress, life and Covid got in the way. Did however manage a little time in the workshop producing 1/4" BSW cheese head screws.



Made on the lathe from 3/8" stainless steel rod with the slots cut on a horizontal mill. Very few of the original screws survived and most of them were in a poor state. Need to make quite a lot as both the timing chest cover and primary drive case use them.

Took the machine to show held in an upstairs hall, which involved pushing the bike up (and down afterwards) a quite steep ramp. It was then I discovered that the front brake didn't work. Might have seemed OK just wheeling the bike about the workshop but when it was required to actually do something it didn't even offer useful suggestions. The original brake plate was missing right from the start and had been replaced with one found in a motorcycle beaker's yard (such things could still found way back then). I suppose it was always going to need a bit of "fettling" to make it do.



Looking at the brake shoes there seemed to be plenty of "meet" in the linings but clearly they were not making much in the way of contact with the drum, so what to do about it?



I started at first to make up a set of "shims" from sheet steel.

These where warped around the end of the shoes at the brake cam end.



With the shims in place the shoes were remounted of the brake plate.



The effect of this was to push the shoes outwards thus bringing them closer to the drum. Did this fix the problem? The short answer was no, improved things but clearly a bit more thinking needed yet.

My replacement brake assembly was clearly meant for a completely different machine, for a start there was no anchor point for brake cable. Probably the anchor was fixed to the fork leg in which ever machine it was meant for originally.



The photo show an original setup.



Compared with the original it can be seen that the positions of the brake leaver is in quite a different place with respect to the brake torque arm. It may be possible to modify the plate but rather more effort than I really want to do. So (for the time being at least) I will go with just fitting an anchor point on the plate plus resetting the shape of the arm to give an improved angle of pull. Looking for an original plate (ideally) or one of a better shape will be an ongoing task. Although the way I have it now is a big improvement over what went before it is a little bit untidy, not only that but should ever find a speedometer drive the cable anchor would almost certainly be in the way.
Another possibly maybe would fix an cable anchor to the fork leg and do away with the one on the plate

Without seeing original drawings of how the front brake is supposed to be assembled, it's tricky to comment on what you have.

However, reversing the brake lever is supposed to increase the brake power, so you might end up with a better brake than the original.

Although the brake action seem much improved I still think as I said before that the arrangement just looks untidy. Therefore I plan to move the cable anchor from the brake to the fork leg.



Stage one was to rivet an anchor onto a length of 20mm flat steel which will be in turn formed around the fork leg itself. Of course it can't be formed into a closed loop just yet as it not possible to slide it over the end of the leg, thus the final forming will have to take place once it is in position.

Cable anchor now in place on the front leg.



The "wrapped around" method of fixing was chosen because the anchor is subject to a fair amount of stress in use and this arrangement is better (in my view) better able to withstand that stress than say a straight "but" joint
A little bit of tidying up to the paintwork etc. will need to be done later, but in the meantime the brake plate and wheel require some more attention.

Good thinking 99 !
A butt joint would be decidedly incapable of likely surviving, for long.
Which could end up being quite nasty ...

I recall seeing a local Commando racebike, with a wider swingarm with a kink that had been butt welded.
I saw this in the pits pre-race, and wondered how it had been braced inside as reinforcement.
It wasn't - it did one lap and pulled back into the pits. with rear wheel steering.
The butt weld had torn apart, almost completely...
In (subsequent) later events, I noticed it had been substantially re-engineered, with much bracing.
(It should never have passed scrutineering ?)

Before the wheel goes back into place there were a few things to sort out. You may remember me saying some while back that the brake drums were bolted to the wheel hubs, five in the rear and three - slightly shorter - in the front. Only at the time when I was putting the drums and hubs back together the correct bolts were missing, so they were replaced with ⁵⁄₁₆" H.T bolts and nylock nuts. However when searching for something completely different (as is often the way) a few of the correct mushroom headed types turned up, not enough for a full set, but enough for the front wheel.



The previously fitted bolts were removed and replaced with. the original types, in addition the ring gear that should be inside the drum that drives the speedo also turned up, so although I don't have the drive I fitted anyway.



The brake needed a bit of attention as well, there is a threaded boss on the plate that's provided for the right-angle speedo drive, so as to block this off I turned up a threaded blank thereby closing the boss off and prevent water ingress. A short bolt also closed off the hole where the brake cable anchor had been fitted beforehand.

Revised setup for the front brake, doesn't work any differently that it did before but (to me at least) looks a lot tidier



Home made brake arm as with so much of this machine the original was missing right from the start.

Motorcycles registered on or after the 1st. October 1937 (in the UK) are supposed to be fitted with a speedometer ( although it was still charged as an extra) and my machine was registered in '38. The bike was actually built in September so might not have had one at first. On this machine the speedo. is driven from the front wheel via a right-angle drive which by all accounts are difficult to find and expensive when you do find one.



For the time being I decided to make one, it is in fact just a dummy made up from odd pieces of metal from around the workshop, but it looks the part.
I have a clip-on GPs speedo. for when I really need to know how fast I'm going.

Nowhere near finished of course, just temporally bolted altogether so that bits don't get lost (again).

I've really enjoyed your build. Going to be an impressive motorcycle

Just a few odd jobs, make up a bracket for the speeometer.



Need to have a small "double set" to keep it clear of the fork links.



Mounted towards the right hand side otherwhise it obstructs the lighting switch. Ammeter stil to br found.

Still had the original tank rubbers, but they where a poor state, but new ones where avaiable. Needed to make two new fixing plates.



Before they could be used however the plates needed to be "dished" to follow the shape of the tank.

I got one from Gaggs when they still had their old shop. They had a lot of New Old Stock and mine was NOS for my 1939 Speed Twin.

I am not sure if they kept their old stock when they shut the old shop and became Timeless Motorcycles but they might be worth a call.

John.

I found a speedo drive with a NOS front brake - for a military Enfield. Which I have as a project.


However, if you look at the drive closely, its full of micro-cracks ?
Its one of those zinc diecastings, so I don't give it much chance of lasting too long.
Someone is making new brass bodies for them ?
Your look-alike body is quite a neat way around the problem !

Just a few small jobs today, fit the nearside tank (knee) rubber plus a little more work on the rear stand. You might remember that I didn't have such a stand and modified another one that I had acquired, genuine New Imperial item, but from a completely different model. The problem was the the stand would not go "over centre" quite far enough as a result the machine wasn't very stable. A certain amount of fettling at the time improved things but subsequent moving about and lifting it on and off it's stand proved it to be still not as good as it might be. simple enough to to remove the stand and grind a little off the "stops" until I got things more where I wanted. Hardest part of the job was getting the return spring back on, got there in the end though.



The machine now seems a good deal more stable that before.



Largely for the sake of appearance I fitted a pillion seat, not sure I would want to ride on it though. Needed to extend the seat bracket so as they would line up with existing fixings. didn't really want to drill holes in the mudguard, I had spent quite a bit of time welding up the many extra holes that were in the guard earlier on. The original seat set-up for the spring frame models was quite a complex affair, cantilevered of the front seat mounting with stays going down to the sub frame rather like the arrangement on Vincent's. Don't think there is very much of a chance of finding one.

Managed to acquire a speedo drive , but it's not complete.



The incomplete drive.

Although making another may well be possible there are some things you would need to know. In particular the outside diameter of the pinion. number of teeth, the diametrical-pitch (that can be worked out from the O/D and the number of teeth) and the angle of the helix. Measuring the angle would be easy enough always supposing you had an original to measure. Most likely to be 45 deg. but would be a real pain if you made one only to discover afterwards it was something different.

P.S Rohan, if you are reading this use my email as we have run out of P/Ms

Someone on your side of the pond is making gears, but unfortunately I don’t know who. I bought a speedo housing off of EBay and one gear shaft was buggered. I was able to buy new gears and the end cap bits. Bought them from VOC Spares. Unlikely they would divulge who their supplier is, but you never know. The gear set isn’t cheap, but a 1/3 the cost of a complete gearbox. One of the speedo rebuilders might have a used one?

Thats sounding hopeful.
I think it might be very expensive to get set up to manufacture these.
You'd have to make/sell zillions to get your investment back.

The one I have is 12 teeth on the driven shaft.
(I found a chart someplace that lists all the combinations.)
I just need to find where I found it again.
The colour of the washer under the grease nipple denotes which one.

Can you measure the angle from a screen pic ? !!
(congealed grease still not entirely gone).


Now where did I put that micrometer ...

Difficult to measure the angle of a round object on a flat screen but thinking about it as the two operate at 90 deg. to one another the angle really has to be 45 deg. The ratio of course is governed by the number of teeth on the driven and following gear. Could be a bit of a "minefield" as there are so many variables,
the number of teeth on the gear inside the wheel hub, the teeth of the gear on the end of the driven shaft, the size of the wheel and whether you want clock or anti- clock rotation. The Information is probably all out there somewhere if we could only find it. Need to know the D.P of the gears as well ( need to know this so as to select the correct cutter,) Then if like Rohan's the body has fallen apart, having a new one cast could be expensive, fabricating one from brass rod would probably be easiest and cheapest way to go.

Leaving aside gears for the moment as I think that discussion may well go on for a while yet, I turned to another problem. The oil seal in the inner primary drive case. The earlier set-up involving bronze plates, springs etc. is no longer needed as the later gear boxes have a 1" dia. sleeve over the input shaft and it is that which passes through the case wall. The seal that was there already had long since surrendered any sealing properties it might have had, which begged the question could a modern seal be fitted in it's place?



So having warmed up the case and pressed the old seal out, measured it, and discovered that there was one available it was duly ordered. The seal is a slight interference (press) fit but upon cleaning the case two radial cracks were discovered, something else to fix.

What a beautiful little clutch case. !

To revert to speedo drives for a moment, I found this someplace
I don't know how - or if - this connects with my 12 tooth driven gear and red washer...

________________________________________________________________________________________
Gearbox Ratio can be determined from the colour of the celastoid washer under the grease nipple or screw.
Ratio 1 : 1 Black Celastoid.
Ratio 2 : 1 No Identification.
Ratio 8 : 3 Yellow Celastoid.
Ratio 14 : 9 White Celastoid.
Ratio 19 : 10 Green Celastoid.
Ratio 21 : 10 Red Celastoid.
Ratio 20 : 9 Light Blue Celastoid.
Ratio 18 : 10 Dark Blue Celastoid.

Once you figure out what you are looking for…. ratio, gear diameter, what style of driven end etc, post it here or send me a PM. I have a few NOS orphan gears. The odds of me having the correct one are somewhere between slim and none, but I’ll have a look. Even if it has the correct gear, the shaft could be modified/shortened.

Finding a suitable oil seal on line was one thing, finding someone who had one was something else. In the mean time there was the cracked casting to deal with. First to try was low temperature melting rods, seamed to be working OK initially, but the application of even modest amounts of heat soon revealed the problem to be much worse that first thought, with the crack extending almost the full width of casting.

.

I think that the best course now is to finish cracking the casting into half and and have it welled using using tungsten-inert-gas welding. Happily there is someone in my M/C club who can do that. Watch this space,