That Clutch!

Last time out on my Velocette Viper the clutch was‭ “‬not what it should be‭” ‬and remembering what the plates were like last time she was apart I decided on a re-line.

Since the plates were now some‭ ‬50‭ ‬years old I opted on fitting new plates rather than just replacing the Ferodo inserts in the old plates and so ordered the‭ “‬kit‭” ‬of new plates from Grove Classics<>. The parts were ordered on Tuesday morning,‭ ‬delivered Wednesday morning‭! ‬that’s service‭!!‬.

So it was out into the garage and start work.

First thing is to clear the decks so it’s remove the dynamo drive covers and drive as well as the rear chain sprocket cover and the sprocket itself.

Primary Case

Velocette Primary Drive












Next is remove the screws holding the two halves of the primary chain-case together.

Last time it was down I used silicone sealer on the gasket and this time it’s proved a right swine to split the joint This time on re-assembly I’ll grease one face so it doesn’t happen like that again‭!‬.

Before I can split the case however I need to remove the dynamo drive pulley,‭ ‬this doubles as the nut securing the primary drive shock absorber and requires Velocette special spanner No.‭ ‬A220‭ ‬to engage with the castellations of the nut.‭

A rake around the tool boxes found this,‭ ‬and its mate,‭ ‬the AS61/2AS clutch peg spanner.

After starting it with a blow from a copper/hide mallet on the A220 spanner the pulley was unscrewed and the chain-case split to give access to the clutch.

Primary Drive

Primary Drive












On a Velo the clutch is unusual in it being on the sleeve gear and‭ ‬hence inboard of the final drive sprocket.‭

This is due to the Velo’s very narrow crankshaft and slim crankcases and this makes the clutch actuation different from the normal run of things.

Instead of it having only‭ ‬4‭ ‬or perhaps even‭ ‬6‭ ‬biggish clutch springs,‭ ‬each one in a separate mount on the top housing, there are‭ ‬16‭ ‬small‭ ‬springs,‭ ‬all in a mount at the clutch hub,

This mount however allows you to adjust the spring pressure on all‭ ‬16 springs‭ ‬at once rather than having to muck about with adjusting each individual spring on its own,‭ ‬and this “spring hub” is lifted by an annular thrust race,‭ ‬similar to as in a car clutch.

Clutch Spring Carrier

Clutch Spring Carrier












The hub‭ ‬piece is in two parts,‭ ‬the spring carrier itself, which screws into the clutch top plate and the pressure piece the springs bear against which doubles up as the clutch securing nut‭ ‬and screws onto the sleeve gear and secures the clutch back-plate.

There is a locking plate fitted to prevent this nut loosening off and which is secured by a‭ ‬small countersunk screw. so next step is to remove this screw and‭ ‬the locking plate,‭ ‬then by applying the AS61/2AS peg spanner, unscrew this clutch nut.

‭ ‬To do this though the primary drive has to be locked to prevent the clutch being turned by the spanner, but replacing the engine shock absorber will do this,‭ ‬engine compression being enough for the job.

On a‭ “‬normal‭” ‬clutch,‭ ‬when you remove the pressure plate its lifting piece tends to drop away and you then remove the clutch piecemeal.‭

On a Velo however,‭ ‬once the securing nut is undone,‭ ‬the clutch is removed in one piece and there are THREE lift pins going through the clutch backplate. These will of course drop onto the floor if you don’t watch for them‭!‬. (I snap a couple of rubber bands round the clutch assembly to hold everything together.)

Now you have the complete clutch assembly in your hands to take to the bench and work on in comfort.

Clutch on Bench

Velocette Clutch on Bench












You just unscrew the spring carrier from the front plate and put it and the securing nut to one side for‭ ‬now.

Then you lift off the front plate,‭ ‬this is a machined part and not just a stamping as in most bike clutches.

Below this is an insert plate,‭ ‬which tabs into the clutch drum, then comes a plain plate which tabs into the front plate,‭ ‬next again is the clutch drum and sprocket assembly.

The drum is formed on both sides of the clutch sprocket. which also carries a set of inserts and so acts as another insert plate.

On the gearbox side of the sprocket next‭ ‬comes a plain plate followed by‭ ‬an insert plate,‭ then ‬another plain plate,‭ ‬another insert plate and then the clutch main body/back-plate so you have a‭ ‬9-plate clutch.

This whole assembly is only just over an inch thick‭! (‬1.070‭“ ‬with the new plates‭!)‬,‭ ‬a VERY slim assembly yet it will cope with the‭ ‬140mph performance of a‭ ‬500cc Thruxton Venom as well as it does the‭ ‬90mph performance of my little‭ ‬350cc Viper.

Slim Clutch

A Very Slim Clutch !












With the clutch apart it’s now a case of cleaning things and then re-assemble,‭ ‬this can be a bit fiddly getting all the plate tabs to seat in their respective grooves but once the body is assembled a couple of rubber bands snapped over will hold everything together.

Attention now is turned to the spring assembly,‭ ‬there are‭ ‬16‭ ‬springs,‭ ‬each‭ ‬1.125‭” ‬long by‭ ‬0.275‭“ ‬diameter,

I’m fitting new springs as well so it’s just take out the old and fit the new but if not then the springs need to be checked for distortion‭ ‬.

When you fit the pressure nut these springs must be able to slide against the underside of it. To facilitate this they do not bear directly against the underside of the nut,‭ ‬there are two shim washers interposed and these are lubricated prior to assembly so that while the springs bear against the lower shim, this can slide on the upper shim which can itself slide against the underside of the nut.

A bit torturous but this does work.‭

The pressure‭ ‬of the individual springs against the lower shim does tends to damage‭ i‬t so,‭ ‬while ideally both shims a should be replaced every‭ ‬time you remove the clutch,‭ ‬you can usually get away with just replacing one of them.

Then its‭ ‬back to the bike with the clutch assembled.

The three thrust pins have to be put into place,‭ ‬stuck there with a bit of grease and the body assembly can be slid onto the sleeve gear.

Ready to fit

Thrust Pins in Place Ready to Fit












Next the spring carrier is screwed into place in the front plate until it bottoms onto the thrust pins,‭ ‬you can feel this happen as the clutch body will move on the gear. This is to give the maximum free length space to the springs.

The pressure nut can now be screwed onto the sleeve gear,‭ ‬there is a special tool for this but by setting the carrier as suggested it will normally allow you to do this with finger pressure‭ ‬alone.

Once the nut is started then the AS61/2AS peg spanner can be used to tighten the nut.‭

Now the rubber bands can be cut away and it’s just a case of refit the primary chain, (Don’t forget to fit the locking plate!).‭

Primary Drive

Primary Drive Assembled












Then close up the chain-case and refit the engine shaft shock absorber along with the rear chain and sprocket. (The other end of the AS61/2AS fits the main-shaft nut.)

Once you’ve done all that, it’s time to set up the clutch.

First thing to do is to set up the spring pressure.

To do this,‭ ‬the‭ ‬first‭ ‬step is to totally disconnect the clutch cable‭ ‬so as to give maximum free play in the system.‭

You now have to screw the spring carrier out of the clutch front-plate to increase the spring pressure,‭ ‬to do this Velocette tool KA62/2‭ ‬is used,‭ a short length of ¼ inch steel rod with a flat on one end.

This inserts through the small hole in the gearbox sprocket and engages with notches in the spring carrier.

If the rear wheel is now turned forwards, then the spring carrier will be unscrewed from the front plate,‭ ‬moving it towards the pressure nut and so will increase spring pressure.

So you now turn the wheel forward a bit,‭ ‬then try the kickstart to test for the clutch slipping.‭

Repeat as necessary and spring pressure setting is correct when,‭ ‬as you press down on the kickstart against compression, the clutch will JUST‭ ‬begin to‭ ‬slip.‭

The clutch cable is now connected up‭ ‬again and all free play is taken out of it,‭ ‬this is setting up the unloaded‭ ‬position of the clutch lifting mechanism.

The spring carrier is now unscrewed further from the front plate until there is‭ ‬just over‭ ‬⅛ inch free play in the cable.

By doing this you have increased spring pressure to where the clutch is no longer slipping under load AND when the clutch lever is released there is no load on the clutch release‭ ‬bearing.

The important thing to realise here is that, on a Velo clutch, the free play in the system is set up on the spring carrier,‭ ‬AFTER the release mechanism and NOT on the cable,‭ ‬before that system.

It does mean however that if you do not get that initial JUST slipping point correctly one way then, because that pressure is a bit low, the clutch can slip under load and if the other,‭ ‬the clutch will not clear fully and will drag, equally if you make a real mess up you can wind up with a clutch that will both slip AND drag!.

Setting it up it this way means that there is no load on the lifting mechanism when it is at rest, if there is then the clutch release bearing will be under load and will wear. Since‭ ‬this is a special,‭ ‬unique to Velocette,‭ ‬it is‭ ‬ not cheap‭!! and as ‬there is only some‭ ‬5‭ ‬thou clearance between each plate at full lift there is little room for error‭!‬.

Since I have assembled the clutch using all new plates,‭ ‬these will bed in over the‭ ‬first few mile so I’ll have to go through this full set up drill again after a couple of hundred miles.

All that’s left to do is refit the cover over the gearbox sprocket and the dynamo belt covers, fire her up and go for a ride.

A Bit of a Hide

Now for something totally different !!.

I have a pair of dogs. Recently, while he was out running loose, the elder one managed to lose his collar.

Since the pup was also outgrowing her puppy collar I decided it was time she moved on to her adult collar and to make up a pair of matching collars for them.

So I went to the local suppliers, LePrevo Leather <>, and bought one 2 inch and two ¾ inch straps of a good leather along with four ¾ inch brass “D” rings, two 1 inch brass “O” rings, some copper rivets and two brass trigger hooks.

Once I had the materials next thing was to measure up. What I intended to make was a pair of martingale collars and for these I needed an accurate measure of the dogs neck size, his lordship measured up as being 16½ inches and her ladyship was 14 inches.

Allowing for the size of the “D” rings this meant that his collar leather needed to be a 14 incher while hers was to be 12 inches to allow her room to “grow into it”.

The  dogs  are a pair of standard poodles, poodles are a long-necked dog and as such I prefer them to wear a broad “fishtail” type collar so next step was to mark out the 2 inch strap for this and cut it to the required shape.


Cutting Template


A cutting template was made from some stiff card and transferred to the leather, which was then cut to shape using a Stanley knife fitted with a new blade.

Cut leather

Leather Main Body

Next a “D” ring was slipped over one of the “tails” and the “tail” doubled over it. This now needed to be fixed in place and there are two options here, you can stitch it in place or you can rivet it place, as these collars are for a larger dog and have ¾ inch wide “tails” stitching is a better option, for a small dog, and so a narrower collar, using ½ inch “D” rings then in preference I’d rivet it.

Leather is not as easy to sew as fabric is and it needs to have the needle holes pre-punched, you can’t just push a needle through two thicknesses of leather. What is needed here is a “pricking iron”, this looks a bit like a fork and is used to mark out and pre-punch the leather.

Once the thread holes have been pre-punched then it’s just a case of using an awl to open and line up the holes’ and then running the needle through.

When sewing leather it is normally done using two needles, one on each end of the thread, so you then run the other needle back through the other way and pull the thread tight and that’s the first stitch made.

Then you just run the awl through the next holes, follow it with the needles and so on till that stitch row is completed.

For security a second row of stitches was run across the “tail”, a bit nearer to the “D” ring.

"D" Ring

“D” Ring Stitched in Place

That meant the first “D” ring was now in place and all I had to do was stitch up the other three and I had the collar main bodies finished.

The bigger collar was 14 inches long and the smaller was 12 inches and the strap was 46 inches long so I had 20 inches of the strap “spare”

This “spare length” was cut down so as to give two straps, each ¾ inch wide by 20 inches long and one of these was slipped through both “D” rings on one collar.

As this loop was to be riveted closed,  a small hole was punched through the strap length, about a ½ inch from either end and another hole a bit over 1¼ inches from one end.

The strap was now slipped through one of the 1 inch “O” rings, the strap end doubled over the ring. A rivet was then put through all three holes and “set up” to secure it in place.

All that was now left to do was to make up a slider to go over the strap loop and secure it.

Completed Martingale

Completed Martingale

For this a short length of the “spare” leather was doubled over the loop  and the ends riveted in place so that it would slide stiffly over the loop and that was that collar completed,

Slider Fitted to Martingale

Slider Fitted to Martingale

all that was now left to do was to finish her ladyships collar as well.


Completed Pair of Martingales

To complete the “sets” I needed leaders to go with the collars.

For these I had the two strap lengths of ¾ inch wide leather.

I just slipped one end through the loop on one of the trigger hooks, doubled it back on itself and stitched the loop closed. As with the “D” rings I used two rows of stitching to secure it.

Trigger Hook

Trigger Hook stitched onto Leader

To form the handle I doubled the opposite 9 inches of the strap back on itself and secured it in place with another two rows of stitching and that was the leader complete.

Leader set

Set of Martingale and Leader

The idea of these “martingale” collars is that if the dog pulls hard when walking on lead then the collar is pulled a bit tighter round his neck, but, because from the way it is made it can only “pinch down” by about 1 inch on a 16 inch collar so it is uncomfortable to the dog rather than choking it.

It is not meant to be worn continually, it should be kept along with its leader as a set, the pair being put on when the dog is taken out and then removed, as a pair, when you get back home.

As long as the slider is run up to near the “D” rings the dog can be allowed to run loose “off lead” while wearing it since the slider holding the loop closed means the dog cannot get his foot caught in the open loop.


There are a number of motorcycling organisations who “Stand Up For Our Rights”.

These are normally national groups and as many of the threats they oppose are international they have joined together to form  an international group.

This “cover group” is FEMA, the Federation of European Motorcyclists Association.

This group has an open website that anyone can access at :-


Have a look, check it out every couple of months and keep yourself up to date on what’s happening on the political side of biking.

A Little Light

With the sidecar fitted and aligned, before I can take it out on the road it needs lights to be legal.

With it being a 1937 machine I just need to show “a white light to the front and a red light to the rear”, after all at that time gas lighting was still common, but as this outfit is to be used on modern roads I need to be a  bit more practical.

What I am fitting is a spotlight set up as a Daylight Riding Light, a white front running light, a red rear running light, a stop light and indicators.

Indicators are totally out of period but in modern traffic on a sidecar outfit they are “A DAMN Good Idea!”.

I had a pair of the Hella round indicator/running lights in stock so these became the basis of my lights.

As the wheel and mudguard (fender) are on the outside edge of the outfit the lights need to mount onto this but as the guard is semi-circular this gives a problem, the Hella units are intended to fit onto a flat, vertical surface and the guard has a compound curve, at the point where the lights need to mount there is a 45° slope to the vertical.

First thing was to make the mounts for the lights. These need to fit onto the guard and give a suitable surface to mount the lights.

As the lights are 75mm in diameter I took a 6 inch length of 75mm OD alloy tube with a 1.5mm wall thickness and cut it into two lengths on a 45°angle.

Mount tube

The sawcut alloy tube

These, when mounted onto the guard will fit onto the guard part way up it and give the necessary vertical surface, unfortunately though the plain cut end does not match the curves of the guard.

tube onguard

Showing mismatch between tube and mudguard, it only touches at the ends

However from fitting the guard onto the sidecar I had a short length of it spare

spare guard

“Spare” length of mudguard

so I took this, fixed some 80 grit abrasive sheet to it.

I next took a black marker, used it to “black up” the cut end of the  tube

tube end blacked

“Blacked-up” end of tube

and then started rubbing the mount on the abrasive sheet.

rubbing in

Rubbing in end of tube to match mudguard

This gave me “witness marks” showing where the guard was contacting the mount and so, where the mount needed trimming back.

witness marks

Rubbed end of tube showing “witness marks” where material still has to be removed

This was done using a Dremel tool and a sanding drum.

Repeated re-blacking, trials and trimming gave me a pair of mounts that were a reasonable fit onto the guard and which, given some rubber beading, would make a sound joint against it.

finished job

Tube matched to contour of mudguard

I now needed bases for the lights themselves. To make these I took a pair of 10mm thick alloy disks of about 85mm OD.

These were each chucked up in the lathe

raw disk

Raw disk in lathe chuck

and had a central 8mm hole drilled through.

After this they were removed from the chuck their place was taken by a short length of 32mm OD bar. This had its end faced flat and then had a central hole drilled into it. This was tapped to take an 8mm bolt.


Disk centre drilled 8mm

This gave me a mandrel to work the disk on and so one of the disks was bolted to it, this meant that I could now turn the disk about it’s centre and it was able to have the edge turned down to size.

on mandrel

Disk mounted on mandrel for turning

This disk was now skimmed down to 75mm diameter, the same as the OD of the tube.

Next step was to turn a 4mm deep spigot on the disk to make a tight fit in the tube.

I then reversed the disk on the mandrel and another 4mm deep spigot turned on the other side, this time sized to mount the Hella lens onto.

finished turned disk

Disk turned to size and lens fitted

Suitable mounting holes were drilled and tapped into the alloy to take the lens mounting screws.

All that was now needed was to supply light to the lenses and rather than use incandescent  bulbs I opted to use LED lights instead.

Going onto Ebay, I ordered up 4 amber, two red and two white LED marker lights. These mount with a 10mm stud on their backs.

As these are the equivalent of a 10 watt bulb the intention was to use two amber LEDs to supply each indicator,one white for the front running light and two reds for the stop light.

Going to the disks, I marked off the horizontal diameter through the lens mounting screws and drilled a pair of 10mm clearance holes above it. One one disk I then drilled a single 10mm clearance hole below the centre line and on the other a pair below the line.

drillee disk + LEDs

Front unit disk fitted with LEDs

Mounting two of the amber LED’s above the line gave me my indicators and the fitting the whites or reds below gave me my front running light and my stop light.

I needed a rear running light as well and so a similar but smaller unit was made up using a 50mm diameter LED rear marker light to supply the lens.

All that was left to do was give the mounts a lick of paint, mount them onto the guard via the central hole in the disks and to run in the wiring.

Finished job

The completed light unit in place


Lining it up

It’s now time to start fitting the sidecar. I’ve not yet refitted the tank after the dynamo belt drive conversion so now is an ideal time to do this.

First thing is to get the chassis connected up to the bikes frame.

The chassis was laid out alongside the bike and put up on blocks.

The front swan-neck was put in position on the bike and loosely clamped to the sidecar chassis, as was the rear ball joint fitting.

Fitting a sidecar has been described as a black art, well now starts the black magic!

First thing to set is the lead, the sidecar wheel has to be set a bit in front of the bikes rear one, how much depends on the type of sidecar, the intended use and the bike itself.

A bike with rear suspension needs more lead than a rigid bike; with a heavy sidecar you needs less lead, with a light sports chair you need more. This all boils down to the answer to “How Much?”  being “It Depends” but it is not critical to a fraction of an inch, I’m starting with 6 inches of lead on a light sports sidecar and this can be adjusted, if needs be, after road test. On my later outfit, which does have rear springing, I’m running with 10 inches lead on a similar sidecar.

So the chassis was slid around on the blocks till I had the appropriate lead and the fitting clamps tightened a bit.

setting up

Lead and level have been set, now it’s the toe-in to do. Notice the two “fine alignment tools” by the front wheel

The chassis was now able to have the support blocks removed and, as the bike was now standing on her wheels as well, it was time to level the chassis.

Working with a rigid bike here it was set level side to side, when the bike has rear suspension you’ll need to have the bike loaded when setting this.

While you want the sidecar level side to side, going fore and aft you want it nose high, even when loaded, so the chassis needs setting with the nose rail between a half inch and an inch higher than the axle rail. Getting these right can be a bit fiddly as with the chassis I am using, adjusting the side to side level will also alter the lead if your not on top of the job.

Now comes the most important of the settings, the toe-in.

With a sidecar outfit, the power is all on the bike side, the sidecar wheel is unpowered.

This means that when running straight the sidecar wheel always drags a bit and tends to pull the bike towards it. It is not a heavy pull but it does get tiring compensating for it all the time, so the trick is to set the sidecar wheel to steer a little the other way by pointing it in towards the bike, to “toe it in”.

Thing is “By how much?” and the answer is “It all depends!”. This is the big variable and depends on the bike, the roads you use, road camber will affect it, how fast you are going etc. so you have to compromise and then make adjustments to suit.

Experience leads me to use an initial setting of around 3/4 of an inch over the length of the bike so a straight edge (here a length of 4 x 2 timber) is laid against the bikes wheels, I have the same size tyres fitted fore and aft so it’s set up on blocks and adjusted so as to touch evenly at four points across the wheels.

Similarly another straight edge is laid against the sidecar wheel, touching evenly against it and the distance between the two straight edges measured, first just behind the rear wheel and then just in front of the front one, the difference between the measurements giving the amount of toe-in.

This is adjusted to suit at the chassis clamps, the sidecar wheel being lifted off the ground and replaced and the straight edges reset before a check measurement is taken so as to remove any tyre distortion from the figure.

Once I had the required toe-in the two main sidecar clamps could be tightened up but this is another setting that will probably be modified after road test.

This left me with the sidecar lean out to set. The bike needs to lean a little way out from the sidecar. With a left-hand sidecar in UK you want the bike to be a little past vertical to allow for the road camber, so you drop a plumb line from the handlebar end and set the lean to around a half inch.

setting lean-out

To set the lean-out drop a plumb line from the handlebar.

I’ve got a right-hand sidecar however and any lean I set will be added to by the camber, if I set too much lean I’m going to feel the bike leaning over, so initially I’m setting so as to have the bike vertical on a level surface so on the road the camber will be giving the lean out.

This is set using the rear upper brace, that one goes to just below the saddle.

setting lean-out

Lean -out is set using the rear brace that goes to under the seat

That’s the main adjustments made and locked by tightening the chassis clamps. Some people will tell you these three fittings are all you need but a fourth one is definitely desirable, without it you can feel the outfit flexing in corners, not only that but the toe-in varies as the outfit flexes, Not Ideal!.

This fitting goes across between the front of the sidecar chassis and a low point on the bike to triangulate the swan neck. Normally you would take it off the front engine plates but a Panther does not have these.

However P&M supplied a mounting point on the engine right beside where the front engine supports are so its taken to there. All you do is adjust the fitting so that the clevis bolts slide easily into place and then lock it up in that position.

adding the body

The lower front brace goes between the front of the chassis and the bike.
Once it is in place then the body can be fitted.

With the basic settings made it now requires a road test to determine what adjustments need to be made to these.

What to expect is that as you pull away there will be a small degree of low speed steering wobble that disappears as soon as you are moving. This is normal and you soon do not even notice it, you don’t after all on your car and it does the same. You can reduce this with a steering damper, but too heavy a damper makes for heavy steering, careful attention to the setting up will minimise it, a better remedy.

Now try some slow turns, towards and away from the sidecar, ideally the effort should be about the same but if turning towards the chair is noticeably heavy then you need to reduce the lead to stop the wheel crabbing. But too little lead affects stability and makes the sidecar wheel more prone to lifting.

Does the outfit run straight under steady power? The ideal is to be able to hold it steady with one finger on the bars, does it pull to one side or the other? This is a pointer to the toe-in setting, pulling all the time towards the sidecar — increase the toe-in, pulling away from it — decrease the toe-in.

Open the gas and as you speed up you should pull a little round towards the sidecar; now shut the gas,as the bike slows on engine braking you should feel the sidecar pull round towards the bike.

If at steady speed you can feel it is pulling only slightly but enough to need constant input to stay straight then a SMALL adjustment to the lean-out can help but don’t overdo it, look on this as a final fine trim to getting the toe-in right.

So far all your tests should have been below 30mph, now it’s time to speed up a bit.

Take it gently and try at higher speeds, it may need a bit more fine tuning to get the outfit handling “Just So” but it’s well worth the effort as with a well set up outfit out on the open road it steers largely on the throttle, needing very little input to the bars.

Complete outfit

Final Result, ready for the road

Timing It.

Having removed the magneto and with replacing the drive dog on it with the POC’s uprated version I needed to retime the ignition.

On a Panther there are no external timing marks and the ignition point is normally quoted as with the magneto set on full advance at a set distance before TDC,‭ ‬measured with a rod down the spark plug hole in the head.

An option is to set it to TDC with the magneto on full retard,‭ ‬determined the same way.‭ ‬This sounds easy but it is in fact not so simple or accurate to determine because there is an appreciable amount of crankshaft rotation at TDC with minimal piston motion and it is easy to be a fair bit out.

I decided to make up a special tool for this.

The obvious way is just to take an old plug,‭ ‬smash out the ceramic and use a rod going down through it.

Downside with this is that the rod is going into the cylinder at an angle so that any distance measured on it will not be an accurate measure of piston movement,‭ ‬not only that but because it is at an angle it can jam the piston rather than being pushed up by it and cause damage.

I’ve a spare cylinder head and using this I found that not only could an old spoke go down the plug hole vertically when angled across it but there was a flat horizontal face on the outside of the head at the plug hole to set the tool on and also act as an index point.

Spare head

Head showing flat area at plug hole

So I took a piece of‭ ‬2.0mm flat aluminium sheet scrap and cut it to fit across this flat area.

I then drilled a‭ ‬5/16inch‭ (‬8mm for the metrically inclined‭) ‬hole in the plate,‭ ‬centred on the plug hole and filed the bottom edge of the plate below that to a chisel edge.

Alloy plate

Alloy plate

As I wanted to keep the spoke vertical I scribed a line up through the hole centre and using the corner of a hand file I cut a‭ “‬V‭” ‬groove on it.

The spoke will be pulled into this groove and so locked at‭ ‬90°‭ ‬to the edge of the plate.

Next I took a length of studding and then drilled across it’s diameter close to the end,‭ ‬the drilling being just clearance for a spoke and an inch length cut off the studding.

Cross drilling studding

Component parts of tool

Component parts of tool

The spoke was then put through the hole,‭ ‬the cut studding put through the plate so that the chisel edge was against the spoke and a nut and washer fitted so that while the spoke was held against the plate it could still be pushed up and down through the bolt.

Assembled tool

Assembled tool

The plate was then put in place on the cylinder head with the spoke going down the plughole and the bottom edge of the plate was held firmly down onto the flat face above the plug hole.

The motor was then gently turned over and as the piston rose up the bore it pushed the spoke up through the bolt.

Tool in use

Tool in use

Since the bolt had been tightened enough to hold the spoke but not enough lock it in position,‭ ‬as the‭  ‬piston went across TDC and back down the bore on the other side,‭ ‬the spoke was left at the TDC position.

The device was removed from the head and a mark was put on the spoke at the chisel edge.

Reference was made to the bikes manual in the POC websites‭ “‬Library‭” ‬to find the correct advance distance for my motor,‭ ‬45°‭ ‬or‭ ‬19/32‭”‬,‭ ‬and another mark made on the spoke at that distance above the TDC mark.

‭(‬If you are making up one of these be careful to check what the correct figure is for your bike,‭ ‬official figure varies by some‭ ‬10°‭ ‬according to the year of the bike.‭)

This mark was aligned against the chisel edge on the plate and the nut tightened down to lock the spoke in place.

The motor was now brought to TDC on the compression stroke and then turned backwards to take the piston back down the bore to before the ignition point,‭ ‬the new tool put in place with the spoke end down through the plug hole and the motor gently turned forwards until the piston was felt to touch against the end of the spoke.

The motor was now at the correct spot to set the magneto timing at full advance so the Magneto could now be set in place and its timing set.

This is a bit more sophisticated than the old idea of using a‭ “‬pencil down the plug-hole‭” ‬but it’s easier to use when set up,‭ ‬it has a clearer index point AND there’s no chance of losing it down the plug-hole.

This new tool is small enough to keep in the tool-set carried on the bike itself, I’ve got an old tobacco‭ tin with the tappet spanners, push-rod tube spanner, mag spanners, a set of feelers, a packet of cigarette papers and now this tool kept in the toolbox, ‬after all,‭ ‬if you have it with you then you won’t need it but if you haven’t got it you will‭!

timing gears

Belt Up‭ (‬Part Two‭)

As the old lady was being laid up for the winter the chance was taken to drain and remove the fuel tank,‭ ‬this was rinsed out to remove any accumulated crap from across the season and the tank stored on a shelf out of the way.‭ ‬With the modern petrol brews having a limited shelf life it’s no longer a good idea to leave the tank full over the winter.

The carburetter was also drained so that the fuel in it could not evaporate and leave a varnish of additives choking the pilot jets.‭ (‬I was caught out by this last winter with the Velo and wound up having to put her carb in an ultrasonic cleaner to clear it out‭!‬.‭)

Next was to remove the magneto and dynamo and shelve these also for now.‭

This had cleared the decks so next step was to remove the timing cover.


timing gears

Open Timing Case

The joint was initially just cracked open so as to drain the oil and then the cover was removed,‭ ‬forgetting of course to catch the oil pumps pressure pad and spring as they dropped into the drained oil‭!‬.

Having fished them out of the drain pan they were wiped clean and put to one side and I found that unlike on the later motors,‭ ‬the magneto timing gear on my bike is not drilled and tapped to take a puller,‭ ‬it needs a claw type puller‭ ‬and, with the one I have, the legs foul against the timing case wall and prevent it getting a straight pull on the gear.

However on the older Panthers, such as this one, rather than the outer drive disc and the shaft being in one piece the shaft has a separate drive disc on one end and the timing gear on the other.

This meant that I could pull the drive disc from outside the timing case where there is easy access for the puller so it was just a case of unscrew the retaining nut and pull the disc.


Old Type Chainwheel, notice amount of wear!

Intention was to fit the puller and apply sufficient tension on it to hold things in place before the disc was heated with a gas torch.

Idea was to get the disc to expand a bit and then apply pressure before the heat was conducted to the shaft and expanded that as well, so it has to be done quickly.

Problem appeared in that the moment the puller screw was put in place and before any real pressure was put onto it, the threaded end of the shaft split in two! BUGGER!! Turns out that this is a not unknown problem on these motors, the shaft end being over hardened in manufacture.

Broken shaft

Shaft showing broken end

So I set to and turned up a pressure bushing on the lathe to press against the shaft end rather than the thread end.

Anyway, that worked, the disc was successfully removed and the shaft and gear could be removed from the timing case.

Next step was to replace the shaft with the converted one from the spare motor, only to find that it did not fit!. It seems that P&M increased the shaft diameter across the war years, TYPICAL!.

differing shafts

Two differing shaft diameters

Not only that but they altered the pressure angle of the gears so they are not interchangeable either.

This meant that I had to repair the damaged shaft, not so easy since it was through-hardened.

So the 4-jaw chuck was put onto the lathe and copper shoes put onto the jaws so as not to mark the shaft’s bearing surface.

shaft in chuk

Broken shaft in lathe-chuck

Using the 4-jaw meant that I could set the shaft to run dead true which was accordingly done and the broken end trued off.

The shaft itself was already centre drilled so it was just a case of opening the bore up to the appropriate tapping size.

Since the shaft was a hard steel I used a cobalt stub drill for this job, a cobalt drill will tackle far harder steels than an ordinary jobber drill will,  but their about three times the price!!

Then it was just a case of carefully tapping out the hole to take a bolt and the job was done.

I then had to transfer the alloy pulley over from the other shaft flange and I could then refit the shaft.

The shaft was then put in place in the timing case and the timing drive re-assembled.

The oil pump gear has a pressure pad and spring to hold it in place, this was stuck onto the centre of the gear with a blob of grease before fitting the outer cover.


Pressure pad in place before fitting the outer cover

Pressure pad in place before fitting the outer cover

On going to refit the magneto I ran into another two problems.

The first was that the new pulley masked the drive dogs on the bike side coupling.


New pulley masks coupling

To get round this the magneto had to be put onto its platform at the rear of the cylinder so that its coupling could be slid into mesh with the other one, BUT the studs that secure the magneto in place fouled the base plate of the magneto and prevented it from sitting down onto the platform.

Simple, you just remove the studs, put the magneto in place and refit the studs through the base plate! If only it were that easy!

P&M in their ineffable wisdom had chosen to use studs with an enlarged collar in the middle. This collar sits down into a counter-bore in the platform so it does not normally interfere with the magneto’s base, but this collar will not go through the mount slots on that base, equally the studs are threaded 1/4 Whitworth on one end and 1/4 Cycle on the other.

Short time remedy is to replace them with 1/4 Whitworth set bolts until I can source some double-enders but its not ideal as a Whitworth thread is more prone to backing off than the finer Cycle is.

While I had the magneto off I took the chance to replace the drive dog with the clubs easy adjust version and herein lay the other problem!.

The drive dogs on my bike, and apparently those on the later models using the “spider” type coupling, are 5/8 inch wide but the dogs on the clubs unit are only 1/2 inch wide, since my bike is among the first to use the enclosed valve motor, it looks like earlier models used a smaller size drive dogs.

Now it was just a case of fitting the magneto and re-timing the ignition.

Before fitting the magneto the endless drive belt for the dynamo had to be put in place, you can’t fit it afterwards, as I discovered!.

New drive

New dynamo drive

Then it was just a case of fitting the dynamo itself, tensioning the belt and refitting the drive cover. Once the cover is back in position the upgrade is invisible.

Dynamo installed

Dynamo installed

Cover intalled

With cover installed no change is visible


Back in the early days of biking (and of cars!) what you bought was the basic machine.

“Luxury” items such as lights were added after-market by the owner to suit their personal preferences and this meant that they came without any  electrics other than a magneto for the ignition.

For lights there was the choice between acetylene gas powered lights and electric ones, gas lights having the advantage of being a complete and separate system whose generator only needed to be kept filled with carbide and water but needed regular cleaning and refilling while an electric systems generator needed to be driven, a gas system was also cheaper than an electric.

A cycle type dynamo driven by one of the wheels was tried but found wanting so it went to being driven from the engine, but it also needed a “power storage unit” that is:- a battery.

Since it was an “add-on” this meant that the generator somehow had to be bolted on somewhere near the engine and then had to be driven from it somehow, even today on a car the alternator still is a “tagged on” part like this even after over 100 years of development!, but modern bikes have moved on from this primitive system.

However my Panther is a 1937 machine.

At this time, while bikes no longer came without lights as a standard fitting this was a recent innovation, as a “for instance” my 1929 Triumph was supplied without lights, they were still basicly a “bolt on” accessory.

The Panther has a 6 volt 36 watt dynamo bolted to the frame top tube, just in front of the seat tubes, and this is driven from the magneto’s drive coupling by a small duplex chain, this chain having a cast aluminium cover.


Position of dynamo

This drive is a known weak point on the bike, being prone to wear and possible breakage, and in the event of breakage it can cause damage to the engine housings and stripping of the timing gears in the event that the broken chain jams the magneto drive.

Dynamo drive

Dynamo drive chain

While it was not available back in 1937, there is a safer modern alternative available in the form of a toothed belt drive and I’ve decided to go this route since the dynamo chain on the old girl is showing signs of wear, as are the drive sprockets.

Investigations on the internet soon showed details of what was available in the form of toothed belt pulleys and drive belts as well as sources of supply of these.

On the Panther the drive sprocket has 30 teeth on it while that on the dynamo has 11, giving a 2.7 to 1 “gear up” in the drive, a maximum RPM for the dynamo in the order of around 7,000 RPM and of some 2,500 RPM at 30mph.

Drive Sprocket

Drive sprocket

I have fitted an electronic 12 volt converter onto my bike and since a downside of this is that it has a higher dynamo “cut in” speed than at the original 6 volts I’m going to take advantage of the conversion to uprate the dynamo speed a little and have decided on the use of a 14 tooth pulley on the dynamo and a 44 tooth as a driver.

This will give a dynamo speed of nearly 3000 RPM at 30mph and a maximum of around 8,000 RPM. From the use of these dynamos on other marques of bike I know this is well within the capabilities of the dynamo.

So I ordered up a pair of pulleys and a suitable toothed belt, which arrived two days later.

The small pulley turned out to be the neat belt width, there being a pair of cheek flanges to retain the belt in place and it was made from steel while the larger pulley was a wider, aluminium, unit and without the flanges so this will allow for a small measure of misalignment between the pulleys. Both pulleys were supplied with a “pilot bore” in their centres.

First thing was to sort out the drive pulley so as I have a spare drive coupling I decided to use that for the conversion.

This had two chain sprockets, one riveted either side of a flange to give a duplex sprocket. These rivets heads were accordingly ground off using a Dremel tool, the rivets driven out and the sprockets removed.

Once the coupling was offered up to the larger of the pulleys it was found that this flange was slightly smaller in diameter than the pulley and the rivet holes matched nicely with the side of the pulley and so could be used to mount the two together.

The pulley centre was then bored out on the lathe to match the register on the flange that had formerly located the outer sprocket. It was then counter-bored to give a good running clearance for the magneto coupling.

New Pulley

Coupling inside new pulley

This coupling is a variation on an Oldhams coupling which has the advantage that it can cope with the two sides being a little out of alignment in both plane and angle but it does needs some room to “work” to do this.

Once the pulley had been bored out it was fitted onto the location flange and the position of the rivet holes marked out on it.

The original rivets were 1/8 inch diameter so it was decided to use 3mm Allen cap head screws in their place so the pulley was now drilled and tapped to suit and then secured in place, the screws being secured in place with Loctite.

New Pulley

Magneto drive shaft with new pulley fitte

That left the dynamo pulley.

The dynamo has a tapered shaft for this to mount onto. This taper is a standard size across all makes of dynamo, it also is the same as that used on magnetos and is a taper of 1:10 on the diameter.

To machine this the top slide on the lathe needs to be set to the correct angle.

To do this I set up a test bar, known to be true, in the lathe and the top slide was adjusted to run true to this.

A 5 inch long ground tool-bit was then put in the tool-holder on the top slide and this was adjusted parallel to the test bar.

The top slide was then reset so one end of the tool-bit was against the bar while a ¼ inch drill was just nipped between its other end and the test bar.

This meant that the top slide was now set to cut a 1:20 taper on the radius, 1:10 on the diameter.

I then chucked up a length of half inch bar, cut a trial taper on it and tried an old chain sprocket on it.

Needless to say it was not quite right but given another couple of tries, making small adjustments to the slide setting each time, and I had a satisfactory result.

All that was left to do was machine the new pulley to suit and all was ready to fit to the bike.


To Be Continued

BMW R850R Side Stand Switch

On the “oilhead” model BMW’s there is an interlock switch so that you are unable to pull away with the side-stand in the down position, you cannot even start the engine when it’s in the down position.

This is done by having a switch that is operated by the sidestand, a BMW special incorporating a micro-switch.

On my R850R this switch had gone permanently open circuit, so I could neither start or run the bike.

On visiting my local BMW emporium for a replacement I found that it was “Not Currently Available”, while it is still a listed spare there were none available, not even in Germany, not only that but they’re grossly overpriced for what they are, according to the dealer the current price is just over £110 !!.

Fortunately it is a simple matter to bypass the switch, so I was not left with an inoperative bike but to do this I had to bypass a safety system, not the best of ideas!.

So, nothing ventured nothing gained, I removed the switch to have a look at it.

Interlock switch

The interlock switch

As expected it was not meant for servicing but when I had a good look I could see how it had been assembled.

There were a couple of moulded tabs and a steel locating pin so first step was the pin.

Switch peg

The metal locating pin half-way out

I gripped this pin with a pair of pliers and it came straight out with a twist and a pull. I then pried the tabs back a little and ran blade round in the joint  between the parts of the assembly.

It took a bit of fiddling what with having to pry and split at the same time but the two halves soon came apart.

Split housing

The opened housing

Now I could see how it worked, there was a plastic cam bearing onto a micro-switch.

In bits

The switch components

The micro-switch body was deeper than the standard one but since it had the wiring loom coming direct of it rather than having the more normal terminals this is probably why.

Anyway, because the standard switch is shorter it can easily be fitted into the available space and it can then be fixed in place.

So I now needed a suitable switch and the obvious place to try round here was the local branch of MAPLINS.

A look on their website confirmed that they had a range of micro-switches, all in the C.O.(Change Over) format, that is that rather than their being simply either N.O.(Normally Open) or N.C.(Normally Closed) their connections were switched from one state to the other.

This meant that I had no worry as to which was the correct conformation for the job, it was just a case of finding which one would fit best into the casing so it was off to the local branch.

Button switch

Plunger type micro-switch

Once there I soon found a snag, the switch plunger on the new switch did not touch the cam.

It turns out that the standard “offset” on a micro-switch plunger is 1.2mm and BMW in their ineffable wisdom have elected to use a non-standard switch.

Idea is presumably to force the purchase of their dedicated (and expensive) switch but however there is a way round this snag, there is an alternative switch has an operating lever.


Basic lever type micro-switch

This lever that can readily be bent into a suitable shape using round-nosed pliers, so I got one of those switches at a price of £2:29, that’s just not quite 1/50th of the price of the BMW part.

lever modified

The lever bent to shape

Once I had the lever bent into the requisite shape I found that the plastic housing round the cam was fouling on the base of the lever and this was preventing the new switch from going fully “home” into position in the housing, but a little careful easing with a router bit in the Dremel soon got round this.

switch in place

Lever switch installed in housing

Now the switch had to be fixed in position. The original had located with pegs on its sides that located into recesses in the housing but the new switch body had a pair of mounting holes rather and these were just under 3 mm in diameter.

These holes however lined up nicely with the recesses in the housing so it was just a case of opening these through to take the appropriate countersunk head bolts.

Assembled unit

Finished job with screws in place

I’ve committed the heresy here of using the old 6BA size for this, simply because I had some in stock along with having the appropriate tap, rather than having to buy in metric machine screws and taps.

All that was left to do was connect the wires to the switch and close up the housing, test the whole assembly and then, once it was found to be working, refit it to the bike.

Job Done!

First Offering

It’s been quite a while since I’ve added anything to this blog, main reasons have been idleness on my part and having been out riding around on the Panther and her stablemates.

I’ve now begun another stage of the project and am prompted to make report.

It’s always been my intention to put a sidecar onto the Panther since doing so will allow me to take my dogs with me on the events that I take her on, as it is, when I go to an event  I have to either use the more modern BMW outfit or leave them behind which is not always convenient.

The sidecar I intend to fit is this Steib

Sidecar 2

As you can see it’s in nice condition

but when I offered it up to the Panther it was immediately obvious that they were not compatible.

Problem was that the Steib was on a chassis dedicated for use with a BMW, the major fittings were in fixed position with no adjustment possible and not only that but they presumed the presence of a front down-tube on the frame.

A problem here straight away because the Panther does not have such a tube!, it uses the engine as a stress bearing member in its place.

Anyway, what it meant was that with the rear fitting coupled in place the front one wanted to be through the timing chest on the engine and undoing the rear fitting and moving the chassis forward showed there was no-where for the front fitting to pick up to when it was moved far enough forwards to allow it to clear the timing chest.

So a change of plans, if the Steib chassis wouldn’t fit then I needed one that would fit, but that would also take the sidecar body.

I began a hunt for a suitable chassis and determined on a Watsonian VG21, a chassis of the same period as the Panther that would also take the Steib body.

Last time I wanted a chassis, everywhere I went I was tripping over VG21’s, but now I wanted one they had become like hens teeth!

I eventually tracked one down and work began.

First thing to do was to convert it to fit on the right hand side of the bike.

Reason for this is that both my other outfits (both BMW) have right-hand sidecars so having another one with a left-hand sidecar is asking for problems.

While doing this I found that the Silentbloc bush that the suspension arm runs on had been replaced with a solid steel bushing and the suspension locked up solid!

After removing this steel bush, and it did not want to be removed!!, I next had to source a replacement Silentbloc but I had a bit of luck here because I found someone who had the correct bush in stock.

So, conversion done and wheel fitted (I’ve not even looked at sorting out the sidecar brake yet!) it was time for the first attempt at offering up the chassis to the bike

At the moment I only have the rear main fitting sorted out so with this loosely fixed onto the sidecar it was connected to the bike and some wood blocks strategically placed.

A bit of shuffling it round and use of a tape measure and there it was in approximate position against the bike.


Sidecar chasssis

First offering up

I was now able to get some other measurements I needed then it was all again dis-assembled.

Main purpose was to check the feasibility of a right hand chair on the old lady, I was fairly sure it would be ok as there is a proper rear mount point for a sidecar at the offside rear , and to get the dimensions for having a swan-neck made up for the job.

This will be a simple piece of pipe-bending, a length of 1¼ inch OD heavy-wall steel tube with a 90 degree bend in the middle, simple to make if you have the facilities, but I don’t so it has to be farmed out.