Shadow Build

[John H]

The early big end pin set had 3 rows of 3mm loose rollers. The newer Alpha set has 2 rows of 4mm caged rollers and the INA set has 1 row of 4mm rollers. The part that presses into the flywheels can range for .003" oversize up to .250". The latter is the choice for race engines. Factory tolerances were pretty lax and flywheels did shift if you braked too hard or dumped the clutch at hi revs. The 1.250 pin will press in with up to 010" interference if you have a press that can do it. At that rate it's not likely the flywheels would ever shift. Prices vary from 400 to 600 bucks.

[John H]

While waiting on the last order which is stuck somewhere in the midwest, I will put an order together for Girdraulic front end parts. Close to a hundred parts in it and many need replaced. All bolts, nuts, washers, studs and links will now be stainless steel. Costs a bit more but will never rust like cad plating eventually does.
There is a modification I will be doing which will be converting bushings to ball bearings in the upper and lower links as well as tapered bearing in the head stock. This will require quite a bit of machining but should improve the suspension and handling considerably.
It's taken 70 years for some ingenious minds to figure out why these forks would bind up under heavy breaking and do tank slappers. Relocating the lower link attachment point on the steering stem down and 1/2" and shortening the springs is a big improvement. Riders that have done the mod are real happy and guys that are still racing Vincents, yes there are quite a few still competing around the globe are impressed. There is a new shock available also but at $$$$$ I'll have to wait on that.

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[John H]

Here you can see the original stem and behind it is the modified stem and to the right is the lower link.

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The eccentric spindle is a feature that allowed for change in fork spring pressure if adding a sidecar.
Building up worn parts is part of the game. These eccentric spindles were turned down and a stainless steel sleeve was shrunk to fit then turned down to the correct diameter for the new bronze bushings that will be pressed into the lower link.

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[John H]

Still waiting on parts so spent some time on the valve train. The rockers are measured for ware and after finding 4 nice ones I polished them then resurfaced the the fork where it contacts the valve stem collar. Six small holes were drilled for lightening.
The hump at the center of the rocker has to be removed so the new style retainer will fit. This retainer holds the rocker bushing tight to the top of the tunnel which reduces wear and noise.

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This is a tool for pressing the rocker shaft in or out the bushing.

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Here is the fixture for resurfacing the fork on the rocker.

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[Lotus54]

I find it fascinating to see the tooling you make to allow proper machining.
I don’t know much about machining, but have learned it can take more time to figure HOW to do an operation than to do actually do the job.

Thanks for putting up the pictures and explinations, I don’t know much about Vincents either and very interesting to learn more about them.

[John H]

I would like for others to show what they are building. I really enjoyed watching your Benelli build.

With the rockers finished, I started on the clutch since I already have all the parts needed to build it.
Several wear points need to be checked and replaced to have a smooth operating unit. Over the years there have been many articles written on how to build it, tune it and keep it functioning well. It's a dry clutch and without lubrication some parts suffer.

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First thing is cleaning and inspection for worn parts. The bushings, seals and clutch shoe linings are always replaced. The clutch shoe carrier C3 which rides on the gearbox main shaft has to hold the clutch shoes in perfect alignment, if not, slipping or grabbing will occur. The 2 steel clutch plates warp easily so will need to be resurfaced. A rubber insulator is added behind the plate to stop the harmonic effect when machining the surface.

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The clutch plate carrier C3 rotates on the clutch shoe carrier C13 and when engaged, forces the clutch shoes out against the drum and acts just like a simple motorcycle clutch, except when you let off the throttle, the action is reversed and the opposite brake shoe lining is forced against the drum and helps you slow down without free wheeling / coasting. A video would explain much better than I can. It actually works really well if it is set up correctly.

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[Lotus54]

Interesting clutch setup. I know drum brakes can be somewhat ‘self-activating’ giving more power due to shoes ‘moving into’ the drum - than lever input. Does this clutch do the same thing?

[John H]

The pilot clutch disk when engaged forces the 'toe' of the clutch shoe against the spinning drum causing the shoes to turn the gearbox main shaft. When reducing engine speed, the reverse happens forcing the 'heel' of the clutch shoe against the spinning drum. That's the simple explanation. Books have been written on details how to make it work as it is all very sensitive to adjustments due to oil leaks and wear.

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The parts are now new or cleaned and ready for assembly. 75 pieces +/-...

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[John H]

These centralizer thimbles (C11/1) when set correctly keep the clutch shoes from dragging when the transmission is in neutral or when the clutch lever is pulled in. This setting also determines the force needed to engage the clutch for drive forward and the reverse force needed to reduce forward drive, as well as engaging the kickstart lever.
Well, what I'm trying to say is when these forces are happening, the tip of these thimbles is rubbing against one of the 9 posts on the centralizer causing an indent which then makes the whole motion of the clutch grab. So with the die grinder I have resurfaced the end just enough to remove the indent . Next is putting the shoe on a fixture and setting the spring pressure and plunger travel. Confusing?

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[Lotus54]

Yes, I’m trying to wrap my head around it.
The plate (vrs shoes) is for low speed? And shoes for higher loads/speeds? Or maybe I’m still way off.

I speculate a lot of reason for a setup with so many parts is due mostly to lack of good materials for the power transfer needed. And perhaps manufacturing tolerances. Modern clutches are so good it is hard to see the need for something like this if you have never been around older machines. On my dirt bike- I’m constantly slipping the clutch (throttle gives power avaliable, clutch determines how much gets to the wheel). But even bikes from 60s/70s would not have put up with that sort of use very long at all.

I appreciate the pictures/info- learning more all the time how much I don’t know about Vincents.