An alternative suggestion was to simply use a flat faced screw in place of the standard adjuster. I too thought of this but decided against it for several reasons: the leverage increase would not be as much as with the larger dowel inside, you would be putting a side thrust on the threads in the cover and the screw's threads would deform in use where they contact the G91 making removal impossible without stripping the cover. I also thought of using a screw to push on the back of the dowel for adjustment but this takes the dowel off it's firm seating in the cover bore and would cause rocking of the short dowel.
Hope this better describes it. Again
was not my idea but it sure works for me. I found with my
clutches the standard lift was not enough to make clean, crunch free
engagements. It does increase effort at the handle bar
up to about half that of a Commando. The nice part about this is
no Vincent parts are harmed. Easily reversed by replacing the
with the standard adjuster. Paul Zell 5/16/07
Patent information for the Vincent Clutch:
Adjustment: Adjust the clutch cable when the handlebar lever is fully pulled so that the top end of G91 hits the abutment G94. Then adjust the clutch actuating pushrod with C42/1 and/or ET27/1AS so that there’s 1/4” play in the cable.
Oil leaks: The clutch needs to be completely dry. If it’s oily, check chaincase seal PD26, clutch sprocket seal PD25, clutch carrier seal C18 and make sure there’s plenty of gasket cement on the splines of clutch shaft G3.
Plates, drum and linings: obviously all need to be true and good.
Smooth lift of plate: make sure that there aren’t any notches worn on sleeves C15. Check that the springs C29 aren’t binding in their cups C30.
Even lift of plate: Check the spring forces under load – for example using a set of bathroom scales and a drill press, measure the force needed to press each spring just into its cup. If they aren’t matched, arrange them in order around the clutch, for example, strongest, weakest, strongest but one, weakest but one, strongest but two, weakest but two.
Shoes pivots: If the shoe pivots C5/1 are worn, they can be replaced, and if the holes in the shoes are worn, they can be bushed, but care needs to be taken to maintain alignment and the bush needs to be thin so that the shoe does not break through.
Shoe centralisation: the plungers C11/1, when both at their outer limits, should just hold the shoes symmetrical without any play. If not, you’ll need to tinker until they do.
Plunger travel: The screws C12 should be adjusted to allow travels of 0.235” plus or minus 25 thou for the plunger in shoe C7/1 and 0.295” plus or minus 25 thou for the plunger in shoe C7.
Shoe clearance: You need at least 25 thou
between the shoe linings and the drum. If less, remove lining
Clutch photo: http://lsvoc.vincent-hrd.co.uk/images/vincent_clutch.jpg
Clutch Parts: http://lsvoc.vincent-hrd.co.uk/images/MO02.jpg
I developed my unit after looking at modern
and tried to incorporate as many of their features into mine as
I drew the entire unit up on AutoCAD to make sure it would work and fit
in properly before a single part was made. What I didn't allow for at
time was variations in clutch cover castings that have be reproduced as
spare parts since the original factory spares ran out. Different
depths on these where the depth was less than that of an original I
fouled by up to 2 mm on the inside of the cover, a minor modification allowed me to reduce the overall width of my unit to allow for some cover variations. But, as on any of the multiplate products or standard clutches if the outer cover is so thick and shallow on the inside they all can foul.
The major difference with my unit is that it
8 bonded friction plates and 7 intermediate steel plates, this gives a
greater surface friction area, hence, the greater the gripping area the less spring pressure required resulting in a lighter lever action than others with less plates. It is also worth noting that the plates I use are standard Kawasaki readily available either genuine or aftermarket. The clutch pack (8 plates) is what is used in their most modern superbikes putting out over 120
The outer pressure plate is made of pressure injected aluminium with recessed design, this allowed me to be able to get so many plates in. It also has a sealed ball race in it that the pushrod button rotates in. This button is radiused to locate the outer ball end of the pushrod, this accomplishes two things, a) It ensures the pushrod always lifts centrally, b) it eliminates pushrod wear as the button spins in the ball race and not against the button as Vincent ones do wearing the pushrod and adjuster away.
Wet or dry running, - In my bikes I have one wet and one dry, I haven't noticed any difference to their operation. Some customers have asked me is it ok to use chaincase oil in the clutch, I recommend to keep the two compartments separate and use different oils but they will be ok if a 10W/40 is used in both but I do not recommend using AFT in both, only in the clutch compartment. If you use the 10W/40 in both the large chainwheel seal can be removed but 3 or 4 x 6mm holes need to be drilled through the chaincase at the chaincase oil level in the clutch compartment to allow the oil to self level. In my instructions I say to drill and tap a hole in the back of the chaincase for the oil level/filler plug if run with separate oil, this hole can be in the rear of outer cover if you don't want to drill another hole in your chaincase.
As I know what it is like to buy a product and then find you need more than what's included I supply the gasket for the outer cover including one for a spare, the C20 mainshaft nut, a pre radiused new pushrod and the 6 High Tensile Socket Head clutch drum screws that I also make.
My ESA adaptor, this increases the effect of the adsorption by 100%, if anyone has ever seen the standard ESA in operation on an engine dyno with a strobe light you can see under high load or quick intermittent loads such as happens changing gears the standard unit becomes fully ramped up on the facecam, when it is in this position it isn't giving any cushioning effect at all. On series D the factory tried to improve on this design inadequacy by increasing from 18 to 22 spring holes, for it to really function adequately however a minimum of 32 of the standard pressure spring sets is required, mine takes 36 sets to ensure it does work adequate. This mod was a proven thing when Alec Corner won our Bathurst races on the Frank Sinclair outfit several years running in the sixties.
The PD9R rubberised tensioner blade I
for the RTV engine, this is a new standard spring steel blade with a
Nitrile rubber pad on it. This reduces the clatter of the primary chain
hitting up and down against the bare steel blade. I give these free
both a Clutch and ESA are purchased. Neal
Vincent clutch plunger travel: About 30 years ago I came across a works drawing for the clutch and noticed that there was some information not mentioned in any other document. The spring loaded plunger C11 is fitted to both C7 and C7/1 shoes and the drawing I have shows that the adjusting screw C12 should be adjusted for travel and then locked in place. I presume the spring tension is not important and that the travel is.
The two springs inside each plunger are found in other places on the bike. One of the springs is from the engine shock absorber (ESA) - PD27 - and the other, that happens to be counter wound and fits up inside the PD27 spring, is from the oil relief valve in the timing chest OP11. The drawing shows that the adjuster in shoe C7/1 should be adjusted for 0.235" (tolerance + - 0.025") travel, and C7 should be adjusted for 0.295" (tolerance - 0.025") of travel. The words 'Check only' are given alongside each of these adjustments. The shoes have their numbers cast into their sides.
I had my friendly draughtsman - an ex employee
draughtsman of the BSA motorcycle factory - redraw the factory drawing
for me and I in turn took a pile of said drawings to the San Francisco international. I thought that they would look
nice on the workshop wall. I only managed to sell two or three and handed the rest to the VOC publishing company
people to sell.
My friend Bill has a very nice Black Prince that had a problem with 'grabbing clutch'. We had tried all the usual remedies so he had a local Black Shadow owner with a machine shop make him an adjuster C42/1 with a built in guide for the pushrod G96. This modified adjuster now keeps the clutch plate C23 square to the rod as it is lifted - no more problems. It is a tube extended down over the push rod - simple as that! Andrew Rackstraw 1/03/02
- I noticed indications of contact between the clutch shoes and the inner clutch plate C21. Per KTB, I slipped an ET98/1 thrust washer over each pin, beneath the plate, to create clearance.
- As noted earlier, the clutch springs
not allowing the plate to lift evenly - despite having been measured
matched so that equal length springs were opposite each other (length
was only in the .010" range anyway). I rigged up a lever
with a bathroom scale, and found up to a 10% force variance between
when compressed a fixed
distance. Armed with these new numbers, I arranged the springs so that equal-force units were opposite each other. The moral of the story seems to be that even with springs from the same source, length is not a reliable indication of pressure when compressed.
I'm happy to report that these mods have fixed
the clutch drag problem, and also created a broader range of engagement
making smooth starts easier. One area I didn't address, but which is
worthwhile, is ensuring that the C11 plungers abut their pins without
clearance. This idea comes from the excellent treatise Big Sid
out a while back, which is
available at http://www.thevincent.com. Cheers, Dave Hartner 10/20/00
The Clutch - Part One: To begin with, one common bitch which has bedeviled Vincent twins since the early Series B 's has been to suffer from a violently abrupt take-up on initial engagement . The engagement span seemed to cover one quarter inch or less and that near full extension of my fingers. The all too simple fault is the lack of frictional bite or co-efficient of friction between the surfaces on the outer plate clutches rubbing faces. Both sides of the inserted segment plate and the inner faces of the two flat steel contact plates in too many cases needed there to be full and firm marrying together to transmit enough torque to move and set the servo links into the leading edge jam mode between shoe segments and drum face . By that point ones fingers were all but fully extended and beyond any delicate control ability. Their load was shot . What was needed to restore that lost control over the frictional modulation too soon spent ?
More and different surface bite / textural
proved the answer and the cure . The flat steel faces were ground
truly flat to each other so ensuring full working area with no cupping
or bowing of any area . The inserted plate is best replaced by its
Ferodo brother if available and it, or the inserted plate, is
both sides on medium emery sheet laid over flat plate
Next, go back to the steel plates and similarly rub them on the emery
a figure eight pattern . Blow clean , ensure all is grease
free . Reassemble cleanly with a fresh set of matched springs if
Re-adjust as per Riders Handbook and test ride . If the
of the clutch mechanism is up to snuff then you will
be rewarded by having a sweet broad release span, this now taking
up with ones fingers nearer to ones palm, and leaving lots of
travel . All of this due to a sharper bite and better
- in engagement action . Only a light kissing surface lay-on is
to force those links out - and all the remainder of the lever / plate
becomes playable like a volume control. Try it and be
To counter the drum wobble always seen, this
result of the necessary operating radial clearance between
those two bronze bushes within the large rear chain-wheel and the shoe carrier shaft, there needs be no less than 20 to 25 thou . gap between any shoe segment at the closest proximity of the inner drum rubbing surface . This to prevent any momentary kissing between shoe segment and the drum as the drum does its dance around the shoe carrier assembly. There must be clearance always when those plungers do their thing. Not sometimes - always !
A light cut off the drum face to improve
and surface grip is suggested, and paired segments need
identical thickness for best grip . Note that none of this alters
in any way the original design concept only seeks to Blue-print and
normal relationship and inter-action somehow lost over 50 years of
pieces about . Observe that friction / lack of that tiny
lash at the big central nut (C -20) interferes with this entire
motion . A nice firm full stroke against ones thumb seems
satisfy the plungers needs, neither too hard nor too soft. More
on high -rev shifting . S.M. Biberman
Dedicated to the Vincent Engineers who designed this clutch - they were brilliant. Also for my daughter, Jacqueline, for putting all this together for me. Thanks to Dave Malloy for helping me to prove my point, and to all the other Vincent owners who encouraged me to write this article - Les
In the early days I have read of and experienced "clutch problems". Mainly oil seal C18/1 would leak profusely, also oil would pass seal PD25. Other malfunctions showed up over the years, clutch slip and clutch binding, necessitating pulling in the clutch lever and counting to five before engaging gear, and shifting into neutral before coming to a stop. All of these problems, some of which are caused by improper parts, can be eliminated by paying careful attention to detail. Unfortunately, no publication that I have read has mentioned all of these details. In the late 60's, I replaced C18/1 with a Bosche distributor "O" ring which is actually "D" sectioned. It has not leaked since.
I had replaced seal PD25 many times before I realized that the scroll on bush PD24 was facing the rotational directional direction, causing oil to be pumped into the bush against a seal that was not doing the job it was supposed to do, i.e. "seal the oil". Again I replaced seal PD25 stock Vincent part from Conway Motors (London). I "soldered up" the scroll - no more leaking.
Some years later I purchased a new PD24. I inspected the scroll and lo and behold I was not the only person to know about the scroll, and probably not the first. Some engineer had redesigned the scroll to face away from the directional rotation, causing a scavenging effect on the oil. Since then I have purchased two more PD24's with scavenging effect scrolls.
Last year (1997), during periodic maintenance, I noticed the clutch carrier felt loose. I duly ordered one new PD24 and one new PD22. I also ordered a new C3 and springs from of our main parts suppliers. Great surprise! The scroll had been replaced with a more generous groove cut into the bush facing the rotational direction. Since I had purchased a new clutch shoe carrier (C3), I reused a serviceable old PD24 (with reverse scroll) and a new seal. I installed the new PD22. I boxed everything up and went for a ride. At first everything was fine. The clutch disengaged instantly and was very smooth on the take off. I had ridden about 210 miles by the time I got home. While the machine was still hot, I dismantled the clutch. PD22 was binding. I reordered a new PD22 and PD24 from another well-known parts supplier. While waiting for these parts to arrive, I sacrificed my old PD22 to make an "in-situ" extractor, as I did not want to take the primary drive apart again. I then removed PD22 and on inspection and comparison with old bushes, the new PD22 was not self-lubricating and had fried. A few days later my new bushes arrived. They were identical to the previous bushes I had bought - same manufacturer ?
I went to a bearing supply store and purchased a large, flanged self-lubricating bush (several actually) and machined it to the correct size. I installed it in time to ride to Dave Malloy's meet in Colfax. No more problems. I checked my spare plate carrier bushes (C17) and they are not self-lubricating. They will never be used in my Vincent.
As written in the Instruction Sheets, "There is often a slight oil leakage past the best of seals, particularly when they are new. In fact, a slight weep is necessary to keep the lip lubricated." This may have been true at the time it was written, but it is unacceptable today. Modern seal design and materials are far superior and may well work fine with a "grooved" PD24. But with my past experience, I am reluctant to try it. To check if bush is self-lubricating, gently apply heat to bush flange - lubricant should rise to the surface. Or using a small sharp wood chisel, pry up edge of flange. A small piece of flange should chip off easily. Inspect the color of material where it chipped. It should be brown in color, like dark rust.
In this article, wherever it states "paint",
means using dark gray primer which dries black and is quick
The reason for painting is so that any unwanted contact from moving
is readily visible. Yellow gloss latex is recommended for
identification" of clutch parts which should all line up with one of
pivot nuts. Multi colors are required for clutch springs and
cups. "Lube" means hi-temp moly paste. EMGS1 is a holding
as described in "Know Thy Beast", third edition, page 119, line
It is easily made using the inner clutch plate as a pattern.
refer to the following publications for additional information on this
* Rider's Handbook
* Vincent Instruction Sheets
* Vincent Motorcycles
* Know Thy Beast
* Spare Parts List
It should be remembered that the clutch plate carrier and the shoes, also the plungers, move every time upon acceleration and deceleration. Also the clutch springs tend to settle down at different rates. Therefore periodic maintenance is recommended at 10-20,000 miles, depending upon riding conditions and/or habits. The dynamo must not be sealed at dynamo housing. This is where the primary case breathes, that is why an oil thrower (PD28) is there to separate the oil. Oil will get past the oil thrower only if the oil level is high (half a cup will do it) and/or too much crankcase pressure is present.
Shoe Carrier: Remove clutch. Pay attention while dismantling for any obvious problems, binding or oil leaks. Should there be any signs of oil leakage, try and determine where, before taking clutch completely apart. If you are 110% sure that oil bushes PD24 and PD22 and seal PD25 are in "A1" condition, you can skip taking the primary drive apart. but if you are only 99% sure, then dismantle it. This is where a good operating clutch begins.
Remove primary cover and primary drive. Clean all parts. Paint primary housing, inside clutch cover, clutch housing, and inside clutch cover. Inspect carefully the clutch shoe carrier bearing surface. Check bushes for galling and excess wear, especially PD22, which tends to wear quicker than PD24. This is probably because the weight of the whole clutch is offset from the bearing surface. Excess wear of these bushes allows sprocket PD20 to move upwards and forward on acceleration, bringing dynamo sprocket into deeper mesh - hence "the mysterious whine".
If oil has leaked through PD22, then PD24, must be removed to replace seal PD25. If removed, ensure PD24 was not damaged in extraction. Try the fit on shoe carrier before reinstalling with Loctite. If replacing PD22, ensure it is self-lubricating. Assemble PD20 and clutch shoe carrier and tighten nut to 70# using tool EMGS1. The PD20 should rotate freely and some end float must be present. You should be able to wobble PD20 slightly if the minimum required 0.001" clearance is present at the bushes. If all is well, remove PD20. Reinstall primary drive and cover after replacing seal PD26. Paint non-contacting areas of clutch drum and clutch shoe carrier. Install and fasten nut to 70#.
With gear engaged, rotate rear wheel while observing the movement of clutch drum (wobble). This can be seen more easily be attaching a small pointer to the clutch cover mounting hole by the kick start shaft plug. Make a note of how much movement exists. There are six splines so carrier can be tried in each position. Finally locate carrier to give the least movement. Once you are satisfied the drum moves as little as possible, mark one pivot nut with yellow paint and also the mating splines closest to the painted nut. This procedure compensates for machining tolerances of shoe carrier and shaft (G3).
Shoes: Check pivot holes for wear. If badly worn, they can be machined and bushed. Wear on outside of plunger housing is covered later. If plunger housing bore is worn, it can be reamed out to accept a thin walled brass tubing insert, available at hobby stores, cut to correct length and installed with Loctite. The brass may wear more quickly than aluminum, but as the tube wall is only about 0.015", it can be easily collapsed with a small screwdriver and replaced. Renew plunger springs at this time and install without lube. Also carefully inspect shoes for cracks, especially in the area where center rib joins the toggle boss. Some replacement shoes have been made with a little less material in this critical area, and they have cracked. I think the chamfer on the lining at this area should not exceed 3/8" and the whole power of the engine may be applied to a weakly supported area, which could cause the shoe to crack. The bore for the toggle link pin should be counter-bored (drilled) to allow pin to be recessed slightly from the shoe surface. Re-drill split-pin hole 90 degrees from original, and trim off excess pin. Obviously, if linings are worn or oil soaked, they should be replaced. Molded linings are again available. A little oil will cause linings to stick (bind) to drum. A lot of oil will cause slippage.
Clutch Plate Carrier: Check nut (C20) and bush (C17) for binding or wear. Replace if required. Again, beware of bush that is not self-lubricating. If shoes show wear on outside of plunger housing do not remove any metal from the shoes. There is precious little there to start with. Using a small die grinder, carefully remove metal from inside the plate carrier flange between the pin clusters tapering towards the pins on each side. Trim halfway through the thickness, beveling halfway through through the width of the flange. Repeat process on all three areas to retain balance. It is preferred to remove pins prior to grinding. Polish off any grinding scratches and paint. I use s/s paint on this item.
Install shoes to plate carrier. Split pins are not required at this time. Install onto clutch shoe carrier. Install nut (C20) but do not fully tighten. With shoes in a relaxed position, check clearance of bush (C17) to nut (C20). A clearance exceeding 0.010" will waste valuable clutch pushrod movement. Adjust thickness of thrust washer (C19) as required. Also, with the shoes in a relaxed position, there must be zero clearance between plungers and pins. If clearance exists, the shoes will chatter at idle speed and may even drag on the drum if the linings are still thick.
Replacement plungers may help, or, measure and record clearance between plunger and pin. Remove shoes. With calipers, measure length of protruding plunger from a "marked position" on plunger housing, i.e. 0.040" between plunger and pin and 0.336" plunger protruding. Remove spring and plunger and using a 3/8" pilot pointed drill bit in a hand-held chuck, remove 0.040" from plunger seat in shoe. With plunger placed back in shoe, the protruding plunger should measure 0.376" (0.040+0.336"). Recheck clearance and adjust as required. A few thousandths pre-load may be a good idea. Clean shoes and paint non-contacting areas. Lube and install plungers and springs, keeping lube off threads. Tighten spring thimble until it just bottoms out, then back off two complete turns.
Assemble shoes back to clutch carrier, again no split pins. Do not fully tighten nut. With gear engaged and rear wheel locked, use EMGS1 to move plate carrier counter-clockwise to bring shoes into contact with drum. The plunger adjustment will be correct if it can be depressed as additional 3mm, which allows for lining wear. Turn plate carrier clockwise to check other plunger. Adjust spring thimbles as required to obtain this measurement. Then back out spring thimbles exactly 1/4 turn. Apply one drop of Loctite to threads and refasten exactly 1/4 turn.
Install shoes back to plate carrier. This time lube toggle links, install link pins and two split pins. Lube the pivot nuts and install plate carrier to clutch carrier. Install two pivot nut circlips. Ensure mating splines match. Install new C18/1 or whatever seal your machine uses. Install nut (C20) and thrust washer. Fully tighten nut to 70#. Put a dab of yellow paint on shoe next to painted pivot nut.
Primary Clutch: Paint non-contacting areas of inner and outer clutch plates. Install inner plate. Paint yellow mark on plate closest to painted pivot nut. Ensure all nine pin sleeves are exactly the same length. Polish off any burrs ar scratches from sleeves and install over pins. Install C27 and nine screws and fasten. With gear engaged, rotate rear wheel and observe "run out" of plate - it should be zero. Mark low area of plate (towards gearbox), add a 0.001" shim cut to fit over three pins closest to the low area. Place shim between plate carrier and inner plate. Reassemble and check again. You may have to add or subtract a little to get the plate to run true. (my clutch has 0.0015"). Mark position of shim on plate carrier. Install lock spring (C45). Shim compensates for machining tolerances of plate carrier/carrier bush/nut.
Install clutch disc, outer clutch plate, and spring cups with six new springs. Do not use C27, instead use nine 5mm x 16mm washers with screws and fully fasten. Pull in clutch lever and insert a tapered drift in lever. Rotate rear wheel. The outer clutch plate may wobble. If so, locate low area (toward gearbox) and slacken one or maybe two screws until plate runs true. Adjust tapered drift in clutch lever to give about 0.010" clearance at clutch plate. The screw(s) you loosened are the heavy spring(s).
Sometimes a heavy spring can be lightened by compressing it in a vice until it becomes coil bound. A spare set of springs could save a bunch of time. If necessary, line up all your old springs on the bench and try some of the longest ones. This part of clutch adjustment may be long and tedious. It is , however, most important that the outer clutch plate is as square as possible at point of contact with clutch disc if a really smooth take off is to be obtained. The springs can be considered correct when you lift the clutch disc underneath and it drops with a clink.
Mark springs and spring cups and their position on outer clutch plate with paint, either six different colors or three colors 1 dot (x3) 2 dots (x3), also a yellow paint mark to line up with painted pivot nut. Install C27 with screws. Install clutch cover. Reset clutch cable and operating lever in the normal manor while paying attention to detail....That's another article.
Note: A self-lubricating C17 can be shortened to become a PD22, but check flange dimension. The oversized bush I machined is available from bearing supply stores, part #EF 2024-16 Bunting, $2.16 each.