FT: Frame (Twin) Early Twin Clutch

craig

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I am assembling the clutch on #323 and have read the clutch assembly instructions very carefully and they state -

2) Fit the shoe assembly to the clutch carrier. Do not omit the washers, C6, which lie between the shoes and pivot nuts, C5, on engines prior to 1/853. These nuts must be pulled up very tightly on the bolts, and these are best held by means of a "crow foot" spanner. When tight they must be locked by punching the bolt metal down into the slots in the nut, but before locking check that each shoe is free to rock on its pin. For later units: see (8) under "Dismantling" above.
(Note:- the bolt C4 is of high tensile steel. Ordinary mild steel bolts must not be used, and in any event the heads must not be thicker than 1/8 in. (3.17 mm), otherwise they may foul the wall of the clutch drum.)


I don't have C6 washers for #323 and need to know the dimensions of these C6 washer to assess whether I need them.

Anyone have such information on C6 washers please?

VincentC6Dimensions.jpg
 
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timetraveller

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I don't have a clutch early enough to have these washers but you should be able to work out what is needed by doing a dummy assembly. As I understand it you are trying to ensure that the shoes pivot nicely on their pins without undue end float and that they are centralised within the clutch drum. Note that there will be a circlip on the outer end of the pins to retain the shoes, unless the system is totally different from the later clutches. So the ID will be the same as the OD of the pins with a little clearance, the OD will be determined by the castings etc of the shoes and the thickness determined by the length of the pins and the thickness of the shoes. Even if these details are wrong a dummy assembly should show you what was intended.
 

nkt267

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Next time i have the clutch apart on #379 I'll take a look..the parts book does not list C6, so is C5/1 a modification of an earlier part?
 

craig

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I am running the early clutch drum with cast holes, but i have 5000 miles on this engine/clutch with no issues.
I am just down for Grosset electric starter fitting. The instructions are quite adamant about these washers.
Cheers
Craig
ClutchMO02.jpg
 

chankly bore

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It would be instructive to see an original C5. Were they longer with a Seeger clip and a C6 washer? How did it differ from C5/1? My series "B" parts list doesn't show C5 or C6 and the drawings date from late 1947.
 

Bill Thomas

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I know, Not too much help, But I have found in early instructions, " Do not omit the washers C6, Which lie between the shoes and Pivot nuts, C5 On Engines
prior to 1/853 ", Sorry no photos. Cheers Bill.
 

Bill Thomas

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I have seen somewhere, That the Mk1 Clutch ony used 3 springs !!, A mod' Dave Hills told me to do, Which works on one of my Twins, But not the other !. Cheers Bill.
 

Bill Thomas

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It also looks like to get the shoes off, You have to undo C5 from C4 , The later type has circlips ???.
Cheers Bill.
 

Simon Dinsdale

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I have an early series B engine here (lower than engine number 300) which was last run in 1967 and not been apart since then and I have just started stripping down for a rebuild. I can have a look at the clutch on it, but it may be a day or two and there is no guarantee its even the original clutch. In saying that I just removed the timing cover to find an original bronze large idler and no real evidence that the timing side has ever been disturbed.
Simon
Curiosity got to me so I just pulled the clutch. Found an early drum (photo 1) with the holes in the back and a different method of securing the shoes to the carrier which may expain what going on.
The shoes appear to be secured with a nut rather than a circlip. The nut has a thin washer / shim under the head which is what you may be refering to Craig. See photo 2.
Photo 3 shows it dismantled. The bolt is a std C4 and the pivot nut is what the clutch shoe pivots on. I suspect the shim is to stop the hex of the nut machining itself into the alloy shoe when the shoe pivots. I suspect the nut in the photo is an original C5 which was later replaced with the C5/1 & circlip.
Photo 4 & 5 are of the factory instruction sheets where they refer to this assembly.

So Craig you only need the shim / washer if you still have the earlier C5 nut arrangement and not the later C5/1 and circlip. The shim measures 1/2" id, 5/8" od and 30 thou thick.

I wll be upgrading this clutch to the later C5/1 when it goes back together.

Simon
photo 1.jpgphoto 2.jpgphoto 3.jpgphoto 4.jpgphoto 5.jpg
 

craig

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Thank you Simon, My B was already using C5/1 and circlips when it came apart.
I tend to read the instructions way after I complete work. So now reading thru the complete instruction there was a concern that I had screwed up as usual.
No wonder I have many miles without problems or wear on the clutch...... Dumb luck.
I am running new pieces with a cast hole drum. New are C3, C5/1, C4, 865, C20, C19, maybe more.
Thank you
Cheers
Craig
 
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