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C: Clutch Comet Clutch Lifting Mechanism


bodlan

Well Known and Active Website User
VOC Member
My Comet has the divided push-rods and 1/4" roller fitted but what should be the orientation of the roller? Flat ends in contact with the rod ends or the circumference of the roller? When I took the clutch side rod out the roller came out with it but it fell off before I could see how it was assembled previously.
 

stumpy lord

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VOC Member
My Comet has the divided push-rods and 1/4" roller fitted but what should be the orientation of the roller? Flat ends in contact with the rod ends or the circumference of the roller? When I took the clutch side rod out the roller came out with it but it fell off before I could see how it was assembled previously.
end to end
 

davidd

Well Known and Active Website User
VOC Member
Think of the roller as a part of a segmented clutch push rod. On the clutch side of the segmented push rod, the push rod may continue turning with the clutch, but if it does, the rotation will stop at the roller. This means that the gearbox side of the pushrod won't be turning and wearing away at the gearbox clutch lever.

David
 

vibrac

Well Known and Active Website User
VOC Member
Watch those 1/4 long rollers they cause a lot of heart ache if they get fitted to a burman clutch
 

oexing

Well Known and Active Website User
VOC Member
You mean a cylindrical roller ? Why would one take a roller at this place ? Standard on many clutch rods is a ball bearing ball between segments of pushrods for mimicking a thrust bearing. The ends of the pushrod have to be hardened anyway !

Vic
 

A_HRD

Well Known and Active Website User
VOC Member
I'm guessing Tim is getting mixed up with the multiple loose Burman clutch rollers (PR50-35X?) used in certain models as the clutch bearing - they are 1/4 dia but a little shorter than a std 1/4 x 1/4 roller - which if fitted to the clutch bearing would indeed cause heartache. For the pushrod - take your pick of any suitable length - or a ball.

Peter B
 

davidd

Well Known and Active Website User
VOC Member
I use the ones that Coventry sells: 57-0394. I last ordered some over a decade ago, but I bought a lifetime supply. They measure .250" in diameter by .234" in length.

David
 

bodlan

Well Known and Active Website User
VOC Member
I am referring to the modification mentioned in KTB when splitting the actuating rod in two. It specifically says to use a roller in the centre but of course there are balls at each end so why a roller in the centre? I think DavidD's logic is the same either way?
 

timetraveller

Well Known and Active Website User
VOC Member
Vic, people who use ball bearings as spacers years ago found that they distorted and become non-spherical. The answer was to use rollers and they have been shown to last in Vincents for decades. If one uses the needle roller thrust race modification which I developed years ago then there is no need to split the push rod at all.
 

oexing

Well Known and Active Website User
VOC Member
You don´t mean balls at each end but domed rod ends ?? Nevertheless I´d use ball bearing balls between any number of split rod ends - unless the "roller" has very domed ends. We don´t have that type on rollers here, just on needle rollers if one likes these types. Balls are widely used there in all kind of bikes, no problem when rod ends are hardened. There is only around 300 pounds thrust on them - or even a lot less with the servo clutch.

Vic
 

bodlan

Well Known and Active Website User
VOC Member
By balls at each end I mean that there is a ball permanently inbedded in the spring plate PR50-18X and a 5/16" ball at the far end of the split rod sitting in a counterbore which the operating plunger pushes against.

Norman, is there a link to the thrust race modification you mention?
 

timetraveller

Well Known and Active Website User
VOC Member
Hi Bodlan. I will send you an email with the details if you send an email to enw07@btinternet.com. The spares company normally has them in stock, at a mark up from my price, but that is a quick way to obtain one if I am not available.
 

Bill Thomas

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VOC Member
This is a Comet, T.T.. Did you ever sort your Mod' for a Comet . Cheers Bill.
 

timetraveller

Well Known and Active Website User
VOC Member
Hi Bill, yes funnily enough I was looking at some of them yesterday and I was only talking to the local Comet owner for whom I developed the kit about two hours ago. I think that I only sold one to that local chap so there are several left.
 

vibrac

Well Known and Active Website User
VOC Member
Yes a bit naughty of burman to make the basket out of 1/4 plate so you would have to buy their special rollers. I got a batch of 1/4 rollers and ground down a whole batch of them on the toolroom grinder back in the day
 
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Bill Thomas

Well Known and Active Website User
VOC Member
Some people don't get on with the standard clutch, But mine seems fine, Just get the revs down, Same as a Twin before putting in gear, I used Commando sintered plates with hand cut slots, When I raced it, But they needed heavy springs, So in 1987, I went back to standard. Cheers Bill.
 

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