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Swinging arm pivot/stud

Submitted by peter_maple on Fri, 03/04/2015
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Heavy Twins

Hi Noccers.

I have had new clayflex bushes fitted in the swinging arm of my 99 but on testing it I found a fair bit of play on the pivot pin. I assumed the pivot pin to be worn and to test this theory I wrapped a single layer ot cellotape around one end of the pin and inserted it into the bushes. It was still slack in the bush but wouldn't go through the centre spacer! So a fatter pin won't do.

Is it just the compression force created by the nuts on the ends of the pin that clamps theinner tube of the bushes rigid to the frame,, or should the pin be an interference fit?, It looks as if the inner tube must have been rotating as it seems to have gouged a ring on the inside of the gusset plates. The basic question is how do you stop the inner tube from moving? Thanks in advance for any suggestions.. Peter M.

Submitted by david_cooper on Sun, 05/04/2015

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Nobody else has suggested anything so...usually I would expect the central tube in designs like this to be gripped by the end nuts. That makes sure the tube is properly gripped and it costs next to nothing to manufacture (unlike interference fits...). If it has moved then the nuts were not tight enough. If the side plate are not too deeply grooved than maybe some flat steel washers will help to hold the tube in place?

Submitted by john_oldridge on Wed, 08/04/2015

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Hi Peter

I had a similar problem on my Model 50 slimline frame, and found that to clamp the spindle up required a lot of force after replacing my bushes, the problem was made worse because after powder coating the frame the rear mudguard mounting tube/frame spacerjust above the swinging arm had quite a thickness of paint on the ends,and caused the frame to spread a little wider than the swinging arm,so I removed this before fitting the swinging arm and then re fitted after removing the slight thickness of paint on the ends. this prevented the frame gussets having to twist ever so slightly because both dimensions (swinging arm and mudguard mount) were the same. Hope this helps.I'm sure you have, but make sure thebushes are a good tight press fitin the swinging arm, mine were slack and I had to seal with lock tight to prevent movement.

Regards John O

Submitted by john_oldridge on Wed, 08/04/2015

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Hi again

I forgot to say David is correct, it's only the tension on the bolt that prevents movement on the inner part of the bush, so it should be tight!

Regards John O

Submitted by peter_maple on Fri, 10/04/2015

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the idea is a no hoperPreviously John Oldridge wrote:

Hi again

I forgot to say David is correct, it's only the tension on the bolt that prevents movement on the inner part of the bush, so it should be tight!

Regards John O

Hi Guys.

Thanks for your advice and suggestions. The rubber bushes were new about a 1000 miles ago and the slack fitting onto the pivot pin is probably due to poor tolerance of manufacture; seems quite a few members have come across this problem! There is however some wear in the hole where the pivot fits in to the gusset plate allowing some movement of the pivot, at least, when the nuts are slack. As I have a spare center spacer I was thinking of boring out the holes in the gusset plates to the size of the spacer tube, cut the ends of the spacer so that I can make the twoend pieces intotwo short tubes { the tube length equal to the gusset plate thickness} with a flange, so that they look like a couple of minature straw boaters made of steel!. Hopefully, these will fit with the flangeson the inside of the gusset plates,and stop the pivot pin moving about in the hole. This is just an idea, it would avoid welding. Comment if you will lady and gents, I won't be surprised if itsnot viable.

Submitted by david_cooper on Fri, 10/04/2015

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If the squeeze from the tight end nuts all went into the new 'top hat washers' then there would not be any pressure left on the gusset plates themselves to stop the washers from rotating in the over size holes. If the gussets are grooved where the tubes inside the bushes have been moving,then maybe some hard steel washers will do the job more simply and effectively.

 


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