A65 Swinging Arm Silentbloc Bushes

[Kevev]

Hi all,

I have read quite a few articles about the A65 swinging arm silentblocs and they do seem to have a bit of fear and mystery about them.

I thought that I would share my experience of tackling the job, in the hope that it may help others who may be contemplating it.

I found the removing of the old silentbloc bushes fairly straightforward, although I am lucky enough to have access to a well equipped workshop and machine shop, so it may not be as easy for someone who only has the usual DIY facilities.

I went with the 'drilling out the rubber' technique as I didn't fancy the smell and smoke that would be created by burning them out. I used a 5 mill drill bit and chain drilled my way around the rubber. After I had finished drilling them I screwed a big tapered tap into their bore until it bit into them and kept on turning it until it just ripped them out of the swinging arm.

Trying to cut the remaining outside sleeves, so that they would be relieved and pop out proved a little more difficult. Mine were not easy to hacksaw, as I found out while trying to do this. I took the blade out of the hacksaw frame and placed it through the swinging arm tube and then re-attached it to the hacksaw frame. Unfortunately there is a reinforced section in the middle of the swinging arm spindle tube bore. Unless you are prepared to cut into this with your hacksaw it's not possible to get all the way through the outer sleeves. The step that this section creates also makes it impossible to simply press the bushes all the way through the swinging arm, hence the reason they have to both come out each side.

I managed to clamp the swinging arm onto one of our milling machines and run an end mill down one side after taking it through the sleeve and barely touching the bore of the swinging arm tube. As soon as I reached the end of the sleeve it sprang out and that was the job done.

I made up a couple of jigs and then pressed in the new silentbloc bushes. What I should have done before this was to put the bushes together outside of the arm and measure the overall distance from the outside edges of both bushes. When they are pressed into the swinging arm and the outer sleeve is flush with the swinging arm, the bushes butt up against each other in the middle of the swinging arm tube bore. I wrongly assumed that they would just be 'correct' but found out after they were pressed in that I could not get the swinging arm back in between the side cheeks of the main frame. After taking some accurate measurements I found that the bushes, although butted together, were .0150" wider than the inside of the frame side cheeks. The inside of the side cheeks measure 9.375". I ended up clamping the whole swinging arm (very carefully because it is now freshly powder coated) on to the milling machine table, clocking it up and taking the necessary 'meat' off the end of the inner sleeve of the bushes. Had I checked and measured before I pressed the sleeves in, this would have been a much easier job with the bushes in a lathe.

Once all was ready to have another go at fitting it to the main frame I first tried the new hollow spindle through the bushes. Greased it up and it pushed through nice and easy until it got halfway and then stopped. I pulled it out and looked down the bore with a torch and I could see that the two inside bores of the bushes were out of line. I turned up a 12" long dummy spindle with a tapered lead on one end, greased it up and tapped it through the bushes several times from both sides. Once I had done this I checked again and the bushes were in line and the new hollow spindle went all the way in, a lovely fit and no problems.

The swinging arm is now back fitted to the main frame and I have left the spindle nut loose until the bike is fully assembled, after which I will get the bike back on it's wheels with someone sitting on it before I fully torque the swinging arm spindle up.

I guess the golden rule and one which I should have stuck to myself is 'do not just assume parts will be dimensionally correct'! Check everything before doing anything like pressing bushes in. It's not so bad if you have a bolt that's too long, you just take it out and get one the correct length. Once something like the silentbloc bushes are in, they're not coming out again without a fight.

Hope this may be of help to some of you.

[Bess]

Hi Kev,
           From the images I cant see the rubber section clearly.

However it looks like the inner sleeves have butted before the outer metal sleeve has reached its position in the arm. It is possible the outer sleeve has moved further than its manufactured position and the rubber has been compromised.

Bess...

[Kevev]

Hi Bess,

I understand what you're saying but I don't think that's the case. I know when I fitted the first Bush the inner sleeve looked to be protruding the same amount as it did.

I won't know for sure unless I pull them out and as it all seems to be ok now I think I'll leave it as it is and see how it goes.

Cheers.

Kev