Swinging arm nut torque

[jhg1958]

I thought I had a bit of play in the swinging arm, so I tightened the nut on the RHS. Foolishly I put too much welly and stripped the nut.

There is not much information on torque settings for the A10 so I have tightened it up until I panicked. Just taken it off to apply loctite blue (instead of the shakeproof washer) and checked the torque on removal.

It was at 40lbf ft so I will refit it this time to this torque.

I hope this is about right, I don’t want to strip another nut or worse the pivot nor do I want play in the swinging arm.

John

[CheeserBeezer]

This arrangement is a serious PITA! I find that most pattern swinging arm spindles, silentbloc bushes and securing nuts are incompatible. The problem is that you need a lot of tension on the nut to grip the centre of the silentbloc onto the inside of the frame plate. I have taken the suspension units off and moved the swinging arm up and down to replicate the normal travel in use and found that, unless I torque up to about 75 ft/lbs, the silentbloc centre sleeve rotates as the swinging arm gets to the top of its travel. By the time I get to about 60 ft/lbs the nut is threatening to strip. The slight movement in the centre sleeve of the silentbloc gradually grinds a circular groove in the frame plate, causing loss of tension and the nut to come loose. Sloppiness in the swinging arm is more often caused by the nut coming loose, due to the aforementioned reason, rather than wear in the silentblocs. I've converted most of mine to a bush and sleeve system which has proved to be very successful. The only downside is they need greasing occasionally. The problem with many of the pattern parts is that the steel sleeves used in the manufacture of the silentblocs are not of the same thickness as the originals meaning there's less room for the rubber. This is particularly the case with the silentblocs which accommodate the crossover shaft as the hollow spindle has to be bigger, leaving even less room for the rubber. Just looking at the silentblocs makes you think, 'these can't work'... and they (often) don't! The other problem is that the threads on the pattern spindles and nuts aren't as good as the originals, no surprise there.

[Swarfcut]

  Is there any other way of joining the inner tube of the silentbloc bush to the frame? The answer would appear to be "No", otherwise this would be a well known mod. The basic conundrum is how to anchor the inner tube to the frame, the original system attempts to do it over a small surface area, requiring a high torque setting on what is in effect a draw bolt nut.

  What would happen if the cross tube of the swinging arm was shortened by a few mm, enough to allow a couple of washers to be tack welded  around the inner tubes of the bushes?  OK, some rubber may be destroyed, but with care I am sure it could be done. This would give a larger surface area to abut the frame side plates, and thus provide more friction to anchor the bush inner tubes.

 Madness maybe, waddya think?  A splined inner tube to the bushes and a splined cross shaft?  ***king luxury...dream on!

 Swarfy.

 

[CheeserBeezer]

The larger surface area is an interesting thought but it would not make any difference as the pressure/mm2 would be reduced as a consequence of the redistribution of the force over a larger area. The way forward is probably utilising a version of the second method you describe. Perhaps cutting a couple of slots on the inner tubes, drilling the frame to correspond with the slots and using pegs made out of hard steel driven through the holes into the slots.... or something like that. But there is so little material to work with, it's going to be a bodge. Maybe weld the plate on as per your first suggestion, then go with the hole and pin solution as described above. Could work, but very little room to work with. Whilst it's quite a big job, I'm happy with the bush conversion I do. The first bike I did this on has done 8000 miles since the conversion and still zero lateral movement in the swinging arm.

[Swarfcut]

  Anyone remember grease nipples and plain bushes on Dad's old pre and post war cars? Then they invented Silentbloc and suspension systems became maintenance free.....for most. Good old BMC stuck with ball joints that needed grease, and Mini trailing arms that needed it but never got it....

 Just thinking that at the time it must have seemed a good idea to BSA's development department and to use a new innovation on a brand new model. Do any other marques use a similar rubber bonded method, or did contemporary designs stick with lubricated bushes?

 The idea with the washers tacked on is to offer a greater surface area for friction on the frame side plates, offering  increased resistance to rotation compared to the much smaller diameter of the original silentbloc bush.

 Good to know there is an existing alternative. Is it available for sale?

 Swarfy.

[groily]

. . . and suspension systems became maintenance free.....for most. Good old BMC stuck with ball joints that needed grease, and   . .
Swarfy.

  . . . self-detaching kingpins on ungreased Morrie Minors iirc?
Can't think of other silentbloc s/arms though, just everyone's favourite isolastics.
But - to be fair - I never had to replace a s/arm on any of the 4 twin-downtube s/arm Beesas I had (I don't think they needed it!) - but pins and bushes in other machines, oh yes, including one compeletey seized-up solid. Started with a squeak, became a groan and then, just like THAT, I was on a rigid - with hairline handling and a very sore bum.

[Rex]

The self-destructing front king pin on Moggies was a "when" not "if" back when they were daily hacks rather than collectors items.
I had a 1954 Hillman Minx and it had more nipples than the local pig farm.

[trevinoz]

Swarfy, my 1966 Norton Atlas has silentbloc bushes.

[groily]

Swarfy, my 1966 Norton Atlas has silentbloc bushes.

omigawd that's dead right trevinoz - and what's more, I've unwittingly been sitting on them on my 650 Dommie too! Hope I never have to go there.

[jhg1958]

I fear that the conversion to bushes would be beyond my capability and probably not worth it unless I drastically up my mileage on the bike.

Apart from being a money black hole it has been a bit of a disappointment to me. A lot more work than the one I owned in my 20s and perhaps as I tuck years under my belt I am less tolerant.

John

[trevinoz]

Groily, when I restored the Atlas about 30 years ago, I couldn't move the spindle so the frame was painted with the swinging arm in place.
Never given a bit of trouble.

[groily]

Groily, when I restored the Atlas about 30 years ago, I couldn't move the spindle so the frame was painted with the swinging arm in place.
Never given a bit of trouble.

Cheers for that! Never had any trouble with mine either, which is why I didn't even know what was in there. Certainly not looking for problems - the thing will probably outlast me 

[Triton Thrasher]

Do any other marques use a similar rubber bonded method, or did contemporary designs stick with lubricated bushes?.

Enfield, Greeves, Francis-Barnett, BMW, lightweight Hondas, Norton, Rickman, Ariel…