What do we see here?

[Bryanj]

Not special just not the"normal" pitch for that diameter, still a standard metric though

[deltarider]

Thanks for clearing that up, Bryan. If the thread of the clovis has been accidentally knackered by me, the LH side will have the same solution, I did RH side: a somewhat longer bolt and a nut on the other side. I believe there's room. Could be it implies temporarily removing the wheel, which is not that much work.
@ Ash Does not seem very off-centre. Camera lens has a will of its own, resulting in a personal view, I guess.

[AshimotoK0]

Functionally I don't suppose off centre is that bad anyway ... I am just trying to jig up some 250k crankcases to drill out a broken off an M6 screw ...trying to use a sleeve in the other half case with a tight fitting, long series drill to guide the drilling centrally.

[Seabeowner]

Never realised they have a special thread.

Just M10 x 1.25 which seems to apply to most 10mm threads on the bike.

[deltarider]

I'm sorry to revive this thread, but there are still a few things not clear to me. It's about the fastening of the rear shocks at the bottom. Let's look at these, what we call, breast bolts (10x32).
I can understand the clevis has a thread on one side, to save space.
What I don't understand is:
A) What is the breast part of the bolt for?
B) And if it is useful, why is the breast part not longer? The inside of the bushing is plain. Why would you need a thread there?
C) Another thing. In the pic we see the clevis and the bolt but no washers. Is a washer or spring washer not needed here?
I do not have a real problem, but I'm just curious what's the ratio behind it.
If you mount the rear shocks, is there a working order to observe? I mean to not damage the threads. In the past I must have done something wrong. On the RH side I have a longer and fully threaded bolt, with an extra 10mm nut against the outside of the clevis.
On the LH side, the bolt has the original length, but does not really fasten.
I must have done something wrong, but I can't remember it. Too long ago.

[K2-K6]

To describe the joints, the rubber composite design (it doesn't need to control geometry here as the swingarm does that) is relatively cheap way of making a joint that can't rattle over time as the rubber flexibility keeps it quiet but allows limited movement.

The centre bore is usually clamped between the shock (at the bottom) with that part not moving at all in relation to the shock.  As the suspension moves, the rubber twists (inner and outer metal parts of the bush move separately) with the rubber accounting for all the movement needed through suspension travel. The inner doesn't move on the securing bolt (it would be better engineering practice to have no threads there as you indicate) but with the bush clamped against the shock forks it shouldn't matter much.

It's a double shear joint, the push and pull forces are taken by both ends of the bolt (it would be very very hard to break the bolt in this design) also it makes no rotation torque on the bolt and so will not come loose even without securing washers etc. In reality you could almost put it there with your fingers and it should be safe.

The top mount is just the opposite in how the centre bush is now on the frame, with the outer on the shock. Same deal force plane though. The top pivot is long and passing through two frame wall sections usually to give support for the one sided design else it would bend that mount if just sticking out from a single piece of metal.  This one will more or less work without the security nut/bolt as all of the suspension load is taken by the main spindle not the bolt.

[philward]

Always facinating to hear an engineering perspective on something we just take for granted Nigel. Never thought about the top mounting spindle going through 2 walls of the frame but when reading about it, makes complete sense.

[deltarider]

[...] it would be better engineering practice to have no threads there as you indicate but with the bush clamped against the shock forks it shouldn't matter much [...]

It seems I am not particularly lucky with these breast bolts. BTW, is that the correct word in English? Please, allow me a sidestep. Below a pic of another breast bolt, the one that is supposed to hold the kick arm in place. Already in 1980, when I acquired my bike, it was wobbly and now this is what the shaft looks like. Needless to say the kick arm slips. If any of you has a tip to improvise something... Suggestions in the international forum were not useful. It's a known CB500 problem; many suffer from it. I hope to find a solution without having to replace the shaft.

[Oddjob]

We call those shouldered bolts, a bolt are those which are partially threaded, like a shouldered bolt, setbolts are fully threaded.

Never had a 500 kickstart slip, I'd just replace the kick start shaft myself, if the knurls are worn you'll never get it to tighten properly again.

[K2-K6]

As above, with shaft worn it's difficult to get a good solution.

Something that's possible to help (this is quite common in moto-X  bikes with kickstart used alot) using a black (engineering) allen/socket bolt, plus a washer under the head and grease on the bolt threads. It can let you tighten the kickstart the most possible to clamp it with the teeth available.

They are the strongest bolt and not plated, so will rust and need to be covered in grease after installation.  If that bolt can't clamp it, then it's absolutely a new shaft as this will take more torque than any other generally available bolt.

[ Guests cannot view attachments ]

This type of bolt.

[deltarider]

Thanks for the advice. Some years ago I have managed to restore grip by using a special file. Alas, now the problem has reoccurred.

[...] Never had a 500 kickstart slip,[...] 

Could be there were various models. Mine is PN: 28300-374-000

[Johnny4428]

Just highlights the necessity to to have these pinch bolts properly tightened in the first place to prevent any movement on splines. Not sure if there’s torque settings for these.

[taysidedragon]

As above, with shaft worn it's difficult to get a good solution.

Something that's possible to help (this is quite common in moto-X  bikes with kickstart used alot) using a black (engineering) allen/socket bolt, plus a washer under the head and grease on the bolt threads. It can let you tighten the kickstart the most possible to clamp it with the teeth available.

They are the strongest bolt and not plated, so will rust and need to be covered in grease after installation.  If that bolt can't clamp it, then it's absolutely a new shaft as this will take more torque than any other generally available bolt.

Otherwise known as a high tensile bolt ( or cap head socket set screw!) 😉

(Attachment Link)

This type of bolt.

[K2-K6]

Yes, I wasn't quite sure how to describe it as deltarider translates to dutch I think, and how that would come out.

Picture to cover it off though.

[deltarider]

I have never quite understood the effects of grease in combination with torque.
A sidestep, if you allow me. In my archives I have a socalled riders report, published in Motor, which magazine in the 70s was a weekly (!). Owners had been invited to answer a long list of questions about the experiences they had with the CB500. In those days the CB500 was a miracle of reliability. There were few complants. Typical complaints however were about the plugcaps and - ofcourse - the sweating/leaking of oil at the head. Honda The Netherlands had issued this recommendation: grease the washers with molykote and then torque the nuts down to the original value.