Rear Damper bottom bolt threads question?

[McCabe-Thiele (Ted)]

The 500 dampers have a threaded plate attached to the rear damper - parts book shows 93000-10032-0A bolt (10 x 32)

Am I right in thinking this is a M10 (1.25 pitch) bolt that has a 17mm spanner head ?

I plan to fit a pair of flanged SS bolts as a replacement.

[Bryanj]

Not 17mm head originally, 14mm i think which makes them oddball or as Honda say "special"

[Oddjob]

If you want to retain the original look and use a 10mm bolt with a metric fine thread but still keep the 14mm head that's hard to find, however my favourite supplier of stainless bolts does just that. I'd get 10 x 35 and if needed trim them down.

Just in case you didn't know, a set bolt (which he sells a lot of) are usually 30mm and under and are threaded full length. You don't want a set bolt in that location.

https://www.stainlessmiddleton.co.uk/32908-metric-fine-bolts-setscrews

His bolts may be more expensive than some but the heads are polished and have no unsightly writing on. They are also top quality.

[deltarider]

The original thread is 'special'. Unfortunately the parts list does not mention this! Decades I ago, when I fitted Koni's, I must have done something wrong, probably by using regular thread bolts. I must have damaged the special thread, which also the Koni's have on the side of the clevis that faces inwards. When I - much later - noticed, I couldn't fasten the bottom of the dampers well, I have solved it by using a few mm longer bolts and adding a nut on its protruding end outside the clevis. The RH side was easy: plenty of space. On the LH side the nut came very close to the sprocket wheel. It didn't touch it, but I didn't feel comfortable with it. So I decided not to risk it and to cut the nut in half. The nut I used has this blue plastic inside to prevent it from coming loose. I don't know the word for it in Englich. In the pic you see the original Honda bolt (CMSNL has them) and the one I now use. The one used actually is a bit longer as shown in the pic. Its head is 17mm where the original is 14mm. I couldn't care less.
I dunno, maybe Honda had this special thread to not have to fit washers.

[Toko_Jo]

The original thread is 'special'. Unfortunately the parts list does not mention this!

It's an M10 x 1.25 pitch for gawds sake .. just like all of the other M10 threaded fasteners on Honda bike for the past few eons. And adding a nut is asking for trouble IMHO.

[Sesman]

That’s telling um🫣

[K2-K6]

It's the shank (plain section under bolt head) that's important as it should fit the shock bore a sliding fit to make the joint design work correctly regarding load and stress distribution.

One side located by that bore/shank, the other by threads in the body. It's a half floating, if you like, joint design that utilises low bolt torque to stop it coming undone, but with very high shear resistance to avoid failure.

[Laverdaroo]

oooo, someone's tired!

[Sesman]

It's the shank (plain section under bolt head) that's important as it should fit the shock bore a sliding fit to make the joint design work correctly regarding load and stress distribution.

One side located by that bore/shank, the other by threads in the body. It's a half floating, if you like, joint design that utilises low bolt torque to stop it coming undone, but with very high shear resistance to avoid failure.

Nice, informative explanation there. Thanks.

[deltarider]

I maybe a nut where it concerns bolts, but on disassembly decades ago there must have been something wrong with the original bolts as it's not my habit to bin parts that can be reused. On the contrary: I've made it a sport to reuse as much original parts as possible. To give you an idea: it was not before this last summer, after 46 years and numerous, numerous adjustments, that I've renewed the 8mm lock nuts of the drive chain adjusters when they finally had become all too round.
Clearly I have made the wrong decision to use ordinary bolts which I happened to have at hand.
Why adding a nut would be 'asking for trouble' is not clear to me.

[Sesman]

Me neither, but I’m sure an explanation is forthcoming……

[Sesman]

Oh, exactly how many years have you owned that bike and how many miles/km?

[Oddjob]

I used Middletons 17mm headed bolt in stainless many moons ago and they were perfect. All he's done is reduce the head size so it matches OE specs.

I've now bought new 14mm headed 10mm bolts to replace all those I bought 40 odd years ago. The brake calipers ones were another I replaced, the 17mm head made them tricky to get a socket on.

[Sesman]

Ken, you have got to start building this bike….the wait is killing me.

[Oddjob]

I wish. TBH I'm so low at the moment with personal problems I'm seriously considering just packing it all away until I'm in the mood again. Just doing polishing to keep my mind occupied.