Honda-SOHC
SOHC.co.uk Forums => CB500/550 => Topic started by: McCabe-Thiele (Ted) on November 13, 2022, 10:49:48 PM
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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.
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Not 17mm head originally, 14mm i think which makes them oddball or as Honda say "special"
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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.
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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.
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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.
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That’s telling um🫣
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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.
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oooo, someone's tired! :o
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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.
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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.
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Me neither, but I’m sure an explanation is forthcoming……
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Oh, exactly how many years have you owned that bike and how many miles/km?
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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.
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Ken, you have got to start building this bike….the wait is killing me.
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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.
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Then get some kit together and catalogue it all up ready, nothing like a bit of progress, even if it is progress to start is always a lifter and good mind excersize mate. Dont bin it yet, you've done so much. ???
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Oh, exactly how many years have you owned that bike and how many miles/km?
Dunno if that question was directed at me. I own my bike since 1980 and it has done over 139.000 km now.
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Sure was….wow, 1980 and 139k miles. That’s impressive. Any major mishaps along the way?
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The camchain tensioner is the only part I really hate. It has already been replaced twice. Chain and tensioner will live for 40.000-50.000 km. The original primary chain is still OK. I have volunteered to see how long it will last. In all these years the bike has proved ultra reliable. Regular use is the best. I have knowledge of someone who was interviewed in an article. At that moment he had done 220.000km using his CB500K1 for daily commuting and his engine had not yet been opened. Plugcaps can cause problems due to their position, especially in the wet. Always start there when you have a problem.
y model, the CB500K2-ED, aka CB500K2 GENERAL EXPORT was the last of the oldstyle CB500s. Assembled in 1976, it shares many parts with the CB550K2. If you study the parts list, you will see some parts underwent modification: gearbox (minor though), clutch adjuster, frontlegs, swingarm etc. Bike has done almost 140.000km. So far I didn't have to replace any fork seals, probably thanks to the harmonica rubbers. I've renewed the damper oil no more than 4 times max. I see no reason why you would do it more frequently. Clutch adjuster greased no more than two times, swing arm maybe 4 times, that is if I did manage to press it in >:(. If I didn't, it's been less ;). Still no sign of wear. I have 4 new rubber boots (carb-head) ready in their packages, but I have no indication the originals leak. I change the oil every 3000-5000km* or every two years, which ever comes first. I don't do short rides. Oilfilter every second oilchange. Oil is not specified as JASO-MA. Actually, it's right on the edge. Never had the clutch slip. Clutch springs and friction plates were at the end of their lifespan at 75.000km and were replaced by genuine Honda parts. Most disappointing part however has been the camchain and its adjuster. I never seem able to do more than 50k with it. Costly! Primary chain has play, but I see no reason to replace. I know of someone who's bike at 220.000 km still had the original chain in. Front wheel bearings are still original, those in the rear have been renewed. Also I needed to replace the drive flange for a good second hand one. This because of the use of a socalled steamwasher which had removed essential grease. Don't use pressurized water! Splines of the kick arm shaft are worn. I think I've found the root cause and hope to publish on this soon.
Although the original rear shocks (5-stage on this model like the CB550K2) were not as bad as many say, I've replaced them nonetheless @ 50.000 by Dutch quality Koni's. They still serve well.
This is how it looks today. http://forums.sohc4.net/index.php/topic,190773.msg2219705.html#msg2219705
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Very interesting assessment of a good old workhorse. These stats are impressive, just goes to prove that these bikes need to be used regularly rather than being tucked up in a shed. As mine is.😃
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9 of ten issues I have had to address, were caused by standing still and not by riding...
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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.
Adding a nut shouldn't give a problem really as it's not really under load at all, just stopping the bolt falling out.
The joint is a double shear/clevis and in simplest form just needs a pin to go through it in handling the loads it has to take, same as a chain really.
[attachimg=1]
You can see the principle load site (illustrated displaced/broken) in picture that the joint has to withstand.
In most shocks though it's been adapted with a shouldered bolt to take load one side, while using the thread on other side. Production/access/assembly reality has given this interpretation that works fine.
The only potential problem if the threads are broken in the koni shock body is if that load capability is now different from the other side which may cause the shock to lean over under load and cause a problem with alignment. If there's no movement in that worn thread area it's not going to give a problem.
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A bit miffed today my order of quite a few nuts & bolts have arrived and the ones for the damper bottoms - thread is too fine (1.25) - I'm guessing a coarser bolt has been used in the past.
I could not find the old bolts before I ordered them from Middletons - good stock though for when I fit new dampers.
For now the old units are cleaning up well - judging by the action the dampers only act one way - upwards reistance - none downwards.
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The odd thing is if you bought a set of Koni dampers in the 70-80s the bottom bolt was fully threaded like a set bolt. Still got a set now and they are exactly like that still so it must work.
Mmm must get those out and polish them up, not using them as I'm fitting Marzocchi Strada Piggybacks.
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Show off! ;) :D
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Yeah, satin black body with chrome springs is the plan, newly hard chromed damper rods, new seals and bellows and new stickers to complete the look. Didn't think the original red with black springs would suit a gold bike.
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I never liked the Koni Red colour, Satin Black with the chrome accenta will look great Ken. Looking forward to seing them. Iwill reply to your PM, out at tthe in in a que and it bleeped so thought I'd reply................I'll take a look later.
Let us know when you manage to get tp the post office then I can have a word with the posty and ask him to hide them for me down by the workshop, he'll stash stuff for me in diferent locations if I'm not in. He just lets the dog know ;D