Honda-SOHC
SOHC.co.uk Forums => CB500/550 => Topic started by: Neilw on July 13, 2026, 04:57:29 PM
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When i originally took the rear wheel off, the photo i took showed two spacers on the right side of the axle rod.
Which when i looked at it looked a bit strange. The parts manual doesn't show a second spacer, but without it there is a gap.
I've fitted one of the spacers to the left and one to the right, but i don't know if this is correct.
I'd love some advice as the wheel doesn't look central in the swing arm or against the botton of the rear mudguard.
Was the original setup the correct one with the two spacers on one side?
Cheers
Neil.
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Definitely not two spacers on the same side on my 500..
Right side is a wide spacer, left side a shorter one.
I found the parts book a good source of checking assembly order.
IIRC the left side spacer should be in the parts book showing the parts for the left side of the drive hub, bearings any seals etc.
Your left side spacer looks as though it's either the wrong one or fitted the wrong way round, difficult to tell from the photo.
My 500 had a wrong sized spacer fitted, an ex-member here Max made me a set in SS of the correct width, I did have the sizes in an old email - now deleted.
If you get stuck PM me and I will give you Max's email address.
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It looks like the spacer in your right hand side is maybe the wrong one can you measure how wide it is
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Also the spacer that should be touching the left side of the swing arm is the one that comes through the seal that extra spacer shouldn’t be there
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It looks like the spacer in your right hand side is maybe the wrong one can you measure how wide it is
The spacer on the right is 40mm, the one on the left is 15mm.
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Is it 40mm or 40mm ish it is hard to measure it built up it should be 36mm that 15mm one shouldn’t be there if you look at the picture of mine the swing arm sits a lot closer to the guard on the rear sprocket
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Is it 40mm or 40mm ish it is hard to measure it built up it should be 36mm that 15mm one shouldn’t be there if you look at the picture of mine the swing arm sits a lot closer to the guard on the rear sprocket
It's 40 mm-ish, more like 39mm, in imperial it is one and half inches.
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Now i am willing to be shot down but is it the correct swing arm?
There are two different ones and without my stored parts books i cant say which is which.
1 has closed ends where the rear wheel spindle has to be completely removed to get wheel out
2 has removable brackets at the ends so the wheel stays complete to remove
I simply do not remeber which type the F is but i do know the spacers are different, also the brake plate and hub although shoes are the same.
Complete wheel assemblies can be swapped bike to bike but not the individual bits except sprockets
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Now i am willing to be shot down but is it the correct swing arm?
There are two different ones and without my stored parts books i cant say which is which.
1 has closed ends where the rear wheel spindle has to be completely removed to get wheel out
2 has removable brackets at the ends so the wheel stays complete to remove
I simply do not remeber which type the F is but i do know the spacers are different, also the brake plate and hub although shoes are the same.
Complete wheel assemblies can be swapped bike to bike but not the individual bits except sprockets
The swing arm is a replacement as the original was rotten. The replacement physically matches the original and also matches the parts diagram for the F2. It has closed ends. I assume the original was the correct one for the bike, as it matches the parts diagram.
I've found anomalies in other areas on the bike.
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Yes that’s an f2 swing arm with closed ends the k3 is open I think the problem is the brake plate but don’t know anything about any different ones if he takes the extra spacer out and pushes the wheel over the rear sprocket will be nearer to the centre of the chain guard and should be more in line with the front sprocket
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Yes that’s an f2 swing arm with closed ends the k3 is open I think the problem is the brake plate but don’t know anything about any different ones if he takes the extra spacer out and pushes the wheel over the rear sprocket will be nearer to the centre of the chain guard and should be more in line with the front sprocket
Which might explain why both spacers were on the right-hand side when I got the bike.
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The 550f has the closed end type of swinging arm, the open end arms were fitted to the models with 4 exhausts as you couldn’t remove the wheel spindle to remove the rear wheel for a puncture for example. The 550f also has a slightly thinner o/s spacer than the 500 as well. It has a slightly longer boss on the brake plate to compensate. Your pictures show the wheel completely out of line, the rear sprocket should be almost directly under the chain guard and yours is way off. It wouldn’t run like that, the chain would not be inline enough for it to operate without a severe risk of it coming off. The small top hat spacer you’ve fitted doesn’t belong there. The silver coloured one goes next to the chain adjuster. So why doesn’t it fit? Seems simple if you know both models very well. It looks to me as if someone has fitted a 500 rear wheel in a 550f arm but still tried to use the 550f spacers. Measure the length of the o/s spacer and that should tell us if that’s the case, I think someone bodged it previously just to get back on the road.
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The 550f has the closed end type of swinging arm, the open end arms were fitted to the models with 4 exhausts as you couldn’t remove the wheel spindle to remove the rear wheel for a puncture for example. The 550f also has a slightly thinner o/s spacer than the 500 as well. It has a slightly longer boss on the brake plate to compensate. Your pictures show the wheel completely out of line, the rear sprocket should be almost directly under the chain guard and yours is way off. It wouldn’t run like that, the chain would not be inline enough for it to operate without a severe risk of it coming off. The small top hat spacer you’ve fitted doesn’t belong there. The silver coloured one goes next to the chain adjuster. So why doesn’t it fit? Seems simple if you know both models very well. It looks to me as if someone has fitted a 500 rear wheel in a 550f arm but still tried to use the 550f spacers. Measure the length of the o/s spacer and that should tell us if that’s the case, I think someone bodged it previously just to get back on the road.
The os spacer is about 40mm (between 39mm -40mm).
What can i do? if it's the wrong wheel, that also means it's the wrong hub and brake plate too. What are my options? Will replacing the brake plate with a 550f one do the job, or won't it fit the hub?
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There are two different hub/brake plate combinations, from memory there is a difference on the outer diameter and i think you can swap one way but not the other just to confuse it.
What you need to do is sort out the sprocet side spacing to get the chain in line then work out what length you need for the other side.
If you want to keep it "standard" easy way is complete rear wheel with axle, brake plate and spacers but to use it safely all you need to do is work out what size spacers you need
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There are two different hub/brake plate combinations, from memory there is a difference on the outer diameter and i think you can swap one way but not the other just to confuse it.
What you need to do is sort out the sprocet side spacing to get the chain in line then work out what length you need for the other side.
If you want to keep it "standard" easy way is complete rear wheel with axle, brake plate and spacers but to use it safely all you need to do is work out what size spacers you need
Removing the left spacer will sort the sprocket side out, and adding it to the right side will give the correct spacing for the wheel. If this makes it usable and safe, I'll go with that option. Longer term, I was going to rebuild the rear wheel with a new rim and spokes, now I'll look for a replacement wheel with the correct parts.
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Remove that odd spacer. Fit the wheel but omit the o/s spacer. Push the wheel as far as it can go and measure the gap left by the missing spacer. As I said the 500 brake plate has a smaller protruding central boss, you can tell it’s a 500 brake plate btw because the 550 has ribs on the piece hanging down where the torque arm bolts too, the 500 is smooth. If you look at the pics 3cs posted you can see the ribs. If IIRC the new gap should match the old 500 spacer, if it does just buy one of those. I’ve fitted 500 wheels into 550s and vice versa and then aligned ok. So hopefully that’s a simple solution. Could be wrong of course as it a few years now since I did this.
Oh and finding a another 550f hub may not be as easy as you think. The rear drum liners crack a lot, probably why you’ve got a 500 wheel in there. If the liner in that hub is ok fixing the spacing could well be much easier.
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Remove that odd spacer. Fit the wheel but omit the o/s spacer. Push the wheel as far as it can go and measure the gap left by the missing spacer. As I said the 500 brake plate has a smaller protruding central boss, you can tell it’s a 500 brake plate btw because the 550 has ribs on the piece hanging down where the torque arm bolts too, the 500 is smooth. If you look at the pics 3cs posted you can see the ribs. If IIRC the new gap should match the old 500 spacer, if it does just buy one of those. I’ve fitted 500 wheels into 550s and vice versa and then aligned ok. So hopefully that’s a simple solution. Could be wrong of course as it a few years now since I did this.
Oh and finding a another 550f hub may not be as easy as you think. The rear drum liners crack a lot, probably why you’ve got a 500 wheel in there. If the liner in that hub is ok fixing the spacing could well be much easier.
The gap without the additional spacer is 15mm, so if that is the difference between the 500 and 550 brake plate i'll do as you say and get a 550 one. There is one for £35, which i can return, so looks the best way forward.
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There may be a problem with that idea Neil. IIRC the 550 brake plate does not fit the 500 brake drum, I seem to recall trying it and being surprised that whilst the drums look identical they were different. It seems to foul on the outside edge. Maybe someone with both hubs and plates can confirm if I’m remembering correctly.
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There may be a problem with that idea Neil. IIRC the 550 brake plate does not fit the 500 brake drum, I seem to recall trying it and being surprised that whilst the drums look identical they were different. It seems to foul on the outside edge. Maybe someone with both hubs and plates can confirm if I’m remembering correctly.
I don't "know" that I have a 500 wheel, it's just what's been suggested on this thread. It could be that I have a 500 brake plate in a 550 wheel.
I don't know how to identify whether the wheel/hub is from a 500 or 550, as the only difference identified so far is the brake plate.
I can do the check if my offer on the plate is accepted. if it doesn't fit i can return it.
This bike just keeps giving and giving!
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Evidently the difference between the 500 and the 550 hub is the outside ribs in the centre. Trigger explained it one time many years ago. IIRC the difference was the 500 had them all the same size and the 550 had one smaller in size right at the edge. Not sure now if they were stamped with a model number inside the drum, if so the 500 would be 323 and the 550 is 374. Not sure if a search of the forum would shed more light on this topic but it’s definitely been discussed in the past.
Hope that helps.
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I think you are correct Ken, pic here of 500 hub
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see how all the ribs are equal, the f2/k3 have one rib that is lower. so this 500 hub not compatable with the f2 brakeplate as this pic.
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There is another difference I’ve just remembered but it is only visible when the sprocket carrier has been removed. The Cush rubbers on the 500 are different design than the later 550 ones. Other than those 2 points they are very hard to tell apart.
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i've been doing some measuring.
The internal diameter of the brake hub is 180mm, with a depth of the brake face measuring 33mm.
The axle has a diameter of 20mm.
AI reckons someone has replaced the bearings from 17mm to 20mm and used a 20mm axle, replacing the 17mm, possibly from a cb750.
The brake plate must have been bored out to 20mm, as none are standard at this diameter (however, AI gets confused on this when questioned) except the CB750, but that wouldn't fit the hub I have, as it is too deep and would foul.
I'm having a CB550 brake plate delivered tomorrow and will see if it fits the hub. It may well be 17mm, in which case I have to decide if
A) I want to get rid of the extra spacer, and if the plate fits, I have it bored out to 20mm, or
B) keep what I have and use the existing spacers, or
C) replace the bearings in the hub, get a 17mm axle and use the new plate I have purchased (assuming it fits). If it doesn't fit, replace the hub as well!
Cheapest is B, neatest would be A, getting back to stock C, but most expensive.
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I think the one bearing is a 6304 which is a 20mm bore as standard. AI is about as usefull as a chocolate fire guard
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If you look at this item (156396720375) made by Max Haywood, he was a member here, he will make you a bespoke spacer if you know the width you need at a sensible price
He says in his listing he can make what you need, tell him you are a sohc member,
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This shows the difference between 500 and 550 the fins on the 500 hub lol the same height the 550 one fin is lower, also inside the 500 hub there’s some smaller holes, couldn’t you just line the sprockets up then get a spacer made up the correct length to fill the gap left on the brake plate side
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If you look at this item (156396720375) made by Max Haywood, he was a member here, he will make you a bespoke spacer if you know the width you need at a sensible price
He says in his listing he can make what you need, tell him you are a sohc member,
Thank you
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This shows the difference between 500 and 550 the fins on the 500 hub lol the same height the 550 one fin is lower, also inside the 500 hub there’s some smaller holes, couldn’t you just line the sprockets up then get a spacer made up the correct length to fill the gap left on the brake plate side
Thank you for the pics, i can see what you mean re the difference. I definitely have to cb500 one. And regarding the spacer, that is my most likely route in the short term.
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If the bearing markings match the bearings specified by Honda then AI is wrong. I suspect it’s wrong anyway as the hole in the swinging arm wouldn’t match the bearings either.
Nice few pics by 3scs, the extra holes on the 500 plate are the holes used by the cush rubbers, the 550 used different cush rubbers that didn’t need these holes so were omitted by Honda.
TBH the solution seems fairly easy, just get a spacer either made or try a 500 spacer and see how that goes. Or just use that weird spacer until you find the parts you need.
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If the bearing markings match the bearings specified by Honda then AI is wrong. I suspect it’s wrong anyway as the hole in the swinging arm wouldn’t match the bearings either.
Nice few pics by 3scs, the extra holes on the 500 plate are the holes used by the cush rubbers, the 550 used different cush rubbers that didn’t need these holes so were omitted by Honda.
TBH the solution seems fairly easy, just get a spacer either made or try a 500 spacer and see how that goes. Or just use that weird spacer until you find the parts you need.
That's what I'm concluding, but it's nice to understand what I have and what I'd need to do to return everything to standard.
Many thanks for your help.
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The replacement CB550 Brake plate has arrived. It doesn't quite fit, which we knew, but it has confirmed for me that the axle i have is the correct one at 20mm as the plate has a 20mm hole. (Ai was telling me it was 17mm on the CB550 for some reason which got me confused).
The new plate is 15mm higher, which equals the extra 15mm spacer i have for the CB500 hub currently installed.
So my way forward while I'm continuing building the bike is to use the extra spacer on the brake side, until such time that i can source a replacement rear wheel with hub (my wheel is heavily pitted and chrome flaked off). I'll keep the new brake plate to go with the wheel when i get it.
So thanks to all for helping me make sense of what i have a what i need to do going forward.
This bike also has the wrong clocks (too small) and lots of little things that i'm having to fix as i reassemble!
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A1 is only as good as the data it's been fed with.
The old maxim applies.
Rubbish in = Rubbish out.
Reminds me of the old joke about asking a computer what is the better wrist watch?
One that is irreparably broken, or one that gains a second a day.
Computer says keep the broken one as that shows the right time twice a day.😃
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Interesting.
I am the original owner of a CB500 K1 1972. Also have a 73.
And had a 78 CB550 for parts and didn't notice any difference in the swing arm wheel spacers, but that was 40 years ago.
The spacer on the right is about 45mm in length. Sits against the brake hub which in turn internally sits against the inner bearing race.
The spacer on the left sits inside the bearing /sprocket dust cover and rests against the left side bearing inner race.
BTW there is a spacer tube between the inner bearing races so you can tighten it up without over axially stressing the bearings.
Without removing the wheel or digging in parts bins, if I recall, the left side spacer is about 15mm but not sure but it barel sticks out from the dust cover.
If you really have to know the dimensions, I can dig in my parts bins because I think i have a brake drum axle hub spare.
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Interesting.
I am the original owner of a CB500 K1 1972. Also have a 73.
And had a 78 CB550 for parts and didn't notice any difference in the swing arm wheel spacers, but that was 40 years ago.
The spacer on the right is about 45mm in length. Sits against the brake hub which in turn internally sits against the inner bearing race.
The spacer on the left sits inside the bearing /sprocket dust cover and rests against the left side bearing inner race.
BTW there is a spacer tube between the inner bearing races so you can tighten it up without over axially stressing the bearings.
Without removing the wheel or digging in parts bins, if I recall, the left side spacer is about 15mm but not sure but it barel sticks out from the dust cover.
If you really have to know the dimensions, I can dig in my parts bins because I think i have a brake drum axle hub spare.
Many thanks. I intend ultimately to replace the hub with a stock 550. I already have the correct brake plate in readiness. In the meantime, I'll use it with the additional spacer, which is 15mm.