[solved]REAR SHOCK ABSORBERS

Good evening All.
I’m replacing the rear shocks on my CB500S.
The upper mounting bolts that run through the seat cowling were a free & easy removal.
Not so the lower mounting bolts and both were a pig to get off. A mix of WD40 and violence eventually released them.
They are stainless steel bolts (?) and needed a 14mm or 9/16” socket, so I reckon 3/8” bolts.
The receiving nut, presumably carbon steel, is welded to a bracket on the swingarm.
On inspection one of the bolts has deformed / damaged threads at the end, and on withdrawing it has damaged the threads on the nut.
I’ll be getting new bolts, but would like advice on my options for the nut.
Option 1 – Re-thread the nut, but not sure how successful this would be given the thread damage.
Option 2 – Hacksaw the welds to remove the damaged nut. Replace the nut at the same time as the bolt, but this would not be welded to the swing-arm.
Option 3 – As above, but ask the garage who will be MOT-ing the bike to pop a couple of welds on the nuts while they have it.
I’d prefer Option 2, but I’m not sure how critical the existing welded nut is.

Is it welded to prevent the holes in the bracket becoming elongated due to the movement of the rear shock ?
Thanks in advance.

The way I a pro would do it is to clean the thread if possible if not I drill it and fit a timesert it is an M10 X125 fine thread

Hi Dave.
I've sourced a couple of replacement bolts (M10x1.25x35 Hex Flanged as you say) and will first attempt to re-thread the damaged nut. Maintaining the nut welded to the swingarm is obviously preferred. It’s a pity it’s on the chain side. There is no over length available beyond the damaged nut due to the sprocket bolts or I could have fitted a longer bolt with a thin locking nut as belt and braces.

Tap & wrench have just arrived so I’ll give it a go this weekend.
Thanks for your reply.

Ran the Taper Tap through the nut and it seems to have tidied the threads up. The new bolt threads on and off easily enough. I'll add some threadlocker and keep an eye on it.

Just an idea for a bodge should it fail, fill the space up between the two lugs with nuts and then put the bolt through it. The thread of the nuts will stop the bolt from coming out and they'll still put the weight on the two lugs of the swing arm.

Hi James.
Not sure if I've picked you up right.
The shock will fill the space between the lugs on the swingarm, so no room for any additional nuts ?

ah forgot about that, ringing up insurance companies and filling in the same form over and over has made my lose my mind a little.

Just a variation on James' idea, how about fitting a slightly longer bolt, then screwing an additional nut on the back as a sort of locknut for peace of mind? You could probably get a half nut to reduce it's visibility & do the same on the other side so it looks as if it's meant to be like that 

Hi Alvi.
It's surprisingly tight (said the bishop to the, blah, blah, blah...)
I did think about a 40mm rather than the specified 35mm, but on the 3rd photo you can see the sprocket bolts and I reckon I have just over 5mm clearance between the 35mm rear shock bolt at the sprocket ones as they pass.
An M10 thin nut is typically 5mm thick, so it would be neat.
I'll go with the 35mm for now and mark a couple of tell-tales to see if it's showing signs of movement.
Think I'll also order some 40mm and thin nuts anyway so I can at least trial fit them and see if there are any clashes.
Many thanks.

I imagine the tapped out thread will be just fine.

It doesn't matter if the thread is slightly weaker, as long as you can get it done up to the correct torque.

Most of the load on it is up and down, plus the side-to-side load is taken by the metal bracket, so as long as you get it tight enough that it doesn't come undone you should be ok.

If I was going to fix it I would have run a tap through it and only got to one of the more complicated options if that failed. To weld it 'nicely' you would have to take the swingarm off (well I would, but then I'm not that good at welding!)

Good evening all.
I fitted a couple of flanged hex bolts 5mm longer than spec. and added a washer to the flanged side to keep the end of the longer bolt off the sprocket bolts. Also went with Loctite. I'll keep an eye on them, but I think the tapped thread will be fine and doubt a thin locking nut will be needed.
Thanks again for the responses.

Solved by the way !