Topic: '76 CB400F work in progress - rear suspension mount point sheared

[mwalters]

So, crap. I'm working on restoring / customizing a '76 CB400F for my wife's 40th birthday, with step 1 being getting down to the bare frame so that I can de-rust and paint it. Last night, while removing the rear suspension, this happened:



So. It seems like the best thing to do is to cut back the mount a bit, and weld in a new section of shank and thread, but I'm wondering if anybody else has experienced this issue, and if so, how you resolved it. I could use some input here. 

[cougar]

mwalters ; While slightly different vehicle. I had the same thing happen on my 1992 Ford Ranger front shock. I took a bolt with the same threads, ground one end down to a rather sharp point. Then welded it what was left on the vehicle. The main concern was keeping it straight. But I do have welding experience and my own equipment . Just my 2cents!   ...cougar...

[MoMo]

Your idea should work.  All stress is on the mount and that is solid-the nut retains the shock from moving side to side so you  could have a high grade bolt welded on....Larry

[calj737]

You can also buy new shock mounts and weld them in, or have them pressed in.

[Don R]

I found tubing that fit over the shock mount, then bushed it down to the thread size making a drill guide. Then I drilled it through, bought a bolt the correct length. Cut off the head and inserted it through the mount. Then I welded the back side.

[scottly]

You could also drill and tap the mount for a short 5/16" or 8mm bolt.

[camelman]

There isn't much sideways load on that bolt at all. I expect that simply welding some threaded stock onto the mounting point will be sufficient just like Cougar did. A decent weld at a location like that would easily hold hundreds of pounds of tension, and you'll never see that kind of a sideways load from the shock.

[mwalters]

Thanks much, all. I had been considering that there wasn't much lateral loading on these threads, and the idea of drilling out the mount, tapping in new threads, and just threading in a new length of appropriately threaded rod seems pretty appealing at this point. I can just as easily weld and then use a die to chase the threads down over the welded area, though.

Hmm. I guess I'll figure out what thread pattern it is and then see what I can find to replace it.

[mwalters]

It's M10x1.25 (M10 fine), for future reference. I spent a bit of time with my welder and bodged on a fix:




Far from perfect, but it will do the job.

Also finished getting the frame into black today:



This is the VHT Chassis / Rollbar paint in matte. I think it looks great!