relocating the rear suspension of a 1979 cb750

hi -

been following these forums for a bit. I recently came into a non-running (haven't even put the whole thing back to gather to try to fire things up) 1979 CB750 (actual model is unknown). I'm going to try my luck on my first project build of a 1979 cb750 but I'm not particularly fond of the hump of the rear section of the frame. I like more of the straight line of the SOHC cb750s. so I'm just curious if anyone has ever considered (or even done) relocating the rear suspension of a 1979 cb750 from it's stock location to maybe more of a location like the SOHC models. any concerns with this? I know this means I might have to chop off more of the rear frame than necessary and using maybe the full length of a stock frame loop in it's place but I'm concerned with any possible structural problems or messing with how the suspension will ride since the length of the rear shocks will need to be shortened instead of using the stock size.

thanks!

sinh

If your unsure of how to take on a project like this, you're probably better off not doing it.

I don't mean to sound rude, or negative here. That said, what you're talking about is a pretty serious bit of fabrication that has the potential to essentially ruin the bike all together.

Either take the frame and your ideas to a professional fabricator (not the guy at work whos uncle JoeBob "used to weld for a living") or find a more creative way to get your result without cutting the frame apart.

Save yourself the trouble and buy a SOHC CB750....

It’s a lot of work. You’d need to fabricate a whole new sub frame on the rear. It’s possible but you’re going to need to do a lot of homework. You need to take into account the geometry of the finished product. Measure everything thirty times (an exaggeration) and expect to spend a lot of time and probably money on it.

When I did my sub frame I did it on a fabrication table. I used a number of various items to jig the important points. Once that was taken care of the tubes then got machined to fit between those important points. Once that was achieved then everything got welded. It was a big process, not too technically difficult, but some experience is needed.

you're not sounding rude at all. appreciate the feedback. I have a direction on how to get what I want and where I want to go. The responses I'm getting are pretty much on par with what I'm expecting.

the bike is getting built, it's just a matter of time.

thanks again for the responses.

Sinh

VonYinzer said:

If your unsure of how to take on a project like this, you're probably better off not doing it.

I don't mean to sound rude, or negative here. That said, what you're talking about is a pretty serious bit of fabrication that has the potential to essentially ruin the bike all together.

Either take the frame and your ideas to a professional fabricator (not the guy at work whos uncle JoeBob "used to weld for a living") or find a more creative way to get your result without cutting the frame apart.

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