Topic: Smoothing CB550 Frame Rails

[tacc13]

I'm in the process of detabbing my frame in preparation for fitting a rear loop and then painting. The rails just above and to the rear of the upper shock mounting bolts have a ridge where it appears two sheets of mild steel come together. It looks as though if I just file the ridge down it will ruin the structural integrity of that area, which is important for the rear shocks. Is there any way to blend this area in with the frame tubes?

Thanks

[calj737]

They're pinch welded. Trim them down, but butt weld the seam back up.

Or, cut off the hoop forward of that location, and re-weld in new shock boss plates. This would allow you to level the hoop and eliminate the drooping rails.

[540nova]

What Cal said, + make a triangular tab from the bottom of the frame rail, and blend it into your hoop. Think "flow".


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[tacc13]

Thanks very much for the advice. I'm now in two minds whether to keep the current upper shock gussets or pick up the Cognito shock mount hardware and just clean the whole rear end up.

[calj737]

If you grab Cognito's studs, weld them onto a piece of 1/2" plate, then weld that to your frame. You'll be nice and sturdy and clean up the droop 

[DaveBarbier]

If you're going to be cutting and welding on a hoop and seat pan start thinking about rear wheel clearance. Honda designed a large cavity for the wheel to raise up into. You can remove the springs from the shocks and install just the shocks to see how far the wheel will raise.

[tacc13]

Thanks Dave, definitely taking it slow if I decide to chop the mounts off. I need to find out if changing the mounts will complicate the registration process. We are anal about mods over here, and my state in particular is renowned for over zealous vehicle inspectors.

Cal - not entirely sure what you mean about the 1/2" plate. Is it a lateral strap that joins the two frame rails together? Sort of a battery/electrical plate on steroids?

Picture shows how it is going to be hard to blend the stock shock plates into the kicked up tail loop.

[calj737]

No, the plate would be the backing plate for the shock studs to mount to. Essentially forming a iangular gusset below the seat rail and to the support leg brace. The stock area is stamped steel so a solid 1/2" steel plate would be cleaner and stronger.

[tacc13]

Ok, something like this?

[BomberMann650]

Thats a nice combo

[calj737]

Ok, something like this?

Lovely.

[540nova]

If you go this route, installing a new shock mount with 1/2" steel, I'd farm it out. That would require a 220v welder, and the forces applied to the weld during use isn't forgiving to mistakes. Not the best situation for a first time welder to learn on.


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[calj737]

If you go this route, installing a new shock mount with 1/2" steel, I'd farm it out. That would require a 220v welder, and the forces applied to the weld during use isn't forgiving to mistakes. Not the best situation for a first time welder to learn on.

Given the stock tubing is 0.060, you won't be using that high of heat to get them together. A beveled edge against the frame and a nice thin root with a cover pass should tie it in quite nicely. Weld both front and back edges against the rails and you should be good.

[tacc13]

I'm trying to do most of the work myself, however I know my limits and can't weld, so am happy to leave this to the experts. There is a gent who works for a high performance auto place here who does private welding work in his own time. More than happy to pay him for the work.