[pwrslv]

Hey!

I've recently bought my first big bike, a sc33 900 rr fireblade and immediately tore it apart to make it more aggressive and fighter looking.

I disassembled the bike completely, powder coated the frame and the rims, painted everything else bymyself and also adjusted the valve clearances.

I decided to go with the 2007 R6R tail section and to do the subcage myself. I had in mind that I will have a passenger riding with me. The tubing is 20x20 with 2mm wall thickness. The angle is not yet determined as I accidently ordered a R1 seat and not R6 so I have to wait for it to arrive before welding more.

What do you say? Should this thing be able to support me and a passenger? Anything else I should be aware of?

I planned that I will cut two slots on the upper surface of the lower tubes to sink the cross support in to the lower support tubes, resulting in tighter alignment and a better weld seam. What do you think?

 

[Guest]

Hi & welcome

With a 2mm wall on box section I would think the main problem would be strain on the fittings & weld where it connects to the main frame, there is a lot of leverage acting on those joints, I would also be worried about flex at the rear, if the 2 pieces are welded together that may be reduced

I cant see how you have connected the subframe to the main frame but just drilling & bolting it through is not good enough imo

Also I would not cut any slots in box that thin as you are losing part of the wall & therefore strength, a good tight butt joint would be better for the cross piece imo

I did a similar shaped subframe on my last project but in tube & added another support which went back under the tank for the reasons outlined above

I hope that helps

 

[pwrslv]

Hi & welcome

With a 2mm wall on box section I would think the main problem would be strain on the fittings & weld where it connects to the main frame, there is a lot of leverage acting on those joints, I would also be worried about flex at the rear, if the 2 pieces are welded together that may be reduced

I cant see how you have connected the subframe to the main frame but just drilling & bolting it through is not good enough imo

Also I would not cut any slots in box that thin as you are losing part of the wall & therefore strength, a good tight butt joint would be better for the cross piece imo

I did a similar shaped subframe on my last project but in tube & added another support which went back under the tank for the reasons outlined above

I hope that helps

Thanks a lot for your input.

The rear fairing is quite narrow so it really cuts down the choices of how to make the subframe. The subframe is connected to the main frame by four 10mm bolts.

If cutting a slot is a no no, I guess I'll have to remove the welded cross support and weld it back after I have welded the upper and lower tubes together. Does it matter if I weld couple of small beams or a long beam? Long beam would be the whole length that the upper and lower tubes hug each other.

Also I forgot to mention that the lower tubes are not yet cut into the correct lenght and they will be approximately the same length as the upper tubes.

How could I make the subframe stronger? Should I get some tube with thicker wall or add some supports?