Subframe Fix ????

[OB_maui]

yes, I suggested this on LA Busas a few weeks ago.

 

[Guest]

Wait until it happesn.... Hopefully you will not get hurt much.... Then sue Suzuki for all their worth.... Just Kidding

 

[OB_Johnnycheese]

I guess you can't read the frame states NO welding or drilling of the frame

 

[OB_speed]

I looked at my subframe. It looked to me like it might be the welds on the sub frame that are failing ? Mine looked okay but I could see how a bad weld on that sub frame might produce a weak point since its not one solid piece.

just an opinion

 

[OB_maui]

JC, I'm sure that's a liability issue. If they do fix the frame, you can bet they'll be welding it to fix it. I think Dana T mentioned that the busa's main frame was t70, which in most cases, you can't weld, he went on to say that the material used in the Busa appears to be a weldable form. The sections in the rear were the failures are occurring look like they're T6061, which most competent TIG welders should be able to weld.

 

[OB_BarryW.]

I'm with JC. Not knowing the exact alloying composition and heat treat of the subframe, I'd be leary of just cutting and rewelding it. It probably needs to be redesigned with better geometry to lower the stress concentration at the point of failure. Welding a carefully thought out gusset at the weak joint should work.

I haven't heard exactly WHERE they're failing...does anyone know?

 

[OB_maui]

if you look under the seat, there are two tube sections welded to a castings. The casting is the boss used to bolt to the frame. It appears that the castings are failing, not the welds, or the tubing.

 

[OB_maui]

unfortunatly this site does not support photo entry's but try this:

http://albums.photopoint.com/j/View?u=378619&a=4790898&p=24970057&Sequence=0&res=high

http://albums.photopoint.com/j/View?u=378619&a=4790898&p=24970928&Sequence=0&res=high

http://albums.photopoint.com/j/View?u=378619&a=4790898&p=24970926&Sequence=0&res=high

the area I'm pointing to is between the threaded boss, and the weld. Replacing this casting with a billet piece makes sence to me but I'm not an engineer. I would turn the end to fit inside the tube section, about .750", then weld.

the tubing is about .788 O.D. I'm not sure what the I.D. is though.

[This message has been edited by maui (edited 24 July 2000).]

 

[OB_BarryW.]

Maui,
Thanks for the pics. Man, I assumed they were cracking at a weld. If they're breaking in the cast piece, some engineer at Suzuki is in for a shiTstorm. Having seen the piece, I think your idea would work. If there's radial clearance, you could even machine the new piece to have a stub on it the same OD as the tube (and a smaller stub to pilot in tubing ID) and then make a collar to slide over both pieces which you could then weld at each end. Or you could cut a slot the length of the collar and weld the full length of the collar in addition to the ends. Oh well, you're probably a better TIG welder than me and that skill will ultimately dictate how well any redesign works in aluminum.

Bottom line is this should be on Suzuki's list of things to recall and make straight, so that we don't have to re-engineer our bikes just to keep our wifes/girlfriends from falling off due to chassis collapse!

 

[OB_Gary Evans]

They are breaking in the cast pieces at the front of the top two sub-frame connections. If I were to attempt a fix it would be to replace these with parts machined from billet. I sure wouldn't do anything like that until the smoke clears at Suzuki and we see what, if anything they are going to do. These fittings are under both tension and bending loads when there is weight on the riders seat. So far there is no evidence of failure w/o luggage but, it appears to be a weak point regardless. I posted a previous explanation of a temporary safety fix if your interested.

 

[OB_DaveD]

Sorry if I appear to have an obsession with this, - but I had an idea how to prevent the potential subframe failures that have been variously reported.

Would it be possible to saw off the cast sections of the subframe (the bits that break), and weld billit sections in their place? the thinking is that billit = stronger than cast right?

Any comments bigabusa/The Motorhead/any metallurgy guys?

 

[OB_DaveD]

JC the manual also states that passengers and luggage can be carried, without the bike folding in half!

Thanks for your comments guys: the I might try the billet idea if Suzuki deny there's a problem (which I'm half expecting!)