Frame bracing, boxing vs tubing.

[Spiff]

Hi again, been a few years since I was last on this forum, still haven't finished my gs but hoping to get there now. So tomorrow I'm starting to brace my frame.
I've been reading this; https://oldskoolsuzuki.info/archives/315
And I see it's a 60x20 1mm box steel that's recommended on the B C and E bracing, but what if I can't find that? Can i use steel tube instead? Or make a box with 1mm steel sheet?
I see both boxing and tubing being used online but I don't know about the pros and cons, I'm sure anything is better than nothing at this point but I wanna do it proper when I'm first gonna do it.

And if anyone is wondering why I'm doing this I'm fitting a sv1000 front fork and a bandit 1200 rear with ?hlins shocks so I think it's for the better.

 

[salty_monk]

You can fold those box sections out of sheet. No reason why not. look at the plane of the forces. You could also just use a single thicker plate and get most of the same benefit with a lot less hassle (that's what Suzuki do as stock on where they brace the frame)....

 

[Guest]

I used a mixture of round and rectangular tubing when I braced & monoshocked my frame. I can say it definitely reduced the "hinged in the middle" feeling of the flexy stock frame. It's never going to be as stiff as say a modern sportbike frame, but is definitely an improvement over stock.

 

[kochic]

I used tube, 16g plate and one piece of tube between the swingarm pivot where I added another engine mount.
Its a work in progress.
Marc

 

[kochic]

these are made with 16g plate.
Marc

 

[kochic]

under the tank.
Marc

 

[kochic]

another picture.
Marc

 

[kochic]

Aluminium engine mount, more than 1lb lighter.
Sorry for the small pictures, I know how to post bigger pics.
Marc

 

[Spiff]

Thanks for the replies, I think I'll just fold some sheet metal for the box sections B and C and use tubing for the rest.

Made the front one today

 

[Buffalo Bill]

Cool thread!
Just like to know if any of these bikes were built for racing?
Because reducing weight is important for race bikes.
Thanks.

 

[Rijko]

Cool thread!
Just like to know if any of these bikes were built for racing?
Because reducing weight is important for race bikes.
Thanks.

A lot of these modifications were done by Yoshimura on the GS1000 racers of the time.
They had powerful engines in a factory (touring) chassis that needed to be stiffened
to handle that power.
Reducing weight is important, but more of a thing that came later on when
technology and knowledge combined to create stiffer and lighter frames.

That is the reason manufacturers like Nico Bakker, Egli, Rickman etc were
big - they were the pioneers that created lighter and stiffer frames for those
engines.

The factories picked up on that quickly, copying and improving on those designs.

 

[Spiff]

I'm hoping the removal of the stock seat and rear of the frame along with aluminium rear swing arm and a lifepo4 battery pluss removal of any unnecessary stuff is gonna negate whatever little weight is put on by this

 

[kochic]

Are you building a 750?
Marc

 

[Spiff]

Are you building a 750?
Marc

That's right!

 

[Spiff]

This was exactly what I need. Homemade easy plate brake!

https://mistrymaketool.com/Home/PostDetail/31

 

[kochic]

I made this with scrap metal for the boxing.
Marc

 

[kochic]

from a flat plate to this.
Marc

 

[GregT]

Cool thread!
Just like to know if any of these bikes were built for racing?
Because reducing weight is important for race bikes.
Thanks.

If you're using a modified stock frame it's still a trade-off. Modern tyres have made frame stiffness even more important. From my experience and watching others, the period style bracing is nowhere near complete enough for modern slicks. The lower frame rails are not touched in the old model bracing. I've gussetted the area where the front crosstube joins the downtubes - and the area where the rear crosstube behind the motor joins the lower cradle tubes.
Just folded 2mm sheet in an "L" section. This is enough to stop the front downtubes "scissoring" under lateral loads. The steering head area is better than Z1's - but that's not saying much.

Talking to the guys involved with running the Team Classic Suzuki Katana in the IOM 2 years ago, the disadvantages of running what is actually a replica of a stock frame vs the purpose built XR69 replicas became apparent very early on. 119MPH laps represent shall we say, very large gonads.....Better suspension and geometry show up very quickly on the IOM.

 

[kochic]

I've gussetted the area where the front crosstube joins the downtubes - and the area where the rear crosstube behind the motor joins the lower cradle tubes.
Just folded 2mm sheet in an "L" section. This is enough to stop the front downtubes "scissoring" under lateral loads.

Do you have a couples of pictures?
Any help is welcome and thanks to the OP for the thread.
I will relocate the headstock and brace the frame between the lower front crostube too.My first plan was to use 2 tubes in a V between the crosstube and the OEM bracing under the headstock.
Marc

 

[GregT]

No, sorry lost the pics I had. Bike's at the owner's place now.
The gussets were simple triangle folded sheet, about 50mm on a side.

I wouldn't have thought there'd be room for an X brace under the steering head with the pipes there.