UK_Lee's guide to fitting a different subframe

OK, I fitted a Y2K gxixer seat unit and subframe on my '89 GSXR 7/11 'fighter project. It doesn't matter what frame your gonna fit it to, as the basic principle is the same.

I decided to do it the following way for several reason.

1) Use the subframe that matches the seat unit - everything will bolt right up, with no problems, you can keep the matching front and rear seats, the seat locks, undertray etc, and all the little detail things that people overlook, like helmet hooks, and a battery tray, somewhere to put your bits 'n' bobs are all there.

2) Should the worst happen, replacement is simple. Cuz your using a stock (un modified ) subframe - a new one will bolt right on in it's place

3) Any aftermarket goodies meant for the donor, will fit easily to your bike too, like a trick undertray,funkey replacement lamps, a pillion seat ( or seat cover),pillion footrests or even those 'off the shelf' twin underseat exhaust conversions etc

4) Done with a little care & attention to detail, it'll look like a pukka 'factory' job.

Here's how i did mine...
this is what you'll start off with
get the stock bodywork off
The next stage, is to cut off the existing subframe, and remove all traces of any 'lugs' etc, from the spars of the main frame.
Bolt the seat unit to the subframe and 'mock' it up on your bike ( i used bits of wood & metal straps ) until your happy with the position of the seat unit.
Next use some thick cardboard to make the templates for the tabs that will need to be welded to the frame, to accept the new subframe. Once they are spot on, cut them out of some thick ( i used 1/2" ) alloy plate, and once they are shaped and in the correct postion, you can get them welded to the frame.
You can see that compared to the old subframe , the lower rails of the Y2K one line up nearly exactly with the main spars of the Slingshot GSXR frame - thus , the lower 'tabs' are dead easy to fabricate . The upper rails of the Y2K subframe are roughly 1/2" too far inboard , and as the main spars of the Slingshot frame kinda 'slope in' just at the point you need to attatch to , the upper tabs are slightly trickier to make - needing a bit of a twist , as well as an offset. DO ALL YOUR TEMPLATES IN CARDBOARD ! time spent here getting the templates EXACTLY right , will pay dividends later on ! .
I then cut the fuel tank mounting strap off the original subframe , and re used it on top of my new 'frame tabs' , using the fuel tank to hold it in postion whilst i welded it onto the tabs
I also extended the fuel tank with a couple of 'ears' so that the tank blended in with the seat unit, and also covered most of the upper tab - this got rid of that ugly gap which often remains when fitting a non standard seat unit. It was easy to do, and the result was exactly what i wanted to acheive
Once all the cutting, shaping and welding was sorted, i tidied everything up with a good polish.
Now all the hard work is done, and the panels are back from the painters, you can sit back and admire your handywork !
 
I think it looks great !, and there's even room for a 'sting' in the tail

Well, Almost ! - I'm using a 5 lb NOS bottle, and only a little bit pokes out behind the numberplate - i covered it in Carbon Fibre to match the undertray - Stealth or what ? !!
So there you go, hope this helps you guys who fancy doing a similar mod.
If you've got any questions or comments good or bad ) lets hear 'em !!

UK-Lee