Kz1300 stretch frame mod

Cutting, welding grinding.

I think I would have cut the pipes down, not stretch the frame. the bikes are already long enough.. just a thought.

"Long enough" is relative to the owners taste I guess.

rdbhere2 wrote: "Long enough" is relative to the owners taste I guess.

ABSOLUTELY! I like seeing guys step out of the box and do what they dream up! Nobody else has to like it, but DOING it is the important thing! So many discoveries have come from this kind of "What if.....?" kind of thinking! I love it! Would love to see some close up detail pics of your project!

And, I have a very strong interest in your project since it involves lengthening the driveshaft, too! To keep a long story as short as possible, The question of how to change the final drive ratio of any shaft-driven bike came up about a year ago since there are no aftermarket gear sets available. The Voyager 1300's engine is turning 4000rpm in 5th gear at 70mph, which is actually pretty high revs for the speed, and everybody I know who has owned one has commented that they ALWAYS try for a sixth gear as they shift. What's needed is a higher final drive ratio to bring those revs down, but nobody makes any gear sets to do that. So, what about another bike's final drive with a higher gear ratio grafted onto the swingarm of the Voyager? Ah, ha! A '94 Honda Gold Wing's final drive is the perfect ratio to give 3200rpm at 70mph, AND it is easily grafted onto the Voyager's swingarm! The only "drawback", if you consider it to be one, is that you must use the Wing's 15" rear wheel (Ah, a car tire can be used now!!!), too (Voyagers use a 16" rear wheel). The Voyager's brake caliper is used on the Wing's rotor, but a new bracket has to be fabricated to hold the caliper since the Wing's rotor is slightly smaller diameter.

OK, those are the basics, and my prototype swingarm has already been modified, sandblasted and powdercoated, and the final drive, rear wheel, brakes and shock mounts have been fit to it. It all looks great on the bike and looks ready to go, but there's no driveshaft, yet. The last piece of this "puzzle" is the drive shaft. Of course, the front half is the Voyager's, and the rear half is from the Wing, but they need to be joined together, RELIABLY! Sounds easy, huh? Well, both original shafts are forgings and to cut and weld them together yields slightly less than original strength.

What welding/joining technique did you use to add more length to your driveshaft? Please be as detailed as possible, with pics, please. I have been talking to a local driveshaft shop about this and he agrees that a hybrid, or modified shaft will never be as strong as an original, but can be reliable for all except dumping the clutch at high rpm's from a standing start. My best solution is to VERY carefully weld the two shafts in the middle, keeping them true as your weld progresses, then slide a heavy-walled sleeve over the joint and weld the sleeve at each end. After all welding is done, true them up and have the shaft balanced. That's where we are in our discussions at the shaft shop!

If I can make up a diveshaft that can stand the engine's total power reliably, then I can make these conversions available for anybody who needs a higher final drive ratio.

So glad to see somebody else tackling a similar problem!

Pm'd you trikebldr.

Back when I worked in a "racing shop" we shortened drive axles. Total length when cut would be about 1/4 inch longer than needed. The weld faces were tapered/vee-ed somewheres between 15 to 30 degrees each face: when the weldor approved, I quit.One point was centre-drilled for the other axles pointy end to enter and keep things concentric. The machining and weld set-up were done in the lathe with the centre rest holding the pieces true at the splice. We welded with "Unichrome" a moderately exotic rod for mixed steel metallurgies, with a high stretch factor. Once a good tack is established, pull the steady and place your welds to keep the shaft running true. A good speed shop should be able to do this. Did you wish to be better, there are several manufacturers of high performance axles (look in the advert section of National Dragster or Hot Rod Magazine), who can do the whole shebang in one piece without flinching; case in point our top alcohol dragster. Given the cancer delays I'll be in your footsteps with my 1300A and GL1100.
Lee in frozen Alberta.