'77 GS750 Front-End upgrade with a 850/1000?

[twist-throttle]

Almost a year ago I bought a '77 GS750 for only $75. It had sat in a garage for the last 15 or so years. Very slowly I have been working on getting the bike back on the road.

Currently I am researching my plan to upgrade my front end. The stock front end is a single disk, spoke rim, 35mm tubes with the axle mounting underneath the tubes... instead of leading in front of the axle.
So far I have bought a used GS1000 master cylinder off of ebay, off hand I don't know if it came from a dual or single disk GS1000. Also I have installed a braided stainless steel brake line & rebuilt the caliper. The rotor itself likely needs to still be turned down or honed from all the miles on it.

But to my point on my upgrade. First off, my fork tubes are rusted through the chrome & they would rip through new fork seals (they are more rusted then the attached image shows). Secondly, I would like to upgrade to the dual disk setup. Finally, I would like to get some larger diameter tubes as well, this is because I plan to "relatively" sport ride the bike, plus these 35mm just look tiny compared to the modern bikes I'm used to.
I plan is to run either clip-ons or a "low" Superbike handlebar.

I have thought about doing the GSXR conversion, but primarily because of money, I am going for more authentic look, yet with some performance improvement.

My plan is to also buy a pair of the original Suzuki star mag rims... so they will be stock size.

So this finally leads me to my question. I am now thinking that I should find some 37mm tubes (without the anti-dive) from a 1000 or 850 that have mounts for the dual brakes. Of course this means that I will need to buy matching upper & lower triple clamps. Also, I plan on using the stock gauges that mount to the top triple clamp.

What model & years of bikes should I be looking for that best meet my criteria? I have read about some 850's having their fork tubes spaced further apart or possibly not finding fork springs for them.
Also, what models have the axle mounting below the fork tubes, I would prefer this instead of mounting in front of the fork... I think underneath looks better if for no other reason.
Oh, and at this stage of research, I think that I'll be doing the "ninja caliper" mod found elsewhere on this site.

Thanks for your time & opinions.

 

[dardoonk]

twist,
Check the thread on my rebuild. I just put an 83 1100 front end on for the same reasons you said

I posted this awhile back;
What you need for the swap I did

 

[twist-throttle]

Dardoonk,

I came across that exact set of posts just yesterday. Incredible job on the bike! Like some others, I have taken inspiration from your work.

Yes, it looks like the GS1100 front-end would meet my goals, except that I'm reluctant to install a set of forks with the anti-dive on them. The anti-dive seems like quite the hot spot for debate. I believe that you can just "inactivate" the anti-dive, but I'm not so sure that I want to get into that when there are forks out there without the anti-dive already. But I'll admit, if for nothing else, the anti-dive does add a little additional mechanical flair to the forks visually.

I do have a question for you on your suggestion... isn't the rear wheel from the GS1100 a 17", versus the 18" that was original on our bikes? What size of tires did you install on yours front & back?

I appreciate your reply, I've already printed out your links for further reading/review... thanks for the bearing sizes as well as I'll need that info for sure.

Again, you have done an awesome job with yours, thanks for sharing your work & knowledge.

 

[jknappsax]

My kit for upgrading the front end of my 1978 GS 750

My kit for upgrading the front end of my 1978 GS 750

I had assembled all the parts to do a front-end swap to dual front discs on my 1978 GS 750, then decided to go with a GSXR front end and wheels, and a GS1000. I bought a GS 650 front end from Duaneage, 35mm tubes that will slip right into the original 750 triple-trees ( I had already upgraded the steering-head bearings to tapered rollers). They are 3/8" shorter than the 750 tubes, which will speed up the steering slightly, and the Progressive springs from my 750 had needed 1/2" spacers, which they won't in the 650 tubes. I also have two slotted discs for the front, a cast tubeless front wheel, the right-side caliper and E type front master cylinder and all the lines. I'd done a lot of research, and assembled all the pieces to do the swap this winter, then last year bought a 1979 GS 1000, and decided on the GSXR upgrade. If you're interested in this package, PM me and we'll talk.

 

[dardoonk]

Dardoonk, What size of tires did you install on yours front & back?

I do not know what model my wheels came off of. They were on the bike when I bought it.
Sizes are as follow:
Front: 1.85x19 wheel & 100/90x19 tire
Rear: 2.50x17 wheel & 140/70x17 tire