1995 GSX600F Wheels on a 1981 GS750E

[Smurf]

Hello,

In an effort to save weight and mount wider tires, I am hoping to mount the wheels from a 1995 GSX600F on my 1981 GS750E.

I have solved the first problem, which was a mismatch between the new wheel and the old speedometer drive. Surgery with a Dremel fixed that.

Wheel bolts on nice and spins nice and smooth with new bearings.

Current problem is mounting the brakes. I had 5mm machined off the caliper carriers at the points where they bolt to the fork legs (red in the diagram) and have enough room now to fit them between the rotors and the legs.

Problem is, the new rotors are 15mm wider than the old ones. I can't mount the old rotors on the new wheel because the center holes are too small and besides, the old rotors are 6 bolt, while the wheels are 5.

So what is your opinion on cutting the carriers some more? I'm thinking of cutting the areas in blue.

Anybody have any other ideas?

 

[HOTT]

I'm assuming by 15mm wider you mean in Diameter?

If so, then lengthening the slot (blue area) is not a problem...

Unless in invades the thru hole for the caliper bolt.

My next question would be, is the caliper deep enough for the extra 15mm?

HOTT

 

[Big T]

Put the entire Katana front end on the bike

 

[salty_monk]

What diameter Are your new rotors? How much wider than stock is your wheel from rotor to rotor?

I suspect your rotors are 300mm in which case you'd need a bracket to move them up and out from the leg.

You may also find that by using the twinpot calipers with the brackets I have that you might have a straight fit with the added benefit of much improved brakes to go with your wider rubber...

 

[TheCafeKid]

Put the entire Katana front end on the bike

What he said. A lot less work, and likely a better fork to begin with. I dunno the width of the Kat wheels but you're likely going to run into a whole heap of other issues if you continue down this path. Caliper offset, rotor offset, spacers, etc etc.

 

[Smurf]

I'm assuming by 15mm wider you mean in Diameter?

If so, then lengthening the slot (blue area) is not a problem...

Unless in invades the thru hole for the caliper bolt.

My next question would be, is the caliper deep enough for the extra 15mm?

HOTT

HOTT,

Yeah, the GSX rotors are 290mm vs 275 for the GS rotors. So I'd have to relieve the blue area 7.5mm. I'm thinking that's going to invade the bolt hole. Maybe try shorter bolts?

I think the caliper is deep enough provided I can get it centered over the rotor.

 

[Smurf]

What diameter Are your new rotors? How much wider than stock is your wheel from rotor to rotor?

I suspect your rotors are 300mm in which case you'd need a bracket to move them up and out from the leg.

You may also find that by using the twinpot calipers with the brackets I have that you might have a straight fit with the added benefit of much improved brakes to go with your wider rubber...

Hey Salty,

My new rotors are 10mm wider than the old ones. And yes, I need brackets to move the calipers up and out. I relieved the red area to move them out. Now I just need to figure a way to move them up. Where would I find twin pot calipers? Would they work with my stock fork legs, your brackets and the wider GSX wheel?

 

[Smurf]

What he said. A lot less work, and likely a better fork to begin with. I dunno the width of the Kat wheels but you're likely going to run into a whole heap of other issues if you continue down this path. Caliper offset, rotor offset, spacers, etc etc.

Yeah, ugly, right?

 

[TheCafeKid]

Yeah, ugly, right?

Well, without seeing it I think the thing I'd be concerned about most is whether or not there's even going to be enough room for everything with the wheel and all between the legs. I'm not for sure either on this, but usually, if you use the entire Kat or GSXR front end a simple steering bearing change and some minor modifications to the steering stops (and sometimes you may have to have the steering stem pressed out in favor of the stock GS stem, which then you wouldn't have to change the bearing type...but neither is difficult) and bobs your uncle. This way everything is matched up and it takes a lot of the guess work and fabrication out of the mix and you know it will work right. The only other major factor is often later model bikes fork legs were significantly shorter than the GS stuff so you could run into ground clearance issues. The solve for that is either a drop top (aka gull wing) top clamp which would gain back some lost length of the shorter fork/smaller wheel combo, or some guys have doubled up the top clamp and had them welded together. Not exactly pretty but it'll get the job done.

On the other hand, if you're into this just to see if you can do it and don't mind the work, with enough money, patience and thought, I'm sure you could make it work. Personally, I'd rather make it somewhat easy and look like it was stock, and have more time for riding it

Good luck either way, sounds like a fun project and there are many here who will say that with some upgrades to the wheels, brakes and suspension components, you simply couldn't buy a factory bike that handles as rides as nice as these do without breaking the bank, if it all anymore since Americans are stupid and only like boring cruisers or razor sharp uncomfortable super sports anymore....

 

[Guest]

The gsx600f front end on my '83. The only thing i had to do anything with was the steering stops and that was easy as drilling and tapping two holes for bolts. The rest bolted right up, same bearings. Here is a picture,

 

[Guest]

Side view with matching rear wheel, plenty of ground clearance too.

 

[Smurf]

King,

That is awesomely sweet-looking. Now I just need to find a front end!

 

[Guest]

This is how it looked last year, and soon it will have a '92 gsxr 1100 swingarm on it. Has an rf900 front end with 1100 gsxr wheels on it now.