Lighter/newer rear brake and rotor, GSXR/Busa swap onto GS750 spoked wheel?

[Chuck78]

Instead of freshening up my stock rear brake and drilling out an 80's GS1150 rotor even more to save weight, I was wondering what more modern rear brake and disc rotor I can swap over to that will bolt up to my axle and wire wheel hub, and have the correct rotor spacing and hub bolt pattern???

I had read of GSXR, Hayabusa, and Bandit brakes being an easy swap. Looking into photos of an '88 GSXR750, it appears that they will all be of the underslung variety, and I see that the calipers must remain that way as to orient the bleeder on the top. The pleasant part of this is that I won't have to weld a brake stay hanger onto the bottom of my aluminum GS1100E swing arm as some have done, if I stay in the GSXR fashion, as they run the brake stay all the way to the frame. I'd much rather weld on the steel frame more than to touch the 1100E alloy swinger.

First off, I wondered if anyone could give me any real figures on weight savings? I'm not looking for more stopping power (rear locks up too easy as-is), just weight savings. Maybe lowering the center of gravity with the underslung brake will help handling? Maybe the underslung placement and frame mounted stay improves the handling forces under hard braking? Maybe both, I suspect the latter is more pertinent.

Of the few modern brake threads I have read, most seem to be running modern 17" cast wheels. I am looking for a rotor that will bolt up to my spoked wheel hub. Any help there? This seems to be info that has not been touched on here as far as my half hour of post searching has turned up nothing.

Thanks!

 

[Chuck78]

I'm afraid that the GSXR/Busa brackets will probably all be for a smaller diameter rotor than the stock size on the old GS rear discs. I think it would be beneficial to downsize diameter slightly, but finding a rotor with the original GS 6 bolt pattern in the correct diameter and offset could be a problem, but maybe since modern lightweight floating front rotors from many manufacturers (Honda, Yamaha, Suzuki) come in a wide variety of sizes and offsets in the 6 bolt pattern, I may have luck finding a front rotor that will fit the bill?

http://www.ebay.com/itm/130704447326

That's about all I can come up with for a rear rotor that is 6 bolt, zero offset, but I haven't gotten any specs on PCD or diameter.
I measured the rear rotor that came on this 80's GS1100/1150 drag bike rear spoked wheel which I believe is the dimension as the stock rotor on my 77 GS750B rear (the later has a nice drilled fan pattern), and it comes out at the standard 78mm PCD and 22mm offset, but in a 274mm diameter. Seems as if it may take a custom bracket to bolt up just about any rotor when using the modern calipers. Ideas?

As far as the modern rear caliper swap goes, seems as if these will work, from old posts that I dug up:

Rear rotors and calipers
Hayabusa all years
'88-'95 GSXR 750
'89-'98 GSXR 1100
'01-'05 Bandit 1200
'98-'05 Katana 750
RF900 all years
I know the GSXR caliper hangers for the years above will work, I'm not sure about other years or models.
On the GS700 you need a Katana 600 hanger due to the smaller axle size.

I found rwcfrank's build thread, and he has a Bandit 600 caliper mounted on a custom bracket with what looks like an old heavy GS1100 rotor, and seems to be a front rotor as well, mounted on the rear? I'm checking with him on details. This could confirm my suspicion that a modern front Honda floating rotor could potentially work on the rear. http://www.thegsresources.com/_forum/showthread.php?t=199072

 

[Chuck78]

Direct bolt on, same diameter, but zero offset:

Rear Brake Rotor Suzuki VS1400

This is the best thing I have found so far, and there are a few decent looking rotors available for it. Custom bracket may still be in order, but a lighter rotor like this is still probably lighter even with a hub spacer. Most of them look to definitely be a zero offset type. I am thinking the stock 22mm offset may be better unless the brake stay arm is re-routed or arched quite a lot, to avoid tire clearance.
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[Agemax]

get a rear caliper and mount from a gsxr1100 like this one....

http://www.ebay.co.uk/itm/Suzuki-GS...22?pt=UK_Motorcycle_Parts&hash=item460789bb56

then fab a location bracket and weld it to the swingarm. eliminates brake stay arm altogether. thats what i did on my GS1000

 

[limeex2]

lighter rotors and calipers to spoked wheels

lighter rotors and calipers to spoked wheels

I would be interested also. My front wheel weight is acceptable, but the rear is very heavy. Not sure about mag wheel conversion as I don't want to deal with the unseen issues with handling/ground clearance. I made swiss cheese out of original rotor. I like the idea of running the caliper on the bottom, lower center of gravity, looks trick. This was my old race bike and handling was acceptable back then, so for street use, maybe a track day, it will be fine