Adding ZX10 brakes to my 1981 GPz

[red and black]

I am trying to add late model rotors/calipers to my 1981 GPz1100, while being sure to keep everything reversible, to go back to stock later on.

I am mocking it all on a GPz550, as seen in the pix. So far I have the rotors on. I think these modern rotors really look good on this bike!!

Not sure if I will go with radial or conventional calipers yet.

[gpzrocker]

Nice, I for one would like to be kept informed.

[quader98]

Originally Posted by gpzrocker

Nice, I for one would like to be kept informed.

same here , do you have them mounted to the rim or are they just sitting there ? are you gonna have to fab a bracket to mount the caliper ? more pics please

[red and black]

Ernie-

They are mounted to the rims. This particular rotor has 7 slots on the inner ring, which line up pretty nicely to the holes in the rim for the original rotor. I am going to make up some small spacers so there is no float in the mounting bolts.

I will have to fab custom brackets for the calipers. 20 years ago i had a BMW race car to which I added custom discs/calipers in the rear, and vette front calipers over vented rotors, so I have some experience with brake conversions.

[Polar_Bus]

, that's really good to know that late model ZX10 rotors will bolt right on to GPz wheels. Kepp us informed with details and pics!

[red and black]

Polar Bus;

Not exactly a "bolt right up". I had to machine a groove in the backside to fit over the slight ring on the end of the hub, to allow it to sit flush.
Next step is to make up 7 bushings per rotor to bridge the gap between the shoulder on the bolts and the rotor slots.

I expect mounting calipers to be much more difficult!

[ratvespa]

heh, I was thinking about swapping a whole ZX10R front end onto my 82 GPz1100, I have one sitting at the shop. my only fear is I would have to do something with the rear as well, it would strange with a 17 front and a big skinny rear.

I did a CBR954RR front end swap on my 91 honda hawk 650, it was pretty much a direct bolt on

[Polar_Bus]

Originally Posted by red and black

Polar Bus;

Not exactly a "bolt right up". I had to machine a groove in the backside to fit over the slight ring on the end of the hub, to allow it to sit flush.
Next step is to make up 7 bushings per rotor to bridge the gap between the shoulder on the bolts and the rotor slots.

I expect mounting calipers to be much more difficult!

I run a 3 axis verticle machining center. Send me a detailed drawing, some aluminum, and I will machine up the caliper adapters N/C as a favor.

[red and black]

I rcv'd the calipers this week (late model Tokico 4 piston radial mount), and now I have a problem. The backside of the calipers are right into the spokes of the wheel. The original config had floating calipers, so there is not much metal on the back side of the caliper.
I would have to space the rotors about 10mm off the wheels to allow enough room. I could make up round spacers, but it would be a lot of effort.
Mounting the radial calipers to the forks will take a fat piece of aluminum, but do-able.
At this point I am considering just re-using the stock calipers, with a basic flat plate bracket to shift the caliper outward to accomodate the larger rotor. The pads are a tad larger than the rotor width, but not much. Larger rotors ought to give me some improvement, as I get increased leverage against the wheel.

Now I know why folks just swap to a newer front end.

[red and black]

I now have everything on the GPz1100. After cutting a lot of aluminum, I decided to make the caliper brackets in steel. I know, more weight, but my welding is much better than my aluminum fab skills. Here is one side, 50% done. I will have the brackets powder coated when finished.

[kawpaul]

So you do not have a tig welder.
May I suggest you do the steel ones as mock-ups and cut your aluminum according to that pattern. Then take to a welding shop to have them welded identical to the steel ones.

[red and black]

sorry for so many posts
here is the bracket finished. i cut and ground away much of the unused metal, to cut weight. it is quite rigid, and came out pretty good. I will connect it up, and take a test ride, with the OEM brake on the other side...one side at a time!