TOPIC:

I'm doing an upgrade on the front of my next project 1000; I've got a set of stock 1980 ltd calipers, they are 12 5/8 inch diameter and 5lbs12oz or a set of newer sportbike calipers (suzuki) that are 10 1/4 inch diameter and 4 lbs 3 oz each. I'm also upgrading the calipers to. The question is, does that extra inch in diameter make the kz rotors worth the extra weight or would it be negligable?

Id keep the big rotors and use newer gpz style calipers with them.

Unsprung weight is a factor worth dealing with. 12 5/8? Mine are 11 1/2. All tolled it could make a difference in handling and ride. That's why I bought the LTD drilled rotors to make up the difference of my H2 calipers. The drilled rotors are almost 1/2 the weight and the H2's are heavier than stock. They have high spots I have to remove to use them.
Steve

I've got some tokico twin piston calipers off a ninja, they seem to be a third of the weight of the kz calipers, more pad surface area, it's either the newer rotors or machine a ton of unused pad area of the kz rotors.

Yeah, i think I meant 11 5/8" for the kz rotors

check with steele,hes running the gpz calipers on his bike.

I changed my stock LTD rotors, to 78 Z1R rotors, more holes, lighter, better stopping
Pete

That's a lotta holes there Pete

I guess I'm getting more religious ....more HOLY !!
Pete

If you are trying to loosen a tight bolt, do you use a 4" long wrench, or the 2' one?
It's all about leverage, the further away from the axle a caliper is, the more leverage it has against the rotating tire/wheel assembly, the easier it is to stop. The bigger the rotor diameter the better the brakes. Buell takes it to the logical maximum with it's peripheral brake rotor and small caliper mounted on the inside of the rotor.
Single disk KZ models use a thick disk, dual disk models use two thin disks. If you use two thick single disk rotors in a dual configeration, you will notice the difference. It takes longer to stop.

Two 1980 KZ1000 drilled dual disk rotors and a pair of 83-85 GPz750 calipers on the front of my 79 KZ750 twin. It stops so hard I wonder if the handlebars are going to bend forward or the rear wheel come off the ground.

I don't agree. In the day duel single disk rotors was all that was available but added a ton of weight to the front wheel. Stopping was better but an unbalanced tire was a wild ride. I still have mine. I can lock up my front tire even with the larger one. No more room for anything more. I have late model disks but need to have them milled. High spots.

swest wrote: I don't agree. In the day duel single disk rotors was all that was available but added a ton of weight to the front wheel. Stopping was better but an unbalanced tire was a wild ride. I still have mine. I can lock up my front tire even with the larger one. No more room for anything more. I have late model disks but need to have them milled. High spots.

Whether or not you agree is immaterial, facts are facts and physics is physics.
And disagreeing with either is just like masturbating, feels good but changes nothing.

steell wrote:

swest wrote: I don't agree. In the day duel single disk rotors was all that was available but added a ton of weight to the front wheel. Stopping was better but an unbalanced tire was a wild ride. I still have mine. I can lock up my front tire even with the larger one. No more room for anything more. I have late model disks but need to have them milled. High spots.

Whether or not you agree is immaterial, facts are facts and physics is physics.
And disagreeing with either is just like masturbating, feels good but changes nothing.

Thanks for the snarky answer. I have two 11 5/8 thick disks and H2 rotors. They stop great. Maybe not better than yours but better than one. Like I said, I'll be putting late model thin, drilled rotors on when I have them turned. I could have these drilled and milled down and I might have to if the others can't be saved. I'm staying with the vintage look.
Steve