Converting to dual front brakes on '79 KZ750?

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17 Sep 2008 07:06 #237489 by grndprix69
I was wondering if the front brakes on a '79 KZ750 TWIN can be coverted from single disk to dual disks. If so, how complicated would it be?

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17 Sep 2008 07:54 #237503 by Sandy
Pretty sure the other fork-leg has the bracket mounting points.
You'd need another caliper(obviously)...remove the cover(on the hub) that covers the holes for the other rotor(should have one on the twin).
You'd have to flip one caliper bracket around,to get another caliper on there,and then you'll have to make up another section of hard-line,or maybe Jeff at Z1 has brake-lines that will bolt right up.

You'll need to adapt the second line,up at he splitter,under the lower triple-tree.
Right now,I have 2 lines tied into a single outlet.I used a longer banjo bolt,but this winter I'll be installing a dual splitter,now that I have one.
Don't get me wrong,it works great,but it just doesn't look symmetric,that's all.Plus,I'm replacing the line from the master,down TO the splitter,so while I'm pulling it all apart,I'll replace the splitter.B)

1977 KZ1000 A-1

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17 Sep 2008 08:29 #237507 by MFolks
If you are doing brake lines and if not done so, consider upgrading to braided SS lines as the older rubber ones age and crack and will expand as you pressurize the braking system.

1982 GPZ1100 B2
General Dynamics/Convair 1983-1993
GLCM BGM-109 Tomahawk, AGM-129A Advanced Cruise Missile (ACM)

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17 Sep 2008 13:04 - 17 Sep 2008 13:05 #237543 by bountyhunter
Replied by bountyhunter on topic Converting to dual front brakes on '79 KZ750?
Just checked mine: the RHS fork has mount holes but they don't look like they are threaded.

That big front disc is so massive I'm not sure why you would need a second one. It already has way more braking ability than the rear.

1979 KZ-750 Twin
Last edit: 17 Sep 2008 13:05 by bountyhunter.

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17 Sep 2008 19:02 #237573 by steell
If you were to ride my 79 750 twin, I'm reasonably certain you would no longer think a single disk works good :)

You want a front brake system that will out stop any Kawasaki up through at least 1985, and you want it cheap?? Read on :D


79-80 KZ1000 brake rotors, thinner than single disk rotors, drilled for even less weight, 12" diameter, and they bolt right on the stock wheel.

83-85 GPz750 brake calipers. These are normally on a 10" rotor on the GPz's, but they bolt right on the 750 twin forks.

95-96 GPz1100 front master cylinder. Buy it used and rebuild it, no shortcuts, rebuild it, or I will hunt you down and dope slap you into the middle of next year. I didn't rebuild mine, I got lucky and no one was seriously hurt, rebuild any used master cylinder you get.

Stainless steel braided brake lines and fittings from Dennis Kirk, the single most expensive item involved.

Z1 Enterprises has the rebuild kits and brake pads.

My Nephew's 85 GPz750 Turbo will easily out run my 750 twin, but it don't come anywhere near stopping as fast as my 750 twin does. :)


I have never tried to squeeze the brake lever as hard as I can, it would either do a stoppie or lock the front wheel if I did that. It's flat out amazing how well it stops now, absolutely no comparison to a stock 750 twin, or a dual disk 750 twin using KZ1000 calipers and master cylinder (that was my first attempt at improved braking).

Total cost was $200-$250.

KD9JUR
The following user(s) said Thank You: damarble, perper

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17 Sep 2008 21:55 - 17 Sep 2008 21:58 #237584 by bountyhunter
Replied by bountyhunter on topic Converting to dual front brakes on '79 KZ750?
I don't know how much stop you need, but I have a very distinct memory really standing on the brakes once and my body shifting forward until my face shield flattened against the windshield (I was not able to push back). I didn't dare let off the brakes to keep from going into the back of the idiot who had just pulled in front of me, but I sure remember the brakes really stopped fast.

The brake systems that use multiple discs increase the heat dissipation of the system so the brakes will handle more heat before they fade. I think a single disc will easily "stop" hard enough to lock the front wheel.

1979 KZ-750 Twin
Last edit: 17 Sep 2008 21:58 by bountyhunter.

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18 Sep 2008 13:03 #237636 by fixer5000
Replied by fixer5000 on topic Converting to dual front brakes on '79 KZ750?
i added another caliper and changed the master to the larger bore a coupla years ago. a lot of people will say the added weight isnt worth it but now this thing stops very well indeed!! as in whoa..i think youll be glad you did it and its easy to do...steve

1978 kz650b pretty much stock
\\\\\\\" get there fast but arrive alive \\\\\\\"
massachusetts

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18 Sep 2008 17:05 - 18 Sep 2008 17:24 #237662 by steell
Started off with single disk front brake on 79 twin, actually, single disk front brake on 79 750 twin, then 80 750G twin, then another 79 750 twin, and absolutely none of those would lock the front wheel, and I hammered the front brakes hard.

Here's the situation, I live on a State Highway in a rural area, it's not uncommon for cars to exceed 100 mph going past my house. I have picked up loads of busted plastic and some metal out of my front yard, due to someone being rear ended by some moron talking on a cellphone, when someone was turning in my drive, or the drive across the street (small business).

So, my procedure is to flip on my turn signals 1/2 mile away, run 60-70 mph right up to the edge of my front yard, hit the shoulder and slow as fast as I can, so I can turn in my drive without getting killed. I pretty much do a full emergency stop every time I come home and there's traffic behind me.
Worked out great so far.

Single disk front brake wouldn't even make the front tire howl. Dual disk KZ1000 front brakes would make the front tire howl. Current dual disk brakes make the front tire scream uncle :D

Back brake is near useless under these conditions, there is so little weight on the rear tire that it locks up if I even touch the brake pedal.

My size may have something to do with it, I'm 6'3" and 235 lbs, and it takes more brakes to stop with the extra weight over someone that weighs 150 lbs.

While looking for something else in the parts diagrams at kawasaki.com, I decided to see what else used the same calipers and master cylinder that I'm using on my 750 twin.

I was surprised to learn that I basically grafted ZG-1000 Concours front brakes onto the dual 12" rotors on my bike. How about that! I accidentally did something right :D

KD9JUR
Last edit: 18 Sep 2008 17:24 by steell.

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19 Feb 2012 12:14 #505031 by newkzfan
Replied by newkzfan on topic Converting to dual front brakes on '79 KZ750?
Does anyone know of a symetrical 4 way splitter, one port for master cyl, two for brake lines and one for the brake light pressure switch?

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19 Feb 2012 12:24 #505037 by jonnybravo
Replied by jonnybravo on topic Converting to dual front brakes on '79 KZ750?
change front ends, dont know for sure but i would bet a 750 4 cyl front end should work

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19 Feb 2012 15:23 #505086 by M357.5

newkzfan wrote: Does anyone know of a symetrical 4 way splitter, one port for master cyl, two for brake lines and one for the brake light pressure switch?


Baja Designs and other companies sell brake light switch banjo bolts. I've used them for years, on my Dualsport bikes and on my streetbikes. They are cheap and easy. Cant say I've ever seen a 4 way splitter.

83 KZ750L X2 + goodies = Project
84 KZ750L the mini ELR replica replica lol
84 ZX750E Turbo modded n' FAAAAASSSSSSTTTTT
85 GPz900r GREEN N' MEAN

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19 Feb 2012 17:54 #505106 by faffi
I'd prefer to run twin hoses from the master to the calipers without any splitters if it was my bike.

If your brake cannot lock the front wheel, you need more stopping power if you want to stop as quickly as possible. Most brakes, however, can lock the front wheel. So what does an upgrade to twin discs bring then? No more twisting of the fork and typically less fade. And usually lower effort, which again can make it easier to modulate. You probably save a couple of tenths going from no brake to maximum braking effort since less effort is needed. This will also lure the brain into thinking the brakes are stronger than they perhaps are since our brains is very poor at judging absolute acceleration, only how rapidly it changes. So if you go from zero to 1G in retardation in 1/10th of a second instead of in a full second, the former will have you believe you're stopping harder all the way compared to the latter.

However, a single disc with high friction pads and braided brake line should stop your bike plenty hard. At least until it fades.

1977 KZ650B1
1980 F1 engine
B1 3-phase alternator
B1 Points ignition

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