Work in Progress: Z1b brake upgrade

So I've been working off and on on this side project for the past month or so.
My '75 Z1b currently has dual disc brakes up front with braided lines and stops more or less well enough. I still wanted to kick things up a notch but the AP racing conversions for spoked wheels are pretty expensive ($800+). I wound up being guided in the direction of the dual piston EX500 calipers that the H1/2 guys use. There are adapter bracket templates floating around that you can copy and use to mount the calipers on a Z1 fork.

Adapter template:


Now, EX500's were only single disc. Luckily that caliper was used on many different bikes in the past 30 years so I picked up calipers from a 1987 ZX750F.
I had one adapter made up to check that everything fits and loosely bolted things together:

There was full pad coverage of the disc and it centered ok.
Other forum members brought up the issue of rotational forces on those two adapter-caliper bolts being located so closely together so we adjusted the template to space them out a bit:



Of course why stop there when you can just have a full length bracket that mounts the adapter to the two stock mounting points of the caliper:




Now I just need to have some new lines made and rebuild the calipers.

If anyone is interested, I can have more adapter brackets made easily enough.

When I had a 72' H2 and was on the 2-stroke Forum a lot, I upgraded my H2 with the EX caliper and used the same mounting bracket pictured. Worked well and nice upgrade.

Calipers dismantled, ultrasonically cleaned and wiped down with brake cleaner. I was able to pull out one calipers pistons with rubber and pliers, but the second one needed a different approach. I had pushed the pistons all the way in (to facilitate test fitting) so couldn't get purchase on them. Normally I use a grease gun to force the piston out, but since these weren't frozen I used a gradually increasing stream of compressed air to gently force them out. Safety first.



Tomorrow I'll grab some paint. I'll paint the brackets black and the calipers either grey or black.

I have custom lines and some semi sintered pads coming from Galfer.
All I need to do now is clean up and lightly sand the discs.

Rebuilt the calipers with a brake crafters kit. Hit them with some caliper paint as well:





Calipers mounted up perfectly. I flushed the old MC and line splitter with methylated spirits, added the Galfer lines, and bled with DOT5 fluid.



The only thing I have left to do is get a shorter bolt for the lower adapter mounting point. The rusty one is just a placeholder.

MoveOver, In the picture of your front wheel, it appears the axle clamp is backwards...the gap between the fork and axle clamp should be to the rear. The solution is to turn the axle clamp around. But of course you already knew that. Tim

good catch

Nice. This is something I need for my "plan your stops" H1.

This project was relatively affordable.
Calipers: 20$ shipped
Lines: 120$
2x Rebuild kit: 60$
Adapters and machining: 60$

Obviously half the cost for a single disc setup.

If you want brackets made, let me know. The measurements are saved in my machinists computer

I have the EX500 caliper on my "74 H2. I bought the adapter from someone that makes them through one of the H2 forums-
I'll probably get a pair for my Z1 soon, calipers are dirt cheap on eBay-

Also looking into this:
kawatriple.com/caliper/tokico/tokicoconv.html

From this thread:

www.kawi2strokes.com/forum/viewtopic.php...ilit=Caliper+adapter

For some reason I'm unable to reply/upload pics(?)
Getting an error message