KZ900 Front Brakes

wrote:

Just a heads up, I'm not sure i'd use those old invader wheels on a Z900, apart from being heavy, they were prone to crack where the spokes meet the rim.....

 

What's the story on these wheels? I haven't seen them on any other KZ bikes that I've looked at. When I get some more money I may trade them out, but for now I'll just be cruising around the neighborhood.

A couple factors to determine whether you mount leading or trailing. The lower fork tube, and the caliper mount bracket, and the hose/pipe. The calipers are non handed, until you get into the calipers that have the bleed screw that  put the bleed screw pointing up, then that hands the caliper.  The bracket you have is either leading RH or trailing LH. Typical for the Kz900 is leading LH. KHI use both for years on the same size bikes, IE the Kz900 “A” models were leading brakes.  With a factory option to add dual calipers, keeping them in the same orientation. The Kz900 LTD used trailing brakes, in a dual caliper setup. Personally I don’t know if there is any performance advantage. 

Maybe this will show what I tried to describe about the bleeder screws.

This is a non handed caliper. Used on the Kz900 “A” ,  LTD and the Kz1000 “A’s” 



Here is a handed used on the Kz1000 LTD models.

 

wrote:

wrote:

Just a heads up, I'm not sure i'd use those old invader wheels on a Z900, apart from being heavy, they were prone to crack where the spokes meet the rim.....



 

What's the story on these wheels? I haven't seen them on any other KZ bikes that I've looked at. When I get some more money I may trade them out, but for now I'll just be cruising around the neighborhood.

Just google "invader wheels broken welds"   they aren't something I'd take a risk on..   There's stories of broken invaders all over the net...

i218.photobucket.com/albums/cc151/BlueCo...ris/invaderwheel.jpg

i120.photobucket.com/albums/o175/DannyF_...rtwo/invadercopy.jpg

Lebowski post=847911Thanks Scirocco. German website is the only option for these rings? Expensive as hell!

Is there a preference on whether the brakes should be front or rear mounted on the front wheel? I've seen both. I have the forks arranged for a front mount, which looks better to me.

slmjim read an article by Kevin Cameron a lonnnggg time ago about caliper in front (leading side) vs caliper on rear (trailing side) of fork legs.  Let's see if he can remember the essence:
Briefly, it has to do with the physics of placing a mass (calipers) closer to or farther away from the steering stem axis (pivot) of the fork legs when the fork legs are considered as a lever and pendulum. 
Consider the forks as a lever (pendulum) that pivots around the axis of the steering stem.


  A mass farther away from the steering axis as projected through the steering head (on the leading side of the fork legs in this case) will effectively be weight on a longer lever (distance from the steering axis to the calipers' mass=longer lever), exacerbating the effect of inertia, increasing steering effort & possibly contributing to fork oscillation (the pendulum effect) that might result in a tank slapper.  Mass on the trailing side of the fork legs will be much closer to the steering axis (much shorter lever/pendulum), reducing the relative effect of the same mass when the forks are considered as a lever, much negating the effect of the mass of the calipers on the pendulum effect.  Not necessarily much of an issue on street bikes unless prone to tank slappers anyway, KC's article dealt with the effects re: race bikes of the day.  I think that catches the essence.

We recently bought a parts lot that has two of what we think are the same calipers, but we don't know what the came off of.  If you're in CONUS, we'd be happy to send a dust seal ring if you're unable to source one locally.

We've dealt with creeping crud in Z1 calipers & MC's for decades.  We usually use a dremel too, with a very small, very fine stainless steel wire brush to gently clean the caliper seal groove.  We then use a Q-tip to wipe a coat of white brake grease into the piston seal groove prior to inserting the seal.  The grease behind the seal helps prevent slow weeping of brake fluid.  If you're seeing a rapid leak that prevents building pressure, follow the advice in previous posts as an outright leak indicates something not

Posts above have good advice in installing seals.  Note that some caliper piston seals are very slightly asymmetrical on the side that contacts the piston. That is, not perfectly square.  If so, the 'taller' edge should face away from the disk, or toward the bleeder hole bore in the caliper's piston bore.

Good Ridin'
slmjim & Z1BEBE

Hey Jim, great article again. I am right in the middle of questioning this. I'm putting a 1/8 mile drag strip beater bike together. I took the dual discs off to run 1. That tank slapper explanation is going to make me put the single disc caliper on the rear trailing. The bike has 2 stock Kaw steering dampers with reinforced welded stock brackets for the reflectors. Just makes sense to keep the weight to the back. But at 63 If I run this bike a few times, don't want no tank slapper going 100 mph shutting down. Plus I did not rake the neck at all, wanted too, but no time, just want it done and running. Has a 1197, .435 webb cams, 38 Lectrons. Paul Gast built it, dynoed at 126 hp. from the previous owner who has since passed away. Too many other projects. Just another day!

So, The dust seal rings finally showed up. Please confirm that I have these installed correctly?

Also, when I removed the piston from the cylinder, I noticed that the little seal that goes on the inside of the cylinder has a chunk missing. It almost looks by design, but this doesn't seem right. Can anyone confirm? This could be why I have leaks...

You have the dust shield installed correctly. I have never had luck getting the ring and dust shield installed as an assembly before. I have had better luck installing the piston seal, (by the way yours is trashed. Either wrong size and got pinched or it rolled out of the grove when installing the piston. Lube is your friend. Red Rubber Grease on the seal and bottom radius of the piston as described before). Then the dust ring, piston, then dust shield/seal.

Mikaw, you were correct. I dismantled the other caliper and found that the internal seal ring was intact. Do you have to use red rubber grease or will any kind of grease work? 

FYI - piston and cylinder both look and feel smooth. I don't see any gashes or significant etching. I think it was probably just an installation error. We will see. 

Make sure the grove in the caliper were the seal lives is clean, clean, clean. It’s critical. No corrosion, dirt, nada. Regular grease will not work. It will contaminate the brake fluid. You can use brake fluid as assembly lube, personally I haven’t. I know Red Rubber Grease is brake fluid friendly. I’m sure there are others. A local auto parts will be able to advise. And should have something on the shelf.

Mikaw is absolutely correct. Some angled pics will make cleaning the groove easier. They are cheap and available at most hardware stores. I once got a small selection of them for $1 on a clearance table at Ace.

Definitely be sure that the grease is brewed for brake systems. I suspect most any brand will do, though I know Volvo service departments use some high quality stuff that seems extra slippery and does not have the stigma of low cost. I mooched some from a friend.

Angled pics? Is there anything else I can use. Groove obviously needs more cleaning tbh.