USD Forks

Thanks fellas, this is encouraging discourse. 

The other consideration I am looking at is how much the ZX6R fork caps sit proud of the top triple. I worry that they might interfere with the handlebars. Which makes me think that having a drop at the clamps of the top triple might be a good idea. Doing that in addition to extending the forks I’m sure would give me plenty of length. 

Of course, I don’t have anywhere near the kind of machining capabilities that Zed1015 has.   So unless I can talk him into making the parts for me… 

If they are the same as mine it's not too complex. Below are the extensions I made, you just then need a length of 5mm stainless Rod that you can cut to the length of the original plus your extension length (these run through the middle of the damper rod) I would also suggest you use OE nuts as they are a smaller spanner fitting so no clearance issues through the pre-load tubes. I cut the extensions from the damper tubes in a set of scrap forks I bought cheap (mainly for the extensions to the outer tubes

 

Fork extensions for the damper rod.
Male thread at one end to screw into the damper,  female at the other to take the cap head bolt at the bottom of the leg , drilled through for the passage of the damping fluid and flats milled either side to take a spanner.


Before and after or after and before depending on which one you look at first.

Like it Rob, simpler than my approach (I needed 75mm)

Wookie58 wrote:

Like it Rob, simpler than my approach (I needed 75mm)

I've done it both ways and also a combination of both on some USD's like the zx7r that have a stepped slider diameter that won't allow the leg to be dropped very far in the bottom yoke.

Again, very helpful. You guys have convinced me that it’s doable. Though I do imagine if disassembly of these forks is anywhere near as complicated as the last set of forks I rebuilt (or like the USD cartridge fork rebuild in the RaceTech suspension bible) is, then I’ll have to buy some tools to do it. Not a big deal really. 

However I do want to discuss the issue I have with the top caps in relation to the handlebars. I took some rough measurements this morning (see below) and there is definitely going to be some undesirable interference. 

What I think might make the most sense is to drop the clamps on the top triple by just enough for good clearance. Kind of like the third photo attached here (stolen from Cognito Moto). If I still need to extend the forks somewhat I can, but maybe not even as much as 32mm. Perhaps splitting the difference between the top triple clamp and the fork extension. 

Stereordinary wrote:

However I do want to discuss the issue I have with the top caps in relation to the handlebars. I took some rough measurements this morning (see below) and there is definitely going to be some undesirable interference. 





 

Which yokes are you using.
When i do a modern swap and don't want the stock clip ons i buy or make bar clamps and fit them in the position and height i want to avoid the  tops..
These are ZX7R .
 
 

At this point I don’t have either top or bottom yokes that I can use. I have looked many times (and continue to check) for ones that will work for what I want to do, but every time I come up empty. Which is why I’m going through all the trouble of measuring and drawing a custom set in CAD. While I understand that custom triples are expensive, until I find something that’s more readily compatible, custom is the plan. I hope to save at least some of the cost by doing the CAD work myself. 

I kept it simple ( and cheap ) as i had the full 10R front end and used the whole lot with the Zeph stem fitted.

Stereordinary wrote:

At this point I don’t have either top or bottom yokes that I can use. I have looked many times (and continue to check) for ones that will work for what I want to do, but every time I come up empty. Which is why I’m going through all the trouble of measuring and drawing a custom set in CAD. While I understand that custom triples are expensive, until I find something that’s more readily compatible, custom is the plan. I hope to save at least some of the cost by doing the CAD work myself. 

What is the issue with using the ZX6R tree's with a re-worked stem. All I had to do with mine was reduce the diameter at the bottom for the lower bearing to fit (I pressed a stainless insert up the middle to reinforce where I had removed material on the out side) you could then use bolt/weld on risers at the height you require
 

The ZX6R triples have a couple of issues for me. There’s the offset, the fact that the ignition mount is not centered, there’s no handlebar mounts, and there’s no mounts for the headlight bracket. It also has a rise at the clamps instead of being flat, the opposite direction I need it to go, meaning I’d have to compensate for fork length even more. 

The main thing for me is that I am trying to retain as much of my original components and aesthetic as possible. I don’t want it to look like I grafted a ZX6R front end to a Zephyr. I want it to look like Kawasaki shipped a Zephyr with USD forks from the factory. 

Granted, anyone keen-eyed enough will notice that radial-mount calipers on a bike from 1990 are out of place. But I still want to make it as stealthily modified as possible. 

Some progress on the conversion axle. Pretty simple design really, just ends that fit the ZX6R forks and steps down to the Zephyr axle size. I'm no engineer, just because I can draw this stuff doesn't mean I know if it's a good design. I worry that the larger diameter butted right up to the smaller diameter would create a weak spot. I also think it might be on the bulky and heavy side. But in theory, it should work.

I had hoped to include an interface for the speedo drive, but it won't work the way I had planned. Still exploring ideas.

Any input welcome. And does anyone here have a 3D printer they would be willing to prototype parts for me? Just to test fit stuff before I commit to having anything made in metal.