Zink Z10 Rear Suspension

[S Lathrop]

I have been looking at the Zink Z10 rear suspension. There were 3 variations that Ed designed for the Z10 rear suspension. The most common was the Z10A or the original. Then came the Z10 B which was some minor changes to the suspension pickups on the frame. The Z10C was a suspension package of updates which widened the front track and replaced the rear upright with a upright that had significantly different pickup points than the original Z10A. The Z10C package was designed as a update for the Z10A chassis pickups.

The Z16 suspension made a big change in the geometry of the rear of the car and it has been the foundation of all the Citation and Zink cars since then. Down side is that the Z10 never had the benefit of this revised geometry.

There is a new problem facing Z10 owners today and that is the availability of VW parts that will give satisfactory service in a race car application. The rear hub is such an issue that is also shared by the FV guys. ICP has come to the rescue with rear brake drums and hubs for FV and the other cars that use the the IRS VW Beetle rear suspension bits.

What I am currently working on is a new rear upright for the Z10 that changes the rear suspension of the Z10 to something that is very close to the Z16, maybe a little bit better, but uses VW parts that one can buy at a VW dealer or a auto parts supplier today. The Z16 used VW Dasher parts and today there are current of very resent models that have parts that are nearly identical. The upright actually looks a bit like a combination of the original Zink Z10C rear but uses VW parts that would be common to the Z16 and both of these cars are vintage legal cars.

This setup will also convert the Z10 to outboard brakes which is a major performance improvement. Some of the vintage die-hard may object to changing a Z10 to outboard rear brakes but I did build several Z10s with outboard rear brakes and all the Z11 FSVs had rear outboard rear brakes. All used VW parts.

As an aside, several years ago, a Z10 customer damaged a Z10/VW front upright and was not able to find a replacement. I made him a new upright that use the same VW parts as the Z16 but was dimension-ed to replace the Z10 VW front upright and associated parts. The big advantage here was that is saved over 5 pounds per corner. If I had to replace a Z16 front upright I would use the same basic part.

I would like to hear from Z10 owners or would be owners about this project.

[BorkRacing]

A question comes to mind. Z10's are raced only in vintage now. Improvements beyond what was run during its life as an SCCA FF are not really allowed. Especially when you say it would create an advantage for these cars. You could argue safety but it would open the door to major revisions of all current Club Fords run in vintage events in the sake of safety...

For example Reynard front uprights are no longer readily available, do we allow them to be redesigned? Will it allow an unfair advantage? Can you move the rear shocks on a Crossle 55 outboard for better motion ratio?

Personally I say if it was done in the day, do it. If it is for safety, do it. Revisions 40 years after the cars release, not so keen on.

Robby

[fleetdude]

very interesting...not sure how many Z10C active users there are now, but i'm one. i have the R Pare rear hubs, but with inboard brakes. you say that this change would be a geometry improvement to equal or exceed the Z16...in what way? would it still use the rear hubs and stub axles which i have? would it eliminate the spacer between bearings and the need to re torque/epoxy the hub to axle? any pics of the Z16 pieces? i'm in pretty good shape with rear uprights right now, but you never know...would the new set-up use the same lower A-arm as the Z10 with shock attachment point (recall that i need a spare LH A-arm, as we discussed)...

[S Lathrop]

very interesting...not sure how many Z10C active users there are now, but i'm one. i have the R Pare rear hubs, but with inboard brakes. you say that this change would be a geometry improvement to equal or exceed the Z16...in what way? would it still use the rear hubs and stub axles which i have? would it eliminate the spacer between bearings and the need to re torque/epoxy the hub to axle? any pics of the Z16 pieces? i'm in pretty good shape with rear uprights right now, but you never know...would the new set-up use the same lower A-arm as the Z10 with shock attachment point (recall that i need a spare LH A-arm, as we discussed)...

The rear upright I have designed would not use the VW parts you currently have .The parts will be very close to what was used on the Z16.

But, the fixture that I will use for the new upright can be used to make an upright that will use the original Z10 parts. It would be a revised version of the Z10C upright.

The biggest change to the geometry is to reduce the camber change as the wheels moves up and down. The camber change of a Z10 is quite large,well over double what the Z16 and later models have. Also the original was optimized for a rear ride height in excess of 3 inches. The new geometry optimized the geometry for a ride height of 2.5 inches and will work well down to about 2 inches.

The new upright allows for almost any combination of calipers, rotors and brake hats. The caliper mounts to a bracket that allows the caliper to mount on either side of the upright. I have built Z10 uprights for outboard brakes but those mounts were fixed. I don't know if I can do something similar to the new caliper mounting system on a Z10 upright with the original VW parts. But I certainly will try to have a bolt on caliper mount.

[S Lathrop]

After completing my work on the new rear upright for the Z10, I decided to take a look at making the same upright geometry for the Z10 but retain the original VW parts that were used when the Z10 was new.

This upright is very similar to the original Z10 C. My analysis of the original Z10 C uprights showed that is was not an improvement over the Z10 A , original, upright. The Z16 was a major advance over the Z10 for rear suspension geometry and the new rear upright brings that improvement to the Z10. For no good reason, I am calling this new upright package the Z10 D rear upright.

Bottom line is that the Z10 D rear upright will be available with either the original Z10 VW parts or with the Z16 VW parts. In both cased the geometry is very close to what Ed Zink designed for the Zink Z16 and the only difference is that the geometry is optimized for a ride height that is about 1/2 lower that what Ed had based his geometry around. That is a rear ride height of 2.5 inches.

Send me a PM if you are interested in either package.