problemchild wrote:Chris said "I used to set my car up with the z-bar unloaded at race ride height (driver and fuel). It was right if it "rattled" while going to the false grid. Droop was adjusted by the length of the arm. In this sense it was only used as a droop stop, not a tuning device".
Say what? Sorry Chris, but this statement is just so impossible. The Z-bar is never a droop stop and is constantly active and influential. The only time it has no effect is the milli-second long periods that it becomes unloaded through travel in the rear suspension..
Greg,
I think I gave away my set up information when I sold my Lynx, I think I got it from either John Mills, Adams or Fred Clark. Maybe Fred or someone can jump in with the exact wording.
When the car was rolling down the pit lane there was no tension on the z-bar. Of course with heim joints the minute you hit a bump that changed, but the idea was not to have the bar have too much effect on the spring rate. It did result in a rising rate as the wheels together went up as the z-bar was added to the spring rate. But when the wheels went into droop together, the z-bar fought against the spring rate. Now Brian is right, if you took the shocks and springs off, the car could "sit" on the z-bar but would not be strong enough to be able to drive the car. [Edit - the rule he correctly quoted is that if you take the Z-bar off, the car needs to be supported by the coil springs - this implies that the Z-bar has some spring fuction.] If you jacked the car up at that point it would look like a zero roll in full droop and picking up on wheel would cause the other wheel to go down, but keeping the total camber the same without changing the chassis roll.
Now I did not put on softer springs like Brian suggested. The springs (think around 110 - 120) were adjusted so I got the right camber with the z-bar
disconnected. I then loaded the car with driver and fuel and set the bar with no preload. Jacked it up and if the droop was wrong, slid the adjusters along the bar till I got the right tension in droop to give me my camber.
This setting was critical and if you changed the weight or as the fuel load changed, you got a either preload or whatever you want to call the other way (unload, post load?) Of course this other loading tended to push the wheels into droop which meant more jacking - not good.
I believe the Z-bar was the third answer to a cable or strap camber limiter or a camber compensator leaf spring (used on the 61-64 Corvair
http://www.corvaircorsa.com/handling02.html). You are right in that it is very rarely in the sweet zone of zero preload, but its much more gentle than the cable, and easier to adjust that the leaf spring. Being persnickety, it is why zero roll has become the standard today (and weight, and aerodynamics..)
ChrisZ