Z-bar Setup advice

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csingletary01
Posts: 73
Joined: November 29th, 2009, 2:00 pm

Z-bar Setup advice

Post by csingletary01 »

I have made it through the first race with no issues. everyone thought I should up grade from my 5/8" z-bar to a 3/4" bar. I have fabbed and installed. I have been working on race cars most of my life, but have never messed with a z-bar before. Any setup stuff you all can help me with when it comes to z-bar.
billinstuart
Posts: 201
Joined: July 17th, 2006, 8:53 pm

Re: Z-bar Setup advice

Post by billinstuart »

Z-bar..kinda like picking yerself up with yer bootstraps. Been several years, but I ran one on my Beach. Like any swaybar, alot depends on the effective length of the "lever" arm where the bar connects to the axles. Usually you have to push the rear end down to connect the bar..most z-bar cars were transported with the bar disconnected.

It's basically a droop limiter, with a secondary function of providing progressive compression springing.

If the car handles ok, and the rear wheels don't tuck under, you're ok.
problemchild
Posts: 901
Joined: June 25th, 2006, 9:34 am

Re: Z-bar Setup advice

Post by problemchild »

The two basic adjustments are the rate (lever length) and the pre-load. If you had a "setup" with your old Z-bar, start with that. If starting from scratch, I would create a "datum" setting .... say two inches of lever length showing past the clevis and zero pre-load at rest with driver in. I would experiment with pre-loading the bar (both directions) and different lever lengths (probably pre-load first).
The stiffer bar should require less pre-load than required previously.
Note: I would try to have the coil springs adjusted to support the car at the desired ride height before the bar is attached.
Greg Rice
"Happy 50th Birthday"
csingletary01
Posts: 73
Joined: November 29th, 2009, 2:00 pm

Re: Z-bar Setup advice

Post by csingletary01 »

Thanks for the advice. Once I slightly pre-load bar, should I then jack up car and check droop? If so how much droop should I have?
problemchild
Posts: 901
Joined: June 25th, 2006, 9:34 am

Re: Z-bar Setup advice

Post by problemchild »

The Z-bar is a camber/droop control device but not a droop limiter (by my interpretation anyway) and I have never measured droop as a spec. I don't consider it relevent. As I suggested, set up the rear springs so the car supports itself without the Z-bar, then attach the Z-bar links and adjust so that the Z-bar is putting "appropriate"opposition to squating or jacking. You are varying that opposition force with lever length and moving the balance with the preload. Unless you have developed a sense of what is right, by previous use, driving and then adjusting will be required.
Greg Rice
"Happy 50th Birthday"
csingletary01
Posts: 73
Joined: November 29th, 2009, 2:00 pm

Re: Z-bar Setup advice

Post by csingletary01 »

thanks again Greg. I have a race weekend at Hallett April 8th thru the 10th with the 8th being a track day. I will experiment with adjustments.
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