Russ Keller, a reader and good friend of 1967beetle.com sent the following information with photos to back up his studied position. His thesis called for “loading” the Z-Bar by altering the travel space at the bottom end of each Operating Rod. With the space filled, the Rods are “loaded”. They are not “waiting” for a “loading moment” when the Z-Bar will be activated.
Russ Keller says:
Because the Z-Bar was active only in harder turning as an anti-sway, it was too little too late.
On our ’67, we engaged the Z-Bar all of the time by installing a polyurethane bushing to take up the 2 inch slack prior to engagement. In this way it was always ready in play and we didn’t have the delay in rear suspension stiffness when needed. It was there right away and really improved the cornering and over-steer. Here are a few pictures we took when we installed the z-bar bushings. It was a cheap and easy improvement and the urethane came in black so it matched the look. It was a big improvement for little $$.
After a few hard test drives we experimented with the length of the test bushing.
Because we bought an extra long piece of the hollow material from McMaster-Carr, we could cut test samples. These ranged from 3 1/2″ down to 2″.
The 2″ was the pick by the drivers–my son, “VW Gary” (Gary Drennen from Gary’s Aircooled Service) and me. As I remember, since the 2″ bushing did not quite fill the space on the Operating Rod, that little bit of “slop” prevented the back (of the car) from feeling springy or bouncy. Springy is a technical term of art…..”Federnd” in the original German.”
Thank you, Russ, for sharing your experiment with us!
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Good one, Jay and Russ. Another reason the community here is so important. We can all learn from each other.
I love it when Readers come up with ideas and solutions! jay
That’s an interesting idea and does not appear too difficult to do. I would be curious to find out how it performs after year of usage.
Good article Russ! If you remember Jay my ’67 was missing the Z Bar! In hunting one down, thank you Jay for saving these hard to find parts, I found a variety of thoughts on why there was even a Z Bar! That included, “you really don’t need it!” The other two were to assist with weight support for when there were passengers in the rear seat and, like a sway Bar for better cornering! As I recall they use of the Z Bar was discontinued in the early ’68 models! At least a friend had an early ’68 that had one! Theory being, they must not work! Just a theory some other Vdub enthusiast had! Having driven mine without and with the Z Bar I think it did make a difference on cornering! As always I enjoy these articles and I find them helpful in keeping my ’67 moving on down the road!
Hello, Dick…I added a lengthy discussion of conclusions which our son and I drew up. See the other article I wrote which has all of the Part Numbers, etc. and which pictures each part. I added our findings in a Comment at the end of the Comments Section. I feel good about this statement on the functions of the Z-Bar, Dick. See what you think. jay
After a year… Well after a week we shortened the spacer because having the z-bar engaged all the time made the ride feel to springy or active. Removing just one inch made a huge difference. With that free play prior to engagement the ride smoothed out. When cornering the suspension (z-bar) applied sooner, giving the handling benefit. When the car was loaded up with the whole crew it almost seemed to act like a leaf spring, supporting the car but also reducing sway. We drove the car like that for about 18 months then gave it to our daughter to drive. We felt it safe and had no worries about her driving it. She eventually moved to the big city “Charlotte, NC” and we had to sell the bug getting her a small SUV, which she then crashed. She was fine, but I can’t help thinking, safe in the 67 but wrecks the newer car. She said “in the bug I had to focus more on driving”. But that’s another topic.
They were removed when the swing axle was replaced by a true IRS during 68/69 model year. The independent rear suspension eliminated the need for the more complex geometry of the Z, in lieu of a simpler “less parts” anti sway bar. I know there were a lot of aftermarket larger anti sway bars that were marketed at that time to create a little more oversteer ” back end slides out before the front plows” which is fun when racing. Until the IRS, they definitely helped improve a good system to make it even better. Too bad so many have been removed because of a lack of understanding and information. The rubber wears out and they get noisy but the parts can still be found.
Hello, Russ…Interestingly, my ’68 Karmann Ghia also has the Z-Bar. I need to refresh the one on my Ghia–I see that the lower part of one Operating Rod is damaged. Check the lengthy Comment which I entered at the end of the Comments Section of the Article which I wrote showing all of the components of the Z-Bar with Part Numbers. Our son and I sat down and hashed things until we could write down our conclusions. Thanks to you and your son, I now understand more of how the Z-Bar operates. jay
Russ, enjoyed the article. I found it very interesting in that I am currently working on a 68 convertible that originally had a Z-Bar suspension, optimum word being originally. The previous owner removed it. I am putting it back in. I have a couple of questions if you (or anyone else) have the time. First off, I believe I have all the parts except one of the linkage rods, I believe I am missing the passenger side, the one I have was attached to the “flat arm”, it is approximately 12″ long. The distance from the large washer to the end of the bottom nut is approximately 6″, the space between the large and small washer is approximately 4″ and the distance from the small washer to the top nut is about 2″. I read on another thread that the passenger rod is 10″ overall length. Can you confirm? Also what is the spacing between the points as I have mentioned above. Thank You for your time and patience. — Jim
Hello, Jim…for information on Z-Bar parts and comparative photos see this Link: https://1967beetle.com/z-bar/
So the final length was 2″?
2″ left 1″ of free play before engagement.
We all need a little free play…
Thanks Russ! This comes at the perfect tor me as I am researching the “klunk” coming from the driver rear of my 67 sedan deluxe. I am sure the Z bars have never been worked on during the 137,000 miles it has been driven.
I have one question, though. Can you provide more information on ordering the spacer tube from McMaster – Carr, perhaps a part number?
Hi, Scott…I just wanted to butt in here to tell you that you can obtain the repair kit for replacing worn parts for your Z-Bar through http://www.wolfsburgwest.com Russ can help with his invention of pre-loading the Operating Rods using the McMaster-Carr part.. jay
Can you please comment on where you sourced the 3″ pre-load spacer you added? Is it made out of hard plastic or rubber. Thanks.
What is the McMaster Carr part number or the Delron “tube”? Thanks.