Z-bar vs. Camber Convertor vs. sway bar

[Claire]

I know what the physical differences are between the '67-'68 Z-bar (aka the equilizer spring) the camber convertor and the sway bar. But if I am understanding them correctly, they seem to do approximately the same thing-

(please correct me if I'm wrong) Stabilize the car by counteracting the inertia, tying down each end of the bar so as one side lifts, it is held down and the weight distributed. (I understand this was only marginally successfull.) It also distributes the weight so that the car rides evenly with an uneven load.

Is there something better about any the design of one over the others? If so, what is it that makes it better?

Just learnin' ! Mine has a Z-bar and will stay that way for at least a while. But I may decide to upgrade it eventually if there is a good enough argument for doing it.
Thanks!
-Claire
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[Chad1376]

The camber compensator and z-bar do a similar thing. They both decrease the rear roll stiffness and make the rear end of the car less likely "stinkbug" and tuck the inside rear wheel under during hard cornering. (The early Corvairs are infamous for dangerous handling from thier swinaxle rear suspension - they didn't include a camper compensator or z-bar)

The factory z-bar, however, has some built in play, and does not go into effect until some suspension movement has occurred. You can shim up the z-bar and eliminate this play for a stiffer and safer ride.

A sway bar increases rear roll stiffness. I'm not sure, but I don't think this is a good idea for a swing axle vehicle. EMPI advertizes a swaybar for swingaxle, and I e-mailed them a few weeks ago, asking if a sway bar was beneficial to the handling of a swing axle bug, but the declined to reply (either it was a stupid question, or they didn't know or care).

I has good luck a few years ago autocrossing my '68 beetle. I decambered the rear end to about -3 deg and shimmed up the z-bar. With the help of some Mikey Thompson slicks, I was able to post a few top 10 times ( beating a few Corvettes and 914's).

[Claire]

Thanks, that helps tremendously. It sounds like the original Z-bar will do just fine, now that I've got the elusive rods and bushings to attach it.

Although I'm not planning to be taking corners at the kind of speeds that you do, I do live on a mountain highway and have about 1-1/2 hours of winding mountain driving in my daily commute. So it was important to me to re-attach my detached Z-bar (that was taken care of today) and then to decide where to go with it from there. Your description helped a lot.

I think I'll leave it stock for now, then decide if I want to modify it after driving with it for a while.

Congrats on your great times!!!!! WOW!!
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[bill may]

a zbar is not a camber compensater nor is it a sway bar. it was used due to downsizing of rear torsion bars in 1967 model year and 68 in usa but thru end of production in 2003. it only compensates to carry load and is not for cornering.
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[Chad1376]

A z-bar and camber compensator look different, but the act nearly the same. Both encourage each side of the suspension to move differentially. In other words, when one wheel goes up, both the camber compensator and the z-bar make the other wheel want to go down. This effect decreases roll stiffness (the opposite of a sway bar).

The factor z-bar does act to increase the rear spring rate when the built in play in the links is taken up by the suspension movement, however if you shim up this play, you will make the z-bar act full-full time and also have a stiffer rear spring rate.

Both 356's and fourmula-v's commonly used z-bars to improve the handleing of thier cars, albiet, without the built in play of the VW system.

VW provided the z-bar at nearly the same time Ralph Nader was cracking down on the Corvair for it's dangerous swingaxle handling traits. Interesting that just a few years later, the swingaxle was replaced by the 4-joint rear suspension.

[bill may]

some porsches also had a camber compensater. on a "sway bar" does one leg go forward and one toward rear of axle? look at a zbar and answer same question.
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SBS #100
http://www.thesamba.com/vw/forum/viewtopic.php?t=453617

[Claire]

Last night I was picking up a pair of seats at Air Cooled Foreign in Fremont CA. I was pleasantly surprised to see a '67 parked out front that was in the process of being made into a drag racer and parts of 67's all over the shop. It turns out that Tim, the owner, is partial to 67's. So I decided to pose the Z-bar/camber compensator/sway bar questions to him.

His response was that the Z-bar and camber compensator do exactly the same thing and that yes, they do help the handling "a little bit" by keeping the tires from pinching under during cornering. He said that a sway bar however performed entirely differently (he did not elaborate on how) but said that he didn't recommend one. He said that having either a Z-bar or a camber compensator to help stabilize the handling was the way to go.
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[exzonie/67' type 1]

How do you shim a Z-bar???
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Phillip
67' Type 1 under construction

[Wade Seymour]

Yea, how do you shim a z bar?

[tacky]

can anybody post a picture of a z bar and a camber compenstor?
i would like to see the physical difference.
this is an interesting subject. i always wondered the same thing.
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[Claire]

Here's a Z-bar in place. It's the rod coming out through the hole, then extending downward and ending in an orange loop. Then there is a rod with bushings that is also painted orange in this photo that goes through the Z-bar loop and then connects the Z-bar to the transaxle:

Here's an old ad explaining the camber compensator with a diagram:

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[tacky]

THANKS I HOPE FOR SOME MORE feedback on this subject.
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[Labora]

[HBRag]

If you install a 3/4" sway bar up front, I highly recommend the camber compensator for the rear. I have a '63 lowered 2" all the way around. A 3/4" bar up front and a camber compensator in the rear, with 15" limit straps. I can load the car into a corner, jump on the throttle and drift the car all the way through with very little roll.

Not to over simplify the setup, but it does turn. I also, but the car on a four wheel alignment rack three different times to get everything set up right. The rear alignment and camber is a HUGE part of the handling.

The car over steers with a heavy bar up front and nothing in the rear.

[exzonie/67' type 1]

I installed a 3/4" Bugpack swaybar on my 67 w a 2" narrowed beam, lowered and it made a big diiference!!!!!!!!!!!! I would highly recomend one if you have a narrowed beam. It made my car a lot more stable on the freeway, no more getting blow off the road from Semi's or strong winds.
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Phillip
67' Type 1 under construction

[exzonie/67' type 1]

Mine has a Z-Bar from the factory and I'm still going to get a camber compensator...............
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Phillip
67' Type 1 under construction

[PJMS]

The Z-bar and camber compensator should not be described as being 'the same'. This is really an over-simplification, although they have common effects.

One thing to remember is that there are two types of CC; one which simply cradles the axle tubes and one that is 'tied' to the axle tubes. In the simple cradled version, it limits the simultaneous downward movement of the axles in either straight ahead driving or cornering. In the case of 'straight' and at high speed, the car raises up naturally, which reduces traction at the rear and increases the feeling of instability (cross-winds etc). Add to that the sudden need to brake hard, and the rear raises up even further. The CC limits this upward movement. In cornering, it allows the car to role but still limits the axle movement and so resists wheel tuck. When you tie the ends of the CC, I think it adds stiffness at the back while still preventing the angles necessary for wheel tuck. However, it should also promote over-steer, which is not a good thing.

The Z-bar works entirely differently. First of all, the Z-bar is not actually the primary element here. The 'system' is based around the fact that these cars also have softer rear torsion bars. Softer rear suspension, increases rear roll, placing more of the roll forces on the front axle and in turn reduces over-steer (or increases under-steer). This has the inherent effect of avoiding the conditions for wheel tuck. What the Z-bar does is put back the suspension lost through using the softer main torsion bars, only when needed. So it is completely ineffective when simply cornering but under heavy loads, it will increase the spring rate progressively (the connecting bar running from left to right is a long thin torsion bar).

What the CC does not do, is reduce over-steer or provide progressive rear suspension. There is an argument, however, that suggests that the inside rear wheel exerts some upward force on the outside wheel through the CC which could result in more under-steer, but I am not convinced of this. What the Z-bar does not do, is limit the simultaneous downward movement of the axles tubes, but VW did alter the camber of the rear wheels to limit the negative effects of this. The Z-bar can be made to replicate the CC characteristics by removing the inherent play in the linkage. However, this may result in some interference, in the system, during cornering.

All in all the Z-bar system is a little more subtle about how it goes about its job, plus, it has more ground clearance and does not use the gearbox as a mounting point.

While the Z-bar cars provide what I would call a more "positive" neutral handling characteristic, IRS goes a step further and makes the vehicle actually under-steer. Manufacturers prefer under-steering cars as they consider them inherently more safe.

[exzonie/67' type 1]

This is the artical I read, pretty informative......

http://www.aircooled.net/gnrlsite/resource/articles/handling.htm
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Phillip
67' Type 1 under construction

[Labora]

PJMS, exzonie/67' type 1

Way to bring some good tech into this. Good read.
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[PJMS]

It is an interesting article, especially since it is reinforced with practical experience. However, he does admit to not understanding how the Z-bar works, which is a little confusing since without that knowledge it is hard to make modifications and then come to conclusions. There is also the curious statement, towards the end of the swing axle section, where he suggests the removal of the Z-bar and fitting of a "small diameter rear sway bar". In addition, although he started with a stock vehicle, he did substantially modify it before testing the various set-ups. However, you can't ignore his results, but I would be cautious about the theory that could be inferred.