Z-bar vs. Camber Convertor vs. sway bar

[rkeller]

[fredy a]

simple question
what is the best way to go for making my 66 swing handle better
Front
3# beam drooped spidles
135 zx
Kybe shocks

back
now idea Smile
165 Firestone f-560
reed Konys

swap the 135 for 145 and then what
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sorry for the spelling

[rkeller]

[drscope]

A while back when I first started road racing I was driving a car that had a lot of different sway bars available in the racing catalogs. The trouble was my budget didn’t allow me to be able to afford that stuff and still be able to pay race entry fees. (I was my own sponsor back then and paying for everything out of my pocket) So I had to improvise.

It was also very important to us that we had several different sway bars to be able to change them as weather and track conditions changed. So spending $150 to $400 on a sway bar was out of the question when we wanted to make sure we had about 10 different bars to choose from.

So we had to make our own. I knew what the basic shape and length was for the bars we wanted, so I went over to the salvage yard and searched until I found several bars of suitable length in different diameters.

We then took them back to the shop and used a rose bud on the oxy/acetylene torch to heat the bars where we needed to bend them until they glowed orange. Then they could be easily reshaped and allowed to cool slowly.

We also made mounts that would bolt to the chassis (or the rear axle) and could slide on the bars. By moving the mounts in towards the center of the car, or out, we could change the effectiveness of the bar so each bar could also be easily tuned.

The point is, when you start messing with this stuff, a lot of guys are limited to what is available from the catalogs and web sites. But that doesn’t have to be the situation.

A rear sway bar can mount almost anywhere to the chassis that doesn’t move. The torsion housing is strong. And depending on how you make your mounts, you can make up clamps that will fit around the torsion housing and can be moved in or out to tune the bar to your liking.

The frame horns will do also, but you run into 2 problems there especially if you are getting into big bars. They aren’t as rigid as the torsion housing. So it is possible for the sway bar to actually introduce a lot of twist and flex into the frame horns.

The other problem is they are too close together to be a good mounting point. The farther you move your mounts out, the more effective the bar becomes. So if you only have your mounts that far inboard, you get a lot of flex in the bar that is lost work.

The next thing to keep in mind is your mounts. On a street car, the sway bars are all mounted in rubber. That is so they don’t transmit a lot of road noise and vibration into the cabin.

By simply changing the rubber out for a harder material, you can sometimes see an increase in the work the sway bar does. But it will also get pretty noisy inside the car!

Today there are also tubular sway bars available. You won’t find these in the VW catalogs or web sites, but they are available on the race car supply sites.

These bars all use the same arms and mounting hardware, but the bar itself which is simply a tube comes in various wall thicknesses. The heavier the wall thickness, the stiffer the bar.

The advantage for the racer is you just carry a few different bars and to change them, you simply loosen a bolt on each arm, and each mount, then slide the bar (tube) out and slide a new one in and tighten things up. They can be changed in a matter of minutes.

Many of the formula cars and light weight race cars use a sway bar that has arms which we call blades. They are a flat arm that can rotate on the bar. The more you lay the flat over, the less stiff the sway bar becomes because of the flex in the arm. Some of these bars have one blade on one side and some have a blade on each end.

Some of these can actually be adjusted by the driver while the car is at speed on track.

So there is plenty of stuff out there if you look and use your imagination.

Just keep in mind, on a race car sway bars are used to tune the suspension to track conditions. We do the same for a street car, but we are looking for a much wider window of effectiveness and compromise because we usually don’t have the time to change sway bars for each time the car leaves the driveway.

If you do start messing with this stuff, it is interesting to make adjustments and changes and see what they do and what the results are.
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Mother Nature is a Mean Evil Bitch!

[66brm]

[Toohey]

Good doctor,

To make a rear sway bar, where would you put the mounting points for a swing axle? I assume that the body mounts would be welded to the torsion tubes, but where would the ends go? Would you weld a tab onto the spring plates or fabricate a mount that goes on the end of the axle tube?

Edit: found a photo that shows it bolts to the underside of the frame horns and has drop links to the bottom bolt of the shock. Would this mean its not worth fabricating ones for the rear and just buy the kit?
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Coat me in chocolate and throw me in a barrel of cats!

[rkeller]

[surfbeetle]

Anyone have a pic on the zbar bushing kit from Wolfsburg West? My 67 has only one plastic pipe on each side and the large bump stop looks different from the WW kit. The WW kit has a total of four plastic bushings and they are not even the same length as the ones on my 67. What I have looks like the photo that was posted earlier in this thread. Thanks.
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67 Beetle Build Thread
69 Beetle

[61SNRF]

[drscope]

The camber compensator and Z-bar are different items that do different jobs.

The main job of the camber compensator is to reduce wheel tuck.

The main job of the Z-Bar was to act as a helper spring. (but it still helps to reduce wheel tuck)

A camber compensator is a safety device and can easily be installed with or without the Z-Bar.
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Mother Nature is a Mean Evil Bitch!

[roflhat]

sorry to be bumping this old thread,
but I couldn't find the answer I was looking for (I may have missed it)
I have a '68 without a z-bar, removed by a PO a long time ago I guess.
Can i use a camper compensator INSTEAD of a z-bar? or do I have to use it WITH with a z-bar?

[redhot]

[KTPhil]

[drscope]

On an IRS car, there is no need for a camber compensator. The camber dosn't change and you don't have the wheel tuck issue to deal with.

The Z bar will help keep the rear from rolling arond. I think Wolfsburg West sells the kit to replace all the links and rubbers for this. You should get it hooked back up.

When you do reinstall it, cut a piece of tubing to take up the slack in the links. This will keep the bar preloaded and make it work all the time. In the stock configuration, it only goes to work after the body starts to roll over.
_________________
Mother Nature is a Mean Evil Bitch!

[KTPhil]

Removing the stock z-bar will not change how it handles, it will just bottom out easier with a load in the back seat. VW put it there for that purpose--overload spring, at the same time they put softer rear springs in, and raised the front ride height. All this was done to decrease oversteer. Undoing it without understanding how the front and rear spring rates and roll stiffness interact is asking for unsafe handling.

[luminarycrush]

Currently, the Z-bar isn't connected - it's never been since I've owned the car. The rods that connect the 'z-spring' to the axle are missing, so, right now it's not doing anything. My car has IRS - not swingaxle - so is this wheel tuck issue still a problem? If wheel tuck is a problem on an IRS car, could a camber compensator be installed as well? I've never heard of that being installed on an IRS car. I was under the impression (perhaps incorrectly) that the z-bar was really just working as an 'overload spring' in my car.

A local VW speed shop I talked with said most of the cars they see don't have the bar connected - people remove the rods because they begin to rattle after awhile. They seemed to think it didn't matter much. Someone apparently did that to my car. I have the z-bar spring with the arms along for the ride not connected to anything. The previous owner put aftermarket front and rear anti-sway bars on the car - the rear is the type which bolts to the bottom.

While I've not ran the car fast through the twisties (it's still a work in progress, though driveable) the car it seems to handle well. It has a fairly stiff ride to it - maybe the PO cranked up the torsion bars in the rear as well? I'm not sure. I've done a 5-lug conversion w/ disc brakes in the rear and put Porsche rims w/ P205/50R17's on all corners (they just fit in the rear w/o modifications, the front I had to install a narrowed beam).

The modification I'm doing is to install air conditioning. The kit from Gilmore Enterprises puts two condenser units w/ fans on the bottom of the car tucked up into the space where the aftermarket rear sway bar currently interferes. I could choose to go source and purchase different condensers and fans and try to find other locations for them - I've seen other kits which place condensers in the rear decklid (a la Porsche 911), the wheel wells, and behind the front beam... but then I'm out the cash for the existing units & have to spend for new ones and I've got to make a bunch of custom AC hose and brackets/mounts. It is a pain I thought perhaps I could avoid.

Considering that the z-bar is doing nothing now, could it not be modified to be an (albeit lighter duty) anti-sway bar? I don't know what I'd have to do to reverse the arm yet, I haven't taken one of them off. I could just weld it on the side I flip it on (as opposed to drilling/tapping).

I do have access to an oxy-acetylene torch. I was under the impression that heating and re-bending a sway bar would weaken it...interesting thought, I'll have to look under the car and see if a different bar could be bent such that it would not interfere with the condenser position... though thinking about it I think it would be challenging to accommodate any bottom-mounted sway bar and still mount the condensers there...

[drscope]

You don't think cutting and drilling and putting bolts in that little skinny bar will effect it's temper?

There is no reason to go through all that. If you have access to an oxy/acetelyne torch, you can make almost any sway bar you need.

Select the diameter you are looking for, then measure the length of the bar you need. Then go to the junk yard with your tape measure and find something of the right diameter and length. Shape dosn't matter.

Heat the bar with the torch in the area you want to bend. reshape it and let it cool slowly. When you have it rebent to fit your needs, the bar is ready to go. There will be no change in temper.

We do this for some of the race cars we deal with because ready made pieces are not always available. This is an inexpensive way to build a selection of different size bars.

Remember, with a road racing car, track conditions are constantly changing, so to be competitive, you have to be able to keep up.

I would also suggest thinking about ways to make your bar adjustable, so you can change the effectiveness of the bar without having to change the bar.
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Mother Nature is a Mean Evil Bitch!

[GA_Boy]

Thanks drscope. I wanted to make a torsion out of my Z-bar but I guess I'de better leave well enough alone.
Marvin

[drscope]

First off, the camber compensator and the Z-bar are sort of safety related pieces. Their job is to keep the outside, loaded wheel from tucking under.

The sway bar is a different animal. The sway bar adds stiffness to the chassis/suspension and helps transmit the load from the loaded wheel to the unloaded wheel in an attempt to keep both wheels in contact with the pavement.

Now, increaseing the size or stiffness of the sway bar at one end of the car, increases grip on the opposite end. At some point, you also begin to loose grip on the same end that the bar is on.

The VW is inherantly prone to oversteer (loose in the rear). So a front sway bar was added. This gave a little more grip at the rear and also added a bit of under steer to the front of the car.

When the ball joint front end was added, front camber settings also changed to positive camber. Again, this was in an attempt to reduce oversteer and increase understeer.

In the hands of the general public, an oversteering car is a problem. This is what killed the corvair. Ralph nader discovered that when the rear end stepped out, people paniced and lifted off the gas and hit the brake. This causes the rear of the car to snap around and the driver is instantly out of control. The result is often injury or death.

An understeering car will respond to lifting off the gas and hitting the brakes and as soon as the speed is reduced enough, the front tires regain grip.

Now, if you reshape the Z bar to work like a sway bar, you are changing it's design. It will no longer work to keep the loaded wheel from tucking under.

But, the real issue with your car is how does it handle? There is NO direct answer to what size sway bar you need. This is directly related to road conditions and what tire package you are running.

Sway bars are used to tune the suspension. First, you must select your tires. Then get the car on a skid pad or other wet slippery surface and safely see which end breaks loose first.

The add or increase the bar on the end that breaks loose and go try again. Keep doing this until you have the car handling in a neutral fashion.

What type of modification are you doing that requires the removal of your sway bar?
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Mother Nature is a Mean Evil Bitch!

[luminarycrush]

So, a question about the Z-bar....

Currently I'm running an aftermarket anti-sway bar in a '69 Ghia. The Ghia has the Z-bar but the rods that connect it to the IRS axle were gone before I got it. The car handles nicely as-is.

Unfortunately, I have to remove the sway bar to make some other modifications which will interfere with it. So, my thought...

If one of the Z-bar arms was flipped so it was the same direction as the other side (no longer a "Z"), would this not have the same effect as an anti-sway bar? Has anyone done anything like this?