Non z-bar early body on 68 swing-axle pan with z-bar

[iancorado]

A giant tree limb fell on and dented the roof of my 68 project car. The chassis is great needs nothing and titled. I think the easiest thing will be to find an orphan body and swap it for my now ruined 68's. I have a few potential candidates that I have found on craigslist. The best being a fairly rust free 65 for $400. My question is this, my 68 is a swing-axle car with the z-bar (which has been rebuilt via wolfsburg west parts). As far as I know the 66 and older bodies do not have the cut out or mounting studs for the z-bar brackets.

Can I mount the 65 body to the 68 pan and delete the z-bar setup?

Or will I need cut out the z-bar section of the 68's body and fabricate it onto the 65 body?

I want to make this as simple and painless as possible any advice would be appreciated, I did a quick search but couldn't get a good answer from the 67 and earlier forum or the 68 and up. I will add a picture of my sad 68 when I get home.

Thanks,

[gargamel]

Only thing I can really tell you is that my 68 was missing the Z-bar. Many have it missing or have taken it out, either due to the clanking sound it made or they saw no real use for it. Whatever the reason, your bug will not fall to bits without it. Earlier swing axles did not have it and I doubt there were rolling over. That part came out in the last years of the swing axle so I would imagine you would be fine with careful driving (swing axle and all...)

I bet you could fabricate it to fit on, if you know what you are doing and dont mind some wondering why you went thru all that trouble for some part that some may think is odd. I know it does serve a purpose so I can't count it out.

[iancorado]

[VW_Buggsy]

If it were me I'd use the 65 body and just not bother with the z bar setup. Once you swap bodies it's kind of pointless to worry about keeping it for any sort of concern over stock or originality of the car.

If you are concerned over it's functionality you can get much the same thing using a "camber compensator" that basically supports the swing axles from underneath and limits wheel tuck.

www.cbperformance.com/ProductDetails.asp?ProductCode=2819

Though unless you are going for aggressive driving it's really not needed for general driving.

Since you invested some loot on the z bar rig I'm sure you can sell it pretty easily in the classifieds, though to be honest it may not fetch the money you've put into it (I dunno what you out into it though).

[jhicken]

Is there any damage to the drip rails or is there any issues with shutting the doors? That dent might pop out easier than you think.

-jeffrey
_________________
Der Kleiner Kampfwagens

[ensys]

Mr. Iancorado:

This is just $.02 from the cheap seats, but it would seem that if you’re reluctant to work the simple damage to the roof (a real testament to the strength of the VW body, eh?) yourself, spend the $400 to get a proper body shop to ease it out for you. It seems to be a pretty clean tub and the Devil you know is always better than the Devil you don’t know.

In any case, I humbly suggest you retain the Z-bar by any means required. The swing-axle is a quirky business and the Z-bar is the hands-down best way to control it’s behavior and greatly enhance the Bug’s drivability in every situation.

As for the actions of others, I would remind you that the world is full of people who will not appreciate the things they don’t understand, simply because it is easier than doing the work or gaining the knowledge. Always be wary of “the easy way out”.

With no intention of insult to those who do not understand it’s function, I will point out that the “camber compensator” works nothing like a Z-bar, will not prevent tuck-under, and is intended to be deployed along with several other suspension modifications for optimal effect, which at it’s best, is not nearly as good as that of a proper Z-bar.

Good luck with your project.
_________________
Keep 'em flying...

S.J.Szabo

[Aussiebug]

When you look at the way the Z bar works, you can see that, as ensys above says, it's NOTHING like a camber compensator.

The ends of the Z bar have sliding links and each side twists the bar the opposite direction, so for it to do ANYTHING, the car has to squat at the rear several inches before the bar starts to twist.

It's really there because the weight of the bug was increasing (1675lb in 66, 1808lb in 68, and more for the cabrios), and the Z bar becomes a "helper" spring for the rear when there are heavy loads in the back or the back end dips hard over bumps etc. A cheaper option to redesigning the torsion bars themselves, when changes to THAT were already in the wings for the following year (IRS suspension).

For info, outside the USA, the swing axle and Z bar continued in manual models for 1969 and 1970. I have a 1970 (Euro spec) swing axle 1500 bug with the Z bars.

Iancorado,

Sorry to see that big dent in your roof, but I have to agree with other posters here, it looks quite repairable (unless there is damage we can't see in the pics.)
_________________
Rob
Rob and Dave's aircooled VW pages
Repairs and maintenance for the home mechanic
http://www.vw-resource.com

[iancorado]

The drip rails seem intact. I will pull out the headliner today and certainly see what I can do. If I end swaping bodies I will probably retain the zbar setup, I guess I'll cut out the body mounting holes and studs and weld the to the new body.

[gargamel]

I would consider doing the recommendation made of just using a camber compensator and call it a day. IMO, It just seems more trouble than its worth.

[Stuart Maingot]

The Autopress vw service manual by Kenneth Ball states the Z bar does not come into play with body roll and is effectively a third torsion bar to aid with additional weight. It is also noted that it was available as a add on kit from VW for earlier models if owners wished to do so. I have a 69 with the units intact and have experimented with additional rubber buffers installed to get the action of the z-bar coming into play sooner under load. Pack 3 adults into the back with caribbean undulating roads and you will appreciate this upgrade.

[VW_Buggsy]

[ensys]

Well. Between the misinformation, disinformation, and raw ego, its gotten pretty thick around here all of a sudden. It would be perfectly understandable if Mr.iancorado began to be sorry he asked.

May I suggest this: In a disagreement, whoever loses their temper and/or resorts to personal attack first, should not be trusted.

Here are the facts as I know them. I strongly suggest some independent study for substantiation.

Swing axles have some of the advantages of IRS, but also have additional quirks that can bite you in the butt if you don’t respect them.

Wheel tuck is the most serious. Porsche/VW learned that this issue could be mitigated by lowering the real roll axis and reducing the rear roll couple to zero (in theory). The actualization was to soften the rear bars (to reduce roll couple; nothing could be done with the roll axis, (tho Benz’s lowered axle pivot did)). This aided “handling” but reduced static load capacity. Hence the “camber compensator” that acts in one direction (to pull the wheels down, pushing the body up, thus increasing static load capacity) without affecting body roll (roll couple again) or participating in “handling”.

The EMPI (and subsequent imitators) version sought to emulate this, but without the benefit of the more sophisticated attachment hardware, so they attached the spring ends with straps around the axle. This provided load capacity but also participated in “handling”. Unfortunately, due to the fixed ends, the first thing the spring tries to do is pull the wheels into tuck before it starts to interact. After that, it provides some limiting effect, owing to the spring’s now-reversed load and the center pivot, and several secondary influences that don’t help at all. The problem is that its action not only adds to the roll couple, if the outside wheel tucks before the changing loads can lower the inside wheel significantly, the tuck will continue.

The Z-bar has none of these weaknesses. First, it carries no load, so it does not act as a “helper” spring. It does not act as a roll bar, so it does not add to the roll couple. It’s sole function is to transfer the load of the dropping inside wheel (as the body also leans) to the outside wheel as thrust upward, thus negating any possible tuck. It is the optimal minimalist solution.

You can demonstrate this action by bending a paper clip in a “Z” and play with it. Remember: the long center is afixed to and parallel with, the body (tub).

The closest thing to a Z-bar is a “virtual Z-bar” that uses a near-flat transverse spring on a low-resistance center pivot with ends attached to the trailing arm/axle via adjustable drop links. A 356 vendor has marketed his version successfully for many years, but one can fabricate their own using an EMPI type spring with a zero-resistance center pivot, and fabbed rigid end attachment links.

The smart money is on keeping the Z bar.

"Having fun" includes keeping the shiny side up while you're doing it.
_________________
Keep 'em flying...

S.J.Szabo

[Q-Dog]

I'd be inclined to push the dents out first and see how bad the thing really is. With the headliner out you can probably get to all of the damaged parts from both sides.

Or, Maybe the OP should consider grafting in a ragtop?
_________________
Brian

'69 Dune Buggy
'69 Beetle Convertible
'70 Beetle

[modok]

The roof can be fixed!! Easier than switching bodies.

[VW_Buggsy]

[ensys]

Well alrighty then. A round of apologies for the house; I’m paying. It is the price of my poor communication skills.

Here in the Midwest, the cities are on a strict grid, and open roads are straight and flat ribbons scribed thru cornfields, and it all reminds me that one of the things I miss most about living on the Left Coast is the myriad daily opportunities to hone a driver’s skills in everyday situations that could be challenging at perfectly sane and legal speeds. From the hills and curves of the streets of San Francisco, to the narrow and winding hiways snaking thru the Santa Cruz mountains, there was always a chance to push one’s personal envelope without endangering bystanders or scaring the horses. I enjoyed living the mantra of “Frequently Sideways” that I learned at the wheel of a ’65 Corvair as a tender undergraduate here in the Midwest, at largely legal speeds in very ordinary conditions. Snowy winters were (and still are) a daily adventure.

Now, maybe its just me, but plying the streets and hiways of the Coast in several iterations of swing-axled cars had a way of focusing my attention and interest in what was going on back there, especially at those times when I found myself teetering on the brink of the dreaded “wheel tuck”, a condition that was all too possible, even at relatively sedate speeds, that threatened to spoil the fun.

So I hope all will understand my mistake in thinking that in addressing this body, I was reaching the kindred souls of other enthusiastic drivers who find a real value in exploring state-of-the-art thinking as a way of making the most of the experience of artfully wheeling a swing-axled machine in daily life. Apparently I mis-calculated. My bad.

In any case, it would seem that inadequate writing skills allowed my little dissertation to be mistaken for an expression of opinion, when in fact it was intended to explain the circumstances that lead the Factory engineers to progress from a naked swing-axle, thru a camber compensator, and arriving at the Z-bar, before deciding that IRS was the answer all along.

Now, I find it neither unreasonable nor naive to believe that the highly trained (what is termed “book larnin’” around some climes) and very experienced Factory engineers didn’t drop the Z-bar in out of guess-work or whimsy, or because they ran out of camber compensators which did the same job just as well.

Nor do I believe that these same engineers passed on the simpler, cheaper approach of stiffer bars or different shocks just because the Factory wanted to spend more money. And incidentally, only the camber compensator used softer bars; that was the whole point.

So what have we learned here?

Well, I’ve learned that when it comes to knowledge, sometimes you can’t give it away, especially to someone who believes the seat of his pants is smarter than Factory engineers. That insult, like water, seeks its own level. That the old chestnut of “My mind is made up; don’t confuse me with the facts” is still valid. And that I have still not learned to successfully tiptoe around prickly egos.

Again, my apologies for my clumsiness.
_________________
Keep 'em flying...

S.J.Szabo

[Aussiebug]

[ensys]

Mr.Aussiebug:

Well, yes and no.

You have to admit that there is something of a terminology issue in your sources.

The Haynes example seems to be referring to a camber compensator, and the Gregories manual is specifically doing so, so neither is applicable to your point.

The Bentley manual seems to refer to a Z-bar (tho "slant in opposite directions" is a bit cryptic), but not clearly so.

And it is true that if one dumps a bunch of load into the car, the bar will be stressed, tho because the Z-bar cross section is usually a fraction of that of the torsion bars, its effect in this situation is negligible.

It is important to remember that a Z-bar is customarily set up neutral (no load on the Z-bar, with the torsion bars carrying all the load of the vehicle and passengers) with the car at its normal load height, so that it is only stressed when cornering, transferring the load of the dropping inside wheel to raise the outside wheel without effecting the rear roll couple.

However, in racing applications, it can be the case that some slight pre-load to taste will be applied to settle transitions in loading, but this is not usually the case on the street.

It is also the case that in racing application, the bar between the arms can get very thick to better emulate a solid axle in transitions, but one is then forced to stiffen the front roll bar to remarkable dimensions to counter the heavy oversteer that results.

Now, it is also true that if one wheel is subjected to jounce while the other is not, some additional force will be contributed to rebound, but once again, that effect will be minimal compared to that wheel's torsion bar resistance.

Thus, it is not acting in any way as a helper spring and has everything to do with preventing tuck.
_________________
Keep 'em flying...

S.J.Szabo

[Aussiebug]

[Slow 1200]

The Z-bar was always used with softer torsion bars, they were meant to work together, which they do pretty well.

myself I prefer IRS

by the way the Z-bar was used all the way to 2003 in non-IRS Beetles