Squareback 'Auxiliary Spring?'

[PlanB]

Hey...

Ran across a 1966 edition of 'Popular Imported Cars' magazine that features an article on "Two New Volkswagens" (the '66 Fastback and Squareback models). This review article describes; " A special feature of the Squareback Sedan is an auxiliary spring in the rear which comes into play under severe load conditions on extremely rough ground or during hard cornering when extra springing is required."

When I searched the archives for references to the 'auxiliary spring' I ran across the Type 3 'M' code for:
267 Auxiliary spring for rear axle
up to Chassis No. 366 500 000 361-368

I've never worked on a Squareback, but I am curious about what exactly is being described here. Might be common knowledge here at STF?

Can anyone enlighten me? Pics?

Thanks!

[aircooledtechguy]

The only spring that I know of that was added in '66 and only lasted through '67 was the factory Z-bar. My '67 Square had one and it basically added 5-10# of weight w/ no added benefit so it was removed. They had them on '66/'67 beetles too. I'm not sure if they lasted into the '68 model year, but by the IRS change in '69 they were no more.

[Marc]

I think the magazine article's probably referring to the M267 overload spring, not the Z-bar which was standard on all swingaxle type I/III from `67-up (the US market only received IRS cars starting with the `69 model year, but the swingaxle lived on elsewhere). No `66 models came with the Z-bar, although production of the `67 model year did start on 1 Aug `66.
Besides the model-year discrepancy, the description of its function given in the article doesn't jibe with a Z-bar. A Z-bar actually reduces the springrate on the outboard wheel in a hard corner (opposite to the action of an anti-sway bar).

http://www.shoptalkforums.com/viewtopic.php?t=117743

[Slow 1200]

the description is misleading, it is indeed the Z-Bar, the Type 3 parts book shows the bar itself to be a different part number for the "regular" z-bar for 67-68 and for the overload z-bar, but all the linkage parts are the same PNs, I'm assuming the "overload" bar was thicker maybe

My guess is initially the system was originally designed solely as a helper spring for Squarebacks, and then they realised that handling was improved so they passed it on to the rest of the range

incidentally, around 65 and 66 at least a couple german car magazines rolled their type 3s on road tests

[Marc]

Interesting. What's the part number for the 1966 bar? Does the parts book indicate that the lower link perches were discrete "bolt-on" components or integral with the axle tubes?

[PlanB]

Thanks for the feedback/input guys...

[Slow 1200]

Interesting. What's the part number for the 1966 bar? Does the parts book indicate that the lower link perches were discrete "bolt-on" components or integral with the axle tubes?

Parts book shows the axle tubes to be the same for the M267 optioned 66s and for all 67-68s: 361 505 105A and 106A, they do have the perches integrated with them according to the drawing.

the bar part numbers are: 361 501 505 for the M267 overload option and 311 501 505 for the stock 67-68 Z-bar

oh, and to make things even more fun, after 69 there was another overload package option M263, which seems to be the same as the M267 for earlier cars, swing axles and all

[Marc]

Sounds like M267 was a pretty serious deal then, needing different axle tubes than the non-optioned cars (so not a "bolt-on" that could be installed in the field). I've never looked for the Z-bar mounts on a `66 Type III body, but I will start now. Just had the first VW gathering of the year here last weekend and there weren't many Type IIIs in attendance, but there are other shows coming up soon.

Although none were sold in the US past 1968, I don't think swingaxle production stopped on Type IIIs for `69 (I know it didn't for Type I - and you can still find the Z-bar mounting points on later bodies) so it's not surprising that the "overload" option still existed; since all garden-variety swingaxles would have a Z-bar by then, the M263 option being listed would seem to confirm that a bigger bar was used for it - presumably the 361 501 505 again.
Looks like the writer of that magazine article just didn't fully understand what a Z-bar does in a corner.

[raggdout63]

My 66 square has the Z bar. The axle tubes have the perches welded onto them. If you want pictures let me know as I pulled mine out last night for some R&R. My square is an original pigalle manufactured in Nov of 65.

[Marc]

I for one would like to see the pictures - get a shot of how the bar is mounted to the body too. Do you have some calipers to measure the diameter? If not, try to at least estimate it (see what size open-end wrench fits around it). A picture of the M-code tag would make the photo essay complete. Thanks in advance...

[raggdout63]

Well I'll get a shot of the mounts on the body, and the size of the torsion bar for you. It's completely stripped apart while I had the transmission out I decided to redo the back end. Where's them code tag for my square located?

[raggdout63]

Ok so I found the VW Birth certificate, which lists 3 m codes
M002 US-equivalent
M251 White Wall tires
M456 Cannot be identified

The torsion bar is 14-15mm in the center and the flat sections on the end are 17mm

Pictures of the driver side and passenger side mount locations. Like i said the entire rear end of the square is out right now.

[Marc]

So, nothing on the birth certificate about the M267 option. I looked at the 1969 "Without Guesswork" VW shop booklet to see if the diameter of the Z-bars used on `67 and `68 cars was specified there (NO)...oddly, according to that publication the "standard (826lb) capacity" swingaxle Squareback used 24mm rear torsion bars and the 1014lb model used the same 23mm rear torsion bars as the swingaxle III Sedan and 'Ghia - yet with different setting angles. Unfortunately there's no mention of M267 and I'm reluctant to assume that it's identical to the 1014lb package...this booklet doesn't always cover every design permutation.
Both VW and Porsche fit 1mm-smaller torsion bars when they added the production Z-bars so this may not be a misprint. One could say that the softer springs were the primary factor in the improved handling (more body roll = better tire grip) and that the Z-bar was merely an adjunct which (by acting as an overload spring) made the smaller torsions feasible. Maybe slow 1200 can shed some more light, if his parts book specifies different torsion bars for M267 and M263 cars.
Without an M-code tag (or mention on the B.C.) it's not conclusively proven whether your Z-bar was factory equipment or added afterwards, but it'd still be interesting to know if it has the 23mm or 24mm torsion bars. Is there a GVWR tag on the car?

[raggdout63]

Ive got the torsion bars out as well. They are the 23mm variety. i can confidently say that no one added this. The rear end of this car seems to have never been taken apart before I lowered the rear end 2 years ago. When I removed the brackets from the car they were not so easily persuaded. All hardware matches the typical VW nuts and bolts that were on the rest of the square.

[Slow 1200]

This is what the parts book says

partsbook.JPG