Swing arm conversion question

[GreenMeanie]

OK this question might be dumb but I went through my books and tried searching and came up empty.

I am converting my 65 Swing axle frame to "IRS". I understand how to make and use a jig for the trailing arms that is no problem.
The question I have is do you use the torsion bars from the 65 and torsion CAPS or do you use the super beetle torsion bar and CAPS? What SPECS should I save the 65's or super beetles for when putting it back together?
After I get the answer I probably will realize how dumb the question was LOL.

[Ol'fogasaurus]

If you can find it, Hot VW magazine did two articles on the conversion; the first article dealt with the actual conversion and the second dealt with the mods needed on the transaxle mount to give room for the CVs which swings axles did not need. The transaxle mounts on a Swing axle are more round than the IRS mounts which are more oval and also had a small flattened spot (I can provide you pix if you need them).

In '69 VW went with IRS and used double spring plates which require you to use matching trailing arms. In sometime in '71 VW changed from double spring plates to single spring plates so matching trailing arms must be used. The main difference being the double spring plates have provisions for 5 bolts with the 5th bolt hole being threaded and uses a fully threaded bolt and backup nut as compared to 3 bolts on the single arm spring plate and trailing arm.

There are three lengths of trailing arms with the two longer ones being used on IRS setups so you must trailing arms to match the length of torsion bars. If you use double arm trailing arms then I you can't use the early short torsion bars which would allow you to use larger then 31" tires. I think with using the single arm trailing arm trailing arms you can use/modify (?) the longer (?) short arm spring plates (with mods?).

The reason for length difference is, as I understand for softness of ride purposes.

I would also recommend the use of a truss/Kaffer bar conversion or use the more expensive “stiffey” setup by Mendola to support the transaxle mounts.

As far as preloading the torsion bars: viewtopic.php?t=110857&postdays=0&postorder=asc&start=0

See, it is easy… maybe a 15 minute job .

Lee

[Marc]

Only four holes on the double springplates, not five. They debuted on the `68 AutoStick Beetle and were used through 1970/early`71, as well as all years of IRS Type III. The "blade" of the control arm where the bolts go is thinner than on the late, 3-bolt arms but it is possible to adapt the late arms to fit double spring plates by grinding them narrower.
In order to use shorter torsion bars, which might be needed to clear really big (30½"+) tires, you have to use aftermarket springplates or fabricate your own.
If you use the 3-bolt control arms, it's possible to shorten and drill stock swingaxle springplates, which of course means you can use the swingaxle bars as well. The swingaxle plates are taller and thicker, and spring steel's not easy to cut or drill. The excess length can be removed with a cutting torch, but a plasma cutter's a lot neater if you have access to one.

Note that `67/`68 bars were smaller in diameter than the earlier, pre-Z-bar versions... they're essentially useless for any other application with the possible exception of a light vehicle like a trike.
The 626mm Type III and 627mm Type I bars are interchangeable and can use the same springplate/splined end assembly.

The "caps" only hold the springplate/splined end assemblies captive, so they can rotate without moving laterally. Depending upon the year of the torsion housing they may or may not need spacer tubes to stand them away; a lot of aftermarket chromed covers come with the spacers unwelded, so you can use them or not depending upon your setup. Another potential pitfall when playing mix-and-match with different vintage components is the selection of the correct rubber or urethane bushings. By using 3-bolt control arms and modifying your original swingaxle springplates and caps you avoid all of these issues, including the tire size limitation, so IMO it's the way to go if you can handle modifying the plates.

http://oacdp.org/wog69/121.png

In case you misunderstood what Lee was saying about the CV joint clearance issue, it's the contour of the frame horn (not the mount) which needs massaging.

[Ol'fogasaurus]

Thanks Marc, I should know better than to be doing too many things at one time especially when I am tired . Marc filled in the rest of which I went brain dead or wasn’t sure of... thanks again Marc.



This shows the two mounts the one on the left is the mounting flange on a trailing arm for a double spring plate and the one on the right is for a single spring plate.



Some where I have pictures of the single and double spring plates side by side but here is a picture of a double spring plate and the matching flange on a trailing arm.







Three pictures of a IRS transaxle mount showing the flattened out area. The mount is a two piece affair and as I said, the Swing axle mount is a more round than the IRS mount plus a flat area, usually done by cutting and welding in a relief in the CV area for clearance.

[Piledriver]

Three pictures of a IRS transaxle mount showing the flattened out area. The mount is a two piece affair and as I said, the Swing axle mount is a more round than the IRS mount plus a flat area, usually done by cutting and welding in a relief in the CV area for clearance.

Actually it's USUALLY done by beating the hell out of the area with a 3+ lb sledge hammer,, but it's PROPERLY "done by cutting and welding in a relief in the CV area for clearance."

[GreenMeanie]

Yup I know about cutting the horns Tops and welding them back in.
Still confused on the Springs Plates I have the Single 3 bolt spring plates I thought I would be taking the super beetle parts and moving them to the 65 frame. Think I will do one part at a time and build the jig off the Super Beetle for the pivot points for the arms and go from there.
I got the rear off a super beetle with macpherson strut front if that matters for measuring purposes.
I am following this article for the Brackets for the Arms but they don't mention what parts to use after words.
http://www.pacificcustoms.com/mm5/graph ... ctions.pdf

[Ol'fogasaurus]

Geee, that looks familiar.

[Marc]

...I got the rear off a super beetle with macpherson strut front if that matters for measuring purposes...

Nope, they all measure the same - year for year, there's no mechanical difference between a Super and a Standard other than the front suspension.

[GreenMeanie]

So I can use the Springs off the Super and my old torsions and CAP off the 65?

Right now I am fighting getting the axle bolts off. All came out except two that stripped on me. Tried Vise Grips and lots of heat and no luck so I might cut the heads off the last two and remove the axle and try vise grips on what is left.

...I got the rear off a super beetle with macpherson strut front if that matters for measuring purposes...

Nope, they all measure the same - year for year, there's no mechanical difference between a Super and a Standard other than the front suspension.

[Ol'fogasaurus]

The early swing axle cap does not have a hole in it to allow the longer torsion end covers on the spring plate to protrude through.

[Marc]

If you don't need clearance for big tires, simply transfer the springs, springplates and caps from the Super onto your pan.

If you do need clearance you'll need to use the early short torsion bars. Simplest way to do that IMO is to use all of the same early parts, after you modify the longer swingaxle springplates to accept the 3-bolt IRS control arms.

Torsion bar lengths/diameters:
http://oacdp.org/wog69/121.png


Don't hold me to it, but to the best of my recollection the inner bushings should be the same from c1960½ through 1979 (there's a left and a right) and the swingaxle outers are the same "knobbed" part swapped side-to-side while the IRS outers are smooth (no knobs, and interchangeable left to right - like the red ones in Lee's picture immediately above). I'd recommend that you tag each bushing during disassembly so you can tell where it came from if you re-use, or to help you decide what to order if you buy new ones.