Transaxle swap:

[Blockheadbob]

New guy here. i have a trike frame not the pan and I would like to know how much trouble it is to swap in an irs transaxle/ Or will swingarm axles bolt on an irs? Any help i can get will be appreciated.

Thanks;

Bob

[cscsonny]

Welcome from Missouri.The VW guys will be along in a minute.

[Doug D.]

Welcome!

Here's a link that'll show the differences in the IRS and swing axle suspensions. If you look at the pics of the two suspensions, you'll note some significant differences in the torsion bar housings and spring plates. Also, the swing axle suspension doesn't accomodate the swing arms that allow the rear tires to move up and down independently of each other in the IRS suspension. Hope this points you in the right direction.

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Try to post some pics of your frame if you can.

[Rsw]

Here is a reply from another forum from a VW expert when I asked the same question.

If you are trying to convert an IRS transaxle to a swing axle then as long as you have a double side covers transaxle rather than a later single side cover transaxle then it supposedly is a doable conversion. You will need everything/all the parts from the side covers out including the drums off of a swing axle transaxle including the side gears in the differential part of the transaxle and some other internal parts found in the differential behind the side covers (check you VW manual for a parts breakdown). You might want to cruise the transaxle forum and look around there as there is a lot of information to be had on swing axle’s and variations per year (look at the transaxle housing codes for gearing and ring gear bolt changes). I did some quick looking and there may be other information there that you need to know; I am not a transaxle type of guy so there is a lot going on that I don’t have the slightest clue on. Below is a diagram of the swing axle assembly supplied by David58.


I would stay away from the ’60 and earlier split case transaxles as it is not as strong as the later transaxles plus the restorers need them. You could run into the forward transaxle mount difference there too (two bolt vs. 3 bolt).

Zooming in on your picture (nice trike by-the way), what can be see of the rear end of your trike is that you (probably) have ”24 11/16 long Intermediate Torsion Bar 65-67 Type III Swing Axe torsion bars” w/swing axle transaxle (I am assuming that it is indeed a swing axle transaxle like you say it is) and everything was taken out of the same bug to build the car. If it is a type III rather than a type I donor then the torsion bar length answer should be found in the torsion bar chart I posted. That’s the trouble with home builds’; they are often a mix of a lot of different models and years.

As far as the torsion tube goes over the years, the main difference is the IRS pivots, the shape of the transaxle mounts (round swing axle vs. oval IRS. The swing axle will fit the oval mounts but the IRS needs to have a relief put in the round mounts for the CVs) the forward transaxle mount; the rest is pretty much the same. The different torsion bar lengths fit in most if not all, it is the spring plates and end covers that do the adapting to the longer or shorter bars. There are some additional information to be had but since you are dealing with swing axles most of it is not germane to the discussion.

[Rsw]

Mine is a swing axle torsion tube with IRS torsion bars and spring plates. The ride is incredible.