Convert to IRS or not?

[Jesse/DVK]

So I bought a project '67 standard beetle with ragtop and will do a full resto on it. Offcourse Cal-look with a 2276 200hp engine. I will mostly drive it on the street and maybe 1-2 times dragracing a year.

As I will start from scratch I was wondering if I should convert the pan to IRS. What are the pros and cons? Also considering I will need a beefed up transmission (with LSD).

I can imagine the ride will be much better and for street driving I think it would be cool to have some spirited driving in the turns.

Let's hear some advices 

[Zach Gomulka]

Swing is simple, light, cheap and does the job.
IRS is more complicated (more parts, more expensive), about 40lbs heavier, handles and rides better. A lot better.

For a car that you plan on driving a lot (a lot is totally subjective), you will enjoy a car with IRS much more.

[Neil Davies]

If it was me, and planning on doing a body off resto, I'd go IRS. Even if you build it swingaxle in the meantime, you may as well fit the IRS brackets.

[nicolas]

If it was me, and planning on doing a body off resto, I'd go IRS. Even if you build it swingaxle in the meantime, you may as well fit the IRS brackets.

this is what i would suggest as well. the brackets are much easier to fit when the  body is off and you can switch between IRS and swing axles whenever you want/need

[Martin S.]

I like the simplicity of the swing axel, but I've never driven a hipo IRS car. I don't see the big advantage myself but maybe I'm just being cheap. I'd rather stick with a Porsche design from a hundred years ago when men were men. Ya know it works! Never trust that new fangled hi tech crap anyways.

[alex d]

I used to love swing axle...until I got an IRS car 

I own one of each now (67 with red konis and stock z-bar and 71 fastback) and I'm very glad I was driving the type 3 when a wild boar came out of nowhere the other night!

[Martin S.]

Did the boar oooooh and aaaaah at your Porsche 930 CV joints as you drover over it? 

[Jesse/DVK]

Thanks for the replies. I think I will weld the brackets so I can choose in the future.

[Bruce]

While you're doing that, clearance the torsion housing for that future Berg 5.

[gkeeton@zbzoom.net]

Swing is simple, light, cheap and does the job.
IRS is more complicated (more parts, more expensive), about 40lbs heavier, handles and rides better. A lot better.

In what ways is an IRS rear more complicated, and more expensive?

[Zach Gomulka]

Swing is simple, light, cheap and does the job.
IRS is more complicated (more parts, more expensive), about 40lbs heavier, handles and rides better. A lot better.

In what ways is an IRS rear more complicated, and more expensive?

More parts! Axles, stub axles, CV's, trailing arms. They are also wider, much more challenging to narrow than a swing is. Swings are stupid simple.

Once you own an IRS car, it's hard to go back.

[Fiatdude]

If you're going to race it even just a couple of times a year.... Do IRS, get the trans setup to handle 930 CV's, put them and big axles in and be done with it -- everything will be bulletproof and DONE and you'll be driving your car -- -- best thing I've ever done to my Ghia!!!! (Oh and the Bus box too!)

[Martin S.]

You need Thing axle stubs as well for the Bus box conversion? Is there a guide somewhere showing how to do it? Cost?

[gkeeton@zbzoom.net]

Swing is simple, light, cheap and does the job.
IRS is more complicated (more parts, more expensive), about 40lbs heavier, handles and rides better. A lot better.

In what ways is an IRS rear more complicated, and more expensive?

More parts! Axles, stub axles, CV's, trailing arms. They are also wider, much more challenging to narrow than a swing is. Swings are stupid simple.

Once you own an IRS car, it's hard to go back.

You do have a good point about an IRS setup having a wider track, than say, an early Swing Axle, but narrowing either is going to take work. Cost is the thing I don't agree with. I'm assuming the OP is wanting to use a 3.88 r & p. Unless you are starting with a late DSC 3.88 IRS trans to convert into a swing axle, you're most likely going to have more invested in a S/A trans to have a 3.88 installed. The OP wanted to use a LSD diff, so that rules out any strength comparison issues going with a Quaife. If they were wanting to go the route of a standard super diff, the IRS is going to be stronger with 10 tooth spider gears. If they're holding out for an actual LSD diff, like an original ZF, they're at the mercey of who has one for sale. They'll most likely end up paying more for a S/A ZF diff. Any axle set for a S/A worth anything is going to run them $700+. All of the IRS components can be had used from Beetles, Things, and Porsches in some cases for half of what you would spend on a set of good S/A axles.

[Martin S.]

Isn't the price of a Pro Street Rancho the same for a SA or IRS with 3.88 RP?

[gkeeton@zbzoom.net]

It depends. Some consider ALL post 67 transaxle rebuilds with a 4.12 r & p. Even though a 73, and later IRS came with a 3.88, some charge extra for a 3.88. Most rebuilders I know consider a 73 later trans. "stock" with a 3.88, and improvements are extra. Most I know consider a S/A "stock" with a 4.37/4.12, and the setup/cost of the 3.88 is extra along with any improvements. Not sure how Rancho does it.

There are many variables in cost. Sure, you could have a S/A setup for less using stock axles. You could have an IRS setup cost more with 300m axles/race prepped CV's. Sway A Way's, and Empi's S/A axles are available for less than $400, but I personally would use Weddle's/Lummus' axles that are $700+. Stock Thing/924/944 halfshafts, and stubs are more than enough for 200 hp. I've come across multiple sets for less than $200. I simply feel an IRS setup would be better/less expensive using easier to find more common used stock/stock replacement parts. 

[Martin S.]

Obviously it's drag race starts that kill trans axle setups. I've been using stock original for a few years now with 200hp by babying it. It sounds like I could get by with Thing axle stubs, Bus CV's, stock axles and a Rancho IRS 3.88 Pro Street Trans and do ok for a few years? I would still have to avoid hammering it with that setup I guess?

[Fiatdude]

I've choose IRS over swing axle mainly because of chit axles out there for the swing or the fact you can't find really good ones anymore

There is two things that kill transaxles -- dumping the clutch with slicks and the other is severe wheel hop -- avoiding these helps make you trans live -- narrower slicks that allow some wheel spin helps too --- a very light car eases issues also

But if you're going all out, you just have to over build everything and just figure how long it is between maintenance --  or figure a combo that works and lives -- I ran a T1 pro-street in the Fiat with the turbo 2165, but I never had anything more sticky some 225 drag radials on the car....

One pro-stock car I know gets away using a type 1 trans by changing the R&P after every race -- he sells them used to street guys afterwards
two of the SS cars (and Mike Lawless) have been using built 002's -- but there has been a rash of 1st/2nd slider problems causing them to hang during shifts --

just do your research and choose your poison

[Martin S.]

It's all easier if you're a seasoned pro at this but would be daunting for noobs and me too.
I'm sure the V8 guys don't have this problem. Bug engines are easy and 200 hp is no problem, but the trans is like voodoo black magic with mystery parts and combos no one can post an online list or source for. 

[gkeeton@zbzoom.net]

Martin, if you would like to use Rancho, give them a call. Mike Herbert has helped me out with stuff in the past there. I would think a standard late 3.88 trans with the Thing halfshafts/cv cups/stubs would live quite a long time for you. Like Fiatdude mentioned, slicks, and wheel hop are two of the biggest issues. If you don't run slicks, and have smooth controled wheel spin when you do get on it, you can get a trans to last a while.

V8 guys have the exact problems we do. What most fail to realize is 200hp out of an Aircooled VW engine is roughly 4-5 times the hp the original parts were designed to deal with. You don't see guys with mid 70's V8 muscle cars that had 250hp from the factory putting 1000+hp through a bone stock driveshaft, and rear end, do you? The reason V8 guys don't seem to have any issues is they aren't making enough power to. A 350 in a 60's/70's Z28 making 500hp is basically the equivalent of a 1776 making 80hp in a Beetle. There are some people that could break a crow bar in a sandbox, but 80hp would take a long time to kill a stock late 3.88 trans in a properly set up car.

Transaxle building is no more voo doo than engine building, it just requires a little more special tooling. You still have to choose components that work well with each other, and for an intended use. Weddle Industries has just about everything you could possibly imagine for a VW transaxle in their online catalog. What things were you looking for?

[Martin S.]

I meant the V8 guys simply go to Summit Racing and order up what they need for hipo drive train parts.

[Jesse/DVK]

Thanks guys for all the replies. I have set my mind to IRS and also convert to disc brakes in the rear to really upgrade the handling of the car.

[Zach Gomulka]

Thanks guys for all the replies. I have set my mind to IRS and also convert to disc brakes in the rear to really upgrade the handling of the car.

That decision you will not regret.

[Martin S.]

Thanks guys for all the replies. I have set my mind to IRS and also convert to disc brakes in the rear to really upgrade the handling of the car.

What are planning to use for the trans? If you don't know, then please do post your solution here later, thanks! 

[gkeeton@zbzoom.net]

A 4.12/3.88 trans with a slightly shorter 3rd/4th is a blast to drive if you are not going to be doing much freeway driving.