Porsche IRS on Beetle.

[stevepugh]

Ok. It's happening and it's happening hopefully this side of the year end. My bug WILL be going IRS.
However, Finding 130x parts is pretty darn hard to find and cars are even harder that are worth stripping for parts. It has been pointed out to me that I can use a 924/944 rear end.

A little bit of digging and it would appear that the 924 / 944 has a removeable rear subframe that encompasses the IRS rear end. This makes life pretty easy in terms of stripping the Porsche. How much of this will fit straight on and how much will I need to source?
I should be able to use my existing Handbrake cables?

ive found someone breaking one that is willing to remove the rear clip for me. But from googling some photos, I can't quite see if the Torsion bar cover is quite right.
Also I'm led to believe that the trailing arm bolt will be the wrong size and I'll need to change the bush, and that the drums will be 4 x 108 and the Beetle is 4x130.

Lastly the 924 spring plates are adjustable and the bolts need to be ground down to clear?

I'm pretty excited that it's actually gonna happen.

[Steve Arndt]

You want to save the trailing arms, brakes, torsion bar grommet/covers, sway bar and mounting brackets, cvs and drive axles. It may be possible to use the torsion tube as a measurement guide for positioning your pivot points on your floor pan.

[stevepugh]

So do the drive axles bolt up to the beetle box? Or are they Porsche specific?

[Marc]

The 924/944 CVs, drive axles, and stub axles are all the same as VW Thing (AKA Trekker, Type 181). Install a pair of Thing final drive flanges on a Bug transmission and they'll bolt right up...If you can't locate OEM Thing flanges, there are aftermarket reproduction parts available, as well as flanges which have been modified by machining off the Beetle-sized CV flange and welding on that portion from a Bus flange which is the same diameter as 924/944 or Thing.

If you run the 924 (non-turbo) drum brakes, everyday `68-up Beetle 4x130 drums will fit with no alterations. If you wanted 5x205, you could use Thing drums - but be forewarned that they increase the track width and you might have fender-clearance issues.
944 and 924T used rear disc brakes (with Rabbit-rear-sized drum parking brakes inside the rotors), with the 5x130 "real" Porsche lug pattern - those'll increase the rear track even more. To hook up Beetle e-brake cables to them you need extension tubes for the sheaths and custom-made "swans" to connect to the parking brake levers at the shoes. http://vdubengineering.com/uncategorize ... -adapters/

I don't know what, if any, adaptation might be needed to connect Beetle cables to the 924 drum brakes - but Beetle drum brake assemblies bolt right up so this shouldn't be a problem.

[stevepugh]

This is all pretty good news. I'm led to believe the Porsche drive shafts are stronger?
The kit I've been offered is a non turbo drum brake setup.
So I'm planning to just use the drums I currently have.
But the torsion tubes from the Porsche and the trailing arms and adjustable spring plates.
I was thinking of a disk setup but this is as you say more work and something for the future. I will be fitting wide fibreglass wings so track is not an issue but time and simplicity is right now.
Once it's all IRS'd I can play with changes later.

The goal was to buy a rusty 1303 and literally ransack the rear. But it's proven hard to do and people selling bug IRS parts know they are rare and charge the earth. But Porsche 924 are ten a penny so seem to be cheap to get parts for. So that's cool.

[stevepugh]

Also, am I correct in thinking that the torsion bars will fit? they are thicker than a beetle and should stiffen the rear up a little? or is this only the 944 torsion bars that are thicker?

[Steve Arndt]

Yes, torsion bars are compatible and are like late model IRS with the extended covers. The late model 968 and 944 turbos had some really big bars.

[stevepugh]

Are all the splines the same tho? so If I got some beefy 944 ones they'd still fit the Beetle Spring plates?

Does anyone know if the 924 bars are the same or thicker than a 1303?

[Ian Godfrey]

all 944 torsion bars fit. 'some' 924's had 23.5 bars and some were the same as super bug.
944's have either 23.5, 24.5, or 25.5. I think it would be much easier to to graft on IRS pivots to your torsion housing than to graft the whole 924 torsion housing on to a car.
you will need beetle style spring plate bushes.
If the 924 has a sway bar, you can graft the mounts on to your torsion housing and use the 924 14mm sway bar, or the 944 18mm or 20mm sway bar. these attach to the double ended camber adjusting bolt on the spring plate.
good luck

[stevepugh]

all 944 torsion bars fit. 'some' 924's had 23.5 bars and some were the same as super bug.
944's have either 23.5, 24.5, or 25.5. I think it would be much easier to to graft on IRS pivots to your torsion housing than to graft the whole 924 torsion housing on to a car.
you will need beetle style spring plate bushes.
If the 924 has a sway bar, you can graft the mounts on to your torsion housing and use the 924 14mm sway bar, or the 944 18mm or 20mm sway bar. these attach to the double ended camber adjusting bolt on the spring plate.
good luck

I think I might have misled with my original post. I had no intension of fitting ht erear torsion housing. I am always going to fit the brackets that are easily available new. But was wondering what I could use from the porsche. It is just easier to purchase a complete rear torsion housing from a porsche as it's all together and all the bits are in one piece.
I just might have secured a nice 1303 tho' this weekend so if this comes off then I will have all the bits that I need to do the conversion. It's good to know tho' what upgrades can be done by using 944 parts tho'.