924Board.org

[Herr-Kuhn]

Can anybody here tell me if the aluminium control arms from the later 924S can be attached back to the early torsion bar tube? The 1977 and 1978 cars have a radically different mount for the torsion bar tube which bolts up to the chassis. The later cars have more of an isolated hanger.

Most specifically, I am wondering if the mount locations are spacially identical and if the double plate design of the later cars (which allows for some height adjustment) will fit the earlier torsion bar tube.

Additionally, the later style suspension has a large swept arm that appears to go up towards the frame rail.

At a minimum, I need the 5-lug guts but I really want to install the aluminium arms as well. I know with enough work it can be done, but the primary question is can it be done without fabricating or welding up a bunch of parts?

[Dutch924-racer]

you need to modify the bar. Needs cutting and welding to reinforce it.
_________________
937 trackday car
Series 2 engine
951S turbo and intercooler
Fast road camshaft
Forge recirculation valve + boost controller

[Karpaazio]

I've got alu control arms fitted on my 78' 924
_________________
Porsche 924 1978 Cabrió:
http://www.garaget.org/?car=219790
Porsche 924 widebody (next up?)
Toyota Crown LS110 1983:
http://www.garaget.org/?car=260537
Audi a6 2.7tt quattro 2000 daily driver

[ideola]

[Karpaazio]

I acquired my spring plates from the same car as where I got the trailing arms from. Doesnt need any welding.[/list][/code]
_________________
Porsche 924 1978 Cabrió:
http://www.garaget.org/?car=219790
Porsche 924 widebody (next up?)
Toyota Crown LS110 1983:
http://www.garaget.org/?car=260537
Audi a6 2.7tt quattro 2000 daily driver

[gegge]

[Karpaazio]

Thank you gegge! Hmm which section needs to be welded could someone clarify me? :0 because those control arms bolted up with those 944 spring plates in my case? Is there some weak spot that needs to be reinforced?
_________________
Porsche 924 1978 Cabrió:
http://www.garaget.org/?car=219790
Porsche 924 widebody (next up?)
Toyota Crown LS110 1983:
http://www.garaget.org/?car=260537
Audi a6 2.7tt quattro 2000 daily driver

[gegge]

Sorry, I was looking at your pics and and that is what I meant by welding. You have done some welding fitting that adaptor from the exhaust manifold. I have been thinging doing the same thing.
_________________
Carl Fredrik Torkildsen

924 turbo -81 Carrera GT RESTOMOD
924 turbo -80 Dolomite De Luxe
924 -85 DP kit, BBS RS, M030 and tuned engine
924s -86 Black on black turbo with Fuchs

[Herr-Kuhn]

The basics I need to know are as follows:

The early car has a cast end piece welded onto the tube which mounts the torsion tube assembly directly to the chassis (2 bolts). The torsion bar is held on center by a stamped steel cover plate which houses the bushings. In comparison, the late cars have an aluminium cover plate that bolts to the ends of the torsion bar tube that in turn bolts to the car.

The later cars with the aluminium arms have the ride height adjustment on the torsion beam, therefore there are two plates which must go between the end of the torsion bar tube and the cover plate...the aluminium mount setup is designed around this. My car does not have a ride height adjustment plate setup...it simply bolts directly to the steel swing arm.

So, on the 1978 cars which are converted to later aluminium swing arms...

Does it have the 2-bolt setup like super beetle?
Did the entire Aluminium arm with the ride height plates directly fit and were you able to use the stamped steel cover plate to house the plates which make up the ride height adjustment?

[Dutch924-racer]

[Karpaazio]

Haha gegge you got me confused well it needs some fab!
_________________
Porsche 924 1978 Cabrió:
http://www.garaget.org/?car=219790
Porsche 924 widebody (next up?)
Toyota Crown LS110 1983:
http://www.garaget.org/?car=260537
Audi a6 2.7tt quattro 2000 daily driver

[Herr-Kuhn]

So with those aluminium trailing arms and the 931 transaxle which drive shafts are you running? Are the driveshafts from a later model 944 with the Audi gearbox?

I have the added complexity of having to come up with some mounts for the transaxle as my car has the early 4-speed gearbox.

[Karpaazio]

Yes you also need those drive shafts! Almost failed on mine( was going to sell them, thought dont need these... Then in the last minute before I sold them I noticed that I needed them )
_________________
Porsche 924 1978 Cabrió:
http://www.garaget.org/?car=219790
Porsche 924 widebody (next up?)
Toyota Crown LS110 1983:
http://www.garaget.org/?car=260537
Audi a6 2.7tt quattro 2000 daily driver

[Herr-Kuhn]

The bigger question still remains...can I mount the late alu control arms to the early torsion bar tube?

The torsion bar mount was changed mid year 1978...for the 1979 model year cars I suppose. I have a theory...I believe the change was done to provide ample footprint for the 931 gearbox being hung off the torsion bar housing...thus the reason for getting a much wider footprint to take the loading of the trans-axle.

Along comes 944 and then this design sticks because it was already into production. The box used in the 1979 NA 5-speed was also a G31 based box and these cars have the same newer setup. So it seems 1979+ all used the newer alumimium torsion bar tube mount castings.

I can't see that much benefit to the large casting and the rest of it when the weight of the trans-axle is hung off the chassis like it was on 944 and on my 924 (1977-1978). I believe that torsion tube mounting change was made specifically to address the added weight on the drive line due to the 931 box having been hung off of the torsion bar tube. The weight of the trans-axle would induce a huge moment about the mounting point...after all, it would be quite the cantilevered load, with the only counter point being the mount for the torsion bar tube!

If you look at the suspension and the mount on the early cars, the 2 footed casting only needs to be enough to support the tube and as well provide ample support to keep the torsion bar from seeing any bending loads during suspension and braking loading. The rubber bushings allow for some compliance in the system.

It is now very clear that I must mount the 931 gearbox from above onto the chassis and not off the torsion bar tube. I have no way to mount the entire 924S center tube on my car.

I still need to know if any of you have used the alu arms on the 2-footed torsion tube mount. I made some measurements today and whilst close, it appears I may have to do some machining work.

[Andrew NZ]

Yes, I have 924S arms on my 77. I can't remember exactly what I had to do, but from memory it was just a matter of machining down the poly bushes to squeeze everything in.


_________________
Andrew
1977 RX924 race car
12a bridgeport supercharged
www.race4-dcup.co.nz