924Board.org

[Robert Hooper]

I am about to change my 924 turbo brakes over to my 924 race car to help the bloody thing stop as it normally doesnt. I am after some info on how this is top be done ??? and also how hard it is ???

Has anyone added brake bias etc in a conversion what about the booster change or remove and go just off the pedal ????

Cheers

Robert
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1982 924 Race Car
1981 931 Road Car

[gohim]

Since your cars are 81 and 82, the master cylinder and vacuum boosters are both the same size.

The biggest problem with the disc/drum brake setup is the fact that the drum brakes are not-self-adjusting. Since the brake system is arranged as an "X", when the rear brake shoes are out of adjustment, the front brakes will not work either without pumping the brake pedal.

The conversion is a straight forward bolt-on if you use the turbo for parts for the 924. The easiest way to do the front is to simply swap the complete struts (of course you may not want to do that if you have special struts or strut inserts on the "Race Car" already). The flex hoses in the front with the ventilated brakes are longer, so you want to move them as well.

In the back, you will need the parking brake cables from the four wheel disc brake car to move to the race car. The hard brake lines that lie on the trailing arms are required as well. the flex hoses on the four wheel disc brake car, and the disc/drum brake cars are the same. The easiest way to do the rear is to disconnect the parking brake cables from each other, and take each parking brake with the backing plate that it is attached to, as a complete assembly over to the target car. You should regrease the wheel bearings and the cv axles while you are in there, so don't forget to buy new seals (the o-rings for the rear bearings as well) before you get started.

[924RACR]

As far as the struts, you could just swap out the uprights and leave your race struts in place.
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[Robert Hooper]

So i am unable to use the currrent suspension i have just as it is...it is specially made cut down shocks etc for smaller travel.....

I though you just swap hubs etc..... bugger

Im not the interesteed in have a parking brake ill just use a bit of wood or plumb into rear brakes.....
_________________
1982 924 Race Car
1981 931 Road Car

[gohim]

You can still use the same suspension parts (front struts, sprints upper mounts, rear torsion bars, trailing arms, spring plates, shocks) with the exception of the front spindles (different diameter). Your modified struts will bolt onto the four wheel disc spindles.

In the back, you don't have to swap the brake cables, but they can come out assembled to the disc brake mounting plates, and drum brake backing plates, so the work necessary is minimal.

You have to swap the hard lines in the back because the ones for the drum brakes screw directly into the wheel cylinders, which are located differently from where the hard lines screw into the disc brake calipers. this is again a simple operation. With the drum brakes, there isn't aren't any rear wheel hubs, the wheel lug bolts crew directly into the drums. With the four wheel disk brakes, there are hubs, and the rotors are screwed to them, so you have to remove the axle nuts to pull the drums and install the wheel hubs for the rear rotors.

Unless the racing class you are aiming to participate in prohibits it or will penalize you for it, you would be better off looking for the four wheel disc brake parts from a later early 944 (pre 85/1) instead of using 924/931 parts. The 944 splash plates are made from steel, are heavy, and rust like crazy, where the 944 parts are made from aluminum and much lighter. Also, the rear caliper/splashplate mounts are a single piece of alloy on each side from the 944, and composed of three pieces of cast or stamped iron and steel on the 924/931. The four wheel disc brake system is much heavier than the disc/drum setup that it can replace, I would want to minimize the weight gain by using the lightest pieces available that have proved reliable (no problem with the alloy 944 parts).