924Board.org

indi9xx · Joined: 01 Nov 2003 Posts: 83 Location: Bournemouth, UK

Anyone out there know of ways of upgrading the 924 4 stud brakes, without going over to the 5 stud wheels.

We have a customer who has just brought a set of 17 inch wheels, then comes to us asking for a brake upgrade... we explained that he should have had the 944 brake conversion, then gone shopping for wheels... but what is done is done..

So, any ideas/options?

We are at a loss, except for maybe cross drilling the front disks and grooving the rear drums.

We would go to the effort of designing something, but this car is a bit of a one off, most people would have gone for the 5 stud approach... ho hum

Jon Mitchell
Independent Porsche Specialists
Bournemouth, UK
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Jon Mitchell
Independent Porsche Specialist
Bournemouth, UK

Mikri184 · Joined: 12 Sep 2003 Posts: 746 Location: Ferndale, WA

What your customer needs to do is contact a VW supplier and buy the disc brake conversion for a late super beetle front and rear and have them redrill the rotors for the lug pattern he needs, spacers may still need to be installed. Cost in U.S is about $600 plus shipping.
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Life is to short to be looking for something?

-nick · Joined: 16 Nov 2002 Posts: 2699 Location: Cambridge, MA

Or you can just get him/her some better pad/shoe compounds. I think Hawk makes some for the 4-lug brakes. You can convert to 5-lug for less than $600. Also, there's no reason to crossdrill/slot the rotors&drums. That's just going to reduce the small surface area you already have. It's really a marketing gimmick. It will only help in the rain.

-nick

indi9xx · Joined: 01 Nov 2003 Posts: 83 Location: Bournemouth, UK

For this guy, he insists on sticking with 4 stud... we are thinking about seeing what we can do to convert 5 stud hubs to 4 stud, but due to the aluminium hubs, its not looking good. Which is a shame, because we have loads of kits on the shelf ready and waiting to convert 924's to 5 stud 911SC/944 brakes..We may find something we can do.. but alas, this guy insists on sticking with the 4 stud patern

(

We have found some improvement of limiting brake fade on 924's with cross drilling, as it seems to help disipate the gas build up between disk and pad during braking and assist cooling a little. But we really want to improve the amount of braking force that can be applied.. so some bigger calipers and larger vented disks would be just the ticket.

Jon Mitchell
Independent Porsche Specialists
Bournemouth, UK
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Jon Mitchell
Independent Porsche Specialist
Bournemouth, UK

ponchojuan · Joined: 20 Jul 2004 Posts: 51 Location: Boston, MA

Jon, I'm sure you solved this issue, but here is a possible link for future reference. EMPI makes conversion kits for VW. The stud pattern may need to be redrilled and tapped, or you might be able to get rotors that fit the porsche pattern from them.

cip1.com sells these kits for around US$300.

http://www.empius.com/d/discbrakekits.html

Andrew NZ · Joined: 22 Jun 2004 Posts: 744 Location: New Zealand

How about machining the edge off the drum to provide a plate to slide Peugeot rear disks over (same stud pattern). All you'd have to do is make some brackets for the Peugeot callipers then. I've done similar things with offroaders, but not sure if it would work on a porsche. What do you think?
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Andrew
1977 RX924 race car
12a bridgeport supercharged
www.race4-dcup.co.nz

gohim · Joined: 02 Nov 2002 Posts: 4459 Location: Rialto, CA

The biggest problem with the rear drum brakes is the fact that they are not self-adjusting, and the rapid wear of the shoes makes for a mushy pedal and poor braking every thousand miles.

Machining off the edges of the brake drum and refitting a disk over the top is an interesting idea. The question is, will the French rotor friction surface end up in the right plane for the caliper (assuming you use the 924/931/944 rear caliper). Is the French rotor the right size to work with the Porsche 11.2 rotor caliper? What do you do for a parking brake?

The other problem would be the front to rear brake balance. If you keep the solid front rotors, I would expect that the front to rear brake balance to be off. Need a proportioning valve?

Andrew NZ · Joined: 22 Jun 2004 Posts: 744 Location: New Zealand

You'd have to use the peugeot calipers as well, which have a built in hand brake. I'd also looked at the Audi discs, but the peugeot ones apear to have a better offset to be able to fit the callipers in etc.

How are the calipers mount on the porsche set up? are they just bolted to the four bolts that hold the drum backing plates on, or are there additional brackets?

I've been wondering about the balance too, infact this is the thing thats stopped me getting too serious about the idea just yet! Anyone want to try it and let me know if it works?

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

CorsePerVita · Joined: 25 Jul 2008 Posts: 1992 Location: Redmond, Oregon

haroldk · Joined: 24 Nov 2008 Posts: 171 Location: St Paul, MN, USA

I was actually going to be looking into doing a conversion using the drums and front rotors as hub flanges as described above. I was thinking of trying Ford parts since I've got a good supply of those. With the right adaptor parts, I'm sure something could be made to fit. That has the added benefit of not needing to pull an axle nut every time you want to change a rotor.

I'd like to go this route since I've got 6 sets of wheels, all told, in 4x108 from my other cars. Since the other wheels I have are between 35mm and 48mm offset, adding thickness to the flange face would only mean I'd need a thinner spacer to use the wheels.

Frankly I was a little surprised I haven't seen this done yet.

Andrew NZ · Joined: 22 Jun 2004 Posts: 744 Location: New Zealand

I did it a few years ago with the Peugeot parts, but when I changed to 944 bits the difference was huge.

In my opinion it's not worth wll thw messing around - just get the 944 setup!
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Andrew
1977 RX924 race car
12a bridgeport supercharged
www.race4-dcup.co.nz

CorsePerVita · Joined: 25 Jul 2008 Posts: 1992 Location: Redmond, Oregon

Scorpio · Posted: Sat Jun 20, 2009 5:25 pm Post subject:

haroldk · Joined: 24 Nov 2008 Posts: 171 Location: St Paul, MN, USA

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

the answer is:

Depends.....

You have two options:

Keep the steel rear trailing arms and stock transmission and use early 944, 924S or 924 turbo rear disc brakes from a car with steel rear control arms. You'd need the rear disc calipers (which are all the same) discs, the caliper adapters (backing plates), the hubs, e-brake cables and hoses.

If you want to use the aluminum rear trailing arms, you'd need to change the suspension carrier, transmission, transmission mount, torque tube, axles, and clutch (a 924 turbo bellhousing, starter, hydraulic clutch conversion might be a good idea at this point as well)

The entire rear end has to be changed because the later model arms don't fit the early style rear suspension carrier and the later carrier doesn't have the ears to hold the 915 transmission. So that means the transmission, the mount, the torque tube and the clutch (to mate the 924 NA to the 944 splines) Basically, got a parts 944 or 924S?

The master cylinder should be changed and the brake line routing needs to be changed as well for both types of solutions. Because the balance is changed and the brake system is split differently. Luckily that is one change that isn't as bad as it sounds.

Or you can read this thread posted by Ideola:

http://www.924board.org/viewtopic.php?p=218957#218957
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)