30mm or 40mm wide front brake shoes on a 1952 Porsche?

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Jeroen van der Velden
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30mm or 40mm wide front brake shoes on a 1952 Porsche?

#1 Post by Jeroen van der Velden » Thu Apr 02, 2020 6:21 am

Hello, at the moment i am working on the brakes of my 8/1952 cabriolet #15011 with steel drums and aluminium cooling rings. According the latest book of Brett Johnson on page 199 all Porsches from october 1951 had 40mm wide brake shoes in the front until the moment they started to use the large 280mm aluminium brake drums (see pic).
When i removed the front brake drums i noticed it had 30mm wide brake shoes on it. I also removed the original front brake drum on my 5/1952 project coupe #11412 and to my surprise it also hade the 30mm shoes on it.
i started measuring the depth of the brake surface on both drums and these are around 38-39mm. When checking the both backing plates i noticed that the 30mm brakes shoes are resting on the backing plate where the retaining spring attaches the brake shoe to the plate. I tried to put on a 40mm wide brake shoe but these do not fit.
Is there anyone who has more information/experience about these early brakes? thanks for your help!
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Last edited by Jeroen van der Velden on Thu Apr 02, 2020 8:04 am, edited 4 times in total.
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Re: 30mm or 40mm front brake shoes on a 1952 Porsche

#2 Post by Jeroen van der Velden » Thu Apr 02, 2020 6:22 am

More pics
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Re: 30mm or 40mm wide front brake shoes on a 1952 Porsche?

#3 Post by Tony Proasi » Sun Apr 12, 2020 1:22 pm

Jeroen

I just unpacked my drums and shoes to get everything ready to reassemble. Mine are also 30mm

Tony
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Re: 30mm or 40mm wide front brake shoes on a 1952 Porsche?

#4 Post by James Davies » Sun Apr 12, 2020 2:26 pm

Maybe a typo? Oct 1952 would make much more sense for wider shoes as this is near the time when the new aluminum brakes were introduced. Though they had been used for a while before that by the factory on competition cars. Some production cars starting in Aug 1952 had the big aluminum brakes also.

There was also a hybrid large brake that used the VW drum bolted to a larger aluminum surface. These were on the Le Mans SL cars (and probably) others in 1952. Perhaps this is what the 40mm shoes were for.

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Re: 30mm or 40mm wide front brake shoes on a 1952 Porsche?

#5 Post by Jeroen van der Velden » Mon Apr 13, 2020 5:02 am

Hi Tony and James,

I think this confirms that they did use the standard VW 30mm brake shoes also for the front brakes on the steel drum cars.

Thanks for your help, i can go on rebuilding the brakes.

Stay safe, Jeroen
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Re: 30mm or 40mm wide front brake shoes on a 1952 Porsche?

#6 Post by Jules Dielen » Mon Apr 13, 2020 6:45 pm

weren't the steel VW drums 230mm in diameter vs 280 for the aluminum or were there steel 280mm as well? My car is end of september 52. I had steel 230mm in the front and aluminum 280mm in the rear. I highly doubt it came that was as braking in itself was an overstatement.
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Re: 30mm or 40mm wide front brake shoes on a 1952 Porsche?

#7 Post by Jeroen van der Velden » Tue Apr 14, 2020 3:57 am

Hello Jules, yes the early steel VW drums are 230mm in diameter. front and rear wheel cilnders are 19mm and the brake shoes 30mm wide in front and rear. It seems that they used the standard split beetle set up with extra cooling rings on the drums.
i am still looking for information on the master cylinder that was used. According to Brett Johnsons book on page 202 they used the VW transporter master cylinder for these early brakes. Both my 1952 cars have this early steel transporter brake reservoir that is a little different then the later aluminium reservoir. The bottom of the steel one is round and the aluminium is flat. (see pic, aluminium left, steel right)

if hte transporter master cylinider was used this means that they had a 22mm diameter master cylinder instead of the later 19mm.

does anyone have information on the diameter of these early master cylinders that Porsche used on steel brakes?
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Re: 30mm or 40mm wide front brake shoes on a 1952 Porsche?

#8 Post by Jeroen van der Velden » Tue Apr 14, 2020 3:58 am

Jeroen van der Velden wrote:
Tue Apr 14, 2020 3:57 am
Hello Jules, yes the early steel VW drums are 230mm in diameter. front and rear wheel cilnders are 19mm and the brake shoes 30mm wide in front and rear. It seems that they used the standard split beetle set up with extra cooling rings on the drums.
i am still looking for information on the master cylinder that was used. According to Brett Johnsons book on page 202 they used the VW transporter master cylinder for these early brakes. Both my 1952 cars have this early steel transporter brake reservoir that is a little different then the later aluminium reservoir. The bottom of the steel one is round and the aluminium is flat. (see pic, aluminium left, steel right)

if the transporter master cylinider was used this means that they had a 22mm diameter master cylinder instead of the later 19mm.

does anyone have information on the diameter of these early master cylinders that Porsche used on steel brakes?
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Re: 30mm or 40mm wide front brake shoes on a 1952 Porsche?

#9 Post by Jules Dielen » Tue Apr 14, 2020 11:08 am

Hi Jeroen,

I'll take a look at mine. Not sure it is original (i doubt it) but it may help.
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Re: 30mm or 40mm wide front brake shoes on a 1952 Porsche?

#10 Post by Mark Todorovich » Fri Oct 29, 2021 3:21 pm

Our 52 is up and running. We have the pads adjusted to what we think is perfect, pedal is at the top. It stops but it doesn’t give me a lot of confidence.
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I drove this car a lot in the 70’s , also VW’s of the era. I always felt like I could lock up the wheels with heavy pedal. I am not there now. I don’t think it’s adjustment, what other variables should I check.
Age of pads
Size of master cylinder
???
The 63 I drive all the time( with discs) stops like a modern car.
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Re: 30mm or 40mm wide front brake shoes on a 1952 Porsche?

#11 Post by Martin Benade » Fri Oct 29, 2021 6:44 pm

I am only guessing that it should have a 19 mm MC bore, but a larger diameter would give less leverage, needing more foot pressure to stop.
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Re: 30mm or 40mm wide front brake shoes on a 1952 Porsche?

#12 Post by Jeroen van der Velden » Sat Oct 30, 2021 4:12 am

I have the same problem on my 1952. It does not feel that it stops like it should. Everything is new/rebuild on the brake system. I already did bleed the system twice. I have 19mm brake cilinders and a 21mm master cilinder. the 21mm master cilinder was already on the car so i did rebuild it. At this moment i think the master cilinder is the probleem. Planning to replace it to a 19mm master cilinder in the next month. Will post again as soon as i have the result.
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Re: 30mm or 40mm wide front brake shoes on a 1952 Porsche?

#13 Post by Harlan Halsey » Sat Oct 30, 2021 5:10 am

The same pedal force will give 1.22 times as much force at the wheel cylinder, moving from a 21 to a 19. Should make quite a difference. Of course, higher friction coefficient linings would reduce the required pedal force too.

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Re: 30mm or 40mm wide front brake shoes on a 1952 Porsche?

#14 Post by Tony Proasi » Sat Oct 30, 2021 10:11 am

If you replaced the shoes you should have them arched and matched to the drums.

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master cylinder, looking for 19

#15 Post by Mark Todorovich » Fri Mar 25, 2022 12:10 pm

After participating and reading this I feel like my brakes need more work. our 52's running pretty well but is stock and I don't think its built beyond the brake capacity. It has all new lines and slave cylinders. We didn't rep[lace the master. I can't identify its specs. From other posts it sounds like a 19/19.5 will produce more stopping power. I have been trying the usual sources, not just 356 but the old VW ones also. Anybody know the Specs on the ones that are available. Even the parts guys I regularly use aren't sure. Prices are about the same.
Thanks Mark
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