4 Digit or very early 356 brake system

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Erich Wagner
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4 Digit or very early 356 brake system

#1 Post by Erich Wagner »

Hello early 356 lovers,

i am rebuilding the rear brake system of my 4 Digit coupe.
The car was " upgraded" to ~1959 Beetle brakes with 22mm wheel cylinders. I was happy with that system the last 5 years.
As i drive my old lady a lot, brakes are worn now and i think about going back to stock parts also because the "pedal way" is quiet far with stock master cylinder and 22m wheel cylinders.

I read in Brett Johnsons Book that early cars had 18mm (??) rear wheel cylinders with no "bleeder screw"..? Does someone know if those wheel cylinders were also taken from any VW or were they spezially "produced" for the rear brakes of the early 356?



Thank you in advance for sharing your knowledge :-)
All the best from Austria.
Eric
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1958 Speedster->resto           1957 Coupe
1954 1500-S Sunr. Project      1951 Coupe Project
1952 Denzel 1950 Coupe
http://forum.porsche356registry.org/viewtopic.php?f=4&t=17124

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Vic Skirmants
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Re: 4 Digit or very early 356 brake system

#2 Post by Vic Skirmants »

At least on the front brakes the bleeder screw was in the brass fitting outside the backing plate. I don't know what the rears had. I also can't answer the question about cylinder size.

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Erich Wagner
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Re: 4 Digit or very early 356 brake system

#3 Post by Erich Wagner »

I expected an answer from you Vic :-)

So the very early cars did have single brake zylinder setup equal to the early VW?
If they had no bleeder on the wheel zylinders, did the backing plates have the cutout for the bleeder screw?

Would be cool if someone has some information about the 18mm rear cylinders..?
I have never seen 18mm. Neither on earls VW's

I know, i have too many questions...
"In torque we trust"

1958 Speedster->resto           1957 Coupe
1954 1500-S Sunr. Project      1951 Coupe Project
1952 Denzel 1950 Coupe
http://forum.porsche356registry.org/viewtopic.php?f=4&t=17124

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Vic Skirmants
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Re: 4 Digit or very early 356 brake system

#4 Post by Vic Skirmants »

My earliest experience is with a 1952 car. It had dual front cylinders, no cutout for a bleeder screw, and the bleeder was in the brass outside fitting.

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Erich Wagner
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Re: 4 Digit or very early 356 brake system

#5 Post by Erich Wagner »

I have not found any hint about the 18mm Wheel cylinders.
Non of the VW guys i know, know anything about 18mm cylinders. I can not imagine that this were specially made for Porsche... or am i wrong?

Finding backing plates with no cut outs for the bleeder screw, i s almost impossible...
"In torque we trust"

1958 Speedster->resto           1957 Coupe
1954 1500-S Sunr. Project      1951 Coupe Project
1952 Denzel 1950 Coupe
http://forum.porsche356registry.org/viewtopic.php?f=4&t=17124

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James Davies
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Re: 4 Digit or very early 356 brake system

#6 Post by James Davies »

pre-As have 19mm wheel cylinders all around. Size was increased sometime during T1 production I believe.

19mm is same as early Beetle, as expected.

19mm for both the early steel brake drums and the larger aluminum drums.

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Erich Wagner
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Re: 4 Digit or very early 356 brake system

#7 Post by Erich Wagner »

Hello James,

i was just confused because of that 18mm in Brett's book.
Great to read that 19mm were standard. Easier to get.

BUT... how long did VW build the Backing plates without cut outs for the bleeder screw and i guess it is impossible to get wheel cylinders with no bleeder screw..?

All the best from Ausria.
Eric
"In torque we trust"

1958 Speedster->resto           1957 Coupe
1954 1500-S Sunr. Project      1951 Coupe Project
1952 Denzel 1950 Coupe
http://forum.porsche356registry.org/viewtopic.php?f=4&t=17124

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Vic Skirmants
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Re: 4 Digit or very early 356 brake system

#8 Post by Vic Skirmants »

Very easy to modify a wheel cylinder by tightening the screw and cutting it off flush. If used with a correct backing plate with no cutout for the screw, no one would know!

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Erich Wagner
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Re: 4 Digit or very early 356 brake system

#9 Post by Erich Wagner »

Sure,

that is a way to go.
I could even modify the backing plates by welding those cut outs and mill them to look like original ones

I just ask myself how long VW built that "non cut out" backing plates for the Beetle???

The early backing plates on the rear axle have one major disadvantage as they do not have 4 holes like ALL later backing plates for the mounting holes but have kind of slots for the mounting holes so the O Ring always "goes" out a bit at each screw.

You get it tight but it's a pain .... whay they built that plate that way will be a riddle for ever :-)

-------
Dammed cold summer this year here in Austria... not that much days to pull out my old lady... so i work on the brakes 🤘
"In torque we trust"

1958 Speedster->resto           1957 Coupe
1954 1500-S Sunr. Project      1951 Coupe Project
1952 Denzel 1950 Coupe
http://forum.porsche356registry.org/viewtopic.php?f=4&t=17124

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James Davies
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Re: 4 Digit or very early 356 brake system

#10 Post by James Davies »

Hi Erich,

The diagram on page 66 of the 1953 Parts book shows the 1950-52 brake setup. I.e. it shows the Porsche-specific parts. So it shows no drums or rear backing plates, as those were standard VW.

But it does show the Porsche dual-master cylinder setup for the front brakes, the Porsche front brake backing plates, Porsche brake shoes, lines, master cylinder, etc.
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Re: 4 Digit or very early 356 brake system

#11 Post by James Davies »

Here's photos of the front braking plate and brake cylinder without bleeders setup. These cylinders with the bleeder built into the upper brass banjo fitting were used until early Jan 1954. From coupe 51642 and cab 60391 onward had bleeders on the cylinder in the front.
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Erich Wagner
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Re: 4 Digit or very early 356 brake system

#12 Post by Erich Wagner »

Ok,
the second picture shows a"kind of" cut out for a bleeder screw. It looks like it was cut out later with a grinder as it is not "round" at the end.
I guess many of those plates were mdified..?

Does anyone have a picture of a rear backing plate with no bleeder screw cut out?

I have not found any pic so far. They were all with bleeder cut outs..
"In torque we trust"

1958 Speedster->resto           1957 Coupe
1954 1500-S Sunr. Project      1951 Coupe Project
1952 Denzel 1950 Coupe
http://forum.porsche356registry.org/viewtopic.php?f=4&t=17124

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James Davies
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Re: 4 Digit or very early 356 brake system

#13 Post by James Davies »

Yes, all the rear backing plates had bleeder cutouts. It was a VW part, and both the Porsche and VW rear wheel cylinders had a bleeder.

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Erich Wagner
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Re: 4 Digit or very early 356 brake system

#14 Post by Erich Wagner »

Very strange that Porsche took the rear backing plate from a car with 17mm wheel cylinder and put a 19mm wheel cylinder in it.
So the middle of the brake shoe is out of the middle for 1mm (half the difference of the diameter)
That means the brake shoe is not "straight) in the drum but 1mm sideway....

Very strange....
"In torque we trust"

1958 Speedster->resto           1957 Coupe
1954 1500-S Sunr. Project      1951 Coupe Project
1952 Denzel 1950 Coupe
http://forum.porsche356registry.org/viewtopic.php?f=4&t=17124

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Alan Hall
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Re: 4 Digit or very early 356 brake system

#15 Post by Alan Hall »

No, if the 19mm wheel cylinder mounts in the same holes the centerline of the cylinder is in the same location as the it was with the 17mm cylinder. (same reason you don't need a different crankshaft when you put in a big bore kit).

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