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Master cylinder sizes

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urban_myth Officially Full-On Dubber

354 posts · joined Jan 2005 ·

#497627
Me and my dad are sussing out the braking system on the floorpan we are building up for my beetle. We need some info regarding the piston sizes of the various master cylinders that volkswagen used on the beetle and the kombi.

Just FYI, we are using VS commodore brakes all round and we wont be using a booster. We are looking to make the pedal feel as soft as it possibly can be without a booster but minimise pedal travel before braking occurs.

1303Steve Scirocco Rare

8,650 posts · joined Aug 2002 ·

#497710
Hi

Early bugs used single circuit 17 mm later ones used 19 mm, in both single dual circuit. I think Kombis were 21 mm. I was using a stock 19 mm MC with 4 spot Brembos all round, they worked fine.

Steve

urban_myth Officially Full-On Dubber

354 posts · joined Jan 2005 ·

#497971
Thanks for that Steve. We spoke to a brake specialist and they recommended a 21mm master, any bigger and the pedal would be very hard. So whats the pedal travel in yours like?

1303Steve Scirocco Rare

8,650 posts · joined Aug 2002 ·

#497981
Hi

It was like a stock Beetle, just needed a tiny bit more effort. This was on my old yellow bug, I plan to use the same stuff on my new one.

Steve

1303Steve Scirocco Rare

8,650 posts · joined Aug 2002 ·

#498163
Hi

These piston areas may help you.

Pistons in my front Brembos 37.5 mm & 26 mm

37.5 x 2 = 18.75 x 18.75 = 351.5625 x 3.1416 = 1104.46875

26 x 2 = 13 x 13 = 169 x 3.1416 = 530.9304

so total area for 1 caliper is 3270.7983

Late Type 3/4 calipers are 50 mm, this is what I used previously, now Jak is using them on his WRX bug.

50 x 2 = 25 x 25 = 625 x 3.1416 = 1963.5 total for 1 caliper is 3927

Stock Beetle calipers 40 mm

40 x 2 = 20 x 20 = 400 x 3.1416 = 1256.64 total is 2513.28

Steve