Skip to content
Aussieveedubbers

Master Cylinder: single to dual circuit?

0 likes
Share Share on Facebook Share on X Share on Reddit

66deluxe Custom Title Time!

1,593 posts · joined Aug 2005 ·

#894969
I want to upgrade my girls beetles single circuit master cylinder to dual circuit. What master cylinder from which year is required. It will stay drums all round but eventually get wide five discs at the front.

Thanks for any help. Damo.
This is my Volkswagen, there are many like it, but this one is mine. Without me my Volkswagen is useless, without my Volkswagen, I am useless.

61 Karmann Ghia 2110cc type1 w Los Panchito's
66 Deluxe Beetle 2270 type 4
10 Subaru WRX Impreza

1303Steve Scirocco Rare

8,650 posts · joined Aug 2002 ·

#894978
Hi

A 1500 Beetle one. You can no longer buy a master cylinder to suit late drum brake bug.

So if you have a 1500 Beetle, a 76 Beetle or a 4 wheel drum brake 1300 12 volt Beetle you use the same one on all of those models.

Steve

68AutoBug Beetle Restorer - Experience over 138\% - YIKES --

11,654 posts · joined Aug 2002 ·

#895050
1303Steve wrote:Hi

A 1500 Beetle one. You can no longer buy a master cylinder to suit late drum brake bug.

So if you have a 1500 Beetle, a 76 Beetle or a 4 wheel drum brake 1300 12 volt Beetle you use the same one on all of those models.

Steve
Hi Steve

that is a bit strange when all NORTH AMERICAN Beetles had drum brakes?? including all supers..

what is the difference? between drum & disc brake master cylinders??

Lee
- Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY---

68AutoBug Beetle Restorer - Experience over 138\% - YIKES --

11,654 posts · joined Aug 2002 ·

#895060
well the pipes may be different but if You are fitting dual brakes You need new pipes anyway...

LEE
- Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY---

grumble Son of Jim - Creator of Good

2,672 posts · joined Jun 2008 ·

#895077
68AutoBug wrote:
1303Steve wrote:Hi

A 1500 Beetle one. You can no longer buy a master cylinder to suit late drum brake bug.

So if you have a 1500 Beetle, a 76 Beetle or a 4 wheel drum brake 1300 12 volt Beetle you use the same one on all of those models.

Steve
Hi Steve

that is a bit strange when all NORTH AMERICAN Beetles had drum brakes?? including all supers..

what is the difference? between drum & disc brake master cylinders??

Lee
Lee the difference between disc master cylinders and drum masters is residual line pressure valve in the drum brake cylinders,this holds a low pressure in the line,the disc brakes don't use this as it will cause brake drag because there are no springs to retract the shoes (pads) and with a booster this is accentuated to the point where the brakes will lock up.

psimitar Son of Jim - Creator of Good

2,506 posts · joined Jan 2009 ·

#895730
if you look at what is available there is only single or dual circuit MC's. Both are 19mm bore size.

The MC does nothing with holding line pressure apart from allowing more fluid into the high pressure side to allow for pad and shoe wear. On old VW's the brake shoe springs are what return the wheel cylinder pistons to there rest position after the MC has been depressed. The return spring in the MC also is what draws back the caliper and wheel cylinder pistons due to it's internal return springs.

Go for a dual circuit MC cos then if a circuit fails you have some chance of stopping 🙂
madness is in the eye of the beholder 👍

66deluxe Custom Title Time!

1,593 posts · joined Aug 2005 ·

#895748
I purchased a new dual circuit M/C disc front drum rear. So hopefully install that along with type 3 rear brakes also. Then add disc brakes to the front later.
This is my Volkswagen, there are many like it, but this one is mine. Without me my Volkswagen is useless, without my Volkswagen, I am useless.

61 Karmann Ghia 2110cc type1 w Los Panchito's
66 Deluxe Beetle 2270 type 4
10 Subaru WRX Impreza

hellbugged 48's and straight cuts

5,080 posts · joined Apr 2003 ·

#895754
you might be looking for those front discs sooner than later..........had dual circuit master with drums years ago.

66deluxe Custom Title Time!

1,593 posts · joined Aug 2005 ·

#895761
hellbugged wrote:you might be looking for those front discs sooner than later..........had dual circuit master with drums years ago.
Not the best?
This is my Volkswagen, there are many like it, but this one is mine. Without me my Volkswagen is useless, without my Volkswagen, I am useless.

61 Karmann Ghia 2110cc type1 w Los Panchito's
66 Deluxe Beetle 2270 type 4
10 Subaru WRX Impreza

matberry Moderator Go hard or go home

8,114 posts · joined Mar 2006 ·

#895763
Dual cct master has a lesser value residual valve as disc's want less residual pressure than drums (I believe 3psi compared to 10psi IIRC). I think you will have a long pedal with the disc master used on a drum system.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE

hellbugged 48's and straight cuts

5,080 posts · joined Apr 2003 ·

#895765
yeah What Matt said 😉

psimitar Son of Jim - Creator of Good

2,506 posts · joined Jan 2009 ·

#895822
Huh, didn't know that. Who says you don't learn something new every day 🙂
madness is in the eye of the beholder 👍

68AutoBug Beetle Restorer - Experience over 138\% - YIKES --

11,654 posts · joined Aug 2002 ·

#895828
66deluxe wrote:I purchased a new dual circuit M/C disc front drum rear. So hopefully install that along with type 3 rear brakes also. Then add disc brakes to the front later.
How do You tell the difference between a Disc or drum front Master cylinder??
I have one I bought from the USA [for a spare]

maybe its for drum/drum duals??

I was always going to put type 3 rear drums on My beetle
but You don't need any more brake surface on the rear unless You have the rear brakes adjusted right UP..

I failed a brake test last year as My rear brakes worked too well... {I had just adjusted them] lol

LEE
- Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY---

psimitar Son of Jim - Creator of Good

2,506 posts · joined Jan 2009 ·

#895841
68AutoBug wrote:
66deluxe wrote:I purchased a new dual circuit M/C disc front drum rear. So hopefully install that along with type 3 rear brakes also. Then add disc brakes to the front later.
How do You tell the difference between a Disc or drum front Master cylinder??
I have one I bought from the USA [for a spare]

maybe its for drum/drum duals??

I was always going to put type 3 rear drums on My beetle
but You don't need any more brake surface on the rear unless You have the rear brakes adjusted right UP..

I failed a brake test last year as My rear brakes worked too well... {I had just adjusted them] lol

LEE
So long as the rears don't lock under everyday braking conditions then I can't see why you fail them?
madness is in the eye of the beholder 👍

68AutoBug Beetle Restorer - Experience over 138\% - YIKES --

11,654 posts · joined Aug 2002 ·

#895867
Hi
the brake test was done on steel ramps and the front/rear brake percentage comes up on a large digital readout up on the wall
[first time I've seen one] steel ramps are part if the machine..
Mechanic drives the car onto the flat steel ramps and hits the brakes..

from memory?? front had to be over 70% and mine was under..
it was raining so tyres were wet...

also tried it on a brake pedal readout machine but it also failed
Mechanic drove it all around town [in heavy rain] and said the brakes worked perfect..???

Lee

PS
they work even better with the rear braking more than 30%

otherwise the fronts just lock up..

1 attachment · Log in to view

- Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY---

psimitar Son of Jim - Creator of Good

2,506 posts · joined Jan 2009 ·

#895898
UK MOT use a set of motorised rollers to place the wheels on. Braking torque is displayed on a large pair of dials to make sure each side is within a few percent for straight braking.
madness is in the eye of the beholder 👍

1303Steve Scirocco Rare

8,650 posts · joined Aug 2002 ·

#895924
Hi

Lee the master cylinder you bought will most likely be for LHD.

Most brake test nowadays are conducted in the mechanics office.

My old 1302 with 4 wheel 4 spot brakes kept failing, the tester put it down to my cars heavier suspension not dipping under braking.

Steve

grumble Son of Jim - Creator of Good

2,672 posts · joined Jun 2008 ·

#895938
1303Steve wrote:Hi

Lee the master cylinder you bought will most likely be for LHD.

Most brake test nowadays are conducted in the mechanics office.

My old 1302 with 4 wheel 4 spot brakes kept failing, the tester put it down to my cars heavier suspension not dipping under braking.

Steve
Steve we all know this happens even though the RTa doesn't acknowledge it,my new brake test machine would fail the vehicle unless it was driven over 30kph and as you say the suspension didn't dip enough to give a deceleration which was a bugger in wet weather. Les

68AutoBug Beetle Restorer - Experience over 138\% - YIKES --

11,654 posts · joined Aug 2002 ·

#897012
New NOS 1500 ATE master cylinder went on ebay last week

went for $132-00

cheers

LEE

was in Australia
- Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY---

66deluxe Custom Title Time!

1,593 posts · joined Aug 2005 ·

#897013
Got one and installed it. Now waiting for resivoir and mounting bracket from CSP. Then pick up disc brake kit on friday.
This is my Volkswagen, there are many like it, but this one is mine. Without me my Volkswagen is useless, without my Volkswagen, I am useless.

61 Karmann Ghia 2110cc type1 w Los Panchito's
66 Deluxe Beetle 2270 type 4
10 Subaru WRX Impreza

Uber Kafer Wolfsburg Wizard

414 posts · joined Nov 2009 ·

#897685
seems to be a lot of left hand drive dual circuit master cylinders being advertised lately ( and not identified as such as well), did someone stuff up an order and bring a whole bunch of LHD units in to the country and is now off loading them everywhere ?

From what I can see they cant be used on right hand drive cars as the pipes will be took close to the tunnel.

psimitar Son of Jim - Creator of Good

2,506 posts · joined Jan 2009 ·

#897816
Uber Kafer wrote:seems to be a lot of left hand drive dual circuit master cylinders being advertised lately ( and not identified as such as well), did someone stuff up an order and bring a whole bunch of LHD units in to the country and is now off loading them everywhere ?

From what I can see they cant be used on right hand drive cars as the pipes will be took close to the tunnel.
They are half the price of a RHD MC. They are also perfectly usable IF you have access to a proper pipe bender but for servicing purposes they are tricky to access properly. With the tank out its much easier.

If you can live with the tight acces then they are a good option.

You can also swap the brake switch to the other side so it's only the rear outlet that uses a tight turn 🙂
madness is in the eye of the beholder 👍