anyone upgraded the master cylinder on a S3?

[V8-ESPRITS3]

I think I need a bigger master cylinder, have fitted some much bigger 4 pot calipers on the front of my S3.

Have bleed them the normal way with some one pumping the pedal, have also tried one of those vacuum pumps (and no not that type your thinking of!) the type for vacuum leak testing, found they pull air in from the bleed nipple so stuck some bluetak around the nipple to seal it, then found my old ezi-bleed system got that working have put around 3 litres through it all, and convinced I have no air in the system. The pedal still has a massive amount of travel, at least 2/3 to 3/4 of travel before its hard. If I pump the pedal only comes up a very small amount. Which kind of confirms my feeling the system is bleed and the master cylinder is not up to pushing enough fluid for the front calipers? Ooo the joy of brake fluid all over your hands, tools, car, drive way, better not be any on my paint work.........I am already close to tears!

[Vulcan Grey]

I kept my 89SE non-ABS original master cylinder (Bendix) when I went to massive 4 piston calipers front and rear on my car.

 

There was only a very slight change in pedal feel, still rock hard.

[Bibs]

Do those calipers have any peculiar internal pathways which mean they need to be removed and bleed upside down?

[mdw]

Car builder solutions have a load of info  in their hints and tips page re master cylinder sizes  when changing brake calipers. Might be worth a look at. 

[CHANGES]

I still use my standard SE master cylinder with 6 pot front and 4 pot rears, 

all works a treat..

However the rears did take some beading,  just as Bibs said ,they needed 

removing. rotating with a slight tapping to get all the air out.. 

[molemot]

I have the 4 pot upgrade to the front brakes and the standard master cylinder/servo unit has no problems. No problem bleeding them, either.

[V8-ESPRITS3]

I kept my 89SE non-ABS original master cylinder (Bendix) when I went to massive 4 piston calipers front and rear on my car.

 

There was only a very slight change in pedal feel, still rock hard.

they have bigger calipers on front to start with do they not? and is the master cylinder not bigger also than what`s fitted on a S3?

My master cylinder setup has one pipe to rear brakes split to each side, and also just one pipe from the front again split to each side? it has another output from underneath which is blanked off? are the Series 4 esprit done the same or do they have 4 pipes from the master? thanks

[V8-ESPRITS3]

Do those calipers have any peculiar internal pathways which mean they need to be removed and bleed upside down?

I really don`t know? hard to find any info! have already tried bleeding them off the hubs and rotating them, while bleeding them at the same time, even used a strip of wood thinner than the discs between the pads so the pistons could move out some, which they did, really at low at the moment hate working out in the heat, things not going right, and covered in brake fluid! When your down thing just keep kicking you....thanks

Car builder solutions have a load of info  in their hints and tips page re master cylinder sizes  when changing brake calipers. Might be worth a look at. 

ok great will have a look, cheers

[V8-ESPRITS3]

I still use my standard SE master cylinder with 6 pot front and 4 pot rears, 

all works a treat..

However the rears did take some beading,  just as Bibs said ,they needed 

removing. rotating with a slight tapping to get all the air out.. 

ok will give it another go in a few days, pretty beat up with them at the moment. Is you master not bigger anyway with also 4 outlets than what`s fitted to the S3? mines an early model 81 which parts wize is the runt of the litter!

[Vulcan Grey]

they have bigger calipers on front to start with do they not? and is the master cylinder not bigger also than what`s fitted on a S3?

My master cylinder setup has one pipe to rear brakes split to each side, and also just one pipe from the front again split to each side? it has another output from underneath which is blanked off? are the Series 4 esprit done the same or do they have 4 pipes from the master? thanks

 

The 89SE had small single piston sliding calipers and tiny rotors, sure, larger than an S3... but much smaller than what I put on.

 

89SE master

 

Original front brakes, 1985 Toyota Corolla caliper and rotor.

 

original Bendix rear (same pads as a Renault LeCar IIRC)

 

New calipers, all 4 piston.

 

New front rotor (bottom) 328mmx35mm

 

new rear rotor (bottom) 313mmx25.4mm

 

Front

 

Rear

 

 

Pedal feel is still excellent!

[Vulcan Grey]

Many of the 4 piston calipers have bleed nipples on each side of the caliper with a bridge pipe across the bottom.  You need to bleed both nipples, one on each side of each caliper.

[V8-ESPRITS3]

Many of the 4 piston calipers have bleed nipples on each side of the caliper with a bridge pipe across the bottom.  You need to bleed both nipples, one on each side of each caliper.

I had to use one bleed nipple as the feed, and the original feed is blanked off, due to it touching my air spring. I have struggled to find any real info if this is still ok to do? Please forgive me on the poor drawing I have just done it fast to help show my setup. Do you think this could be a problem?

[V8-ESPRITS3]

The 89SE had small single piston sliding calipers and tiny rotors, sure, larger than an S3... but much smaller than what I put on.

 

89SE master

 

 

 

 

 

 

 

from the picture looks like the front has two outlets? one to each front brake? mine is only using one, then split to two with a t-section. I have done away with all the original lines and now used stainless flex throughout. I have used a double banjo from the master and done away with the t-split. but its still the basic layout.

Edited July 18, 2014 by V8-ESPRITS3

[Vulcan Grey]

Ah....  yeah flex hose instead of hard line will definitely make the pedal feel softer!!!

 

The drawing is fine.  Yes that is ok to do with the caliper feed line through one of the nipple ports, and then the middle feed port blocked off.  The plug just can't be allowed to plug the internal tube.  That is often done.  Might be a little more difficult to bleed.

 

Yes, the 89SE master has 2 lines, one for each front caliper, and then one line for both rear brakes, and there is a tee-connector (no proportioning on the non-ABS cars like 89SE,  and the Sport 300 and X180-R had ABS but no proportioning valve).

[V8-ESPRITS3]

Used a bleed nipple for plug so should not be a problem? any ideas why the pedal travels too far? love your project very nice!

[Vulcan Grey]

the pedal travel could just be due to the flexy brake lines, since you don't have hard lines any more.

 

or it could be the master cylinder diameter and stroke are not matched to the calipers as you thought.

[V8-ESPRITS3]

the pedal travel could just be due to the flexy brake lines, since you don't have hard lines any more.

 

or it could be the master cylinder diameter and stroke are not matched to the calipers as you thought.

ok thanks will give it a go with hard lines, never knew they would cause a problem? willing to try anything! cheers 

[V8-ESPRITS3]

ok, done all the brake lines again! all hard lines as it was before, and just the stainless flex instead of the rubber flex. Bled the brakes perfect then checked the brakes and nothing pedal to the floor! sweet FA! took the master cylinder off and tried the pedal again just to make sure its working? and the feel is exactly the same? very small resistance like against a spring just as it was with the master cylinder? the pin on the servo pushes out when the pedal is compressed so I think for sure the master cylinder is dude. Dead as a dodo.

Edited July 24, 2014 by V8-ESPRITS3