MikeRJ
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| posted on 19/7/13 at 11:56 PM |
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Usually the port closest to the pedal end of the cylinder is the front. However, both ports will deliver exactly the same pressure so it won't
make any difference to pedal feel or brake performance (which is why it passed IVA).
I doubt you need to look beyond the reasons given by BT and others. The Sierra master cylinder simply isn't compatible with the pedal ratios
used on most Locosts and having a very hard pedal and poor brakes is a common complaint of those that have used them.
[Edited on 19/7/13 by MikeRJ]
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40inches
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| posted on 20/7/13 at 09:45 AM |
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The Sierra MS has 2 ports at the front, these go to the front brakes, and 1 port at the rear, this goes to the rear brakes usually with a
"T" near the back axle.
Fitting the Fiesta MS will only take half a day, you know it makes sense
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britishtrident
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| posted on 20/7/13 at 12:42 PM |
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It really makes no difference the cylinder bore size is the common for both ports therefore the pressure output is the same , switching to a
smaller bore cylinder is the simplest way to make the brakes more responsive.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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justy75
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| posted on 20/7/13 at 01:34 PM |
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Thanks guys - so what you are saying is that either port should be fine? I think i'l wait until the Fiesta one arrives and just go with that
one.
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justy75
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| posted on 20/8/13 at 09:02 PM |
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Thanks all for your help - problem solved!
Some feedback on these Fiesta master cylinders
Having purchased one of these and now had it fitted, I thought that I would offer some feedback for others who have or are considering getting a
Fiesta or 19mm master cylinder, as an alternative to the tried and tested Sierra master cylinder.
I originally had a Sierra master cylinder, with HiSpec 4 pots and EBC greenstuff pads. My original feeling was that the level braking was poor. Other
than the exceptionally long stopping distance required to stop the car, it had an incredibly wooden feel to the pedal, with pretty much no feel. It
also took a lot of force to stop the car.
I was aware that the Greenstuff pads were not the best but wanted to try and improve the actual braking before changing the pad compound and getting
the Mintex 1144, as everyone seems to have recommended these as offering a significant improvement over the Greenstuff.
As I couldnt find an early Fiesta non servo master cylinder, I opted for one of these as I was advised that it would be pretty much perfect.
Unfortunately it is not a direct fit as the holes are narrower than the Sierra one so a bracket had to be made.
It is also a bit longer in length than the Sierra one (roughly 1/3" longer). This caused another problem initially as it touched the Webers. By
mounting the bracket behind I was able to make it fit, but beware its a bit longer and may cause a few issues particularly if you are limited for
space in that area.
Was it worth the money and effort? Yes.
Still using the Greenstuff pads the braking has improved maybe somewhere between 80-100%. Stopping distance is definitely shorter and requires far
less pressure to stop the car. The pedal actually has feel now too and does not feel wooden at all. I can actually lock the wheels now too if need be.
Only downside if you call it that is that it seems to have slightly longer travel, with a noticeable first part of the press seemingly not doing
anything, but then the braking kicks in and all is good.
If you are running a Sierra master cylinder and you think that its braking is not up to scratch, then this is Definitely a worthwhile upgrade.
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OliilO
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| posted on 20/8/13 at 09:21 PM |
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I'm considering this too, good to hear your experiences.
Did you use a servo fiesta master cylinder or did you managed to find a non-servo one?
Also did you need to change any of your pipe work or is it the same as the sierra MC (2 ports at front and 1 at the rear of the MC)?
Thanks.
Oli
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justy75
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| posted on 20/8/13 at 09:30 PM |
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Hi,
No I couldnt find an early non-servo Fiesta one, so this was one that originally would have had a servo (The exact version of this mc are in another
post headed Fiesta master cylinders going cheap!)
It does have a couple of extra ports that just needed capping off, but I let a mechanic friend sort out the pipework and the capping.
Forgot to mention that the Sierra reservoir fitted straight on.
Thanks
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Andy S
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| posted on 20/8/13 at 10:20 PM |
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It may appear that way with Dual cylinders but the pressures are different in use due to the internal pressure passages - the cylinders are typically
marked P and S - P for primary for the Front and S for secondary for the rear.
On my Fury they were installed the wrong way round by the guy that started the car and in testing the rears locked easily - did the research and
re-plumbed - now the front lock up eventually with far better balance.
quote:
Originally posted by britishtrident
It really makes no difference the cylinder bore size is the common for both ports therefore the pressure output is the same , switching to a
smaller bore cylinder is the simplest way to make the brakes more responsive.
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britishtrident
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| posted on 21/8/13 at 07:03 AM |
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quote:
Originally posted by Andy S
It may appear that way with Dual cylinders but the pressures are different in use due to the internal pressure passages - the cylinders are typically
marked P and S - P for primary for the Front and S for secondary for the rear.
On my Fury they were installed the wrong way round by the guy that started the car and in testing the rears locked easily - did the research and
re-plumbed - now the front lock up eventually with far better balance.
quote:
Originally posted by britishtrident
It really makes no difference the cylinder bore size is the common for both ports therefore the pressure output is the same , switching to a
smaller bore cylinder is the simplest way to make the brakes more responsive.
Sort of ............... The internal passages have no effect on master cylinder output pressure. However a very few (mainly 1970s designed
RWD) cars with a front-rear split used a stepped piston in front brake circuit to increase the pressure bias towards the front brakes but these
systems are very rare, the only one that I know of that a builder might come across are on some Vauxhall Omegas or Carltons. These days no
production cars I know of have a front-rear split system all are diagonal split so cannot use a differential pressure master cylinder.
Quite a few relatively modern FWD cars have 4 ports on the master cylinder with two ouputs lager sized sized threads. The larger sized threaded
ports are for the rear brakes and used with pressure regulator valves screwed directly onto the master cylinder body.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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40inches
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| posted on 21/8/13 at 08:50 AM |
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quote:
Originally posted by britishtrident
quote:
Originally posted by Andy S
It may appear that way with Dual cylinders but the pressures are different in use due to the internal pressure passages - the cylinders are typically
marked P and S - P for primary for the Front and S for secondary for the rear.
On my Fury they were installed the wrong way round by the guy that started the car and in testing the rears locked easily - did the research and
re-plumbed - now the front lock up eventually with far better balance.
quote:
Originally posted by britishtrident
It really makes no difference the cylinder bore size is the common for both ports therefore the pressure output is the same , switching to a
smaller bore cylinder is the simplest way to make the brakes more responsive.
Sort of ............... The internal passages have no effect on master cylinder output pressure. However a very few (mainly 1970s designed
RWD) cars with a front-rear split used a stepped piston in front brake circuit to increase the pressure bias towards the front brakes but these
systems are very rare, the only one that I know of that a builder might come across are on some Vauxhall Omegas or Carltons. These days no
production cars I know of have a front-rear split system all are diagonal split so cannot use a differential pressure master cylinder.
Quite a few relatively modern FWD cars have 4 ports on the master cylinder with two ouputs lager sized sized threads. The larger sized threaded
ports are for the rear brakes and used with pressure regulator valves screwed directly onto the master cylinder body.
This seems to be true of the Fiesta MC in this discussion, they are definitely plumbed in with a diagonal split, so irrelevant which pipe goes to
which corner. But check out the brake balance valve 
Fiesta brake line diagram
As a point of interest, would there be any benefit fitting one of the pressure limiting valves (item 6 in the diagram)to the rear brake line? Assuming
they are still available.
[Edited on 21-8-13 by 40inches]
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mcerd1
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| posted on 21/8/13 at 09:18 AM |
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quote:
Originally posted by 40inches
But check out the brake balance valve
yeah its a bit of a beast 
took me a while to work out what it was on my first car (a 1979 gold 1.1 'L' )
the diagonal split was a big safety feature in the sales bumf for the mk1
[btw - I'm not that old - i got the car in 2001 ]
quote:
Originally posted by 40inches
As a point of interest, would there be any benefit fitting one of the pressure limiting valves (item 6 in the diagram)to the rear brake line? Assuming
they are still available.
I would of thought it would be harder to find valves that exactly match your requirements...
my first instinct would be to go for two separate master cylinders with a balance bar to give you enough adjustment to get the brakes right
(admittedly that means you end up with a front/rear split which might not suit drum braked cars as well if the fronts did ever fail....)
[Edited on 21/8/2013 by mcerd1]
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Andy S
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| posted on 21/8/13 at 09:22 AM |
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Just be aware that with some dual masters there is a definite front and rear circuit connections, They are not the same as there may be no direct
mechanical link from the pedal to the secondary circuit where it is reliant on the pressure developed in the primary circuit to act on the secondary
piston - if there is no pressure in the primary then there is a safety mechanical link present as the back up but in normal operation it is not in
contact with the secondary piston. The pressures are therefore not the same as the pedal is depressed and the port spacing and the internals provide a
timing for the brake actuation. Connect them the wrong way round and you will always lock the back before the front as no pressure can get to the
front until high pressure is developed in the rear.
Just make sure that when you have a cylinder with P and S cast into the body the P is for the front brakes.
This was the type supplied with my 2004 Fury kit
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40inches
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| posted on 21/8/13 at 10:47 AM |
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quote:
Originally posted by Andy S
Just be aware that with some dual masters there is a definite front and rear circuit connections, They are not the same as there may be no direct
mechanical link from the pedal to the secondary circuit where it is reliant on the pressure developed in the primary circuit to act on the secondary
piston - if there is no pressure in the primary then there is a safety mechanical link present as the back up but in normal operation it is not in
contact with the secondary piston. The pressures are therefore not the same as the pedal is depressed and the port spacing and the internals provide a
timing for the brake actuation. Connect them the wrong way round and you will always lock the back before the front as no pressure can get to the
front until high pressure is developed in the rear.
Just make sure that when you have a cylinder with P and S cast into the body the P is for the front brakes.
This was the type supplied with my 2004 Fury kit
Now this is interesting, the Fiesta MC is marked P and S, the rear P and front S, I have plumbed my brakes with P to front brakes and S to the rear,
however the Fiesta was definitely diagonally split. Strange!
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Davey D
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| posted on 21/8/13 at 01:40 PM |
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I found the best way to bed in a new set of pads was to give the car a good tonking on a trackday
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Kozy
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| posted on 20/9/13 at 02:56 PM |
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Hi guys, I know this particular problem is now solved, however here's a handy link if you are wondering about master cylinder to caliper piston
ratios and the effects on pedal travel and brake force, even with a brake booster.
www.blackartdynamics.com/BrakeDev/Index.php
Ok you need to know a fair amount of info and there's a lot of information in the results, but there is a pedal input force and pedal travel
display which should give you some idea how well matched your components are!
Hope it is of some use! Unfortunately no input for twin master cylinders though!
[Edited on 20/9/13 by Kozy]
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britishtrident
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| posted on 20/9/13 at 05:26 PM |
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quote:
Originally posted by Andy S
Just be aware that with some dual masters there is a definite front and rear circuit connections, They are not the same as there may be no direct
mechanical link from the pedal to the secondary circuit where it is reliant on the pressure developed in the primary circuit to act on the secondary
piston - if there is no pressure in the primary then there is a safety mechanical link present as the back up but in normal operation it is not in
contact with the secondary piston. The pressures are therefore not the same as the pedal is depressed and the port spacing and the internals provide a
timing for the brake actuation. Connect them the wrong way round and you will always lock the back before the front as no pressure can get to the
front until high pressure is developed in the rear.
Just make sure that when you have a cylinder with P and S cast into the body the P is for the front brakes.
This was the type supplied with my 2004 Fury kit
This a safety related issue so please don't post bad information you clearly don't understand hydraulics or the laws of
pressure --- in normal operation even during initial application the hydraulic pressure in both circuits must be equal at all times.
The pressure in both circuits is equal and rises simultaneously if this were not the case cars with diagonal split brake hydraulics would pull to
one side on initial application of the brakes.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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mcerd1
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| posted on 23/9/13 at 07:54 AM |
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quote:
Originally posted by britishtrident.... in normal operation even during initial application the hydraulic pressure in both circuits
must be equal at all times.
The pressure in both circuits is equal and rises simultaneously if this were not the case cars with diagonal split brake hydraulics would pull to
one side on initial application of the brakes.
+1 that style of MC is designed to give equal pressure in both circuits automatically
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hughpinder
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| posted on 7/11/13 at 01:03 PM |
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Just reading the last 2 posts, and I initially thought the same, however, I think the brake fluid for the fronts will be pushed into the calipers
first, and once they stop moving, the rear cyclinders will move, thus providing a very slight bite on the front brakes befiore the rears? Is this
right?Once ther is no move movement the pressures will be the same in both circuits?
Just my thoughts for discussion.
Regards
Hugh
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britishtrident
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| posted on 9/11/13 at 11:49 AM |
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quote:
Originally posted by hughpinder
Just reading the last 2 posts, and I initially thought the same, however, I think the brake fluid for the fronts will be pushed into the calipers
first, and once they stop moving, the rear cyclinders will move, thus providing a very slight bite on the front brakes befiore the rears? Is this
right?Once ther is no move movement the pressures will be the same in both circuits?
Just my thoughts for discussion.
Regards
Hugh
Probably every tintop you have ever driven will have diagonal split braking, when you just lightly touch the brakes in a tintop do you feel the brakes
pull to one side or a reaction through the steering wheel?
Disc brakes work on pressure not movement, a 1g stop in tintop requires about 100 bar/1,500 psi, in a Locost style car the pressures are lower at
circa 33 bar/500 psi .
Apart from the action of two light centering springs , the center piston in a tandem master cylinder is free floating by Newtons laws it must be in
equilibrium, that is the force ( & pressure ) on either side of the floating piston must be equal.
One practical issue is slight mechanical "stickion" of the free floating piston. The engineers who designed tandem cylinders cleverly
got around this by using a higher rate spring with pre-load on the side of the piston nearest the pedal.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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mark chandler
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| posted on 9/11/13 at 12:21 PM |
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If your pedal does nothing for the first inch of travel lengthen the pushrod into the master cylinder, do this in small stages if you get carried away
you will block the fluid return hole causing the brakes to lock on.
Just lengthen so you have a little free movement before the brakes start to operate, when it feels normal 
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40inches
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| posted on 9/11/13 at 01:16 PM |
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After I fitted the Fiesta master cylinder I had about 20-25mm movement on the pedal, sort of like a two stage after taking up the slack. I bled the
brakes three times and made sure the rear drums self adjusted, didn't make a difference. So I took the drums off to check the adjusters and
found this:
 
I knew that if the master cylinder was lower than the brakes the fluid could run back, but I assumed that because the fluid reservoir was remote and
well above the MC it was OK, not!
A 10 pound residual pressure valve fitted in the rear brake line, near the MC, cured it and took away the excess play.
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onenastyviper
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| posted on 9/11/13 at 07:17 PM |
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I thought rear cylinders had a spring inside them to keep the pistons in contact with the shoes?
At least they do on my ford fiesta rear cylinders 
"If I knew what I was doing then it wouldn't be called research would it?...duh!"
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