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Front Brake Upgrade


DoctorDee
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Eventually, I am able to get back into the garage.....So, it's out with the wallet and  off we go.... Can I first draw upon the vast amount of knowledge found herein.

Brake upgrade cos the brake pedal has about as much "feel" as a large rock.

Currently the set up appears to be sierra 2.0 litre with out a servo.

Master cylinder is cast aluminium with the number 22 on the side and bog standard calliper's on the front and drums at the rear.

I would like to retain the master cylinder as is, so I thought I would go down the "RichyB" route and swap out the front discs for Focus st as per his article in Autumn 2017 of magazine

My question revolves around caliper brackets.....Do I have to buy a set of mondeo brackets or will the sierra one's I have fit the mondeo caliper's..

Postage prices on the brackets are around £18....aaaaaaaaaaaargh 

As usual any help will be appreciated

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What's the piston diameter on the new calipers? Your old ones are 60mm right? Are the ST ones a sliding caliper design I take it? If so, I'll run some numbers into a spreadsheet I have to give you an idea of what change you'll see at the pedal...

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Thanks Richyb66 will do

Brumster.....I believe the originals are 54mm and the Focus st are 57. I cannot claim credit for this info it comes directly from Richyb66's highly informative article.

I believe the mondeo's are sliding caliper

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I went back and checked the calipers I have removed from "thing". Just in case it was a murphy's.....Definitely 54mm.......Would not have surprised me in the slightest if they had been a wierd non standard size.

Be grateful if you could run your spread sheet for me

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2 hours ago, DoctorDee said:

I went back and checked the calipers I have removed from "thing". Just in case it was a murphy's.....Definitely 54mm.......Would not have surprised me in the slightest if they had been a wierd non standard size.

Be grateful if you could run your spread sheet for me

Here you go ;) 11% change in caliper/piston ratio, so easier to press but obviously you will end up trading travel for that (your pedal will go longer to achieve the same pressure as before). I assume all other aspects remain the same ie. master cylinder, pedal pivot points, etc.

 

Brake piston calculations - Std Sierra to Mondeo.pdf

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Thanks very much Brumster....I have some thinking to do.....The Brakes are rubbish on "thing"....It gets through the MOT ok but I doubt that it would lock any of the wheels in a "brown trouser moment". 

Changing to st discs etc  is the thick end of £250 these days.....I've got a Ford Ka master cylinder in the "bitza" box.....

Living with a  Robin Hood "build" is not like having a Westfield

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Thanks that's very kind of you.

Sorry, letting my insecurities show through in my last post....

Onward and upward, stiff upper eyebrow an all that....

I feel a gallon of fuel and a zippo moment coming on.....

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Before you reach for the zippo, the standard Sierra brakes will stop a car with 5 passengers etc. comfortably. Your car is nowhere near that weight,  could you just refit a servo if you have room,  If not you could just fit a smaller master cylinder, I believe the KA ones are 21mm and Sierra 22? so little difference. I think people have fitted 19mm in the past.

I had thought about removing the servo on mine but driving with it disconnected was terrifying!

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Thanks Peter, I wouldn't burn "Thing". It's currently on axle stands and I built the garage it sits in especially for it.

The Garage is worth more than the car.

I laid a driveway from the front gates to the bottom, or top, (depending how you look at it) of the garden.

Nope, wouldn't burn "Thing"..... It would be a  complete admission of total and utter failure.

I bought "Thing" as a "just runner", about four or five years ago.

This is the history based on the box of paperwork I was given by it's previous owner.

It seems to have started life as a bit of a "budget" build, somewhere in the North East of England..

It originally had a pinto engine and a brake servo.

Shortly after it got through it's SVA it was sold to someone in the West of Country.

The engine was changed for a Zetec 2 litre and the brake servo removed, (no room), instrumentation changed and a multi function motorcycle speedo, rev counter, fuel gauge and all sorts of other stuff. Wires everywhere behind the dash.....

Engine management system was programmed by the gent who converted it.. again it seems to have been a bit of a "budget rebuild.

It went through a further two owners hands before the "idiot savaunt", (myself) came along and was daft enough to buy it.

After purchase I discovered it leaked water everywhere, drained the battery overnight, alternator began screaming like a banshee and had the stopping power of a tea tray on wet grass.... plus a cast of thousands

Replumbed it, sorted the alternator, stopped the battery drain.

Then my wife fell ill, then I fell ill... Unrelated stuff ...These things happen when you get past sixty..... hey ho

Onwards and upwards,,, back in the garage ....we will not be beat

Thankyou for your kind reply, will let you know what I end up with....Big thanks once again to brumster for the use of his spread sheet

 

 

 

 

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Are right, so Mr Logical eventually surfaced,(thanks in no small part to the Brumsters spread sheet and Peters comments), I decided to start at the beginning and work my way to the end.

Try a pedal ration of 3.56 to 1 without a servo.....don't see how a 19mm master cylinder is going to compensate for that.

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My Zero is on standard brakes all round, with a Ka m/c and no servo, and works lovely. Granted it's a smidgen lighter than a 2B but as Peter said, given these brakes were designed to haul up a tonne-plus of Sierra, I don't really see how they can't be made to work for our application....

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There is always a way.... So I have a KA master cylinder which I will have to use with a remote reservoir  in order that the bonnet will close......What did you use for your master cylinder push rod please  Dan

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