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Discussion Starter · #1 ·
What i need to know is will a sigle 3/4 master clyinder be big enough for the folowing brake calipers ? Wilwood Dynalite 4 pots that have 4 x 1.380 diameter pistons and a pair of Citreon xantia front calipers these are the same as the Citreon BX that will be used for rear as they have the built in handbrake cable connection. There wil be a servo fitted.
 

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I have the larger of the 2 mopar alloy master cylinder. (1 1/32?). It doesnt create enough pressure unless I put 2 feet on the pedal ( manual, wil 4 pots and stock drums). Wilwood have recomended a smaller 7/8 master cylinder that should help. They have a good Q and A on thier site and reply promptly too you could give them a try.
 

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What i need to know is will a sigle 3/4 master clyinder be big enough for the folowing brake calipers ? Wilwood Dynalite 4 pots that have 4 x 1.380 diameter pistons and a pair of Citreon xantia front calipers these are the same as the Citreon BX that will be used for rear as they have the built in handbrake cable connection. There wil be a servo fitted.
Not even close I'm afraid :tdown:. You don't really want to put any fronts on the rear as there are bigger than those designed to go on the rear biasing the braking to the rear too much. Best to use something like rears from Granada , Citroen, Golf .

Why single circuit ? Seems like the weak link after fitting all those discs ?
 

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Discussion Starter · #4 ·
Not even close I'm afraid :tdown:. You don't really want to put any fronts on the rear as there are bigger than those designed to go on the rear biasing the braking to the rear too much. Best to use something like rears from Granada , Citroen, Golf .

Why single circuit ? Seems like the weak link after fitting all those discs ?
I knew you would jump on this Kev that was what I was hoping :tup: as I have seen you with brake post in the past . The Citreon calipers that i have is the ones that people have used in the past for a rear 9 inch brake conversion so just went with that as its been done plenty of times before if these do offer to much braking to the rear can I not just fit a bias valve to reduce the braking ? So what do you suggest I do in the way of master clyinder Kev with the parts I have
 

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I knew you would jump on this Kev that was what I was hoping :tup: as I have seen you with brake post in the past . The Citreon calipers that i have is the ones that people have used in the past for a rear 9 inch brake conversion so just went with that as its been done plenty of times before if these do offer to much braking to the rear can I not just fit a bias valve to reduce the braking ? So what do you suggest I do in the way of master clyinder Kev with the parts I have
Yup, I know they've been used in the past , depends on what size fronts they have used with as to whether 'you' get away with it. Many of the conversions are on Yank motors so have much larger ( than Brit /upgrade aftermarket ) front calipers that allow it to self balance. I tend to see bias valves as a bit of a band aid, you don't see them on OEM apart from load self balancing ? Backing the pressure off sort of defeats why they were fitted in the first place ?

Back to basics then.:tup:

What car and are you stuck for space for a combined m/c /servo ? Also intended purpose ?
 

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Discussion Starter · #6 · (Edited)
Car is a 100e engine is a 360 ci supercharged mopar front brake discs are 300 mm with the willwoods ford 9 in ch rear with the merc 126 discs and Citreon axantia calipers there is no space for a combined servo master

Thanks
 

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Ok, know where we are starting then :) What about servo /m/c bellcranked under dash ? The other way is twin m/c on a shared pedal ( per Wilwood style). you can also fit these with remote reservoirs and reverse mount m/c so they come back into the car. Uisng a 6.25 pedal ratio and 3/4 m/cs ( as each is supplying a seperate axle, the volume will be fine and pressure good without servo assist).

The feel of twin m/cs takes bit of getting used to when you are used to a servo but will work fine.It also provides you with 2 seeprate circuits so safer. It will also provide an inbuilt way of adjusting rear brake line pressure via the balance bar.
 

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Discussion Starter · #8 ·
Thanks foryour input Kev could you explain what a servo /m/c bellcranked under dash is and is this setup a dual circuit arrangment ?
 

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I think there might be some pictures in tech here somewhere already ? Basically it converts the forward push of the pedal via bellcrank to a 90 degree motion . This pushes on the rod going through the servo and to the twin circuit m/c. I did one on a T using Fiesta bell crank and bushes .

Many modern cars have a rod going from the drivers side across to the passengers side ( saves making too many RHD specific parts :incheek:) . You can rob the stuff from them. Imagine the car resting on the drivers side after a crash and that's how you'd fit the parts.

You could build in a degree of adjustability so you coud increase the pedal ratio by moving a pin.

Time to eat, I'll look for some piccies shortly if you haven't found them by then.
 

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Discussion Starter · #11 ·
That looks a good setup there Kev so if I was to make this unit up myself I guess I sould be choosing a servo unit from a larger saloon car like bmw, Volvo ? in order to have the right cappacity for the calipers I have
 

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Ideally working with a unit from an all disc brake car would be the way to go. They are generally between 7/8 and 1 inch .

7/8th is a little on the small size but will give good line presure but at the expense of longer pedal travel , especially with the larger Citren calipers on the rear . I'd aim at the 15/16ths as a good compromise and more readily available.

The diameter of the servo dictates the amount of assist provided so best to go for the biggest you can get in there .

There's quite arrange available in apanese cars, even the smaller ones seem to have large bores.

Try to get one that mounts at 90 to the bulkhead then you wan't have any bleeding problems.

When you make your mounts / bellcrank make sure the pushrod operates STRAIGHT to the servo or you will lose line pressure.
 

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Thanks , I try my best to pass on my hands on experience ,I don't use Google to give tech.

I'm not always spot on but I try to advise what I would use personally based on the restrictions of the build I'm told about..I'm always concious that someone may be spending money based on what I say , I know how hard that is to come by.
 
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