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Uprated Front Brakes, Mastercylinders,


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117 replies to this topic

#101
cybernck

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so the 2 port abs mc's work then?? I was under the impression they didn't??


You need a pre-1998 m/c as the the later one will have a different bolt pattern. Or fit the later servo too :).
 
 

On the MC there are four connections, and it looks like two compartments on the reservoir bottle.

Is it usual to put the back two lines on to the MC so they are served by the same compartment? (And put them back nearest the bulkhead)


They are originally connected "cross-diagonal" or front left + rear right and front right + rear left.

But I see no reason why you couldn't do fronts on one and rears on the other. That's how I'm going to do it anyway.

#102
dobboy

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You need a pre-1998 m/c as the the later one will have a different bolt pattern. Or fit the later servo too :).
 
 

They are originally connected "cross-diagonal" or front left + rear right and front right + rear left.

But I see no reason why you couldn't do fronts on one and rears on the other. That's how I'm going to do it anyway.

 

Thanks Cybenck, the reason i ask as i'm toiling with the idea of fitting a bias valve somewhere around the rear beam, as i think one of my compensators might be shot anyway, and i have bigger brakes for the front.

 

So, if what you are saying is correct, then i could have the front brakes off the front compartment, blank off one of the back compartments, and use the other back compartment as a single line feed to the back brakes/bias valve.



#103
cybernck

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Exactly, but no need to fit the bias valve near the rear beam - it will be much easier to do so and have access to it if mounted in the engine bay, near the master cylinder.

Get a knob adjuster type bias valve as they are much more compact than the lever type. But it's arguable if you'll need any sort of compensator or bias valve anyway.

#104
dobboy

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Cybernck, i spoke to someone yesterday and they told me the reason the lines are plumbed cross-diagonal is that as the reservoir has two compartments, it's a kind of fail safe thing that if you lost a compartment for any reason (leaky seal to MC?) you would always have a bit of front and a bit of back brakes.

 

I've just finished plumbing and connecting mines, i opted for a single line to the back with a T-piece near rear beam. I put that into the same compartment as a front, and put the other front in a compartment to itself.

 

The guy i spoke to said it would be doubtful i'll need a bias valve as my front brakes are upgraded (283mm), but i've left myself the option the way i ran the pipes to add one if i think it's needed.


Edited by dobboy, 09 April 2014 - 09:14 AM.


#105
Anthony

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That's correct (for a 4 line system)

 

Basically you're plumbing the car in as a 1.6 GTi is as standard - one line to each of the front brakes from one half of the MC and one line to the rear from the other half that is T'd at the rear.

 

I've had 283mm GTi-6 brakes on a 205 without a rear compensator and they've been fine without problems of the rears locking prematurely, but I know that some people have had issues that way and have needed to put a compensator back in to take the rear effort down a little.  Try it and see.



#106
dobboy

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Anthony, i've shared my back line with one of the fronts on the MC , and the other front on its own.

 

It should be ok?



#107
Anthony

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It should be fine I'd imagine, but personally I'd run it as per a 1.6 with a front-rear split.



#108
dobboy

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Thanks. I'll see what it's like. Should have long enough length pipe to swap if required.

#109
cybernck

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That's supposedly the reason for it, but a general agreement is that when m/c fails - all brakes are gone anyway.

I guess a cross-diagonal arrangement may help for a split second if a brake hose or a piston in one caliper goes.

Still, it's best to avoid doing doing strange brake combinations, as noted already :).

#110
Tom Fenton

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You don't understand the logic. The diagonal split means if 1 front hose bursts you still have the other front and it's opposite rear working. Look at the fluid reservoir and you will see that there is a weir inside so that one half can lose all it's fluid and the other half work as normal.

#111
cybernck

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That's effectively what I said. But if m/c fails, all brakes will be lost anyway (as suggested in the other topic).

#112
Tom Fenton

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No it is not. You said that if one caliper fails then it might help for a split second. It will allow the other system to continue to work indefinitely.

#113
cybernck

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Have you actually had it happen or just talking in theory?

I've had a corroded rear pipe crack (near a rear brake compensator) and I lost all fluid from the bottle and all brakes. Completely stock 1.9 setup.

Luckily it happened just when I was pulling out from a mechanic's garage.

#114
jackherer

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That's what happened with mine years ago, totally stock 1.9 and a rear line on the beam cracked and the pedal went to the floor and it had no brakes, loads of people have posted to say they've had the same too over the years.



#115
Tom Fenton

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Yes had it happen on a 306 with a blown rear wheel cylinder, brake pedal longer but still enough there to stop you.



#116
cybernck

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It's easy to test it - when you bleed the brakes, going by that logic, fluid level would be lowered independently in the two halves of the bottle.

But I've never had it go like that, on any car.

#117
mmatthej1

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Advice, please - my son's turbo diesel 1.8 STDT seems to provide indifferent braking performance (front discs/rear drums), so we're looking for an upgrade that would provide a worthwhile improvement but on a good ' bang for buck' basis!

 

Maybe replacement front calipers would be enough? Which ones best? (14" wheels, btw)

 

(Don't want to overdo it - seems like GTI6 cals might be OTT, quickly reading past comments!)



#118
mmatthej1

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No responses, so have raised as seperate posting in same forum! (with good responses!!)