[31zook]

I installed a suby MC today, it works, but no better then before and i think my brakes are dragging now. What could have caused this? It's on a 1.3 WT (so boosted)

other info that may help, i have a willwood prop valve, and the piston lenght has been set by the guy before me who used it in his boosted zook. Could it be that the piston is jamed or not returning due to being stiff or un-lubed?

Im fairly lost and i need my car for tomorrow....

cheers

[BlueSuzy]

My front brakes have dragged before, They were seized with dirt..

Once they were cleaned out and rubber greased, they were fine again.

The system should run un-pressurised..Because your foot gives the pressure..

[finlay113]

if the slide on the caliper is seazed they will drag

[royce]

crack a bleed screw to see if there is any residual pressure there front and rear, should be none on the front and a little on the rear (to hold the wheel cylinders out a bit)

If there is the master cyl might not be returning fully, or you have front and rear mixed up

[LAY80N]

Have you checked each brake caliper/drum bleed nipple for residual pressure? Take the zook for a drive round the block, come back and leaving the engine running crack each brake bleed nipple. If one squirts out under pressure you have found your line that is holding pressure. If none squirt out then there should be no residual pressure in the system, so your brake dragging may be from the usual causes (sticking pins/slides, failed drum components etc).


Note: you will need to re-bleed your brakes after you test this.


Layto....

[31zook]

before it was working fine, like no drag and would roll on a flat surface.

something else i should put in is that the brake pedal has no play in it, it is all force from the first touch of the pedal.... is that right?

[TZAR]

31zook wrote:

before it was working fine, like no drag and would roll on a flat surface.

something else i should put in is that the brake pedal has no play in it, it is all force from the first touch of the pedal.... is that right?

no

[BenT]

31zook wrote:

I installed a suby MC today, it works, but no better then before and i think my brakes are dragging now. What could have caused this? It's on a 1.3 WT (so boosted)

I bet the push rod between the booster and master cylinder is too long and you have no free play in your pedal so its holding the piston in all the time.

Ben

[PJ.zook]

Exactly as Ben said, you need to fab up youre own length rod out of a bolt or whatever. You must have a teeny amount of play.

[31zook]

ok, i have been all through my FSM to try to understand how they work better, and i have two last questions,

can the push rod be misaligned?

does anyone know how to work out the right length or know the correct length for the push rod?

[royce]

distance from master mounting face on the booster to the cup where the push rod site plus the same on the master side minus a bit?

if its too long now its all bled if you undo the nuts holding it to the booster it should sit away from teh booster a bit, this amount might be a good start

[31zook]

I wondered if i could just undo the booster nuts and slip it away from the booster.... thus not having to bleed my brakes again.... also you make a good point royce, that is so flipping logical with the way you would measure it, i don't know why i didn't think of it...

[31zook]

Ok i undone the booster bolts slipped it forward and shortened the push rod by not much, but enough to make the brakes not drag, so im about that.

But shouldn't this set up work better then stock? I sort of expected minimal effort for big braking power, but it's the same if not more effort and the same braking force..... It has a prop valve on the back btw, do i need to loosen that off? or should nearly all the brakes be at the front?

Im only on 205/75s...

[royce]

Arent the subi ones a larger bore? larger bore = less effort generated at the wheels for a given input pressure but it needs less pedal travel to do so

[Gwagensteve]

royce wrote:

Arent the subi ones a larger bore? larger bore = less effort generated at the wheels for a given input pressure but it needs less pedal travel to do so

Exactly. The advantage of the Subaru cylinder is a higher harder pedal and better proportioning. Pedal effort will be higher, that doesn't mean your brakes are "worse"

Steve

[31zook]

ok, well i guess i didn't get what i was expecting, and thats ok, as long as im not sitting on a ticking time bomb....

so what would make less effort and more wheel power?

[royce]

smaller mastercyl, at the expense of longer pedal travel

or a bigger booster, but youll lose feel

better bet still is vented vitara fronts with quality pads

[31zook]

or joeblows rear disk kit, with pintara calipers.... ok, ill fuss with teh rest later. good to know its all working how it should

[royce]

front brakes do more for stopping than rears, do them first

[jdk81]

royce wrote:

smaller mastercyl, at the expense of longer pedal travel

or a bigger booster, but youll lose feel

better bet still is vented vitara fronts with quality pads

+1
The vented vit fronts and factory pads on it, is the way to go.
The braking is fantastic.

It is a modification which should be done when putting bigger tyres on.

[31zook]

sweet stuff, where do you get these kit's from? is this the sort after lwb 16v front brake calipers?

[royce]

yep thats it, grab some calipers from a wreck, new rotors and pads and you are away

[31zook]

cool beans

[Brett]

a bigger booster will make the pedal easier to push down. i have no idea what booster you would use.

that what your after aren't you?