Pedal feel non-assisted brakes

[mattysshop]

Hi all,

Went through on the weekend and did the fluids in the project car, when we were bleeding the brakes (1" willwood master, with twin remote res) after all the air was bleed out of the system, what is the pedal ment to feel like?

as currently it has about 60mm of travel (some resistance) and then you gradually get harder as it goes down to full pressure (not bottom out)

the brakes on the front are VZ commonwhore twin pistons & rotors, and the rear are AU falcon discs (caliper activated hand brake), new teflon lines through out, and new hardlines to suit, using Penrite 525 super dot 4, everything it brand new, or reco'd.


as i have not really delved into non-assisted brakes, i was wondering if a relativly spongey pedal is normal, i was expecting the opposite considering the 1" bore master..

cheers,

[allencr]

Find out what is moving by having the pedal pumped and feeling & looking at everything. If nothing is moving twisting expanding compressing & bending when it shouldn't, then it's air. Sure, even the hard line expands & pad compresses a bit, but not enough for you to see. The only things that should move are piston to pad, without that 'squeek/squeel' shit, a little caliper flex and all the seals getting squeezed between their piston & bore. The flex lines will wiggle a little & try to straighten up.

What's 'twin remote res'??

[oldcorollas]

should be firm, and reach a solid end... unless you either have air somewhere, or flex.

even KE10 have a fairly hard pedal

[trdee]

does it pump up or is it always the same? also im not sure on the principles of how braking system works, but if i understand correctly, then a too small master cylinder will not move enough fluid to get the pistons in the brakes moving through their full range of motion. if that is how it works then maybe the master is slightly too small which is why it has such a long pedal travel?

i could have all that concept arse about though...

[oldcorollas]

no, thats true, and when it reaches the end, it wil not feel as solid as you have more "leverage" and can induce more flex with less pedla pressure..
1" is a reasonably sized bore tho.

[mattysshop]

no, thats true, and when it reaches the end, it wil not feel as solid as you have more "leverage" and can induce more flex with less pedla pressure..
1" is a reasonably sized bore tho.

thats what we figured, especially as 1" is larger than the VZ and AU that the calipers came off.. i actually thought we would have almost the opposite problem.. hardly any pedal movment which would result in very very touchy brakes!... which is not cool for a 1JZ+GT35R - 1000kg street car...

i'll need to have another look, but from what i could see during bleeding, the only thing that flexed was the sliders on the calipers..

correct me if i'm way off, but adjusting the rear hand brake on caliper acting hand brakes also adjusts the pad-rotor clearance, as in the older disc brakes on AE82/86/92 and GT starlets etc... what i normally do for these cars is squeeze the brake pedal to the floor as hard as possible.. hold it down, and lift the hand brake right up, then release down, lift up, release down... repeat this several times and eventually the hand brake is adjusted, this also changes the pedal feel as the return point of the piston has been adjusted..

would this be the same as the falcon rear discs which the hand brake is activating the caliper?

sorry allencr, i ment remote reservoirs

[TRD-12A]

with handbraking activating rear calipers (especially ones with locating pins) you need to pump the pedal until pedal goes firm then lift handbrake up and down a few times because what happens if that pin doesnt locate properly then you will have a shit pedal, the locating pin is there because the piston actually spins whenever the hanbrake is activated if that pin isnt located if the pin is located you will have a nice pedal and a nice handbrake, in saying that i dont remember AU rear calipers having that, the handbrake is located inside the disc with shoes, also maybe the fact the master is so big on the return stroke it could be sucking back too much fluid thus sucking the pistons back and thats why you got so much travel.

[andrew_mx83]

my experience with non-assisted brakes is that they are hard as hell to push, no spongyness at all unless they need a bleed

[thechuckster]

Matty: is the handbrake just operating on the handbrake mechanical-complexity at the back of the caliper - or is it a rally-style in-line hydraulic handbrake that's also acting on the existing handbrake mechanism?

[Draven]

my experience with non-assisted brakes is that they are hard as hell to push, no spongyness at all unless they need a bleed

This.

Only even driven one unassisted car, but it felt like I was trying to push the brake pads against the rotors with my feet - like stepping on concrete

[andrew_mx83]

yeah you know the one...

[Draven]

yeah, linden's half shitbox, half track beast

[mattysshop]

Matty: is the handbrake just operating on the handbrake mechanical-complexity at the back of the caliper - or is it a rally-style in-line hydraulic handbrake that's also acting on the existing handbrake mechanism?

chuck: it's just a stock rear falcoon setup, i can't remember which model exactly they were from.. it's mechanical, activating on the caliper, there is no internal drum assey... diff is hilux + 4 link conversion + mini tubs + coilovers in a TG gemmie


after getting it fired up on the weekend (mega thanks to JP!!), and driving it gently up and down the street... then looking over for leaks, i'm very confident that it is just due to new stainless fittings etc not seating correctly... once we can get it back down to the workshop and on the hoist we will go through and seat them all through repeatedly tighten/loose then we will see where were at..

i'll be doing a build thread on this Gemmie soon

[oldcorollas]

they're leaking? or sucking in air? or?

[mattysshop]

yeh i think there might be a bit of air in the system, either getting sucked in through un seated fittings, or possibly air in the master still as i didn't bleed it on the bench..

we will start with rechecking all the fittings and bleeding again, see where that ends up!!