Alright guys.. Im abit dim on this side of things so bare with me.
On my corsa I will be running 300mm with 4 pot calipers on the front and GTE rear caliper and disks.
I want a Bias pedal box from CompBrake.
Can some one please educate me on the difference between the mastercylinders (0.625, 0.7 & 0.75) and what one would be a good recomendation for the brake set-up stated above for road and track.
My Corsa pedal box with pedal in the nova feels great. It could be due to the play in the nova linkage to the other side you already lose some pedal ratio taking up the wear/play from years of use?
I'm going to be running a floor mount pedal box and havn't got a clue what brake, MC setup to go with. Will I need 4 pots with the weight of the transaxle? Will I still need 4 pots up front? I'm assuming so as thats where the weight will still be transferred in majority.
The transaxle doesnt weight enough to require 4 pot rears no, most cars with rear brakes barely use them at all, as Lee hints at, they are a pub ammo mod really to even fit standard sized rear disks.
only real advantage of disk rears is they are easier to maintain than drums
vx220 rear brakes are still single piston, and they have a gearbox and engine to have the weight of.
likewise on my nova I have to have the rear bias turned down to avoid locking the rears up.
and the better your brakes work of course, the more weight shifts away from the back anyway
Jimspeed007 sent me a brake calculator. I've put all the info in to the best of my knowledge. For what im going to need it for I think the best set-up for me and my budget is a comp brake pedal box with an in car adjuster, .625 cylinder on the front and a .725 cylinder on the back running hispec 4 pots on the front and Vauxhall callipers (code 35) on the rear.
if anyone else wants a copy of the brake calculator , its an excel program, either pm me an email address or show me how to host it somewhere people can get to it :beer:
Hi,
Been to where car lives tonight for a quick measure up to see what brake pedal ratio is & see if a hole can be drilled.
From pivot to middle of foot pedal is approx 26cm
From pivot to cyclinder mound is approx 4cm
This gives a ratio to my knowledge 4.33:1 which i trust just isnt enough.
If i drill another hole approx 2cm further up (is this correct?) this will give 6.5:1
Not knowing alot about pedal ratio's will going from 4.33:1 to 6.5:1 really make all the difference i'am looking for?
Just gotta get the damn pedal off so i can drill it now!!!!!!!
Yes, if the master cylinder hole is raised, there will be more leverage.
However, there are things to be aware of -
Pushrod doesn't appear to be adjustable, so either the hole is VERY carefully marked and drilled to ensure the pushrod has the master cylinder piston in the right position, OR some means of adjustment may be needed.
Second potential problem is that the pedal is going to move more for the same master cylinder movement and so there'll be a much lower pedal when brakes are applied - this may be a problem if the pedal hits the floor under extreme use if the brakes get 'spongy' - make sure the fluid is kept fresh and perhaps braided hoses would be a good idea.
Third, check the angle of the pushrod isn't going to cause a problem with it's operating angle causing binding at the cup.
Thanks for the reply.
If you look at my pictures regarding the pushrod, i take it the item you mean is in (i think) picture three & is adjustable. So that should be ok.
Cant see me hitting the floor to be honest. Can hardly move the damn thing at the moment to be honest.
I have looked into the angle & to be honest it looks if i drill 20mm further up, looks a better angle than OE!
I do run braided hose straight from master cyclinder to calipers so should be ok in that instance.
Going now to have a 'play' in garage & hopefully sort it out.
Only problem is the car wont run at the moment so i wont be able to try out if it works.
Good read this, ive got Alcon 4 pots on the front with Golf single piston caliper on the rear. Mine uses standard m/c which is ok but is a bit spongy and does travel a bit but you do get used to it. To stop the rears locking up i used in line reducers that are fitted to Novas.
Now im thinking of fitting a pedal box to get a harder higher pedal and hopefully more braking force as it is quite hard to lock the front up on mine at present, but not usre if it will increase the braking pressure over the standard m/c, does anyone know if it will?
Surprised you're getting a spngy pedal with that setup, however some cars were notorious for a poor pedal - late model Cortinas were two. In that case it was the hoses expanding.
In theory, to get the same line pressures with a pedal box Vs a single cylinder, the area of each of the new cylinders should be half that of the single - that way you're still applying the same force to the same area and hence same line pressure.
As above, a smaller front cylinder and a larger rear will give more line pressure to the front than rear, but exactly how much difference will come down to experimentation but one size different may be enough. Other option is finding different calipers that will fit that will give more front or less rear total piston area.
If you haven't already done so, you may wish to fit braided hoses as they are supposed to be a significant improvement when a spongy pedal is a problem.
[edit] Forgot - check the firewall brake mounting - flex or cracking will also cause an apparent spongy pedal - and could cause a lot more.
All the lines are braided, im looking at AP cylinders .875 for the rear and a .625 front that should stop the rear locking without having in line reducer but i suppose its a case of trial and error again lol.
Been for a tinker on car today & re-drilled brake pedal to a 6.5:1 ratio.
Didnt quite go to plan as i couldnt get the brake pedal off the car so had to drill in situe which wasnt ideal.
Anyhow all back together & i must say i can feel the difference sat in the car. Unfortunatly until i sort the engine i cant go for a spin to see if it was succesfull or not, but so for so good.
Here is a couple of pics of what i have done.
Martin
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