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BIGGER DISC'S
roadrunner - 11/1/07 at 09:40 PM

Is it possible to improve braking by fitting bigger disc's and still keep ford calipers, is there such a thing as an extending bracket.

procomp - 11/1/07 at 09:53 PM

HI you can get a 300bhp 145 mph severn type car to stop more than good enough with std cortina/sierra front and sierra disks on the rear. it is what most of the cars in the 750 mc were using untill they were allowed to use lighter items.

As chris says better pads and fluid or look at what master cyl you are using the ideal setup will have a floor mounted bias setup to allow better control of the brakes.

cheers matt

roadrunner - 11/1/07 at 10:00 PM

I'm using brakes of a 1.6 sierra, and i think, the master cylinder came off the servo(not fitted servo), i just dont seem to have much feel through the brakes, they work ok if you press well, but would like a bit more feel to give me more confedence.

tks - 11/1/07 at 10:09 PM

i bet its your master cilinder / pedal
size.

the smaller the distance from the pivot point the bigger the force..

anyway what you would get is more interim brake force due to being able to feel better how hard you press..

sow not a on / off situation..

Tks

TimC - 11/1/07 at 10:16 PM

Basics of brakes in PPC Mag would be well worth a read for you me thinks.

PAUL FISHER - 12/1/07 at 12:43 AM

quote:
Originally posted by roadrunner
Is it possible to improve braking by fitting bigger disc's and still keep ford calipers, is there such a thing as an extending bracket.

I could be wrong but,
my understanding of the advantage of using larger disc's,while still using your ford calipers,that you would get improved braking,due to increased mechanical advantage,in the same way as leverage works,the longer the lever the easier it would be to stop it,this would then mean the brakes would not have to work as hard,so in turn would not run as hot.
But as pointed out above look what cars run in the 750 mc,I also look what caterham run on there cars,as I said before they spend £££££ in development for us locost builders,they only run 253mm discs on the front of 260csr,thats a 430bhp per ton car to stop,and it will out brake most other super cars.

Mr G - 12/1/07 at 01:49 AM

My 283mm Cossie Disc Upgrade

tim windmill - 12/1/07 at 09:31 AM

hi brad, ive got cossie disks with the 4 pot calipers and i dont think that there is any noticable difference in stopping power than the standard disks and calipers as i had on previous build

mcerd1 - 12/1/07 at 12:24 PM

Sierra 1.3 = 240mm solid discs
Sierra 1.6 to 2.0 (non-ABS) = 240mm vented
Sierra with ABS, 4x4, V6 & Granada = 260mm vented (4x4's and granada's have different discs but the same calipers)
Cossie 4x4 & Granada Cossie = 278mm vented discs (again different discs - same calipers)
Cossie 2wd = 283mm vented discs with 4 pot calipers

Dax do a mounting kit for std sierra calipers (240mm vented) for the cossie 4x4 discs - but it might not be what you need

btw - I have a set of old cossie 2wd calipers and discs spare
(calipers probibly need serviced or exchanged and discs are scrap - good for trial fitting)

SaveTheDodo - 12/1/07 at 12:27 PM

The answer to the original question is that Raldes sell (or certainly used to) larger discs and brackets to allow the standard callipers to be mounted further out on the disc.

Brake force is a product of the piston size (not exactly the same as the pad size) and the effective diameter, so larger discs with the same calliper will increase your braking, but not as much as a 4pot calliper on the original size disc.

Do check your master cylinder for effectiveness first though, as others have pointed out. "Feel" is probably a function of pad hardness & condition not the calliper/disc size.

Otherwise, this is one of those times when it is worth saving for the ideal (4-pot callipers on original size but higher spec discs), not spending half as much on an inferior fix. Then you get better brakes, and lower unsprung weight.

Toady1 - 14/1/07 at 09:28 AM

i know what you mean by there not being much feel, almost like a block of wood on the brakes isnt it?! mines the same, but just push the pedal hard and it stops very quickly! mine has the 240mm vented discs and cheap as chips pads on it. my limiting factor is the shite kumho tyres!

gttman - 14/1/07 at 10:28 AM

adding bigger disks would improve the braking force due to the distance the pad travels...... but I do not think it would add extra feel you are looking for and so proably isn't the best thing to do.

What i'd do is try some other pads, prabably the softer the better but go with what other people who have been through a few sets recomend.

I had the same problem with my Ultima, it braked great but the pedal was so wooden, I hated it..... changing the pads improved it no end but changing to 4pots improve it dramatically to the stage I was happy with, and they had exactly the same disc and pad size as the previous 2pots!

[Edited on 14/1/07 by gttman]

Bob C - 15/1/07 at 11:16 PM

brakes convert kinetic energy into heat & have to dissipate that heat. A bigger disc is a bigger heatsink. So it will be less prone to fade than a small one.
From a fade perspective, putting bigger calipers on the same old disc is counterproductive - the caliper covers some of the heat dissipating area
Bob