brake specs..need consult

[bacoa]

Hey guyss need abit of advice,
Based on my calculations for FSAE, i've currently chosen a kawazaki zx10 brake calipers(all four wheels) and plan to use 5/8"(mc for front) and 3/4" for rear and also i'm using 220mm diamter disc brakes...do u guys think that this might be overkill? Also i'm planning to run steel tubin from master cylinder to the a-arms and only then use braided hose..wat do u guys think..??really need a consult on this

Regards,
David

[Adam D. Bell]

I depends on what you calculated your wheel end torques to be with weight transfer. I will advise that you will have different free travel on from the front and rear M/C's because the running clearance between the pad and rotor will be the same all around and you have different diameter m/c's and you will need to more a different amount of fluid to fill that gap. (you can find M/C's that can be shimmed to address that)

But as far as Over-kill goes go the numbers and a desired input from the driver to get the wheel torques you want.

[Bill Kunst]

good choice on the steel lines as this will get rid of some "squish". The only problem is that on a real car, you might be saving money, on a small car like fsae the cost of the fittings to convert back and forth may result in the same price or more (so nothing gained). Keep in mind that you may want movable pedals, though, and should keep driver size in mind.
Bill

[bacoa]

tx bill,
What do you think of brake specs of using, 4piston calipers(kawazaki zx 10) and 220 disc brakes (kawazaki zx 10) with master cylinder of 5/8" for front and 3/4" for rear. With this specs i get a foot pedal force of about 25kg.
The thing i worry about is pedal feel..cause 25kg is light and i'm worried the driver will exert too much..u think that is likely to happen with drivers?

[RonBurgundy01]

David,

25Kg is quite a light force to be applying to the brake pedal, especially in the thick of racing (you'd be supprised how strong your foot can actually be!)

The zx10 calipers are more than likely overkill but dont stress to much about that, it is better to have too much brake force than not enough hence not being able to lock up the wheels. It is also a pain if you've started to design your uprights for these calipers coz you don't really want to have to go backwards in design.

There are a few things that you can do if you decide that 25Kg is a bit light for driver input. Firstly, if it is not out of the question, change the ratio of areas between the M/C and the caliper pistons (make sure that you only use 2 of the 4 pistons for this calc to). If you can't alter the M/C size, then try changing the mechanical advantage of the pedal to the M/C. By shortening the pedal, you decrease the moment arm and hence reducing the force applied to the piston. Depending on how you have the M/C arranged in relation to the pedal position (by this i mean if your M/C's run backwards towards you rather than having the pedal push directly onto them) you could change the distance from the pivot point of the pedal to the M/C center line.

As for the steel tube rather than a braided line...if you still have too much force after going through all the above areas you could run a full braided system to actually increase the "squish" (yes i know this is not really a good thing but it can actually help if all else fails). Taking it a step further, if the rules permit (which i have not actually checked) you could try running un-braided rubber lines because the squish will increase again due to the rubber lines expanding more than the braided lines.

Sorry about the length of this post, I hope it has helped you out a bit but more than likely i have just told you what you already know! haha.

Cheers

Matty

[bacoa]

Tx Matty,
I was thinking of changing the pedal ratio too and run the lines with braided hose all the way..but then my team members thought that if there is a adjustable pedal box, why not a adjustable pedal ratio too which would make it easier for everyone..haha..have no idea if it works.thanks anyway.

[drivetrainUW-Platt]

steel line is dirt cheap, and if you go with a simple flare fitting tee for splitting from side to side and have your flex lines made to match it, it all goes together pretty easy, watch out for the calipers and masters thou, they are where the fittings get tricky

steel line is easy to find, any autoparts store will have all you would ever need to do a formula car for under 10 bucks....