Starting from scratch on a brake system design.

[Kozy]

Just wondering how you kit car guys go about designing a braking system from scratch on a new build?

Is it a case of copying a setup from a similar car/using the donor car brakes, or is it a bit more involved with lots of calculations, maybe even some specialised software to work out ideal component sizing?

I remember talking to one chap who had issues with his kit car, where the guys that built it originally had fitted some massive vented front discs, paying no regard to the amount of energy they were going to deal with and a result, they never got hot enough to work properly. Sounds like they didn't really 'design' the brake system, so much as 'fit whatever was lying around'.

I'm interested in how people determine the sizing of various components, to get the correct balance, ensure they operate at the right temperature etc.

[pigeondave]

Normally someone else has done the brakes on a kit car and there are known sizes that work.

if you want to put numbers on things there is a download Excel file here

http://www.pirate4x4.com/tech/billavista/Brakes/

I don't know how good it is, but one day I'll get round to using it.
Like you say bigger is not always better.

[Kozy]

Checked it out, thanks for the link. It's one of the better ones I have seen actually, it does actually take in to account the mass of the discs and the energy going in to them for one, as well as working with boosters, and crucially using tyre grip instead of acceleration as an input. All in, rather good!

Reason I ask is because I've written something myself, but really it's over the top for the cars it's written for as the majority of owners just don't understand it, nor do they really need to. I think it might be of more use as an application to design kit car brakes from scratch, if there isn't something like it that exists already at least (thought that Excel spreadsheet is pretty close)

Here's my version - http://blackartdynamics.com/Brakes/BrakeIndexMX5.p... (Not IE friendly)

It's written for MX5s and in all honesty it's total overkill. I made a basic version too, http://blackartdynamics.com/Brakebasic/BrakeIndexM... which was aimed at being a bit more intuitive (get all the dials in the green = good brake setup) but still, a bit more than most MX5 drivers really need.

It's closed loop calculation which constantly updates to find the front wheel lockup point, which is what I think makes it pretty powerful as a tool for setting up brakes. A change to the brake bias will change the total deployable brake force, the acceleration, weight transfer etc, which is how it actually works in reality.

I'm wondering if a version of that page, but listed with a load of typical kit car brake setups, ranging from stock donor vehicles to a range of aftermarket performance calipers, might be interest to the kit car community? I wrote the thing (the whole site really) out of boredom/curiosity, but it'd be great if it actually became a useful tool for people given the amount of work that has gone in to it, as it's clearly wasted being aimed at Hondas and MX5s.

[Kozy]

No interest then. Fair enough!

[one eyed mick]

Kozy said:

No interest then. Fair enough!

I think it is too far advanced for the normal kit car builder to be honest,the kit is usually lighter than the donor so std brake will do the job [ onthe road ] a lot of stuff that is fitted is bling . The serious track day or race driver may be interested but that a different game

[Kozy]

one eyed mick said:

I think it is too far advanced for the normal kit car builder to be honest,the kit is usually lighter than the donor so std brake will do the job [ onthe road ] a lot of stuff that is fitted is bling . The serious track day or race driver may be interested but that a different game

Yea I think that's the problem, it's too much.

It's a shame, I'd love to do something useful with it, but I think unless I could sell it to the aftermarket brake kit manufacturers, it's just total overkill!