BIG brakes

Meurz

New member
Ok, I think my next mod will be BIG brakes. Not big but BIG. I found out that the stockers are not able to do their job properly at all and that was with some downhill mountain cruising. I had a set of 205 brakes which I have sold because I don't want to test / put months of work in it and nobody sells a proper adapter (I just haven't got the time or tools for it at home). Like with my clutch I think I'm going to invest into the future of my car. The weight will go down a bit in the future, and a built engine will come in some day. I however would like to do some trackdays (Holland is next to Germany and it's Ring, get my point?) in the near future so I decided a proper big brake kit is what I need.

I've did a search :D on this but I didn't find a topic all about big brakes, just pads and disks upgrades. It also seems like Rocketeers' Wilwood kit is the only big one used on here? I've read both positive and negative reviews on this site and others, plus a kit available in Europe will save me a lot of additional costs, so that would be nice.

As Griffin said in another topic, overkill isn't that bad when looking at brakes. I also like to play on the safe side of things and don't want to get another even bigger set later on if I decide to go crazy with a rebuild.

I'm looking at the monster 6 kit from Hispec: [click]

Or this nice kit from Tarox (6pot): [click]

And I've been talking to Pit Road M for a nice kit involving 4pot Outlaw calipers with 335mm discs (which they use themselves all around their track prepped RC) 8)

If anyone knows of other bolt on kits, please let me know. I'm currently looking and comparing, so if you have any input, please discuss 8)

Thanks, René.
 

SBCelicaGT

New member
René-

If you've got money to burn, by all means, go for it. I'm sure they will look quite nice and probably work quite well if set up properly.

That said, there are much less expensive ways to gain improved braking starting with uprated pads, fluid, and ducting.

If you want a full opinion, you need to fully divulge all the details of your situation. Such things to include would be:

Last time you bled your brakes
Type of fluid used
Type of pads used
Type of fade experienced (loss of peddle pressure, or just lack of slowing. One is due to poor quality fluid, the other is due to low temperature pads)
Plans for the car (power, weight)
Plans for the driver (autox, road course, rally, etc.) How many events a year?

Too often people think that more is better/safer. That's not always true. For instance, big brakes are heavier than small brakes. More rotational weight can actually lower lap times. For the fastest lap times, you will actually want the smallest brakes you can get away with, not the largest. Just something to think about.
 

Conan

New member
I'm with Adrian on this one. Going BIG is the way you take when everything else preventing overheating fails. Look at F1 cars pushing over 4G of stopping power. Do you think they are using 750mm discs and quad 24 pot calipers? :twisted: Instead, their brake components are built with material able to function at extreme temperatures.
 

furpo

New member
if you are going to do this then consider the rear to front piston area and caliper radius compared to stock.

there is another reason why you would want to go for bigger brakes, that is to avoid having to use pads that are no good for general day driving.

also, i think you will find the weight of the 14inch disk with and aluminum hat is close to the weight of a stock disk.

roger
 

Meurz

New member
SBCelicaGT":k78ydfvf said:
Last time you bled your brakes
Type of fluid used
Type of pads used
Type of fade experienced (loss of peddle pressure, or just lack of slowing. One is due to poor quality fluid, the other is due to low temperature pads)
Plans for the car (power, weight)
Plans for the driver (autox, road course, rally, etc.) How many events a year?
Last bleed: About 3 months ago
Fluid: Stock Toyota
Pads: Stock and bit higher temp (can't find the spec atm)
Fade: lack of slowing and minimal peddle pressure loss - mostly lack of slowing down
Plans: 400+ crank, bit of weightsaving (not drastic - stays a road car)
Plans for driver: road course, circuit driving. Events a year: no idea uptill now.

Additional info: car is weekend car, not dd. If I drive it, I like to boot it when it's warmed up enough (brakes too). I wouldn't want to say money is no object but like I said I want to invest in awesome stoppers. I know they cost money but I personally prefer a perfect setup at once over changing little things to tune the setup which I suspect will not match my needs.. (Do you know people with a higher hp 185 who do trackdays (not a 3 min autox) with stock(ish) brakes? Well I'm sure they are around, but you get my point hopefully)

Too often people think that more is better/safer. That's not always true. For instance, big brakes are heavier than small brakes. More rotational weight can actually lower lap times. For the fastest lap times, you will actually want the smallest brakes you can get away with, not the largest. Just something to think about.
I know bigger isn't always better. That's why the 12pots I've seen which barely fit under 18" are way over the top for me. 4 or 6 pot with a nice disk surface is the way to go imho.
I'm not trying to break the Nurburgrings' laptime, I just want to be able to go faster and thus stop faster several times in a row like you do on trackdays. If I want to set new laprecords I shouldn't have bought a tank like the 185 in the first place :D

@ Conan, I know. But they don't weigh 1500 kg and use a 'bit' different tires, downforce, etc. I think to compare you have to look at 'normal road going' cars like touring, GT, rally, etc. (I know, also very different than my car, but you get my point :wink: )
 

Simba

New member
Get some SS lines, flush the system with motul 600 fluid, and get a full set of the new EBC yellow street/track pads.

Unless you're pulling 30+ laps on a road course with extremely hard braking, that'll do everything you need it to do.

I would also be careful if you do decide to go with larger rotors and calipers. Bolting on a huge set of 6+ pot calipers isn't going to do you much good if the fluid and pressure requirements are beyond that of the stock master cylinder, which they usually are.
 

Meurz

New member
Well the Hi-Spec set is made for the GT4 cylinder. Pit Road M can also supply me with a bigger one if needed.

Thanks for the input so far guys 8)
 

CMS-GT4

Active member
We need a good braking duscussion thread.

I myself will be running stock brakes till next year. Upgraded pads and tires alone did wonders for stopping distance. Fluid and lines are must if your going to do any runs that are longer than 15 minutes. If your a canyon carver or track driver, fluid endurance is a must. Most likely if you already do this stuff, you have4 already figured out the limitation of the stock 185 system.

I have seen lots of customs jobs done on st185s. A product that used to be offered that I do not see anymore is the "Rally Brake kits."

There used to be a few companies that provided some wide calipers and wider brake discs for the gtfour that were designed to provide better braking and heat disapation and still fit a 15" wheel.

IMHO I think the st205 setup with better pads and fluid will suit most peoples needs. I would suggest finding a lighter 2-peice rotor instead of trying to use a spacer to fit the 205 rotor. A caliper bracket has to be made for the 205 setup anyway so finding a rotor that fits better will keep you from having to worry about longer studs or anything.

Since I plan on changing the bolt pattern next year I will also be making my own front brake setup. I will be using calipers and lines simular to the rocketeer package but will use a rotor hat suited for 5x114. Since I will be doing hill climbs and track events, I will most likely get something 12.5"-13". I am going to do a bit more research before I decide on the exact rotor size. I want to look into master cylinder upgrades as well.
 

furpo

New member
yes a good brake thread.

well the maths is very simple for the sizing of the caliper combination. just compare the caliper piston area to that of stock (note on an opposing piston caliper only use on side for working out the piston are). if the piston area is greater in the replacement caliper then the fluid pressure for a given clamping pressure will be lower. if you do not want to alter the front to rear bias then the piston area ratio from old to new will ave to be the same. in saying all of that the torque arm of the caliper to torque arm of the tyre has to be considered. i am sure you all went to primary school so can work it out. this is given that the pad material remains the same front to rear (i.e. pad coefficent of friction).

it does not matter how big or small your brakes are the limit is always going to be the tyre if you can lock the wheels up. what does matter is if the pad overheats then the pad coefficent of friction reduces to a point where you can no longer lock the wheel. thermal equation are a little bit more complicated and are subject to a lot of variables. in this case we are dealing with a very heavy car stopping from high speed quite frequently. In this case it is best to take as many measures as possible to reduce pad and disk temperature.

if you are going tarmac racing in a 1500+ kg car you are going to run into brake trouble very quickly. trust me. if you can keep pad temperatures below 600 deg C you will be doing very well even with the biggest and best brakes. to give some idea WRC rally cars run the best of everything including water cooled callipers and they still run into brake problems.

we have braided lines and opposing calipers for only one reason. to reduce compliance. this is a good thing however if you think that these will help you stop quicker go jump of a cliff. when brake fluid boils is becomes a gas and becomes much more compressable than what is was in its liquard form, the only reason expensive brake fluid is required is because the temperature limit of the old fluid has been surpast.

so to sum up

- the force path for a braking system is as follows, peddle pressure through a lever arm to fluid pressure, caliper fluid pressure can be figure from the master cylinder size and master cylinder rod force, pad clamping force is the caliper fluid pressure x effective piston area, disk friction can be figured from the clamping pressure and pad coefficent of friction, the disk retarding torque is a lever arm from the pad and the force is the disk friction, the wheel retarding force can then be worked out considering the raduis of the tyre as the lever.

- the heat energy can be figured from the change in velocity in a period of time of the vehicle. just trust me that the maths is all bad for a heavy car.

- compliance is another important part of brake technology but it has nothing to do with how fast your vehicle stops.

roger
 
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