Brake Failure into hungry

[plohl]

holy sh*t, how much power does your car have! I watched another one of your videos and gps says you're doing 200 through the kink!

[MossRatt]

Hey madjak, I think you're on to something there with the handbrake. I do engage it when I park up.
The latest photos show bubbles on the back of the pads as if they have been cooked.
The other side pads look like new btw.

[madjak]

Yup you should never let the car sit with the handbrake on after heavy braking. Not only is it bad for the pads but it can warp the rotors or even boil the braking fluid.

Get used to parking on a flat surface and leaving the car in 1st gear if you are worried about it rolling. I usually take a couple of wood chocks with me at one event where we have to park on a slope.

[Red_Bullet]

Yes, not using the handbrake was one of Doug Chapples tips in driver breifings, now I see why.

[Magpie]

I always park the car in gear and/or chock after a session. When it is loaded onto the trailer the park brake is no applied.

Think about it, the rotors can be over 500°c, you then clamp pads to them, the heat then travels to the pads, calipers and then fluid. If you do not cool them down fast enough then you will have heat soak. The small air gap between the pads and rotors is sufficient to reduce the heat transfer.

I would pull the calipers off and check the condition of the seals and change fluid.

[RS2000]

The latest photos show bubbles on the back of the pads as if they have been cooked.
The other side pads look like new btw.

If the other side looks like new, then I'd say the handbrake is dragging while the car is in motion. Adjust both sides so there is no tension on the cables when the handbrake is off.
I had one side dragging at the first event I did after buying my MX5, & completely burnt off all the paint on the Hawk Blue backing plate. However, the pad material didn't show any ill effects.

[rascal]

Burning the paint off isn't necessarily a sign of anything wrong.
The nice blue paint on my hawk blues burns off at the first meeting I use them.
It's only to make them look pretty in the packet. Doesn't affect usage..

[MossRatt]

holy sh*t, how much power does your car have! I watched another one of your videos and gps says you're doing 200 through the kink!

I think I have a telemetry accuracy issue between the gps data on the app, the integration into the software and the reading coming off the speedo.
My speedo hits 180 through the kink but doesn't move beyond that, and I'm assuming the speedo is slower than the actual speed. The raw data from the GPS app tends to vary depending on the accuracy of the receive signal it has to the corresponding satellites.
So I wouldn't rely on it to be too accurate, but it looks good!

I'd like a speed gun at the kink one day to measure the accuracy!
How fast have you and others gone through the Kink, and would your speedo's be accurate?

As for the horsepower of the car, I wouldn't know but I will get it on a dyno next year when I upgrade the factory ECU.

[Trackphotos]

My car peaks at about 175kmh at the braking point for Karussel as measured by a qstarz 818xt gps. Stock power NB8A, minus a couple kmh because of aero drag from wing and splitter, and rolling resistance from twingroove tyres. Used to be more like 178kmh before I made the aero change. If you've got a fair bit of power under you, 200kmh isn't unreasonable.



If you want accurate data retrospectively, I'm happy with the other GPS I got recently, the Qstarz bt-q1000ex. It's a standalone recorder so you can just stick it in the car somewhere and it will log it all for you, it goes to sleep after X minutes without movement, and wakes up as soon as it detects vibration again so you only need to turn it on in the morning and it'll log all day. It can be paired via bluetooth with a phone running Racechrono or something similar, and you can use your phone for realtime sector splits and lap times. That just involves one extra thing you need to keep charged, put in the car, and start logging on before each session, but the realtime data is pretty cool. If you only intend to use it paired with a phone for realtime data, the cheaper non-standalone Qstarz 818xt will do fine, which is what I used for a couple of years before buying the newer one.

The paint on my Winmax pads bubbles on the first day, but they've never failed me yet. Sounds like other people's suggestions of handbrake dragging in use, or being put on when the brakes are still hot, could be good things to check out.

[ianoz]

hint on the BT-q1000ex - they take the same battery as a lot of older Nokia phones - a BL-5C
I've got a couple of spare old phone batteries and just swap them in during the day.

[93_Clubman]

Adjust both sides so there is no tension on the cables when the handbrake is off.

And similarly when adjusting the rear caliper adjusters make sure this is the case.

[manga_blue]

Adjust both sides so there is no tension on the cables when the handbrake is off.

And similarly when adjusting the rear caliper adjusters make sure this is the case.

The rear brakes only self adjust with tension off the cables and pressure from the hydraulic circuit. So make sure that you have the tension off the cables and the lever arms at the rear calipers are free to move (i.e. not seized). Then push the brake pedal down hard a few times until you no longer here the adjusters taking up.

[Guran]

Anyone here heat treat their new rotors before use? I do it for the willies on the racecar, I think I'd do it for any car I tracked. I get good life from mine, and never had a crack - but the heat treatment is meant to extend life, not (AFAIK) to prevent cracking. The Wilwoods are slotted, but for stock rotors I go plain.

Heat treating steel will either soften it or harden it, depending on the temperature/time profile of heating, holding and cooling. What are your heat treatment conditions Ed?

[greenMachine]

Anyone here heat treat their new rotors before use? I do it for the willies on the racecar, I think I'd do it for any car I tracked. I get good life from mine, and never had a crack - but the heat treatment is meant to extend life, not (AFAIK) to prevent cracking. The Wilwoods are slotted, but for stock rotors I go plain.

Heat treating steel will either soften it or harden it, depending on the temperature/time profile of heating, holding and cooling. What are your heat treatment conditions Ed?

I put them in the oven, on separate racks, and build up to about 150 over 2-3 hours, hold for an hour, the take it up to 250-300 in a couple of steps over an hour, then leave it at oven max for at least two hours. At that point I turn the oven off but leave them in the oven without opening the door, overnight or until they have cooled to ambient. That is the ideal (?) but the timings can be a bit variable depending on various happenings in and around the house ...

[manga_blue]

Guran = serious metallurgical research expert IRL