Spa Trackday: BIBLICAL FL brake failure (Glowing Disc!)

[Gearhead999s]

Originally Posted by JuniorM3

No sorry doesn't apply to me, I'm a mechanic my self. I teach and coach drivers, I own my own Championship winning race team. And engineer my own car. And i won championships in touring cars.

Not from what I am seeing on this post.Conserving brakes in a showroom stock type car is a must if you want to finish out a long session.I was taught this by one the best racers that Canada ever saw in showroom stock cars.He could turn the same laps as his rivals all race long and then out brake them because he had brakes left to use.

I am not saying that the E92 does not need better brakes,just use the brakes with in their design limits.

[Jangobipbip]

i own M3 and 007 GT3 cs, and M3 braking system is "shit" after several laps like Spa compared to GT3 system, and it's normal when you see the original M3 calipers....you have to be softer with M3 brakes if you want to go fast. It can't support an agressiv driving (concernin the brakes of course)

just my 2cents after having tracked both several times.(2.549 in Spa with GT3-starlane)

[JuniorM3]

Originally Posted by Checkcaptain

Still waiting for your laptime?!

2.51.712 With passenger. Half tank of gas.

[JuniorM3]

Originally Posted by Gearhead999s

Not from what I am seeing on this post.Conserving brakes in a showroom stock type car is a must if you want to finish out a long session.I was taught this by one the best racers that Canada ever saw in showroom stock cars.He could turn the same laps as his rivals all race long and then out brake them because he had brakes left to use.

I am not saying that the E92 does not need better brakes,just use the brakes with in their design limits.

I agree that you have to save your brake it they can't take it.
But my brakes were fine for 3 hours with the mods but suddenly broke. Unexpected with in half a lap.

[Robin_NL]

LOL Junior Strous in the house. Welkom hier. Beetje pro drivers are needed here!

Ik reed op Assen 5 mnd terug ook de hele voorremmerij in de hens.Trackday dus.

Anyway a very warm welcome here man.

Give the guy a brake/break, he drives/races faster than 99% of us here. I'm sure.

Here are some pics of him:



James Bond like:

[JuniorM3]

Originally Posted by lucid

I voiced this concern in your DIY thread, so I'll follow up on it as I am curious: did the ducting stay where it was supposed to stay at the right orientation? Even then, it is not clear how effective it will be without the backing plates as the stock plates will most likely block most of the flow. Plus, the stock rotors have not been designed for forced cooling.

I updated my DIY thread. The ducts did stay in place without the backing plates. But i installed the backing plates for the track day. Check the DIY it looks nice.

Originally Posted by lucid

If you were to say that you have not experienced this issue on another 400hp+ 3700lb+ car (which sells for $60k) when you drove it the same way you drove the M3, then we can blame it on BMW engineering.

I think i would have less probs with the Merc and Audi...

BMW M3: Single piston front and rear calipers.
Merc C65 AMG: Brembo 6-piston caliper front and 4-piston rear disc brakes.
Audi RS6: 6-piston caliper front, Single rear floating caliper.

[lucid]

Originally Posted by JuniorM3

But my brakes were fine for 3 hours with the mods but suddenly broke. Unexpected with in half a lap.

Unless the rotor and caliper temperatures were at ambient temperature before your last session, I don't know that things suddenly broke. The caliper and rotor temperatures could have been progressively building up before the failure during the 3 hours--meaning whatever cooling the system experienced between sessions might not have been enough to bring temperatures down to ambient levels and residual temperatures might have been high.

Regardless, I share your frustration in that this car should have been shipped with some form of brake cooling stock.

[lucid]

Originally Posted by JuniorM3

I updated my DIY thread. The ducts did stay in place without the backing plates. But i installed the backing plates for the track day. Check the DIY it looks nice.

I missed your update. Thanks.

Well, it looks like blowing air onto the inner surface of the rotor doesn't cut it. Better than nothing, but clearly not enough for an E92 M3 at stock trim and weight when it is pushed hard. There needs to be a way of getting the air to flow into and through the internal rotor cooling vanes. That is what I meant by the stock rotors aren't designed for forced convection of this type.

[aus]

Originally Posted by JuniorM3

6 laps, with passenger. So around 15 min. On track.

Damn. That doesn't sound right.
Maybe Driver >>>> M3 brakes.
Like someone else said, your beyond 99% of the people here. You need the new GT4.

[e46e92love]

Originally Posted by smookey

i own M3 and 007 GT3 cs, and M3 braking system is "shit" after several laps like Spa compared to GT3 system, and it's normal when you see the original M3 calipers....you have to be softer with M3 brakes if you want to go fast. It can't support an agressiv driving (concernin the brakes of course)

just my 2cents after having tracked both several times.(2.549 in Spa with GT3-starlane)

So you are saying a track focused 130k car has better brakes then a "performance" 3700lb 70k coupe? Really? Shocking.....

Please laugh, I'm just trying to point out that its kind of ridiculous for any of us to compare a GT3 to ANYTHING BMW makes. Its like comparing a G37 to an //M3, its not fair to the G37.

Cheers,
e46e92

[Gearhead999s]

Originally Posted by lucid

Unless the rotor and caliper temperatures were at ambient temperature before your last session, I don't know that things suddenly broke. The caliper and rotor temperatures could have been progressively building up before the failure during the 3 hours--meaning whatever cooling the system experienced between sessions might not have been enough to bring temperatures down to ambient levels.

Regardless, I share your frustration in that this car should have been shipped with some form of brake cooling stock.

As the pads wear down over the day the thermal barrier to the piston decreases in size which can cause a problem suddenly as the day goes on if you dont start easing off on your braking.I have not seen pads bent like thay since my 5.0 Mustang days

[e46e92love]

Originally Posted by JuniorM3

I think i would have less probs with the Merc and Audi...

BMW M3: Single piston front and rear calipers.
Merc C65 AMG: Brembo 6-piston caliper front and 4-piston rear disc brakes.
Audi RS6: 6-piston caliper front, Single rear floating caliper.

I mean no disrespect sir, as you are a pro, and I'm not even capable of standing in the same room, BUT, I would bet the merc winds up having the same issues. But perhaps, I'm wrong......

The RS6, maybe, maybe not. RS4, my bet is the brakes are fine.

Cheers,
e46e92

[Jangobipbip]

Originally Posted by e46e92love

So you are saying a track focused 130k car has better brakes then a "performance" 3700lb 70k coupe? Really? Shocking.....

Please laugh, I'm just trying to point out that its kind of ridiculous for any of us to compare a GT3 to ANYTHING BMW makes. Its like comparing a G37 to an //M3, its not fair to the G37.

Cheers,
e46e92

not comparing, just explaining......

[lucid]

Originally Posted by Gearhead999s

As the pads wear down over the day the thermal barrier to the piston decreases in size which can cause a problem suddenly as the day goes on if you dont start easing off on your braking.I have not seen pads bent like thay since my 5.0 Mustang days

That could have been a factor, and looks like the pads are really worn down.

[bavarian19]

[Gearhead999s]

Originally Posted by MERCSUk153

Well the GTR in the video weighs more than the M3 you didn't see that it's brakes failed or faded. He is not the first one to complain about M3 brakes being the weak link. The RS4 and C63 both use 6 piston and the M3 single and you don't think that that could be a factor or atleast underpowered.

GTR is also a lot money than a M3 in Canada,and is big time ugly

[lucid]

Originally Posted by MERCSUk153

The RS4 and C63 both use 6 piston and the M3 single and you don't think that that could be a factor or atleast underpowered.

I don't see how the number of pistons has much to do with the system overheating (maybe a variable in transferring heat to the caliper and the fluid, but not clear if more pistons would actually result in less heat transfer). It might have had something to do with the warping of the pad, but the real issues simply seems to be overheating.

[Radiation Joe]

Originally Posted by MERCSUk153

Well looks like his single piston got overheated and got stuck. If you have a six piston brake then the braking power is much more evenly applied an less prone to the overheating. 6 pistons clamping power instead of it going through a single piston would definitely help. Less stress on that single piston also would prevent it from getting stuck like that which may have caused the overheating.

I have to agree that it looks like the piston or seals failed. This is not that uncommon when you ask stock components to work at temperatures they were not designed to work at.

Theory:
Those rubber guides that the caliper slides on deform under pressure and cause the pads to contact the disk unevenly. This probably caused the piston failure. There are solid guides available for other BMW calipers that prevent this. No one has produced them for this caliper, yet.

I ran eight piston Brembo calipers on my pig of an RS6. They didn't save that car from either cooking pads or cooking rotors. When you ask 4000 pound cars to stop like 3000 or 2000 or 1200 lb cars, sometimes you run into problems.

I can get the stock calipers to work at ungodly temperatures, but why bother. If you are that serious about tracking the car, put on a nice set of aftermarket brakes and save a few pounds while improving pedal feel.

Bottom line is that the stock brakes are not crap.

[Radiation Joe]

James Clay,
Are you reading this?

Who makes those caliper bushings?

I know, I know, if we need the bushings we should just buy the PF BBK. But they're so much cheaper insurance.

[Gearhead999s]

Originally Posted by Radiation Joe

James Clay,
Are you reading this?

Who makes those caliper bushings?

I know, I know, if we need the bushings we should just buy the PF BBK. But they're so much cheaper insurance.

A box of the bronze caliper bushings came with my 1st set of Hawk pads.I have little taper wear on my used pads since I put them in.I am pretty sure that my pad supplier had them made up for me.

[lucid]

Originally Posted by MERCSUk153

Well looks like his single piston got overheated and got stuck. If you have a six piston brake then the braking power is much more evenly applied an less prone to the overheating. 6 pistons clamping power instead of it going through a single piston would definitely help. Less stress on that single piston also would prevent it from getting stuck like that which may have caused the overheating.

Applying the braking torque more evenly does not mean you will have less heat to dissipate in the system (I can't tell if that is or isn't what you are saying above). The heat is being generated during the conversion of the kinetic energy of the car to, simply put, heat. That's what a brake system does. If you go faster, you have more energy to convert into heat. Ideally, the heat would be transferred into the rotor entirely, but obviously that is not the case.

As to how the heat generated at the pad/rotor interface is trasferred to the rest of the system other than the rotor. The pad makes direct contact with the caliper at various places, so there is conductive heat transfer there. The pad also makes contact with the pistons, so there is conduction there as well. And there is conduction between the caliper and the pistons. (Never mind the convective and radiant heat transfer between the rotor and everything else). Would having more pistons decrease piston temperatures? I don't know as that depends on the specifics of the contact areas in all of the interfaces and many other variables such as the masses and materials of the individual components, but I don't think we can simply assume that it will. If you have more total pad/piston contact area, you might even increase piston temperatures (more energy might flow into the pistons as opposed to the rotors). You'd need to analyze the entire system as a thermal curcuit.

In general, the bottom line is when there is excess heat in the rotor that you can't transfer into the environment via rotor cooling, everything will eventually heat up, and parts of the system will begin to fail.

[Advevo]

lol@strous

I know junior he has driven his M3 to the max

And yes the single piston caliper is not up to that sort of job. You can put in some ducting and race pads but heat building up with such a heavy car and even add a passenger you can figure out what will happen.

I find it exceptional that you have driven that long with it.

When you have some mechanical knowledge of braking you know how more the pads are worn you get lots more heat into youre caliper. The caliper could not stand the heat any longer.

junior you drove a GT4 with big race brakes but even the heavy GT4 cars have brake problems in one hour races.

Weight is the enemy of brakes.

Put some 6 pot AP calipers on the front with pfc pads but even then you should be careful because of the weight of youre car.