Brake failure

When I was driving Track Moonhawk around the circuit I noticed that it's rear drum brakes fail (efficincy goes to 0) in just 5 minutes while front discs still hold up at reasonable temps. So I took Barstow onto gridmap and tested some brakes + pads combos. So, results:
Regular drums + full race pads: 960 Celsius, 0.1 efficiency, still working
Race drums + premium pads: failure at 680 Celsius 0.2 efficiency
And strange things
Race drums + semi race: 690 Celsius 0.5 efficiency
Race drums + full race: 660 Celsius 0.8 efficiency
So on a third lap track car loses its rear brakes. It's not how it shoud be, right?

 

no matter how much money, time, and effort is put into a track car, it's still going to be period accurate. not sure why the race version doesn't have discs in the rear, but the overheating should be normal for old drum brakes like those.

 

Agree, overheating and fade is ok. But they simply fail. When they reach 660 dergees they stop working at all. And as from my results, racier brakes die earlier for some reason

 

thats odd. are you doing a lot of left foot braking while under power? for me the rear ones are pretty hard to heat up unless i'm pushing it really hard for a good amount of time

 

I agree that some brakes do overheat quite easily, some even so much that they fail.

Consider for example Trans Am series that run at 70's, they certainly did not had brakes failing after 3 laps, so perhaps some more tuning or more options would be needed.
They mention here discs at rear too for Mustang 1969 series http://thecarsource.com/shelby/transam/transam69.shtml

It does mention here that brake pedal arrangement was to account brake fade on camaro, but consider what kind of tracks they did run and what kind of speeds:
https://www.caranddriver.com/review...-donohue-trans-am-camaro-archived-test-review

1967 Richard Petty #43 Plymouth had drums all around:


Disk brakes not available that would of taken the heat so it had drums all around, this is from attached PDF which has a lot of good stuff from 1968:

Notice ceramic lining, we are talking about 1967 race car here, race cars had far better tech back then than many think today.

Oval racing does require a lot from brakes, smaller ovals you just accelerate and brake to corner.


There are trouble with more modern vehicles too for example Sunburst Hillclimb, that is only few laps and brakes overheat and fade at WCUSA and at Road Atlanta, so that might need bit beefier brakes too.

So considering race variants should be used for racing, they should perhaps have bit better heat tolerance or lowering heating than top street models.

 

4 minutes of WCUSA City Race 1. Quite brake-intensive with its height difference, but...
And also, Track Barstow has some grippy modern tires, so modern brakes would make some sense probably
As I noticed, its drums can accumulate more heat, but they cool down much slower
--- Post updated ---
Btw, don't you know what is that "Slope" stat?

 

The problem you're encountering is that you're using Aluminum drum brakes. Aluminum has much better thermal properties than iron, which is why they cool off faster, but it also has a melting point of about 660C. So your brake drums are literally melting, not your pads. That said, I agree that beamng should give older period correct race brakes a bit better performance.

 

Thanks, switching to steel ones solved it. But shouldn't melting result in other things like fusing with pads, blocking brakes or simply exploding?
And thermal properties are fine but why put brakes that last 4 minutes of race track onto track-specific car? Or am I driving the wrong track?

 

I think that aluminum drums would have steel lining, or maybe ceramic?

If you manage to melt aluminum drum, then there would be issues of wheels not being where they are supposed to be.

Drum sits on bearing and wheel bolts to drum, so if drum fails, then wheel will not be attached to where it should, which causes certain challenges.

Another bit to consider is that drum has bearing cowl/runner in it, then there is grease and bearing. If you run brakes at 600C there might be certain bearing lubrication challenges, also as if drum is aluminum and bearing cowl is steel, they have different expanding when heated that might also cause bit of an issue, even when bearing is set, bearing cowl should not run away as it has no space to run away, but it might move a bit which introduces bearing play.

Article I posted mentioned 900F which is 482C, while 700F would be point which after wear increases a lot, that is 371C so maybe brakes should just run bit cooler? I'm not really sure, I don't have all the data here and I'm sure devs have done a lot of research regarding this, so generally I think they have been set right, but maybe lacking the beefy race options.

 

Alright, I'm using track car improperly. Devs' commentaries needed.
And so, what is the "Slope" stat?

 

Well, I get over 600C for rear brakes too, so maybe we both use it improperly

No idea about slope, if I had to guess, maybe something to do with brake pressure ramp up, but that is probably not it.

 

I just realized how small they actually are.

They are 8 inches in diameter on 1750 kilo car, what could go wrong?

 

Those weren't much bigger on Petty's race car either, but they had cut holes for cooling and brake shoes had cerametallic lining.

@Darren9, I think they use IR thermometer

I'm tempted to do little maths here, but torque for BeamNG vehicle brakes is something I'm not sure where to get?

 

1100 kg Dacia Logan has 8 inch drums in the rear too...

 

Yeah, I don't think the aluminum drums should just cease to exist at 660C. I would imagine they have some form of liner in real life, and the aluminum is just there for its thermal properties. You should still be able to melt them, but not after 3 laps.

 

Aluminum as radiator/heatsink, right. And maybe they are not really designed for continious load because they are just enough for one hard braking

That's an important property. Seriously, it's not quite safe when you lose ability to slow down in just a moment

 

There is indeed that, but bit hard to see what it is ingame.

For Moonhawk race brakes that is 4000F and 3000F maximum, which I find to be plenty.

I just upgraded them brakes, but there still is few bits missing, so I did not touch brake torque, but at least it can be used for racing purposes with these, I would need to research lot more data to get them where I want and I might head to bed for now.

 

Moonhawk Brake master cylinder linkage is something I'm not sure of what kind it is:


Brake pedal usually hangs from above MC actuator link, there is something like 40-50mm between pivot of brake pedal and master cylinder center, now brake pedal in Moonhawk should be mounted quite high to be able to push a rod that goes to brake MC, also it is off sideways too, maybe it is designed to have some sort of bend in pedal and some additional links?

Steering column/shaft/axle are not lined:


I calculated brake torque for my brakes with Mustang II data then. Brake pad Mu I guessed to be something around 0.5 for optimal temp (I'm guessing brake torque values are for optimum temp / maximum achievable).

Some bits Wilwood, some bits Baer, still lot to tinker, but I might wait fixes Goosah mentioned to work much more on that. It's like modern day old track car setup, to cope with high brake stress of WCUSA.

I think WCUSA has also high ambient temp for additional stress test, racing line has also high grip, it is like a test bench for brake setups

Big thank you to @Goosah from insight of this brake business.

Update: Hmm, something like 48-49cm brake pedal in Moonhawk could work.

 

Nah. I tested it and it is only stock/drum brake killer track.

First big turn have quite long S turns that we can pass without braking, After medium right hander and narrow S turns we have long right turn without braking and very long straight. That straight is long enough to cool brakes. However there is chicane on that straight that might cause a little problem. Big right hander that isn't really that narrow. Later there is easy right turn and narrow left turn, but sometimes we don't need braking. Then medium braking on Laguna Seca turns and another medium braking on last S turns. Finish line sector is another good cooling spot.

And that's it. I never overcooked brakes here. Sport Moonhawk needed 3-4 laps to cooked drum brakes, Hillclimb SBR4 max temp was around 400C, on long straight it dropped to 200C, never overcooked. Very good track.

 

With slippery tires any brake will hold up fine, but when you have grippy rubber like in race variant, it is different story.

Now when you compile that with lots of engine power, you get a lot more new brake zones.

Put widest Clockwise 533 tires to your Moonhawk with supercharged big motor and see how brakes fare after that

 

Hillclimb SBR4 is quite powerful yet I didn't cook brakes. There are few good corners that don't need braking, just simply release gas pedal and you can slow down enough to make it without slide. Every straight is long enough to cool them.

The real problem is when we have powerful sport car but without race kit (K-Series) where we need slow down much more than in race car. I think Hirochi Raceway is better for killing brakes. There a lot of corners that you need brake with same amount of straight sections line in WCUSA.