Is it my driving or is it the pads?

[andyk5]

Originally Posted by CSG Mike

Depends.... which stock wheels? There are several stock wheels for the GR86.

Stock 17s off the base model.

[CSG Mike]

Originally Posted by Matt93SE

I agree with Mike on everything but this portion. He'll get you sorted on the hardware.


in the braking application/ driving habits standpoint, there are a couple theories and here is mine:

Braking harder and shorter puts greater heat into the rotors, but is easier on the pads and reduces pad wear and fluid temps.

The brake pads have some finite "insulation" value as the friction material rejects heat buildup by nature and attempts to keep the heat in the rotor. BUT... a longer, softer brake application squeezes the pads on the rotor longer, which forces more heat into the pads-->pistons-->caliper-->fluid. This causes higher brake fluid temps and greater pad wear.

Thus, a short, HARD application of the brakes keeps the heat in the rotors and out of the pads.

I cannot explain the proper physics behind it, but that's what I've seen and experienced in >20 yrs of doing HPDEs and racing.


Real-world example: my kids both race go karts. Both race the same class and are in the same chassis... Within 5lb overall weight, same engine, tires, brakes, weight distribution, alignment, etc. Their fastest times each day are both within 0.25 sec.
Thus everything is pretty much identical but the driving technique.

My daughter brakes very late and very hard- straightline threshold braking nearly every time. The pads last half a season on her kart- maybe 15-20 race weekends although I've stopped counting hers and just watch the pads and replace when necessary. I wind up changing hers about once a season.

My boy brakes early and soft, and drags the brakes almost to the apex then accelerates out. He gets roughly 3-4 race weekends out of his pads. He also trashes front tires with understeer while the girl wears the rears more.


---Back to cars---
I have experienced the same on track with our endurance racing team. The guys that try to be "easy on the brakes" wind up with cooked brakes before the end of their session and the front tires take a beating as they drag the brakes into the turns, overworking the outer front tire. The veteran racers on the team do a quick stab of the brakes to slow the car then get off them, and we stay within the grip limits of the tires. faster lap times and less wear on both the tires and brakes.


Sooooo to answer your question, the guys that keep their foot of the slow pedal the longest will have longer brake pad life *assuming they're running same lap times* as the guys dragging the brakes over longer distances.

This is quite anecdotal. While I get that it's your experience, it won't be everyone's experience.

Remember, correlation is not causation.

The bolded sections tell me that the root cause is out there to be determined.

Here's some food for thought. Perhaps your son is actually scrubbing transfer! Maybe the slower drivers on the team are over-braking AND leaning on the tires harder, while driving less effectively/efficiently. This can quickly be determined with even the most rudimentary datalogger. For your kids, a simple temp paint application will point you in the right direction!

[CSG Mike]

Originally Posted by andyk5

Stock 17s off the base model.

BM4 will absolutely not clear stock 17's off of the base model!

[Matt93SE]

Originally Posted by CSG Mike

This is quite anecdotal. While I get that it's your experience, it won't be everyone's experience.

Remember, correlation is not causation.

The bolded sections tell me that the root cause is out there to be determined.

Here's some food for thought. Perhaps your son is actually scrubbing transfer! Maybe the slower drivers on the team are over-braking AND leaning on the tires harder, while driving less effectively/efficiently. This can quickly be determined with even the most rudimentary datalogger. For your kids, a simple temp paint application will point you in the right direction!

We have AIM Mychrons on both karts. The daughter clearly brakes harder and for less time/distance than the boy. they both have roughly the same speed (within 1-2mph) at the apex, but the boy is still braking while the girl is already back on the throttle and accelerating. He is using both braking and turn-in to scrub speed which reduces lateral weight transfer in a kart.
Since they have a solid axle and both rear tires are stuck to the track, the kart understeers massively. This in turn overloads and wears down the front tires. while the daughter is using more straight-line braking and coating thru the apex to lift the inside rear and rotate the kart, then throttle out just after apex. If I could average their driving habits out, they'd be a master of trail braking.

note that a kart handles and corners completely differently than a car, but the point of the brake wear is still the same-- the boy brakes softer and for longer time & distance and has significantly more wear on the brakes than the girl. Yes this is just one anecdote, but i see the same repeated in both karts and cars for the last 20 years or so that I've been playing with cars.

in my old 240SX, I used to get >40hrs of race time on a set of front pads. I sold the car and the new owner- who is many seconds/lap slower than I was- tends to ease onto the brakes early and not use them to their limit. he went through a set of pads in a season, maybe 20hrs total track time.

[blsfrs]

Originally Posted by CSG Mike

This is quite anecdotal. While I get that it's your experience, it won't be everyone's experience.

Remember, correlation is not causation.

The bolded sections tell me that the root cause is out there to be determined.

Here's some food for thought. Perhaps your son is actually scrubbing transfer! Maybe the slower drivers on the team are over-braking AND leaning on the tires harder, while driving less effectively/efficiently. This can quickly be determined with even the most rudimentary datalogger. For your kids, a simple temp paint application will point you in the right direction!

Mike, your characterization of @Matt93SE 's observations as "quite anecdotal" is quite incorrect. His post has all of the hallmarks of a good scientific study.

A good study limits the variables so you can tease out causality. In this case, the carts were the same. The drivers weighted the same. They ran the same courses for the same number of laps at similar lap speeds. The only variable was their driving style. Through repeated trials (events), there was a consistent outcome. The brakes of the driver who braked the hardest in a straight line lasted longer than the one who braked more gradually.


Does all this correlate to our cars? Seems plausible enough.

[CSG Mike]

Originally Posted by Matt93SE

We have AIM Mychrons on both karts. The daughter clearly brakes harder and for less time/distance than the boy. they both have roughly the same speed (within 1-2mph) at the apex, but the boy is still braking while the girl is already back on the throttle and accelerating. He is using both braking and turn-in to scrub speed which reduces lateral weight transfer in a kart.
Since they have a solid axle and both rear tires are stuck to the track, the kart understeers massively. This in turn overloads and wears down the front tires. while the daughter is using more straight-line braking and coating thru the apex to lift the inside rear and rotate the kart, then throttle out just after apex. If I could average their driving habits out, they'd be a master of trail braking.

note that a kart handles and corners completely differently than a car, but the point of the brake wear is still the same-- the boy brakes softer and for longer time & distance and has significantly more wear on the brakes than the girl. Yes this is just one anecdote, but i see the same repeated in both karts and cars for the last 20 years or so that I've been playing with cars.

in my old 240SX, I used to get >40hrs of race time on a set of front pads. I sold the car and the new owner- who is many seconds/lap slower than I was- tends to ease onto the brakes early and not use them to their limit. he went through a set of pads in a season, maybe 20hrs total track time.

Make that bolded part happen!

So it sounds to me like your son is using both the trailing and throttle application as a band-aid to get the rotation that he wants, and ends up only exacerbating his push issue. While I know it's not easy to instill in him, I think we'd agree that he needs to just have a bit more patience. Does he have any other skills (driving or non-driving) where patience is a hallmark virtue, that you can equate corner entries to?

With the elaboration, it sounds like he may actually be driving more effective lines, but is just losing more time than he makes up on cornering speeds, due to the timing of his brake and throttle application. Slow-in fast-out vs fast-in slow out. If their ultimate lap times are only 0.25s apart, the boy has to be making up time somewhere on the girl. Is he significantly lighter?

From here, we can speculate that due to his front loaded (but not threshold) braking, he continues application of the brake in a heightened temperature state, and under that state, is when the majority of the pad is wearing, rather than the actual deceleration portion of the braking. While karting doesn't have as many choices as cars, adjusting the brake pads to one more suited to his driving style can result in superior results.

If you want to share some data files, I'll gladly dig deeper, as this is genuinely interesting.


re: 240, I bet he's over-braking and under-driving in general.


Re: pad choice:

CSG brake pads can be broken down into a few major categories. Both the published and unpublished compounds can initially be divvied up into ABS-friendly and ABS-unfriendly. Most brake compounds commonly available to weekend warrior and non-professional type motorsports are ABS-unfriendly; use of ABS with these pads will result in really quick pad wear. These pads also tend to be happier at lower (but still well within track range) temperatures. ABS-friendly pads will tend to be less happy at lower temperatures, but will tolerate higher pressures and higher temperatures better, as well as potentially have characteristics like endothermic ablation, or a digressive friction/temp or friction/pressure profile.

[CSG Mike]

Originally Posted by blsfrs

Mike, your characterization of @Matt93SE 's observations as "quite anecdotal" is quite incorrect. His post has all of the hallmarks of a good scientific study.

A good study limits the variables so you can tease out causality. In this case, the carts were the same. The drivers weighted the same. They ran the same courses for the same number of laps at similar lap speeds. The only variable was their driving style. Through repeated trials (events), there was a consistent outcome. The brakes of the driver who braked the hardest in a straight line lasted longer than the one who braked more gradually.


Does all this correlate to our cars? Seems plausible enough.

While I understand your viewpoint, I do this for a living, and tend to scrutinize a bit more. There's still a few too many variables unaccounted for. The biggest one is line, and loading.

For example, I can drive identical lines, and cause understeer, or oversteer, in the same car, by adjusting my loading, while carrying virtually identical speed. This is a large part of the work I do for a living.

This is where the datalogs come in. While absolute readings (1st order derivative of velocity) show a result, relative readings, trends, some analysis will yield quite a bit more detail into HOW and WHY things happened (2nd order derivative, aka jerk).

[timurrrr]

Originally Posted by CSG Mike

KE = MV²

You keep forgetting the "/ 2" part.

[timurrrr]

Originally Posted by CSG Mike

BM4 will absolutely not clear stock 17's off of the base model!

I believe CSG has a page saying that all 2022 wheels will fit with 3+ mm spacer?

[Matt93SE]

Originally Posted by CSG Mike

Make that bolded part happen!

So it sounds to me like your son is using both the trailing and throttle application as a band-aid to get the rotation that he wants, and ends up only exacerbating his push issue. While I know it's not easy to instill in him, I think we'd agree that he needs to just have a bit more patience. Does he have any other skills (driving or non-driving) where patience is a hallmark virtue, that you can equate corner entries to?

With the elaboration, it sounds like he may actually be driving more effective lines, but is just losing more time than he makes up on cornering speeds, due to the timing of his brake and throttle application. Slow-in fast-out vs fast-in slow out. If their ultimate lap times are only 0.25s apart, the boy has to be making up time somewhere on the girl. Is he significantly lighter?

From here, we can speculate that due to his front loaded (but not threshold) braking, he continues application of the brake in a heightened temperature state, and under that state, is when the majority of the pad is wearing, rather than the actual deceleration portion of the braking. While karting doesn't have as many choices as cars, adjusting the brake pads to one more suited to his driving style can result in superior results.

If you want to share some data files, I'll gladly dig deeper, as this is genuinely interesting.


re: 240, I bet he's over-braking and under-driving in general.


Re: pad choice:

CSG brake pads can be broken down into a few major categories. Both the published and unpublished compounds can initially be divvied up into ABS-friendly and ABS-unfriendly. Most brake compounds commonly available to weekend warrior and non-professional type motorsports are ABS-unfriendly; use of ABS with these pads will result in really quick pad wear. These pads also tend to be happier at lower (but still well within track range) temperatures. ABS-friendly pads will tend to be less happy at lower temperatures, but will tolerate higher pressures and higher temperatures better, as well as potentially have characteristics like endothermic ablation, or a digressive friction/temp or friction/pressure profile.

My son is just a n00b 7yr old driver that doesn't listen to his parents, faster big sister, or his coach. He's just gonna have to figure it out on his own by getting beat until he learns to stop braking and turning early..
...ICYMI, karts- everything but shifters anyway- only have a single brake on the solid rear axle and the front wheels spin free. the only wear on the front tires is from turning loads. thus if he's pushing so bad he's wearing out front tires, it's because he's not initiating turn in and pushing through the entry while still standing on the brakes to slow down enough to make the thing turn. Because of the front tire scrub burning away kinetic energy, he's actually reducing brake use and thus pad wear.

If he would brake later, harder, and in a straight line, THEN give the steering input from turn in to apex while coasting, he would reduce tire and brake wear and go faster. if he could get that concept into his thick lil 7yr old brain, he would whoop his sister's arse.
.....instead he does the classic "driving harder" instead of "driving better" and tears stuff up while still being slower.

[CSG Mike]

Originally Posted by timurrrr

You keep forgetting the "/ 2" part.

It's a constant, and unimportant to the relative discussion at hand.

[andyk5]

Originally Posted by CSG Mike

For example, I can drive identical lines, and cause understeer, or oversteer, in the same car, by adjusting my loading, while carrying virtually identical speed.

Hey, lets talk about this. Care to elaborate?

[CSG Mike]

Originally Posted by andyk5

Hey, lets talk about this. Care to elaborate?

It's just car control. Overload the front tires, or the rear tires, with how you load up the car.

[timurrrr]

Originally Posted by andyk5

Hey, lets talk about this. Care to elaborate?

If you're accelerating up to ~0.15G, the front tires will have less grip, while rears will have more, causing a shift in balance towards understeer.
If you're decelerating up to ~0.15G, the opposite happens and you shift balance towards oversteer.