Racing Brake XT910 vs XT970

[beastmode13]

Which Carbotech compound are you going for?

Are you resurfacing the rotors each time you try a different pad?

XP12 or RP2. Hopefully there will be reports from other Tesla owners by early next season.

I resurface the rotor by using a more abrasive pad than the one that was used before. Typically in one of two day of easy street driving, the old compound will wear off the rotor through the abrasion. Visually the rotor will be shining and bright, the wheels covered with a heavy layer of brake dust. My street driving isn’t hard/hot enough to bed the material onto the rotor. A good test I use to check for material bedding is to spray water on the rotor. If distinct rust mark foams within 30min it indicates the rotor as clean of pad material. Rust mark would still form on a bedded rotor, but it will be faint.

XT910 has been the rear pads on my car for three track days. Two at Buttonwillow, one at Laguna this past weekend. At Buttonwillow, it was paired with XT970 in the front. At Laguna, it was paired with Porterfield R4. The XT910 actually is doing amazingly well on the rear when paired with more aggressive front pads.

 

[beastmode13]

Brake dust from resurface operations.

 

[SILENTKLR]

Good job on keeping this thread alive guys. I’ve been lurking and watching a number of threads related to tracking the 3. I’m working on putting a car together for the track and these conversations/projects have helped immensely.

 

[beastmode13]

FWIW. One of the fastest driver uses XT970 front and rear without any issues. I over use my brake, thus I’m way slower.

 

[Dangerous Fish]

I used 970 front and rear the last time I was on track and after 15 consecutive laps there was no drop in performance. After the event I looked at the recorded (estimated) brake temperatures from Scanmytesla and they hadn't plateaued, but it was very encouraging as on the same track the OE pads would trigger the brake temperature alert after 2 laps and give up after 5 or 6.

I left the 970s in for street use and they have been perfect for that too. Even when stone cold they stop the car really well. The only downside is that they have now started to squeal when using them to stop at low speeds, but there's always going to be a compromise somewhere if you want to keep the same pads in for street and track.

 

[destructure00]

I used 970 front and rear the last time I was on track and after 15 consecutive laps there was no drop in performance. After the event I looked at the recorded (estimated) brake temperatures from Scanmytesla and they hadn't plateaued, but it was very encouraging as on the same track the OE pads would trigger the brake temperature alert after 2 laps and give up after 5 or 6.

I left the 970s in for street use and they have been perfect for that too. Even when stone cold they stop the car really well. The only downside is that they have now started to squeal when using them to stop at low speeds, but there's always going to be a compromise somewhere if you want to keep the same pads in for street and track.

Are you seeing the same rapid wear that @beastmode13 did with the 970s on the street?

 

[Dangerous Fish]

Are you seeing the same rapid wear that @beastmode13 did with the 970s on the street?

I'm not doing many miles at the moment and in any case I haven't had the pads out since before the last track day, so can't help there.

 

[Lunares]

2 months of street driving with XT970. No visible wear on rotor, but 2.5mm off the pads.

Do you feel the pad wear is from track or street driving?

With hold mode I use the brakes so rarely have to believe it's actually the track usage

 

[beastmode13]

Do you feel the pad wear is from track or street driving?

With hold mode I use the brakes so rarely have to believe it's actually the track usage

As I stated. The massive wear was from 2 months of street driving.

 

[Lunares]

As I stated. The massive wear was from 2 months of street driving.

Wasn't sure if you had checked them right after the track day

just don't know that could be given that I only touch my brake pedal about 5-10x per day on my commute to work/back

 

[beastmode13]

Wasn't sure if you had checked them right after the track day

just don't know that could be given that I only touch my brake pedal about 5-10x per day on my commute to work/back

Your daily drive isn't my daily drive. You might have different results than what I experienced and documented here with the same setup. If anything, I've been over the top transparent about the mods and actual results I have for the benefit of the nascent Tesla performance-oriented community. Anyone is welcome to contribute with facts and data so we can get beyond the data of one or a few.

 

[Lunares]

Your daily drive isn't my daily drive. You might have different results than what I experienced and documented here with the same setup. If anything, I've been over the top transparent about the mods and actual results I have for the benefit of the nascent Tesla performance-oriented community. Anyone is welcome to contribute with facts and data so we can get beyond the data of one or a few.

Sorry, didn't mean to say that I didn't believe you! Am sure that it happens, it just baffles me to what is going on, why they would degrade that fast, and how to avoid it.

I'll probably be switching to XT970 or one of the other ones you recommended when I go to buttonwillow / streets of willow next year. Hope to see you there!

 

[beastmode13]

Braking is a function of two different frictions, adhesion friction and abrasive friction. There is some whitepaper about this on the internet.

Below is from StopTech/Centric White Paper Glossary - https://www.apcautotech.com/getmedi..._and_APC_Technical_Whitepaper_E1-Glossary.pdf

Abrasive Friction - The mechanical rubbing of the brake pad material directly onto the rotor disc, resulting in the mechanical wear of both pad and rotor.

Adherent Friction - The transfer of a thin layer of brake pad material, which sticks (adheres) to the rotor face. The layer of pad material, once evenly established on the rotor, is what rubs on the brake pad. The bonds that are broken, for the conversion of Kinetic to Thermal energy, are formed instantaneously before being broken again.

Here is my theory for the accelerated wear from two months of street driving. The braking functioned mostly on abrasive friction. The pad never gets up to temp for proper deposition of pad material on the rotor. The slotted rotor also accelerates the wear of pad, as it is designed to allow gases to escape, and the edges to "bite" into pad.

One of the fastest Model 3 trackies is using XT970. So it is more than capable and sufficient for fast lap times.

 

[Knightshade]

The "gasses to escape thing" is leftover from the 1950s, hasn't been relevant in a long time FWIW- see also:

Pulp Friction - Those Poor Rotors


Author is the same guy who wrote much of the Stoptech white paper stuff you cite.

Slotting is useful to reduce glazing on a track though- albeit with some longevity trade-offs.

 

[beastmode13]

The "gasses to escape thing" is leftover from the 1950s, hasn't been relevant in a long time FWIW- see also:

Pulp Friction - Those Poor Rotors


Author is the same guy who wrote much of the Stoptech white paper stuff you cite.

Slotting is useful to reduce glazing on a track though- albeit with some longevity trade-offs.

Great to see him update his thinkings. I’ll update mine as well.

 

[TexasTeslaRacing]

Wow the brake dust from the 970’s is insane. Stopping power is addictive like others have posted. Front brake bias is even more pronounced. Perhaps a XT970 in the rear would help. MPP rotors and these brakes are incredible.

 

[Dangerous Fish]

Well I'm not suffering from that much brake dust with the 970s, so I think the rotors will have a bearing on this. I'm on stock rotors still.
More dust than the stock pads for sure, but not 'insane' amounts

 

[beastmode13]

Endless EX90 pad arrived. They are the most expensive pads by a large margin, I hope they will be worth it. Slight mishap, they sent me the rear pad for standard M3 instead of P3. Either way the rear pad is puny next to the 1149 shape pad for the Racing Brake RB460 caliper. The sensor cliper/hole on the 1149 will not be used.

 

[Lunares]

Endless EX90 pad arrived. They are the most expensive pads by a large margin, I hope they will be worth it. Slight mishap, they sent me the rear pad for standard M3 instead of P3. Either way the rear pad is puny next to the 1149 shape pad for the Racing Brake RB460 caliper. The sensor cliper/hole on the 1149 will not be used.

View attachment 490445

View attachment 490444

How much did those run for the whole set?

 

[beastmode13]

How much did those run for the whole set?

MSRP $390 each set, same price front or rear. If it works for me at Laguna Seca, then it is well worth the $. Nothing worst than not having confidence in your brake on the track.