Racing Brake XT910 vs XT970

[destructure00]

After doing some reading I'm wondering if this is not rotor wear but pad material transfer as discussed here:

Abnormal brake pad transfer (deposit) - RacingBrake Forums

 

[beastmode13]

After doing some reading I'm wondering if this is not rotor wear but pad material transfer as discussed here:

Abnormal brake pad transfer (deposit) - RacingBrake Forums

Yep, it’s uneven transfer of material. Not rotor wear. XT970 is pretty gentle on rotor.

 

[beastmode13]

@destructure00 Try warming up the brakes on the out lap seems to reduce the uneven deposit.

FWIW. Porterfield R4 has worst deposit issue. Photos are from my fronts after 2 sessions.



The best advice is from @mcbarnet007. “You are over using the brake, just use less brake.” Hard to argue with that when he is the current P3 BPR lap time holder.

 

[destructure00]

@destructure00 Try warming up the brakes on the out lap seems to reduce the uneven deposit.

FWIW. Porterfield R4 has worst deposit issue. Photos are from my fronts after 2 sessions.

View attachment 504545 View attachment 504546 View attachment 504547

The best advice is from @mcbarnet007. “You are over using the brake, just use less brake.” Hard to argue with that when he is the current P3 BPR lap time holder.

Thanks for the info. I was taking a pretty easy out lap, and maybe 70% on green, and them maybe another 80-90% on next lap before going all out. Maybe I just go easier on the throttle, lower turn-in speed, less brake, lower battery consumption...win/win right?

Each successive track day I've been to I've been using more battery. Used to be 40% per session, then last time out was about 45%, today is nearly 50% per session. Currently sitting at a supercharger 20 miles from the track trying to get enough to finish the last 2 sessions and keep a little bit of power for the straights.


BTW my pedal feel got real soft...still seems to brake fine, just requires a longer throw of the pedal. I thought I remember you mentioning this before as well.

 

[beastmode13]

Thanks for the info. I was taking a pretty easy out lap, and maybe 70% on green, and them maybe another 80-90% on next lap before going all out. Maybe I just go easier on the throttle, lower turn-in speed, less brake, lower battery consumption...win/win right?

Each successive track day I've been to I've been using more battery. Used to be 40% per session, then last time out was about 45%, today is nearly 50% per session. Currently sitting at a supercharger 20 miles from the track trying to get enough to finish the last 2 sessions and keep a little bit of power for the straights.


BTW my pedal feel got real soft...still seems to brake fine, just requires a longer throw of the pedal. I thought I remember you mentioning this before as well.

The soft pedal feel but still brake fine is most likely due to the uneven pad material deposit. The uneven deposit will self-correct with a few weeks of street driving, depending on your driving style and distance.

I use about 5% of charge per lap at Laguna Seca and Buttonwillow. Making a trip to SC after each session is a must now. I think with improving skills, in particular not over braking, I should be able to maintain or reduce the energy consumption while improving my lap time.

 

[destructure00]

I use about 5% of charge per lap at Laguna Seca and Buttonwillow. Making a trip to SC after each session is a must now. I think with improving skills, in particular not over braking, I should be able to maintain or reduce the energy consumption while improving my lap time.

I used 55% in the 3rd session, OMG (90% -> 35%). Decided to skip session 4. Got signed off to move to HPDE4 next time out. Who knows what that will do to consumption. I hope you are correct about improving skills and reducing energy consumption!

 

[destructure00]

I put the stock rotors and 910 pads back on tonight. Pedal feels a lot better...maybe still a bit soft, will bleed brakes later and see if that makes a difference.

Here's some aftermath pics. Seems like I used up a lot of pad, didn't measure before though so I'm going off memory of what they looked like and the large amount of brake dust.

Left rear
Left front

Right rear
Right front

These are the left front pads. Rears are about the same.

Brake dust, anyone?

Left front close up.

 

[beastmode13]

@destructure00 The rears look good, not so with the fronts. What brake fluid are you using? BTW, did the cooper gasket sealant work for the rear pad?

 

[beastmode13]

]

Need to learn how to swap brake pads and bleed brake fluid anyway

Replace the stock caliper check valve with Speedbleeder will make bleeding/flushing brake fluid a breeze. Only tool you need is a 11mm box wrench and a catch bottle.


Speed Bleeder Bleeding Brakes Bleeding Motorcycle Brakes Automotive Bleeder Screw Brake Bleeder SB1010S-SS for both front and rear.

 

[destructure00]

@destructure00 The rears look good, not so with the fronts. What brake fluid are you using? BTW, did the cooper gasket sealant work for the rear pad?

I'm debating running brakes again as-is for TC8 vs cleaning the rotors up and trying to do a better bed-in process. Thoughts?

Had Motul in there previously, flushed with SRF the day before, so probably mostly SRF with a bit of 2 month old Motul 660 mixed in. I have another liter of SRF in the garage, need to go engage ABS again then bleed it through.

Copper sealant worked well, rear outer pads were adhered to the caliper just fine even after yesterday's track session. My only hesitation with it though is leftover residue. The RB adhesive comes off clean...sealant leaves a thin layer.

 

[Dangerous Fish]

Have those RB rotors only ever been used with those pads? The left rear pads don't look fully bedded in, but it might just be the photo.

 

[destructure00]

Have those RB rotors only ever been used with those pads? The left rear pads don't look fully bedded in, but it might just be the photo.

I used the rotors with XT910s for awhile before the 970s. Thought I cleaned them up ok before switching to the 970s but it's possible I didn't do a good enough job.

970 pads have only been on these rotors.

 

[MasterC17]

I used the rotors with XT910s for awhile before the 970s. Thought I cleaned them up ok before switching to the 970s but it's possible I didn't do a good enough job.

970 pads have only been on these rotors.

I would try cleaning up the rotors and re-bedding them on the 970 pads. I wouldn't worry too much about the soft pedal. I find my pedal is always a little soft and spongy mid-way through a track day and usually for a day or two after, then it seems to "tighten" back up again. As long as you aren't experiencing fade, it's really not an issue. You definitely are not boiling the SRF. It can probably be explained at least partially by some expansion in the brake lines (even Stainless ones). I've experienced it on other cars too, so it's not Tesla specific.

 

[destructure00]

Pedal feel/longer throw is the only thing that's bothering me right now, so if that's a relatively normal thing then I guess it's ok. Definitely did not experience weaker brakes at all....that was a nice change to be confident in them the entire day.

Will clean and rebed before TC8 and see what happens. I suppose worst case is that they do the same thing again and I just get used to a squishy pedal on the track.

 

[Dangerous Fish]

Are you monitoring brake temperatures either with ScanMyTesla or with a IR thermometer on the rotors?

I'm getting some Carbotech pads to try in a week's time and will be using SMT to ensure they go thru a proper heat cycle during bedding and to keep an eye on temperatures on track. So far, the SMT data from the car has been very close to the rotor temps I'm measuring, so I think it could become a very useful tool in the future, especially as you can monitor them in real time from within the car.

 

[destructure00]

Are you monitoring brake temperatures either with ScanMyTesla or with a IR thermometer on the rotors?

I'm getting some Carbotech pads to try in a week's time and will be using SMT to ensure they go thru a proper heat cycle during bedding and to keep an eye on temperatures on track. So far, the SMT data from the car has been very close to the rotor temps I'm measuring, so I think it could become a very useful tool in the future, especially as you can monitor them in real time from within the car.

I'm not doing it now, but that's a great idea. I'll check out SMT. I have a IR temp gun but by the time I do a cool down lap, drive to the parking lot, and read them I don't think it would be accurate info. If SMT can give me live info in car that would be ideal. Can you record and replay data as well?

 

[Dangerous Fish]

I'm not doing it now, but that's a great idea. I'll check out SMT. I have a IR temp gun but by the time I do a cool down lap, drive to the parking lot, and read them I don't think it would be accurate info. If SMT can give me live info in car that would be ideal. Can you record and replay data as well?

Yes, it records into a CSV file so you can then use various tools to analyse it. All I've used so far is a utility called UDP logger which draws graphs from the data. I'm sure there are other ways but I haven't explored them yet. I tried using a screen video capture app and then overlaid the gauges onto onboard video which worked to a degree, but I think I must have had some data drop-outs as it wasn't in sync all the way through a multi-lap session.

Here's a graph from UPD logger from a track session. The Y axis scale is a universal one for all the various data feeds, which is one of the things that isn't go great about using this utility. Temperatures have been logged in Celsius here.

 

[destructure00]

Yes, it records into a CSV file so you can then use various tools to analyse it. All I've used so far is a utility called UDP logger which draws graphs from the data. I'm sure there are other ways but I haven't explored them yet. I tried using a screen video capture app and then overlaid the gauges onto onboard video which worked to a degree, but I think I must have had some data drop-outs as it wasn't in sync all the way through a multi-lap session.

Here's a graph from UPD logger from a track session. The Y axis scale is a universal one for all the various data feeds, which is one of the things that isn't go great about using this utility. Temperatures have been logged in Celsius here.

View attachment 505079

Thanks for that. I just ordered the OBD2 adapter cable. Seems like there's a ton of BT dongles available, what are you using? Looks like SMT recommends the OBDLink MX.

 

[Dangerous Fish]

Thanks for that. I just ordered the OBD2 adapter cable. Seems like there's a ton of BT dongles available, what are you using? Looks like SMT recommends the OBDLink MX.

That's the one. Not worth trying to save a few bucks on cheap clones. Just get the one that works!

 

[MasterC17]

Yes, it records into a CSV file so you can then use various tools to analyse it. All I've used so far is a utility called UDP logger which draws graphs from the data. I'm sure there are other ways but I haven't explored them yet. I tried using a screen video capture app and then overlaid the gauges onto onboard video which worked to a degree, but I think I must have had some data drop-outs as it wasn't in sync all the way through a multi-lap session.

Here's a graph from UPD logger from a track session. The Y axis scale is a universal one for all the various data feeds, which is one of the things that isn't go great about using this utility. Temperatures have been logged in Celsius here.

I had no idea SMT could do that, that is awesome. Ordered the adapter and the dongle, thank you!