Are you seeing this? (Excessive rear brake dust)

[Black306]

I’m not seeing this in either of my Model 3s, but I have those set to Roll mode. When driving my Model 3s, I’ll use generative breaking down to about 5 to 10 miles an hour, then use the brakes. Unfortunately, the Cybertruck doesn’t have Roll mode.

I’m suspecting Cybertruck’s version of hold mode significantly uses the rear brakes. Pictured below are front and rear rims cleaned at the same time. Fronts are showing very little brake dust while the rears… see for yourself.

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[btcrealm]

24k miles and not seeing that.

 

[J.Graham]

Have you turned off “brake assist with regen”.

 

[Black306]

Have you turned off “brake assist with regen”.

You mean this…

 

[btcrealm]

I ironically have that turned on.

 

[Black306]

Interesting. I might have to do an experiment.

 

[Rvp.770]

The technician at tesla service. Told the vibrations I feel between 40 and 50 mph. Was from the truck using the brakes while regen was active. I think I will try turning that setting off to.

 

[Black306]

Mine was already off. I’m going to try and turn it on and see if it makes a difference. Not too hopeful, but it doesn’t hurt to try.

 

[Beetlebug62]

I have that setting on, but assumed that was for cold days when the cold battery couldn't accept the amount of regen, so using the brakes to assist in slowing the truck.

And, that was one of the first things I noticed when I removed my wheel covers. Both of the rear wheels have a light coating of reddish brake dust. I think I only had about 700mi on the truck when I removed the covers.

And compared to my old BMW, that's nothing!

 

[Black306]

That's what I'm assuming too; "Apply Brakes When Regenerative Braking Is
Limited" is for when it's cold or battery is near/at 100% SOC, so it does not apply the brakes when full regen is available.

Wouldn't be the first time I've experienced a Tesla configuration that was not intuitive though. The setting could be the inverse in practice; "Don't Apply Brakes When Regenerative Braking Is Not Limited." That would make sense to me if turning on the setting reduces how much brake dust accumulates.

Rims can get like that in <300 miles. I've cleaned the rear rims far more than the whole truck! So we'll see what happens in a couple weeks.

 

[dalton108]

That's what I'm assuming too; "Apply Brakes When Regenerative Braking Is
Limited" is for when it's cold or battery is near/at 100% SOC, so it does not apply the brakes when full regen is available.

Correct. I have had it on since they first gave it to us on CT and I never have any noticeable brake dust in the rear. I wonder if this impacts AWDs more than Beasts?

 

[Black306]

Let the experiment begin!

Odometer : 5417

 

[furbyland]

My understanding is that the brakes are used as part of the regen contribution as needed/determined by the software. The regen is frequently not enough on its own to slow it down, so it adds in the brakes. I don't think the setting that has been reference is the cause, whether on or off. I think the setting is for when conditions prevent the battery from accepting the amount of regen that would be needed for better stopping, so in that case it will add in the brakes. I could be wrong, but I know I read this thesis somewhere.

 

[Black306]

Dude, I totally agree. My belief is the setting shouldn’t make a difference. Even states in the info popup brakes are applied when cold or battery is close to 100% SOC.

Trying this out in the slim chance it does
make a difference. Anything to stop cleaning the wheels so often!

Side note: there is the option for Roll mode in the off-road app. Just took a spin and there is definitely enough stopping power with regen only. Really wish this was an on-road option.

 

[HaulingAss]

I’m not seeing this in either of my Model 3s, but I have those set to Roll mode. When driving my Model 3s, I’ll use generative breaking down to about 5 to 10 miles an hour, then use the brakes. Unfortunately, the Cybertruck doesn’t have Roll mode.

I’m suspecting Cybertruck’s version of hold mode significantly uses the rear brakes. Pictured below are front and rear rims cleaned at the same time. Fronts are showing very little brake dust while the rears… see for yourself.

Two things can cause more that the typical nearly non-existent brake dust:

1) Use of the brake pedal (usually due to approaching stops too suddenly for regen only braking)

2) Brake calipers in need of cleaning/lubing. This doesn't need to be done regularly in most driving environments but driving through de-icers or alkaline dry lake beds/alkaline dust can cause surface corrosion on the caliper pins which can prevent the brake pads from retracting as designed. A clean and lube of the calipers will fix it.

Edit: Having inspected your photos more closely, it looks more like surface rust of the discs from lack of use, than brake pad dust. If the truck is parked out in the rain, or driven in the rain, an occasional one second moderate application of the brakes at 40-60 mph should clean off that rust in a manner that allows it to just blow away. If you don't do that, the automatic brake application when approaching a stop will rub the rust off onto your wheels (because you are going so slow).

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