2021 Model 3 Performance - Warped Brake Discs

[PerformanceEV]

2021 Model 3 Performance. 98% of all braking I do using regen braking only, however when I do need to use the brakes they judder badly.

Booked into Tesla Service Centre and they have advised that both front brake discs are warped and need replacing, and they are not covered under warranty. They say the car must have been driven through water with hot brake discs, really?

I purchased the Tesla 2 years old with 23k miles.

One of the reasons I bought the Tesla was due to the fact that I was told by a Tesla salesperson that you never need to replace the brake discs or pads due to the regen braking feature, so I am disappointed to say the least.

Would be glad of thoughts from the forum please!

 

[Soul Surfer]

Trouble is that it is a "P" and you purchased it used. There is a possibility that this may have been a pre-condition by the other owner, driving it hard? Brakes are never really a warranty "thing" unless a blatant error is perceived. They fall under the "wear & tear" category, IMO.

 

[Dangerous Fish]

Have you got photos of the discs you can post here?
You don't know how the previous owner treated them, but apart from that what a lot of people call "warped discs" are actually discs which have built up high spots on the surface due to corrosion or the driver braking hard repeatedly and then stopping with their foot on the brakes.
I personally know Tesla owners who are on the original discs and pads with >150,000 miles on the clock, so it is absolutely possible for them to last a long time if you treat them properly. Sadly, a lot of owners don't.

 

[jmaddr]

Second for the corrosion accumulation. Ever leave your car for a week or so and then when you take off the rears “pop” loose? That leaves a level of accumulation that needs to be scraped off though braking (which we hardly do driving on city streets). I know they said the front but its very possible its actually the rears. Tesla are known for parts cannons.

Have both F and R turned for very cheap. No way you are below the minimum thickness.

 

[afadeev]

2021 Model 3 Performance. 98% of all braking I do using regen braking only, however when I do need to use the brakes they judder badly.
Booked into Tesla Service Centre and they have advised that both front brake discs are warped and need replacing, and they are not covered under warranty.

This sucks, but it's not unusual.
Rotors and pads are wear items, just like tires. These are NEVER covered by the OEM warranty.

They say the car must have been driven through water with hot brake discs, really?

No, it's just a lame-ass guess they gave you, since they don't know.
How do they know the rotors are warped? Unless they took them off the car and measured the run-off (I bet they didn't), they just made this excuse up to have you buy new set of rotors to make the problem go away.

It's exceedingly difficult to warp modern rotors.
What usually happens and causes shudder under braking is one of the two things:

1. You deposit an uneven amount of brake material on the rotor, so the rotor's surface area exhibits uneven areas of friction. Thus the shudder. Ways of arriving at this outcome vary, but the solution is the same - you need to remove the uneven pad deposit off the rotor (clean the surface with a brillo pad, or throw another set of pads (e.g.: track pads) into the calipers to 'scrape' off the old pad's material off the rotor), and re-bed the pads from scratch.
   • You have Brembo brakes, so here is Brembo pad bedding instructions for your reference.
2. Your rotors did get physically distorted, usually from either massively over-torqued wheel bolts/nuts after the car was services by a guerilla; or from over-heating them on track. It is impossible to rule this out, since you bought the car used.
   • If #1 doesn't work, your only option is to replace the rotors.

I would do #1 first, though.

I purchased the Tesla 2 years old with 23k miles.

That certainly doesn't help your cause, since no-one knows what happened to the car before you got it.

One of the reasons I bought the Tesla was due to the fact that I was told by a Tesla salesperson that you never need to replace the brake discs or pads due to the regen braking feature, so I am disappointed to say the least.

Sales people lie.
For a living.
If you didn't know then before, you certainly know that now.

HTH,
a

 

[rpiotro]

Have you got photos of the discs you can post here?
You don't know how the previous owner treated them, but apart from that what a lot of people call "warped discs" are actually discs which have built up high spots on the surface due to corrosion or the driver braking hard repeatedly and then stopping with their foot on the brakes.
I personally know Tesla owners who are on the original discs and pads with >150,000 miles on the clock, so it is absolutely possible for them to last a long time if you treat them properly. Sadly, a lot of owners don't.

Like this? From a friend's Honda S2000. This is more prevalent with new pads. The material binders haven't cooked up yet. This is less likely after a few miles on the pads.

They say slotted discs cannot be resurfaced. He found a guy that did it. Took off a very minuscule amount. Just enough to clean them up. Lesson learned.

If I need to make a sudden stop from speed I will continue to creep very slowly so the hot pad is not sitting in the same spot.

 

[Dangerous Fish]

Like this? From a friend's Honda S2000. This is more prevalent with new pads. The material binders haven't cooked up yet. This is less likely after a few miles on the pads.

They say slotted discs cannot be resurfaced. He found a guy that did it. Took off a very minuscule amount. Just enough to clean them up. Lesson learned.

If I need to make a sudden stop from speed I will continue to creep very slowly so the hot pad is not sitting in the same spot.

View attachment 1026075

Yes, exactly that and you are absolutely right to not come to a complete stop afer the brakes have been used very hard, if you can help it.
Most have learned the hard way now, but on trackdays it was very common to find drivers 'warping' their discs after doing 10 laps in their road car, coming into the pits and sitting in the pit lane with their foot on the brake while chatting to their passenger. The rest of the day they'd have to put up with a pulsing brake pedal.

 

[DomDeWild]

Like this? From a friend's Honda S2000. This is more prevalent with new pads. The material binders haven't cooked up yet. This is less likely after a few miles on the pads.

They say slotted discs cannot be resurfaced. He found a guy that did it. Took off a very minuscule amount. Just enough to clean them up. Lesson learned.

If I need to make a sudden stop from speed I will continue to creep very slowly so the hot pad is not sitting in the same spot.

View attachment 1026075

As a machinist, I can tell you it is very difficult to resurface slotted discs. As the rotor turns on the lathe, the tool bit jumps a thousandth or two every time it hits a slot. This jumping usually breaks off the tip of the tool bit, and with six slots, that's six 'jumps' for each rotation on the lathe.

How fast was the lathe turning, and what type of tool bit did he use? Just curious.

 

[dbeiler]

Rotors and pads are wear items, just like tires. These are NEVER covered by the OEM warranty.

Brake pad lining wear is usually not eligible for warranty replacement, but other aspects of the braking system are. I've replaced pads and rotors under warranty during a previous stint as a Ford technician. It's usually up to the technician to distinguish between abuse and a repair subject to warranty. If the technician forms an opinion that the vehicle was abused, they won't submit a warranty claim. In that case, the OEM never even gets the chance to deny a warranty claim.

How do they know the rotors are warped? Unless they took them off the car and measured the run-off (I bet they didn't), they just made this excuse up to have you buy new set of rotors to make the problem go away.

Brake rotor runout is measured on vehicle. The dial indicator clamp is secured to the knuckle or spindle. Both rotor runout and hub runout are checked at the same time.

It's exceedingly difficult to warp modern rotors.

It is the minority of brake pulsation causes but still quite common. The rear rotors on my truck warped to over twice the spec limit runout after cross-country towing a 6x12 Uhaul trailer with failing surge brakes (brake line leak). Obviously an extreme use case as the truck brakes were doing more work than intended but still illustrates how exceeding braking GVWR will result in severe rotor warp.
A P3D has an only 800lb difference between its empty weight and GVWR. One 200lb person in the driver's seat and now you're down to 600lbs remaining. Three American sized passengers in the car and it's over GVWR.

Pad etching onto the brake rotor friction surface is the most common cause of brake pulsation problems. As many people have already noted in this thread, if you park the car with hot rotors and leave the pads pressed against them, you WILL get pad etching and subsequently a noticeable brake pulsation.

Pad etching will be a very common problem for the foreseeable future. Tesla, in their obsessive and even detrimental cost cutting fixation, has not installed park pins in their gearboxes. Instead, the vehicle is held in park by clamping the rear pads against the rotors. Put a Tesla in park with hot rotors and voila, you have pad etching on your rear rotors. Park pins have been used in automatic transmissions and EV gearboxes since their inception, but along come the Tesla engineers who KnOw BeTtEr, fix a thing that wasn't broken in the first place, and cause a major problem in the process.

 

[Dangerous Fish]

To be fair though the rear brakes on a Tesla (esp. Model 3 with regen on the rear motor) do so little work you have a job bedding pads on them and to get them up to anything like the temperature required to cause etching requires a LOT of heavy braking.
All the Model 3's I've seen with pulsating brakes caused through excessive heat have done the fronts and the rears ended up OK.

 

[rpiotro]

As a machinist, I can tell you it is very difficult to resurface slotted discs. As the rotor turns on the lathe, the tool bit jumps a thousandth or two every time it hits a slot. This jumping usually breaks off the tip of the tool bit, and with six slots, that's six 'jumps' for each rotation on the lathe.

How fast was the lathe turning, and what type of tool bit did he use? Just curious.

Don't know about the tool bit but I was told he turned them at a low speed and made just a minuscule cut.

Whatever he did it worked. No-one else would even try it.