Warped rotors AGAIN!?!?!

[GreaseMonkey]

I don't know enough about 1PD to know how quickly it would kick in the friction brakes when letting off the accelerator at a high rate of speed...

Never. If you lift your foot off the go pedal, the car never applies the friction brakes. That’s why if you are traveling faster than what the regen is capable of handling, you will need to physically apply your brakes, otherwise your car will overshoot where you intent to stop.

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[Mach-Lee]

Few more things to add.

When charged to 100% and in one pedal I get serious vibrations when braking at 60-80mph.

When in two pedal and not charged to 100% I don’t seem to feel much vibration. Some but not much.

I bedded the brakes again today on an open road and the let them cool down.

really not sure what’s up here.

If you charge to 100%, the battery is already full, so it will not use regenerative braking. Friction braking will be used instead for one pedal drive until the battery charge level is low enough to support regenerative braking. I think you need to be below about 90-95% SoC to get full regen. The Mach-E uses a blended braking system, so this transition happens seamlessly.

I guess that’s one downside of charging to 100% every day, you will use more of your friction brakes, and your driving will be less efficient. Charging to 90% most of the time and only going to 100% a couple times a month (for LFP) is optimal.

It definitely sounds like you still have warped rotors.

 

[OH2AZ2OH]

My rotors seem to be slightly warped at 54k miles. I've been noticing it for the last 10k miles or so, but I had to really pay attention to feel it. It's been pretty rainy this week, so I haven't completely ruled out rotor corrosion. When I first noticed it several months ago, I did a handful of gentle stops in Neutral from speed, just enough brake pressure to hit the high spots. That maybe helped a little. If it ever dries out here again, I plan to try that again.

 

[dolvio]

Most of the discussion to this point has been due to a semantics issue. If your car is applying mechanical braking when using 1pd and pulling your foot off the accelerator, there’s a brake problem. Same thing with 2pd drive and light brake application. The underlying cause needs to addressed by a competent dealership. Simply replacing the rotors (etc) wont resolve the issue unless they also happen to inadvertently fix it while dealing with the rotors. Make sure the dealer understands just how your car is a actually braking and how wrong/off/messed up that is from a normal mach-e..

I’ve read elsewhere that if the battery is highly charged (say 95% or more) regen braking won’t be applied and the mechanical brakes are activated. True?

 

[Kamuelaflyer]

I’ve read elsewhere that if the battery is highly charged (say 95% or more) regen braking won’t be applied and the mechanical brakes are activated. True?

Yes, as the energy created by regenerative braking would have nowhere to go. The big “but” though is that normal mechanical braking wont cause warped rotors. Something else is amiss. Plus, iirc, you indicated that whenever you lift your foot off the accelerator in 1pd, you’re getting mechanical braking. That’s definitely not normal except in a very limited set of circumstances. Pressing the brake pedal while in 2pd shouldn’t be giving you mechanical braking right off the bat either.

 

[dolvio]

Yes, as the energy created by regenerative braking would have nowhere to go. The big “but” though is that normal mechanical braking wont cause warped rotors. Something else is amiss. Plus, iirc, you indicated that whenever you lift your foot off the accelerator in 1pd, you’re getting mechanical braking. That’s definitely not normal except in a very limited set of circumstances. Pressing the brake pedal while in 2pd shouldn’t be giving you mechanical braking right off the bat either.

What I realized is when I hit the freeway at higher speeds I’m often fully charged or between 95-100%. That’s when the 1 pedal and foot off is vibrating the wheel badly. Very badly.

2 pedal driving at higher speeds and heavy braking gives the same result.

1 pedal driving normally does not give me the bad vibrations.

 

[Kamuelaflyer]

What I realized is when I hit the freeway at higher speeds I’m often fully charged or between 95-100%. That’s when the 1 pedal and foot off is vibrating the wheel badly. Very badly.

2 pedal driving at higher speeds and heavy braking gives the same result.

1 pedal driving normally does not give me the bad vibrations.

Still shouldn’t be causing warped rotors.

 

[B177y]

@dolvio , I just went back through this thread to see if you ever mentioned what was done by the dealer the first time your brake rotors warped. I couldn't find anything that mentioned that. If I missed it, my apologies in advance.

My thought is if on the first dealer visit for your warped brake rotors they just resurfaced the rotors (basically remove material to remove the warp), that then removes mass from the rotors and can make them more likely to warp again as there is now less material available to absorb and dissipate heat.

If your rotors were replaced with new rotors, then my thought above is irrelevant.

I agree with other posts that warping rotors is an indication of something wrong, either a stuck or intermittent sticking caliper or some other brake system issue. Or possibly (no offense) driving style of two-foot driving or repeated hard stops, but neither of those sounds like your issue.

 

[dolvio]

@dolvio , I just went back through this thread to see if you ever mentioned what was done by the dealer the first time your brake rotors warped. I couldn't find anything that mentioned that. If I missed it, my apologies in advance.

My thought is if on the first dealer visit for your warped brake rotors they just resurfaced the rotors (basically remove material to remove the warp), that then removes mass from the rotors and can make them more likely to warp again as there is now less material available to absorb and dissipate heat.

If your rotors were replaced with new rotors, then my thought above is irrelevant.

I agree with other posts that warping rotors is an indication of something wrong, either a stuck or intermittent sticking caliper or some other brake system issue. Or possibly (no offense) driving style of two-foot driving or repeated hard stops, but neither of those sounds like your issue.

Hey, correct. First time they machined the rotors. They would not replace them without trying this first. My wife always drives in 1 pedal and so do I. Only recently have I used 2 pedal to keep the rotors a little cleaner.

I really don’t know what’s going on here.

 

[Kamuelaflyer]

Only recently have I used 2 pedal to keep the rotors a little cleaner

2pedal drive uses blended braking. It uses regen until your brake pedal deflection us sufficiently high enough to warrant mechanical braking.

 

[B177y]

Hey, correct. First time they machined the rotors. They would not replace them without trying this first. My wife always drives in 1 pedal and so do I. Only recently have I used 2 pedal to keep the rotors a little cleaner.

I really don’t know what’s going on here.

Since the rotors were machined, then I'll go with my theory that is what made them more prone to warp again.

Insist on new rotors for this next visit to the dealer and also insist on a full brake system check. Check the calipers (make sure none are stuck/sticky) and possibly a flush to get any burnt or overheated brake fluid out of the system.

 

[OH2AZ2OH]

Since the rotors were machined, then I'll go with my theory that is what made them more prone to warp again.

Insist on new rotors for this next visit to the dealer and also insist on a full brake system check. Check the calipers (make sure none are stuck/sticky) and possibly a flush to get any burnt or overheated brake fluid out of the system.

And, to be completely thorough, ask them to run an indicator across the hubs before installing the new rotors. More than once, I have seen warped rotors caused by uneven hubs.

 

[dolvio]

And, to be completely thorough, ask them to run an indicator across the hubs before installing the new rotors. More than once, I have seen warped rotors caused by uneven hubs.

It’s odd that it happened in the first place. The first time I noticed it was when I was fully charged 90+ and pulled off the pedal in one pedal mode. The wheel shook so hard I was worried.

I want new pads and rotors but they wouldn’t do this without skimming first.

 

[Jarratt]

The regen brakes are an independent system. They don't use the brake rotors, so regen braking couldn't be the source of your warped rotors...

Agreed, however we just had an experience w/our car with rust or dirt(we live at the end of a 3 mi dirt road) getting into our brakes and causing a warped rotor feel after only 18K miles using almost only 1-pedal regen.

We were able to fix it thanks to advice here -- we went downhill in N (which turns off regen) and then working the brakes even coming to a hard stop, After several runs the problem which the tech at our dealership diagnosed as "definitely warped rotors" was gone. The dealership was willing to fix for $1600. I sent the Gen'l Mgr the Tech Service Bulletin Technical Service Bulletin (TSB) 22-2023. Its las paragraph reads as follows:
Maintenance Tip to Prevent Sticking:

"To prevent rust buildup, owners recommend occasionally shifting the car into Neutral while slowing down from higher speeds. This disables regenerative braking and forces the mechanical brakes to engage, effectively "polishing" the rotors"

 

[Keytone]

Has anyone come across this yet? We do a mix of one pedal and normal to burn rust off sometimes and I’ve got warped rotors for the second time. The vibrations are violent at higher speeds. What the issue here?

This has also been chronic since I've purchased the car in the fall of 2024. The only times the brakes ever get used are when stopped or when I put the car into neutral on a hill to gently apply the breaks to clean of the rust after rain and thereby realise the shuddering.

1 pedal driving is always used and deceleration scoring is almost always above 95%.

The dealer, at no cost, did resurface both front rotors 8 months ago, but the issue returned and continues to exacerbate for the past 3 months.

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