Rusty Brake Discs?

[SCOOTERSD]

Is anyone else seeing any of their brake discs with rust on them and then even rust collecting at the bottom of the wheel? When I took my car in to a Lucid approved body shop for some paint rework, the owner of the shop pointed out that my rear passenger brake disc and wheel had rust accumulations while the other wheels didn’t. By the time I drove it home it had blown(?) away. After our recent 1000 mile trip and the car sitting for a couple of days the rusty substance has reappeared - only on that back wheel. Pics of both back wheels below….

 

[Coho]

Is anyone else seeing any of their brake discs with rust on them and then even rust collecting at the bottom of the wheel? When I took my car in to a Lucid approved body shop for some paint rework, the owner of the shop pointed out that my rear passenger brake disc and wheel had rust accumulations while the other wheels didn’t. By the time I drove it home it had blown(?) away. After our recent 1000 mile trip and the car sitting for a couple of days the rusty substance has reappeared - only on that back wheel. Pics of both back wheels below….
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Are you using regenerative braking? Perhaps using the friction breaks for a few stops each day will keep them pristine. Or move to Arizona.

 

[Adnillien]

Are you using regenerative braking? Perhaps using the friction breaks for a few stops each day will keep them pristine. Or move to Arizona.

Even in Arizona, I have to use the friction brakes after a car wash to keep the rust off.

 

[yiling1990]

Is it just 1 wheel that has this rust? I'd be less concerned if it was all wheels or even just both wheels on the same axle, but only 1 wheel makes it seem like the brakes aren't evenly applied to rub the rust off.

 

[SCOOTERSD]

Are you using regenerative braking? Perhaps using the friction breaks for a few stops each day will keep them pristine. Or move to Arizona.

I use regen almost exclusively around town but certainly use the brakes occasionally. Both the body shop owner and I just found it strange that only one of the 4 wheels appears to rust. I know it is not a problem unless the car sits and the rotors pit but that is highly unlikely as much as I love driving Moby.

 

[borski]

I use regen almost exclusively around town but certainly use the brakes occasionally. Both the body shop owner and I just found it strange that only one of the 4 wheels appears to rust. I know it is not a problem unless the car sits and the rotors pit but that is highly unlikely as much as I love driving Moby.

Just use the friction brakes to brake hard a few times from high speed. It will clear off the rust in a jiffy.

 

[CLTGT]

Like the above, I would not be worried about the presence of rust unless it does not go away with some usage of the friction brakes. The uneven application causing just one disc to show signs of rust after conventional braking does worry me a bit and I would ask Lucid about it. I know how the brakes work on my '73 Mustang and this would worry me as the pressure from the Master Cylinder should be the same to the backs and the same to the fronts. There is a proportioning valve on my Mustang (has 4 wheel aftermarket disc brakes) that lets me adjust the brakes to where I want them to be front to back, but the brakes are supposed to be applied equally in the back, or the front, so that you do not get abnormal steering under braking. Not really sure how they do it in this case.

 

[#499/?]

All 4 of mine are constantly rusted like that; if I gun it and brake often enough it will start to dissipate but it returns quickly.

 

[xponents]

Like the above, I would not be worried about the presence of rust unless it does not go away with some usage of the friction brakes. The uneven application causing just one disc to show signs of rust after conventional braking does worry me a bit and I would ask Lucid about it. I know how the brakes work on my '73 Mustang and this would worry me as the pressure from the Master Cylinder should be the same to the backs and the same to the fronts. There is a proportioning valve on my Mustang (has 4 wheel aftermarket disc brakes) that lets me adjust the brakes to where I want them to be front to back, but the brakes are supposed to be applied equally in the back, or the front, so that you do not get abnormal steering under braking. Not really sure how they do it in this case.

Perhaps related to torque vectoring?

 

[ViperSSD]

Rusting brake rotors are also normal on ice cars, just a car sit through some rain and then a couple days afterwards.

 

[Dog poop]

I noticed it only on my rear drivers side brakes. I attributed it to the lack of actual brake use or not enough pressure when I do use brakes to fully engage the rear brakes.

 

[Bobby]

I noticed it only on my rear drivers side brakes. I attributed it to the lack of actual brake use or not enough pressure when I do use brakes to fully engage the rear brakes.

If you are only noticing it on one, I would have that looked at. Perhaps that caliper is not functioning or needs adjustment. It would be hard to notice because of the regen.

 

[Dog poop]

If you are only noticing it on one, I would have that looked at. Perhaps that caliper is not functioning or needs adjustment. It would be hard to notice because of the regen.

Good input. I’ll look at setting something up. Also I’m assuming the rear baking system is similar to that of a standard ICE vehicle where the rear brakes only engage upon heavy braking needs.

 

[kae02]

I am also seeing similar issue but the rust is on outer edge of wheel just behing lug nuts. The rust on rotor clears away after manually braking but referring to pictures posted by OP, there is also rust on outer wheel just behind lug nuts. Is that normal?

 

[Steveinarizona]

Rusting brake rotors are also normal on ice cars, just a car sit through some rain and then a couple days afterwards.

The difference is that on EVs the friction brakes are used less. The brakes should last longer but it is a good idea to do a hard braking every now and then.

 

[Rogue]

So what are the affects of not braking hard on occasion? Serious corrosive damage from rust? Cosmetic issues only?

I ask because I could probably count on one hand the number of times I've done more than tap the brakes (~8-9k miles).

 

[Worldwide Beagle]

It's more than cosmetics. Serious rust pitting can and will occur. I do not know how long it takes. The discs are soft iron and can show rust in dry Denver in hours. I have seen brake discs where one side of the brake caliper freezes up, the brake pad on this frozen side then never touches the disc, that side of the disc rusts in six months to the point of deep pitting, and the disc is ruined. If a pad never touches the disc, the disc will keep rusting and rusting and rusting.

Decades ago, When I put high value Porsches in storage for months, I pulled the pads and sprayed both sides of the disc with waxy coating. The idle discs could rust to ruin otherwise. I think Euro cars shipped to the US still coat the discs with a non oily spray that burns off with use or a squirt of cleaner.

This is just my opinion, but I think rusty discs need long slow moderate brake application for 30+ seconds at a time to burnish/grind off the surface rust. Not hard step on it till it almost locks. When bedding in new pads and discs on Audis, we get up to 60 and then do a moderately hard slow to a stop. And repeat three to five times.

Many times you will see advice about using very hard brake applications to fix brake judder. That's usually caused by a layer of baked on brake dust on the pad or disc. And very hard braking it needed to burn or wear it off. But, again in my opinion, surface rust is different. Think of your brake pad as sandpaper, and moderate applications sanding away the surface rust.

 

[Rogue]

It's more than cosmetics. Serious rust pitting can and will occur. I do not know how long it takes. The discs are soft iron and can show rust in dry Denver in hours. I have seen brake discs where one side of the brake caliper freezes up, the brake pad on this frozen side then never touches the disc, that side of the disc rusts in six months to the point of deep pitting, and the disc is ruined. If a pad never touches the disc, the disc will keep rusting and rusting and rusting.

Decades ago, When I put high value Porsches in storage for months, I pulled the pads and sprayed both sides of the disc with waxy coating. The idle discs could rust to ruin otherwise. I think Euro cars shipped to the US still coat the discs with a non oily spray that burns off with use or a squirt of cleaner.

This is just my opinion, but I think rusty discs need long slow moderate brake application for 30+ seconds at a time to burnish/grind off the surface rust. Not hard step on it till it almost locks. When bedding in new pads and discs on Audis, we get up to 60 and then do a moderately hard slow to a stop. And repeat three to five times.

Many times you will see advice about using very hard brake applications to fix brake judder. That's usually caused by a layer of baked on brake dust on the pad or disc. And very hard braking it needed to burn or wear it off. But, again in my opinion, surface rust is different. Think of your brake pad as sandpaper, and moderate applications sanding away the surface rust.

Many thanks. @Bobby, may I suggest an addition of this information to your website and pinning this thread.

How many of us would think to use the brakes and check for rust given the superb Regen braking? Certainly not for me.

 

[Worldwide Beagle]

I am also seeing similar issue but the rust is on outer edge of wheel just behing lug nuts. The rust on rotor clears away after manually braking but referring to pictures posted by OP, there is also rust on outer wheel just behind lug nuts. Is that normal?

What you are referring to is the surface of the car's axle wheel hub. It's the part of the axle/half shaft that holds the brake disc onto which the wheel is bolted. It is a precision ground flat piece of thick steel. It tends to easily get surface rust since it's steel, but looks bad. Mostly cosmetics. Good or High end tire installers will always have a big battery drill with a wire wheel attached to buff it off before remounting tires. Very common. They should usually buff off any other rust in the area, on the studs or where the wheel hub center section fits in the cutout of the wheel flange.

I have seen that rust on the steel hub very often fuse and galvanically bond the hub lightly to aluminum wheel. Common in Colorado. Your lug nuts are off but the wheel stays on. Often, you have to smack the shit out of the tire with your palms to break the rust bond and free the tire. This occurs most often after winter use, if the wheels have been on for years, or horrible mag chloride salt spray. When it does, not a big deal. Just smack it. The tech will then take the wire wheel and buff both the inner wheel hub and wheel axle hub surfaces that meet.

You can paint the steel hub with any old black high temp spray engine paint, but that requires carefully taping up the wheel studs and masking around the area. Most tire installers recommend a very very light application of white lithium grease rubbed onto to the surface of the axle hub that rusted. That should prevent the hub and wheel sticking again. Keep all grease off the studs.

 

[joec]

When it does, not a big deal. Just smack it

The original all-purpose fix for everything.