Brakes sticking problem after rain

I'm posting this to see if anyone else is having this issue with their Leaf. Every time I park mine in the garage after driving in wet conditions, the next time I drive it, with 8 or more hours in between, the brakes seem to stick to the rotors. I have to apply some 'gas' to break the connection and the more time between driving, the stronger the adhesion.

I know I need to get in touch with the dealer, and I will, but I was wondering if anyone knew of a service bulletin on this or have had a similar experience.

worldlyone said:

I'm posting this to see if anyone else is having this issue with their Leaf. Every time I park mine in the garage after driving in wet conditions, the next time I drive it, with 8 or more hours in between, the brakes seem to stick to the rotors. I have to apply some 'gas' to break the connection and the more time between driving, the stronger the adhesion.

I know I need to get in touch with the dealer, and I will, but I was wondering if anyone knew of a service bulletin on this or have had a similar experience.

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My experience is that when it is wet the brakes are very hard to modulate at slow speeds. If you are trying to easy up to an intersection, or in traffic, you get a neck snapping stop from less than 5 MPH. I spoke to the service adviser at the dealer who said, "Yeah, Leafs are like that." It is a hazard? I don't know- because it is stopping. But far from a smooth and controllable stop.

garypq said:

My experience is that when it is wet the brakes are very hard to modulate at slow speeds. If you are trying to easy up to an intersection, or in traffic, you get a neck snapping stop from less than 5 MPH. I spoke to the service adviser at the dealer who said, "Yeah, Leafs are like that." It is a hazard? I don't know- because it is stopping. But far from a smooth and controllable stop.

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The brakes can also be dry and exhibit this type of "grabbiness." There are other threads that cover that. It will be interesting to hear from others on the OP's point.

Interesting. Have not experienced either wet brake problem, and we do get a bit rain in these parts.

Bill

Yes, I have the same problem. I also have had it with the disc brakes on my ICE cars. When wet the calipers tend to stick to the rotors as they dry if the parking brake is set. I believe that it is because of a small amount of rust that develops but that's just a guess.

Since I consider it normal for disc brakes, I pay no attention to it. If you are parked on a flat area try leaving the parking brake off and see if it still happens. I predict that it will not.

Of course, the Parking Brake is NOT a disk brake at all,
but a drum brake in each of the rear wheel hubs.

garygid said:

Of course, the Parking Brake is NOT a disk brake at all,
but a drum brake in each of the rear wheel hubs.

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Then perhaps those are the ones that are sticking when they dry out. I've never paid it much attention because it is so common when parking after a wet/snowy drive. I reflexively use the parking brake when parked all the time in every car. If the OP doesn't use the parking brake and still sees the sticking then my hypothesis falls apart.

dgpcolorado said:

Yes, I have the same problem. I also have had it with the disc brakes on my ICE cars. When wet the calipers tend to stick to the rotors as they dry if the parking brake is set. I believe that it is because of a small amount of rust that develops but that's just a guess.

Since I consider it normal for disc brakes, I pay no attention to it. If you are parked on a flat area try leaving the parking brake off and see if it still happens. I predict that it will not.

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I wonder if it's related to the boundary layer effect which the Tesla turbine exploits? http://en.wikipedia.org/wiki/Tesla_turbine" onclick="window.open(this.href);return false;

Do people really regularly use the parking brake? The only time I ever use it is if I happen to park on a steep hill - which is rarely.

LakeLeaf said:

Do people really regularly use the parking brake? The only time I ever use it is if I happen to park on a steep hill - which is rarely.

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Interesting that you mention that. I always use a parking brake because I've driven manual transmission cars for almost 40 years and it is a second line of defense against the car coming out of gear and rolling. Even when parked in a level area I trained myself to always use the parking brake and put the car in gear so that I never, ever, forget to do so when parked on a slope. After so many years of doing it, setting the parking brake is completely automatic for me.

I just assumed, incorrectly it appears, that others were taught to drive this way also.

With the LEAF, I'm not sure how the "Park" setting blocks the car from moving so I use the parking brake to be sure the car won't roll when parked.

Without regard for rain I do notice this touchiness. But it is on and off like going thru a drive thru. This is just an example. When I stop to order I may get the neck snapping business but when I get to the pay window it's OK. No rain here in Sacramento so not due to that. Red lights once in a while too.

dgpcolorado said:

With the LEAF, I'm not sure how the "Park" setting blocks the car from moving so I use the parking brake to be sure the car won't roll when parked.

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The Park setting works just like an auto transmission ICE car - it sticks a metal projection or hook, called a pawl, into a notch between two teeth of a special parking gear. The parking gear can't turn at all without breaking the pawl. If that gear can't turn, the whole reduction gearing is frozen, and the front wheels can't roll, at least not both in the same direction. However, if one front wheel is in mud or on ice, the differential could allow it to spin the opposite direction from the way the other one is rolling. (I assume the limited slip feature of the differential is not active when the car is turned off, but perhaps someone can correct me on this.)

Ray

^Thanks for the explanation planet4ever. Much appreciated.

The Leaf has a standard "open" differential with no limited slip function. Traction control is done by braking the spinning (less traction) wheel and modulating power applied. It uses the ABS sensors for input. Thus, no, it does not function when the car is off.

planet4ever said:

(I assume the limited slip feature of the differential is not active when the car is turned off, but perhaps someone can correct me on this.)

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Braking surfaces are bare steel and will readily develop a thin surface rust when left wet. I would frequently see this after washing a car and then immediately parking it.

Would not often notice this issue when parking after a drive, probably because normal braking warms the rotors.

I would posit that the LEAF's braking surfaces don't reach as high a temperature thanks to regen, and dry more slowly than an ICE car's brakes, making the surface rust effect more noticeable.

You might try dropping out of ECO mode and performing a few robust stops on the last mile to warm up the rotors, or leave the parking brake off, if these can be safely accommodated in your situation.

Light aircraft owners who use their planes infrequently, will sometimes resort to stainless steel rotors. Not as good a material from a brake performance standpoint though.

planet4ever said:

(I assume the limited slip feature of the differential is not active when the car is turned off, but perhaps someone can correct me on this.)

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TomT said:

The Leaf has a standard "open" differential with no limited slip function. Traction control is done by braking the spinning (less traction) wheel and modulating power applied. It uses the ABS sensors for input. Thus, no, it does not function when the car is off.

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You're correct that the LEAF does not have a proper, actual, limited slip differential, and no, it does not function when the car is off.

The LEAF does have a "Brake Limited Slip Differential" (Nissan LEAF Service Manual, BRC-34). Current VWs have this; they call it an "electronic differential lock". It's not an actual device or component, but rather just a happy side effect of an open differential. If one driven wheel starts to spin, the BLSD system grabs the brake on that wheel, upon which the open differential causes more power to be transferred to the other wheel.

worldlyone said:

I'm posting this to see if anyone else is having this issue with their Leaf. Every time I park mine in the garage after driving in wet conditions, the next time I drive it, with 8 or more hours in between, the brakes seem to stick to the rotors.

Click to expand...

What are the symptoms? Is there any chance that you may have driven off immediately after relasing the parking brake and it's not yet fully retracted?

If you don't use the parking brake,then it might be worth a trip to the dealer. The brake piston's sealing ring has square/rectangular cross section. When the piston is extended (when you step on the brake), the ring is twisted slightly in its groove. The ring's twist provides the "spring action" that returns (retracts) the piston when you release the brakes. The pads should not then be so close to the rotor that they would bind.

The baffling thing is, on your car, why would this only happen after the car has sit for a while? If one of the brakes' piston ring is somehow defective and fails to retract the piston, I would imagine you would feel this "grabbing" after every use of the brakes and not just after the car has sit for a while.

And oh, there's the caliper's sliding pin as well: in a single-action caliper such as those on the LEAF, the piston pushes on only one pad onto the rotor. The sliding pin allows the piston's pushing action to then pull the opposite pad into the rotor. If a pin is poorly lubricated, maybe as a factory defect or maybe because the pin lost its seal and allows grit and gunk in, it would not be able to slide freely. That might result in the opposite pad being in too much contact with the rotor and causing binding problems like what you experienced.