When braking the car "pulsates"

Hello Leaf lovers!

please, tell me I don't have to spend 200 dollars just for diagnose, and some extra hundreds to fix this disgusting behaviour of the car.

A few weeks ago, all of the sudden, the car started "pulsating" when breaking. Since then, it always did.

Of course it doesn't happen if I just slow down braking when I'm driving for example at 70-80, or 90 km/h on the highway.
However, if I'm driving slower (40-50 and below), when I break, even though my foot is perfectly still on the brake pedal, the car literally pulsates, as if I was breaking and releasing my foot continuously, it's almost like dancing. And not just "a little bit", it's very pronounced, and feels horrible.

Any guess?

Thank you.

Warped brake rotors. Usually happens if you brake hard to a stop and then sit with your foot on the brake without moving for a few minutes. This would happen coming off the highway offramp from high speed and then braking at the last possible second only to arrive at a red light. When stopped the brake pads are clamped tight on the rotors and as they cool there is a hot spot under the pads that doesn't cool as quick causing the rotors to warp.

Thank you so much VitaminJ!

OMG!
Would I expect a 40k dollars car (Canadian dollars lol) to fall apart or tore just because of a little hard breaking!!!???

It seems like we're talking about a cheap 7000 car that came out as a gift after collecting points buying washing machine detergent!!!!
I've been driving many cars in my life, for long time, even much cheaper than this, and such a thing never happened.


Anyway, is it expensive? Do I have to replace them all?

Is there any way for me to go to the dealer and tell them the symptom and what to do, so that I'll only pay the intervention, and not also the "diagnostic" process?

If I don't do anything, is it dangerous to keep driving like that?

Thank you!!!

It's pretty common on a lot of cars, especially heavy ones. I would never go to the dealer for anything unless it's under warranty. Go to Brakes Plus or somewhere like that and tell them you have warped rotors.

Slight warping may be fixable by machining the rotors. Seriously warped rotors requires replacements. This started to become an issue in the Nineties, as steel got more expensive, and rotors got cheaper. If you think it was something you accidentally caused, you might want to invest in quality aftermarket units so it isn't likely to happen again. I suggest you use B mode more often, if the car has it.

thank you for your suggestions guys!

B mode what?

I have D, Eco, N, and reverse.

AriesMu said:

Would I expect a 40k dollars car (Canadian dollars lol) to fall apart or tore just because of a little hard breaking!!!???

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I've owned several Nissans, and their brakes seem to be an Achilles Heel. The front rotors tend to warp rather easily, and by the time the car had 50k miles. OTOH my Audi A3's rotors had no noticeable warpage by the time they were replaced at around 90k miles (because they had worn too thin according to Audi's specs).

My Leaf had less than 27k when the lease expired so I didn't have it long enough for the problem to be noticeable. 48k km (30k miles for us metrically-challenged Americans) does seem a bit premature though. The previous driver could have been really hard on the brakes.

Anyway, is it expensive? Do I have to replace them all?

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Not necessarily. If the rears aren't warped (usually aren't unless they are really old) they don't have to be messed with. Rotor warpage can be fixed by replacement (expensive, but longer time before it happens again) or by "turning" the rotors (basically shaving them, cheaper but the rotors will warp even sooner).

Is there any way for me to go to the dealer and tell them the symptom and what to do, so that I'll only pay the intervention, and not also the "diagnostic" process?

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At least here in the US, mechanics and dealerships only charge a diagnostic fee if you decide to not have the work done after they've figured out what the problem is. I've never seen it as a separate charge.

If I don't do anything, is it dangerous to keep driving like that?

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As long as there is sufficient depth on the pads, and there are no other issues with the brakes, it's not dangerous to drive, just annoying as hell.

AriesMu said:

thank you for your suggestions guys!

B mode what?

I have D, Eco, N, and reverse.

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2011 and 2012 cars, and the base model Leaf S don't have B mode unfortunately. The reason Leftie suggested it is because B mode has a more aggressive regen profile than D (or Eco on the non-B-mode cars) and regen will slow the car down, albeit not as effectively as a decent set of friction brakes.

I guess the OP would have to use Eco mode for more Regen, right?

LeftieBiker said:

I guess the OP would have to use Eco mode for more Regen, right?

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Yes. That would be correct. Also "touching" the brake pedal. That is, slightly pressing on the brake pedal to get full regen without getting much braking.

Actually the best thing you can do is just let off of the accelerator much further in advance. If it's still not slowing down fast enough then use B or Eco mode to slow down faster. The most efficient and best-for-your-car way to slow down to a stop is to shift into neutral dozens of miles from your stop and let it slowly reach zero mph. Of course that might not make the rest of the traffic too happy. But still don't let others make you drive like a NASCAR racer. I drive my cars like I drive my school bus, taking my time to slow down and speed up and using motor/engine braking whenever possible.

Warped brakes are common up here in the mountains. People just don't understand that brakes can only handle so much. I know of guys that chew through brake pads and rotors every six months! One of the school mechanics that had been here for over 20 years said he never had to replace a bus brake from wear because the school bus drivers were all trained on how to downshift whereas he was replacing the brakes on the school cars that the teachers would take to Denver every other trip! The teachers apparently had no clue as to what the selections past D meant. He ended up putting on oversized slotted and drilled racing rotors and ceramic pads on all the cars so as to not have to change them so often.

Thank you everyone!

I appreciate your thorough suggestions.

Another factor can be the cold - I noticed the OP is in Toronto. The colder the LEAF's battery pack, and the older and more degraded it is, the less regenerative braking it allows. Especially in the colder months, we find ourselves having to use the friction brakes on our LEAF a lot more than we used to.

Last year, we had our local auto repair shop grind down the rotors to keep the car from "pulsating". That helped, but the rotors are slowly starting to warp again, as we live in the mountains.

To maximize regen, and thus minimize use of the friction brakes, you could try driving around on the lowest state of charge that you feel comfortable with and that meets your needs. Even at 30% charge, our regen is limited, but not by as much as at 80% charge.

Also, we find that our LEAF allows more kW of regen at slower speeds, not faster speeds. (This is the opposite of what I would have expected.) Driving more slowly on downhills can help some.

The bottom line, in my opinion, is that the LEAF's overall braking system is poorly implemented and does not age well. This is partly a consequence of the relatively fast degradation rate of the main battery pack. It's too bad, because the rest of the car has been pretty reliable in our experience.