Do I Have Warped Rotors?

Recently leased a 2014 Nissan Sentra SL
It has 800 miles on it now. Immediately I felt a slight vibtation when coming to a stop.
It is intemittent happens about 50% of the time. Brought it to my dealer and he said he
couldn’t feel the problem on the test drive, if it persists come back to him.
I plan on going back to service next week.
As I apply the brakes it slows down smoothly but just before coming to a complete stop
is when it vibrates. Most people say my car has warped rotors causing this,
My question is: How can a brand new car with 10 miles on it have warped rotors?

New brakes can build up residues on the rotors that come from the resins in the pads as they break in. A hard stop or two (not lockup) will get the rotors hot enough to burn off the residues. After a while, the pads stop, or at least minimize the residue deposits and your good until the next brake job.

But there also could be a factory defect in that the rotors weren’t cut straight in the first place and need to be replaced. Usually you feel that from day one though.

I agree with @keith but I’d add that the car could have little “lot rot” too. If the car sits around without being driven, the rotors and the pads can rust. Under where the brake pad sits, it rusts a little more causing a pulse when you stop. It may just go away as you drive it but it may get worse. In that case the dealer will be able to feel it and will have to fix it.

I don’t think the rotors are warped, for what it’s worth

With warped front rotors, you usually feel it when braking at higher speeds. If they’re particularly bad, you might feel it when braking at, say, 35 mph

It’s also possible the ABS system is somehow causing this pulsation. Dirty or defective wheel speed sensors used to be infamous for causing “false ABS activations” and pedal pulsations just before the car came to a complete stop

If the rotors were warped, you’d notice symptoms near 100% of the time, not 50% of the time. I agree with the others who don’t think they’re warped.

also a tire with a busted band can have the same effect

The rotors are most likely ok. It’s easy enough for a shop to measure the run-out and say for certain. I suspect either something is binding due or it is the ABS kicking in, due to a problem with one of the wheel sensors. An inspection of the components by the shop will likely turn up the cause.

I’m assuming you are braking in a normal way, a gentle deceleration, not jamming on the brakes to stop as quickly as possible. If the latter, it is normal for the ABS to kick in.

Yes I am braking normally.
It’s smooth all the way until just coming to a stop that i feel the vibration.
I guess it could be the ABS too but it’s a very faint rumble like feeling for a couple of seconds,
However it’s not normal, I have a 2001 car that stops perfectly all the time. I want it corrected.
My problem is it doesn’t happen every time I brake, so I need to tell service something specific.
Does everyone who helped me here with this agree that it’s something with the brake system?

Thank You

If this were happening to my Corolla, I 'd first suspect something wrong with the brakes. Since your car is so new, it should be easy to find what’s causing it. Measuring the rotor’s run out would be where I’d start. It is possible to warp new rotors when installing the wheels, if the wheel install procedure isn’t followed correctly.

“…agree that it’s something with the brake system?”

If, after the rumble starts, you let off the brakes momentarily and the rumble immediately goes away for the time the brakes are off, then it would be hard to say it’s not the brakes. Does your owner’s manual say the ABS light comes on when ABS is activated? Do you see the ABS light during the rumble?

No the ABS light has never come on,
I will let up off the brake next time the rumble happens, and post the result.

Just some food for thought. I wonder if this particular model is manufactured overseas for the U.S. market?
Sometimes the ride over on freighters can take a little bit of a toll on cars due to the salt air and rocking on the ocean swells.

If the vehicle was parked in a stall with the park brake set and even with the car being chained down maybe a rotor, or rotors, could have been damaged to some degree by that.
Some cars at one time were even shipped overseas with plastic covers over the brake rotors with the covers being removed during a pre-delivery inspection before being placed for sale on the lot.

Some Japanese built Subarus suffered manual transmission damage due to things like this and it’s likely that many won’t remember back about 20 or so years ago a Japanese freighter captain actually killed himself due to some new cars becoming damaged in transport after going through some rough weather which led to saltwater spray entering the storage areas. That wasn’t the captain’s fault of course but obviously he had a very strong sense of duty in regards to his job.

Brought the car to the dealer today, after test drive they could not feel the rumble when braking,
but they noticed when starting the car the brake pedal went down to the floor, so they are changing the master cylinder tomorrow.
Does anyone think an intermittent master cylinder can cause abs ruble when braking?

Could it be the CVT acting up right before the car comes to a stop?