# Pulsating brakes



## phantasm72

The front brakes of my car pulsate when applied, which is much more noticable at high speeds.
I am guessing that the rotors are no longer completely flat.
What do you need to do to fix them? Is it possible to machine down, or replace the rotors without having any special tools or is it something best left to the experts?


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## nap

depending on what kind of car this is and the thickness of the rotors and how warped they are, there are a lot of different answers.

with some vehicles, it's as easy as pulling off the wheel and the brake caliper, possibly 1 or 2 screws used to hold the rotor in place and rmoving the rotor and putting a new one on. Some others are a real pain in the rear.


If there is enough material left, a rotor can generally be machined to return it to a flat and parallel surface.

so, what kind of car and how many miles are on it?

the other thing that can be very important: if the rear brakes are not working properly, it causes the front brakes to do a lot more work than they were designed to do. That can cause the brakes to overheat and warp the rotors.


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## Bondo

Ayuh,... Generally speakin',...
If the rotors are warped, it's from the calipers not releasing as they should...
Odds are, you'll need new rotors, 'n calipers...


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## Giles

Pulsation during brakeing, that can be felt through the whole vehicle, is mainly caused by "warped" rotors.
"Petal pulsation" is mostly influenced by variation of rotor thickness. This problem is more prevalent in rotors that have been turned.
Unless you know the person turning the rotors, I would highly recommend replacing. Many times, I have had rotors turned down and they were machined UNDERSIZED. This is dangerous and has no excuse but ignorance.
Replacement is sometimes less expensive then machining.


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## beerdog

What I have seen on my cars is pulsating in the brake petal is caused by unueven pad wear. Vibration felt in the steering wheel (sometimes the whole car) is due ot warped rotors. A bad caliper either stuck or not working will cause severe brake pull to one side. I agree on the rotors. Depending on the car replacements can be 5-10$ over the cost of machining. Of course some rotors are expensive so turning them sumetimes saves alott $$$. Sounds like it is time for a basic brake job.


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## ukrkoz

* Warped brake disks myth - read before you start turning your rotors *

StopTech : Balanced Brake Upgrades​


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## phantasm72

Giles said:


> Pulsation during brakeing, that can be felt through the whole vehicle, is mainly caused by "warped" rotors.
> "Petal pulsation" is mostly influenced by variation of rotor thickness. This problem is more prevalent in rotors that have been turned.
> Unless you know the person turning the rotors, I would highly recommend replacing. Many times, I have had rotors turned down and they were machined UNDERSIZED. This is dangerous and has no excuse but ignorance.
> Replacement is sometimes less expensive then machining.


Its definately just felt in the pedal, as a passenger, I feel nothing during braking
its a 2001 Neon. High milage, so im pretty sure the rotors have been replaced at sometime, but if its not too difficult, Ill see what I can do to replace them myself.
Anyone have experience with this type of car?


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## ukrkoz

here's a sample of Blanchard ground rotors

Old Britts, NORTON, Rotor, Disc Brake


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## ukrkoz

phantasm72 said:


> Its definately just felt in the pedal, as a passenger, I feel nothing during braking
> its a 2001 Neon. High milage, so im pretty sure the rotors have been replaced at sometime, but if its not too difficult, Ill see what I can do to replace them myself.
> Anyone have experience with this type of car?



for ur purpose, simply buy new rotors and replace them. they will run about $30-40 for quality ones.
it's about 20 minutes per side to replace one. basic tools required.

THEN DO ROTOR BREAK IN PROCEDURE AS ADVISED. or you'll be replacing rotors for the rest of your life, or paying grossly for resurfacing them on old, wobbly lathes they use in tire shops.


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## beerdog

Good article. The only cavet would be that it is written by a company that also want you to buy their high performance brake components. Regardless, it is a good article. One more tips.

-Use a torque wrench for all bolts. Including the wheel lug nuts. Uneven torque between fasnters can cause uneven wear and warping. Especially on the lug nuts.

How many miles since your last brake job?


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## nap

beerdog said:


> -Use a torque wrench for all bolts. Including the wheel lug nuts. Uneven torque between fasnters can cause uneven wear and warping. Especially on the lug nuts.


very VERY good point. Too many people over torque lug nuts and they do not tighten them equally. Both can ruin what you just fixed.

If you have aluminum wheels, you should re-torque the nuts after 50-100 miles of driving as well.


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## phantasm72

beerdog said:


> How many miles since your last brake job?


 Front brakes have never been done since I had the car (about 60,000km)
I had the rear shoes replaced about 8 months ago, and the checked the front brakes at that time and said the pads still had a lot of life left in them.

So for replacing the rotors, its just remove the tire, remove the caliper, pop off and replace the rotors.
You dont need to bleed the brakes or anything, correct?


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## phantasm72

ukrkoz said:


> THEN DO ROTOR BREAK IN PROCEDURE AS ADVISED.


 Generally, whats involved in a break in procedure?
I know rotors usually come with a film of oil to prevent corrosion during their store-life, that needs to be cleaned off, but other than that, I am not aware of anything that needs to be done


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## nap

especially due to the common use of anti-lock brakes, I suggest never pushing the caliper piston back without first opening the bleeder screw. It can push dirt into the ABS controller and cause a lot of problems.


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## beerdog

60k miles! Wow...put new pads on. A basic set of pads is cheap. Spending a little extra for good pads is worth it IMHO. Plus, you will be taking it all apart soon anyways. Plus, you risk causing other problems since the pads and rotors have worn out together. New rotors with uneven worn out pads is not good. I know the temptation to stretch them as far as possible is irresistable, but your car will thank you.


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## beerdog

oh... you see different versions of breakin. Typically it is some method of cycling the brakes. Some versions will say do 10 hard stops from 30 miles per hour. Some will say do gradual stops. Most good pad suppliers will have a break-in procedure included with new pads. I have never seen a break-in procedure included with new rotors. Google disk brake break-in.

Technically ...you onlyhave to bleed the brakes if you open the system. A good mechanic will always bleed the brakes when you do the brakes. It gets any trapped air out of the system. It is also a good way to flush out dirt and old fluid. I will ususally flush my system each year by 'bleeding" a 1/2-full bottle through each caliper. You can also get this done at many shops for 50-100$.


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## nap

beerdog said:


> 60k miles! Wow...put new pads on. A basic set of pads is cheap. Spending a little extra for good pads is worth it IMHO. Plus, you will be taking it all apart soon anyways. Plus, you risk causing other problems since the pads and rotors have worn out together. New rotors with uneven worn out pads is not good. I know the temptation to stretch them as far as possible is irresistable, but your car will thank you.


actually OP said 60k KM, not miles. That is about 37k miles

actually having to replace rear shoes in 37k miles or even 60k miles is a bit odd. The fronts should wear out before the rears as the fronts do about 85% of the braking. I would wonder if there was wheel cylinder problems (seizing).

anyway, I would replace the pads along with the rotors (if you were considering differently). Chances are if the rotors warped or have hard spots due to overheating, the pads are crap as well.


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## polarzak

phantasm72 said:


> Generally, whats involved in a break in procedure?
> I know rotors usually come with a film of oil to prevent corrosion during their store-life, that needs to be cleaned off, but other than that, I am not aware of anything that needs to be done


Pads should be "bedded in". The procedure is SOMETHING like drive at 40 mph and apply the brakes moderately to an almost complete stop, and then accelerate to 40 for a few miles to cool the brakes and apply the brakes moderately to almost a compelte stop, and do this a few times. I may be slightly off on the mph or the exact procedure, however you get the picture. Your best bet is to either do what the disk manufacturer recommends, or google "breaking in rotors". You will probably get two or three different procedures, and technical reasons why to do it...pick one procedure that suits you. Breaking in really does extend the life and quality of braking.


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## phantasm72

Thanks guys.
Managed to change out the rotors no problems. Car is braking fine now.
The pads still looked good, so I let them be. 
So thanks for all the advice. I was surprised at how easy (and cheap) a job it was. Hardest part was getting the tires off...


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