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-   -   Pulsating brakes (http://www.diychatroom.com/f46/pulsating-brakes-95429/)

phantasm72 02-13-2011 10:33 PM

Pulsating brakes
 
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?

nap 02-13-2011 10:57 PM

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.

Bondo 02-14-2011 08:19 AM

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...

Giles 02-14-2011 09:48 AM

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.

beerdog 02-14-2011 07:53 PM

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.

ukrkoz 02-14-2011 10:49 PM

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

StopTech : Balanced Brake Upgrades

phantasm72 02-14-2011 10:51 PM

Quote:

Originally Posted by Giles (Post 590937)
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?

ukrkoz 02-14-2011 10:55 PM

here's a sample of Blanchard ground rotors

Old Britts, NORTON, Rotor, Disc Brake

ukrkoz 02-14-2011 10:57 PM

Quote:

Originally Posted by phantasm72 (Post 591361)
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.

beerdog 02-15-2011 07:50 AM

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?

nap 02-15-2011 02:18 PM

Quote:

Originally Posted by beerdog (Post 591461)
-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.

phantasm72 02-15-2011 03:10 PM

Quote:

Originally Posted by beerdog (Post 591461)
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?

phantasm72 02-15-2011 03:13 PM

Quote:

Originally Posted by ukrkoz (Post 591364)
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

nap 02-15-2011 03:15 PM

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.

beerdog 02-15-2011 03:28 PM

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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