Twin_Cam UltraDork
May 26, 2012 1:38 p.m.

So my 2000 Saturn goes through front brake rotors every 3-5K miles. I have tried expensive rotors, cheap rotors, and different pads, both expensive and cheap. I don't drive like an idiot, riding the brakes constantly. I'm that guy that leaves 16 car lengths between me and the next car in slow traffic so I can just cruise at 10 mph and not have to touch the brakes. In other words, I don't beat on them, and they warp really, really quickly. I have been changing the front brakes every 7K miles or so, mostly because I don't want to deal with hubs and bearings. The symptoms I get are pulsating brake pedal and pretty violent steering wheel shake.

I have been having these "warped rotor" symptoms for about 1,000 miles now. I had heard that a bad bearing will cause brakes to do this. So, this morning, I decided to do an experiment. I changed a rotor on just one side, the left side to be specific.

The symptoms went away completely. So now I'm led to believe that it's actually a bad left bearing or hub that is causing my rotors to warp badly. Is this plausible? If so, I'm paying a shop to change it. After replacing the entire front suspension on this car, I'm totally done with unbolting steering knuckles and sway bars.

fasted58
fasted58 UltraDork
May 26, 2012 2:00 p.m.

Have you checked wheel bearings? GMs of that era are notorious to last 70- 90K miles. If one is bad, replace both sides. Just my .02

jrw1621 PowerDork
May 26, 2012 3:20 p.m.

To check bearings: With the car on the ground, grab the tire and rock the tire back and forth/in and out. If there is a metalic-ish clinking sound/feel then you will feel there is a bad bearing . (Hard to explain just feel for loosness not firmnesss.)

Going through brake pads in 5k miles:
Are the front struts so worn that the car then dives violently to stop and therefore puts additional stress on the front brakes? If this is the case, you will likely be wearing through front tires quickly too with oddities like cupping of the tread.

Are the rear brakes not working? Thereby causing the front brakes to do all the work and wearing out quickly.

Is the car "a little down on acceleration"? This could be a sticking/dragging front caliper which is slowing the car because the brakes are always on a little. To test, find a slight incline and be sure the car rolls freely while in neutral on this slight incline (real slight.) If the car does not roll freely, the brakes are dragging.

nderwater UltraDork
May 26, 2012 3:59 p.m.

Ditto the above.

You're going through pads at something like 20-40 times the normal wear rate - that would signal to me that there's something seriously wrong with the brake system. For a street driven car, get this sorted asap.

AngryCorvair PowerDork
May 26, 2012 4:09 p.m.

yes, a bent or incorrectly machined hub can cause this.

Twin_Cam UltraDork
May 26, 2012 6:32 p.m.
  1. I will try the "shake the wheels" method.
  2. To clarify, it's rotors I burn through, not pads.
  3. Suspension is new all around. That's not the cause.
  4. The rears are drums, I'm not sure how much work rear drum brakes do on any car...and how could I check this?
  5. My car is always "a little down on acceleration." It has 100 horsepower on a good day, has power everything, and has 160K miles.

Blah.

iceracer UltraDork
May 26, 2012 6:40 p.m.

Something may be causing the rotors to over heat. The slide pins on the caliper could be froze up. The piston not returning as it should. But then it seems the pads would wear excessively. Any play or hub warpage would most likely result in knock back of the caliper piston.

fasted58
fasted58 UltraDork
May 26, 2012 7:16 p.m.

In reply to Twin_Cam:

do the pads wear even top to bottom?

Tom Suddard SonDork
May 26, 2012 8:01 p.m.

Sounds like you're bedding your pads in improperly. It's almost impossible to actually warp rotors.

belteshazzar UltraDork
May 26, 2012 8:39 p.m.

except not

SlickDizzy UltraDork
May 26, 2012 11:33 p.m.

+1, non-car person incompetence has a high correspondence with truly warped rotors...seen it enough times to know it's a thing.

Tom Suddard SonDork
May 27, 2012 7:06 a.m.
Twin_Cam UltraDork
May 27, 2012 8:11 a.m.
fasted58 wrote: In reply to Twin_Cam: do the pads wear even top to bottom?

I tried new pads at one point, and the old ones I took off weren't worn out, they were about half gone, but they were slightly crooked, more front to back than top to bottom, though. Just yesterday when I did my rotor experiment, the pads (the new set, they have about 10K miles now) looked perfectly flat and even.

I also grease the caliper pins with lithium grease every time I change rotors or take the caliper off of the bracket at all. I don't think they're bound up.

And as a more serious response to an earlier question, the car isn't down on power, I don't think the pads are dragging or anything. The car will roll at stoplights before I slip the clutch, and I can push the car when it's off by myself. There's also no excessive heat from the wheel well area after a drive. I've felt dragging brakes before when I bought cheap-o Autozone pads for my dad's Civic...that isn't it.

As for "bedding in," I have noticed there's a bigger argument over how to do this correctly than there is for synthetic vs. dino oil...so how do you do it? I read back when I changed brakes for the first time that a couple of panic stops from 25 mph do the trick. Apparently, after reading the article that Tommy posted, it's many rather quick stops from 60 mph. I'd love to be able to do this, but I don't have a test track at my disposal, and doing this on the highway, even at 3:30 AM when it's deserted is probably a good way to get pulled over. And I still have to drive to the highway (and thus use my brakes) before I can bed them in. What to do what to do....

iceracer UltraDork
May 27, 2012 10:48 a.m.

For a daily driver with street pads, bedding is easily done by normal driving without over heating. This from experince of driving cars with disc brakes for The past 40+ years and never having a problem. I take that back, my KJ would sometimes get a vibration, a ggod hard stop would remove it. Kind of goes with the pad build up theory.

Wally UltimaDork
May 27, 2012 2:14 p.m.
fasted58 wrote: Have you checked wheel bearings? GMs of that era are notorious to last 70- 90K miles. If one is bad, replace both sides. Just my .02

I would guess this. My Malibu needs bearings every 90=100k and will do what you are describing. The rotors aren't warping so much as wobbleing with the hub.

belteshazzar UltraDork
May 27, 2012 3:37 p.m.
Tom Suddard wrote: Oh. Okay. http://www.stoptech.com/technical-support/technical-white-papers/-warped-brake-dis...

that's so odd, in light of people bringing me warped rotors to turn on a daily basis. in some cases even visibly warped.

Tom Suddard SonDork
May 27, 2012 3:46 p.m.

I thought so, too; another forum member linked to this article a few weeks ago.

Moparman HalfDork
May 27, 2012 5:08 p.m.

In reply to belteshazzar:

I have personally not seen a warped rotor which was not either abused in competition of was thinner than the stated minimum thickness. That being said, I have not seen all vehicles driven in all conditions, but I would bet that warped rotors are exceedingly rare.

Twin_Cam UltraDork
May 27, 2012 6:13 p.m.

Further wrinkle to the story:

For a while now, I've had a slight steering wheel vibration at highway speeds. I chalked it up to losing a wheel weight or something like that. But I changed that left brake rotor and now it's gone. Was it so warped and unbalanced that it was making the steering wheel shake?

Curmudgeon MegaDork
May 27, 2012 7:31 p.m.
belteshazzar wrote:
Tom Suddard wrote: Oh. Okay. http://www.stoptech.com/technical-support/technical-white-papers/-warped-brake-dis...

that's so odd, in light of people bringing me warped rotors to turn on a daily basis. in some cases even visibly warped.

Oh yes, rotors definitely do warp.

The thinner they are, the more prone they are. But Stop Tech is also correct in that pad material will stick to a rotor and cause very similar symptoms. That can be removed with a whizz wheel.

belteshazzar UltraDork
May 27, 2012 7:32 p.m.

so when, every day, people bring me rotors. i put those rotors on a lathe, and can SEE how warped they are with the naked eye, and confirm and measure how warped they are (nevermind the "invisible pad transfer" in that article). then i proceed to cut them straight, return them to the customer, and everybody is happy. what exactly is happening there?

i feel like it would be me telling Tom Suddard there's no such thing as E30's.

Curmudgeon MegaDork
May 27, 2012 7:34 p.m.
Twin_Cam wrote: Further wrinkle to the story: For a while now, I've had a slight steering wheel vibration at highway speeds. I chalked it up to losing a wheel weight or something like that. But I changed that left brake rotor and now it's gone. Was it so warped and unbalanced that it was making the steering wheel shake?

It can happen. There has to be 'venting clearance' between the pad and rotor. If there is, say, .002 venting clearance and the rotor is either warped, not mounted square, or has pad material stuck on it, say .006 thick the rotor will 'hit' the pad and this is picked up as a vibration in the steering wheel. I've never seen a vibration caused by an unbalanced rotor but there is no reason that it couldn't happen.

06HHR New Reader
May 27, 2012 7:46 p.m.

I've seen that StopTech article and sort of scratched my head. I've seen and been the proud owner of more warped rotors than I care to remember. The number of shops that turn rotors in my neck of the woods is dwindling down to 0 (Pep Boys don't count). Lately it's been almost as cheap to buy new ones for my stuff as it is to have them turned so I don't miss the option of turning them as much. But it is very much possible to warp a rotor, and it happens more than people (the StopTech folks) seem to think.

Curmudgeon MegaDork
May 27, 2012 7:50 p.m.

I guess Stop Tech has their reasons. FWIW, Toyota says if brake vibration is mild, use a whizz wheel and put a non directional finish on the rotor. They say to replace in the event of severe vibration. Mercedes says do not ever cut their rotors, replace only.

EDIT: While I can't find a picture of it, I have seen rotors with a 'ghost outline' of the pad friction material shape on them, and it's not something you can wipe off. That does support the 'pad material transfer' thing Stop Tech's paper mentions but does not mean that it is is the ONLY thing which can cause brake vibration.

John Brown MegaDork
May 27, 2012 8:22 p.m.

stopTECH has never been in a GM service department, I can guarantee that! I see warped rotors on a daily basis. Cadillac CTS-V is the only one that does not succumb to the Quasi-plague during one of my test drives ;)

I has a tech tell me there was no vibration on an Infiniti G35 once, I brought it back like a Daytona24 pit stop. Rotors were DEFINITELY part of the problem after that!

1 2

You'll need to log in to post.

Also on Grassroots Motorsports

Win Some CRC Goodies

2 days ago in News

We're picking our favorite 30 entries to the Show Us Your Shop Contest so far and sending them some prizes.

Buy One, Get One Free

2 days ago in News

Give your friend a subscription and we'll give you one for free for being such a good buddy.

Pay It Forward

2 days ago in Articles

Passing your street survival knowledge on to the next generation pays dividends.

Pirelli World Challenge Announces 2015 Schedule

5 days ago in News

Next year's schedule includes events across North America at some of the nations's most challenging courses.

2014 Dodge Challenger R/T Redline

6 days ago in New Car Reviews

While Dodge's muscle car revival has not gone without its fair share of criticism, the Challenger Redline gives us a ...

Podcast Episode 37: JG and David talk about auctions and future collectibles

1 week ago in Articles

JG and David discuss the auction scene, and future collectible cars.

Swap Meet at the $2014 Challenge

1 week ago in News

We're just over a week away from the $2014 Challenge. Now there's a swap meet. Will you be there?

OUR SPONSORS

Birthdays

Grassroots Motorsports Magazine

Subscribe Today

Also get your instant access to the digital edition of Grassroots Motorsports Magazine!

Learn More