Ellcapitan

My stock front rotors (with 44K miles, and already cut once, and God knows what kind of pads are on there) were pulsating, once warmed up, pretty bad.

So, the other day, I was going over a long steep mountain road (near West Point), where I was able to get up some good speed and really BURN the SHxT OUT OF MY BRAKES! I made several 90-ish to 20 mph HARD DOWNHILL burns with the brakes, all the while, the wheel jack-hammering in my hands. I was figuring if I totally roast them, what the hell--I was planning on replacing them soon anyway.

Afterward, I continued on the same stretch of highway, which was level thereafter, for about a half hour, allowing them WAY more than enough time to cool off. To my astonishment, now they are just about completely smooth, in normal driving. (I suspect they'd pulsate again if I heat them up like I did again, though.) The only detectable remnant of the problem that is still noticeable is a faint chirping sound from the front, when the brakes are applied, and the car is decellerating.

I think I've finally broken them in correctly. I'm still not too thrilled with overall braking performance, and so I'll still be replacing the front rotors and all pads with upgraded stuff, but I might have just bought myself a little more time before I do...

I'd LOVE to hear other people here try the same thing with their warped rotors, and mysteriously straighten them out too! (I guess they might not have actually been "warped" per se, maybe just glazed?)

dug-mac

My brakes always pulsate when heated up - and I'm not talking repeated hard stops - just from running on the highway and stopping. The wheel shakes like a mofo, but then after they cool down and I'm back to running on secondary roads they do even out a bit - they're not perfect, but certainly not as bad as when they're hot. I've decided to just accept this and not get them cut again - wouldn't matter if I did as they would be warped again in no time. So yeah, my experience is similar to yours...

ThreePointTwoTeeEl

iTrader: (1)

yea werd me too I changed my front rotors and my shaking went away then like a week later the shaking came back...I didnt break them in tho....I dont know where I could Break the Brakes in Legally.

SatinSilverTypS

iTrader: (1)

my father follows the same method when he notices his rotors starting to warp. works like a charm he says.

pmptx

Just consider that you may want to look at or bleed your brake fluid if you possibly boiled it.

Ellcapitan

I didn't notice a mushy pedal (well, at least not more so than normal TL mushiness).

Ellcapitan

Yes, mine were exactly the same way. But by doing this, I've raised the heat threshhold, of when the pulsating starts, to a point beyond what might usually be considered "normal driving", and as such, I don't notice it anymore.

jean

>>ditto....
Mine did the same thing...
I wasnt sure if turning the rotors would solve the problem, and since my TL is now 6 years old , I figured the dealer would not service the brakes under warranty.
So decided to cut my running around to a minimum and did the complete brake job myself and installed Mountain rotors and Hawks HPS pads about a week ago. A little DIY search here made my life real easy (with thanks).

( I am still wondering if turning the old rotors could straighten them out??)

J.

01tl4tl

The OE rotors make better doorstops than car stoppers
trash them and get quality- I dont care what brand- but buy quality

Here is a pad bedding method that wont get you arrested
http://heeltoeauto.com/httech/YaBB.pl?num=1184261899

ThreePointTwoTeeEl

iTrader: (1)

werd^^Ill have to try that somewhere just dont know where yet ill have to think.....Hopefully its not too late now since there warped or already or something.

01tl4tl

Its far more likely to have bad pad material transfer layer from improper bedding or improper use- like dragging down a hill with brakes on lightly- same in stop and go traffic

Getting them good and hot and doing the procedure will clean off the old stuff and make a new layer
If your rotors have black or other streaks on them- not a nice even look to them- you may have uneven pad deposit and thats the real problem
Others may have OE rotors AKA the warpmasters

Ellcapitan

From what I understand about "warping" brake rotors, what happens is this: When the pads are not (or not properly) bedded, pad deposits form unevenly on the rotor surface, as mentioned above. At this point, slight vibration may or may not be felt.

What happens next is: During normal use, the rotor heats up unevenly, which varies the level of friction w/ the pads. With the amount of friction not being uniform around the whole surface of the rotor, a minor vibration/pulsation is felt, but only when the rotors are heated up (because the friction will only vary noticably when hot).

Finally, over time, what happens is: The higher friction areas on the rotors wear at a different rate than the relatively lower friction areas, causing the rotor to become out of true, in other words, ever so slightly thinner in the higher friction areas (not actually warped). At this point, a more pronounced vibration/pulsation would be felt, even when rotors are cool. (They'd now have to be turned or replaced.)

As far as warping goes, I've read that, contrary to what most believe, it is very unlikely for street-driven rotors to physically get warped. But, of course, anything is possible; with repeated rapid heat cycles (ie. you'd have to be REALLY hard on your brakes), the hotter areas of the rotor expand (as hot metal does) at different rates than the relatively cooler areas, and over time the rotors will physically warp. Molecular changes in the metal, from the hot spots, will continue to make the problem worse, and render the rotors unsalvageable. (Rotors must be replaced, and if this is the case, it wouldn't be a bad idea to check the wheel bearings as well.)