Car shake

[GrassyKnoll]

Ok so I think I have a problem with breaks.

Every time I hit the breaks (more noticable at higher speeds) the car gets a nasty little shake. What would be my best bet in determining which break(s) are causing this shake and how would I fix?

Any insight? I'm pretty n00b when it comes to breaks.

Thanks

[Huffer]

You either have:

1. loose brake pad
2. warped rotors (which can be caused by #1)

Easiest thing to do - whip off the wheels, check the pads don't move. If they move, you'll need to resurface the rotors and check the pads for uneven wear.

If the pads are fine (even wear, and look consistent side to side) then the rotors may be warped.

[sansMYSTi]

Most likely warped rotors - you need to either have them milled or replaced.

[jey]

Could just be uneven deposits of brake pad left on your rotors. There are some myths behind the "warped rotors" diagnosis, check out this link:

http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml

It's worth a shot - find a nice empty stretch of straight road and get up to a decent speed (like 60+) and slam the brake pedal down, hauling it to about 5 mph as best as you can. I've found this to fix the "warped rotor" problem before.

[Huffer]

^^ you don't want to do that on old or cold rotors and have them crack under the heat of the emergency braking!

I still think it's best to take the rotors off and lay them on a flat surface - or use a spirit level to see if they're not flat.

[jey]

^^ you don't want to do that on old or cold rotors and have them crack under the heat of the emergency braking!


I have never heard of rotors doing that under normal circumstances. If your rotors are so old that they will crack and fail under emergency braking, it's time to replace your rotors. Better for them to fail while you're testing them then when you're about to hit something on the road and you actually need to stop!

[Sarra]

It's a common misconseption that rotors can warp because they get too hot.

That misconseption has lead to another misconseption that rotors cannot warp at all.

The only real way (that I have read about) to warp rotors is to get them extremely hot then cool them off extremely quickly. IE, keep one foot on the brake, one on the gas, and drive around the block at 25 mph repeatedly, then hose your rotors down. That'll make lots of steam, and if you do it just right, warp those rotors. If you have crappy or drilled rotors, they'll even crack if you get it right.

Anyway. I'll relate my personal experience with rotors, and the dreaded 'shudder while braking'.

I had some OEM pads on, and I got my rotors pretty hot a few times. I mean, they were glowing. Because of that, I got uneven deposits on the rotor surface. I toasted the front pads, no pad left, and SUPER baked the rear pads, they were hard as steel. I could yank the parking brake while driving, and the car woudln't even slow down!

I got a new set of pads, a pad designed for street or auto cross use. They're a ceramic hybrid, and they have better stopping properties, or so they claimed. After I got the car warmed up, with the new pads on, I got the rotors heated up slightly, drove on the freeway. Then, I found a clear out of the way area, and took it to 35, and stomped the brakes, but not hard enough to engage the ABS. I did that a few times, and after that, the shudder was almost completely gone.

Now I've baked the new pads, they went faster and easier than the old ones (they caught on fire). Now I'm gonig to say 'screw it' and sell the car. I have too much stuff to replace on the car. Once everything is fixed, I'll have put more into fixing the car than the car is currently worth (put $3,500 into the car, another $3,500+ to go, car is currently worth "$6,000 ish"). I'll end up getting another money pit, but at least this time, I'll have forwarning about it. :(

[Huffer]

^^ you don't want to do that on old or cold rotors and have them crack under the heat of the emergency braking!


I have never heard of rotors doing that under normal circumstances. If your rotors are so old that they will crack and fail under emergency braking, it's time to replace your rotors. Better for them to fail while you're testing them then when you're about to hit something on the road and you actually need to stop!

Maybe so, but a visual inspection will show up the "oldness" of the rotors in a MUCH safer way than a 60mph emergency brake on a road.

Better for you to change them out without having to test them, and risk damage to the car.

Rotors will deform quickly if they are cold, and are then subjected to the extreme pressures of an emergency stop.

[GrassyKnoll]

I will be checking them out this weekend.

I bet it happened when I was drifting in snow. The breaks heat up real quick with e-braking and drifting then get covered with snow.

It makes perfect sense.

With warped rotors, what is my best course of action. New rotors all around?

[sansMYSTi]

Look into the cost of getting the effected rotors turned and compare that to the cost of new ones (plus the labor involved if not DIY). If you are going through the removal/install anyway, you might as well be putting on new parts. Plus, it gives you a chance to upgrade calipers, pads, hoses, suspension etc. while you are at if it is your budget.

[shazapple]

I dont think getting rotors turned is a solution to the problem, cause if you warp the stock rotors then the turned ones will warp much quicker and easier