Jerking Brakes

[CarpenterGuy]

ok, i pulled the wheel off today to look at my brake rotors. i figured they were warped. when i brake, my truck shakes (high speeds) and it pulses at low speeds. i figured it was warped rotors. what could it be? should i take the rotors up to somewhere that can measure the thickness accuratly?

[Jimmiee]

The only way you can tell if the rotors are out of round is with a dial indicator. The thickness has nothing to do with your problem.

[jeremiahweed28]

It definatly sounds like warped rotors so far. Does it only do it while you are using the brakes?

IDK what the safest thickness for your rotors are but you may be able to get them machined at a shop, then you wouldent have to replace them, but they may be too thin already.

[ct9a]

Judging whether a rotor is warped or not by eye is hard, unless they're very warped. It definitely does sound like that's the problem though, unless there are other symptoms indicating something else, I would have them turned.

[cascott325]

you shold be able to get a machanic to shave them, i think NAPA can do it too.

[Z71_guy]

if you can feel the brake pedal go up and down when braking the most likley problem would be warped rotors, the best solution is to put new rotors on dont get the cheap ones they will warp faster a good mid level rotor is fine.
Do you know when the last brake job was, if new rotors where installed at that time they may be able to be turned beware when you turn the rotor under spec it will warp a lot faster and could cause further braking problems. i know if you go to oriley's and buy there premium pads they will turn your rotors for free, another warning on that part when my dad got his turned there they actually made them warped by not cleaning the mounting surfaces on the rotor.
if you take the rotors into a good shop they will charge you to turn them but at least you know they were done right (we charge $20 per rotor)

[CarpenterGuy]

I dont know when the last brake job was. I just got the truck about 1000 miles ago. The brakes have maybe a little over 50% left on them. The rotors have alot of life left so they appear. There's no grooves on the rotors either. By what all of yall have said, it looks like i'm going to have to take the rotors off and have them checked with one of those caliper measuring tool things.

[mhevezi]

Carpenter Guy,

It definitely sounds like warped rotors. Any shaking or pusling in your brakes are usually due to warped rotors. If you pull them off, don't even both with measuring them, just take them down to a shop to have them turned. It's usually very cheap, and is 90% likely to be your problem. Plus it will give your pad a nice, clean smooth surface to grab.

If you want to save time and make your life a little easier, you can buy a 2nd set of new rotors, just swap them, and turn the older ones at your leisure. Then, the next time you need to have your rotors turned, you can just swap rotors with your other set & go. You don't need to waste a few hours waiting for the rotors to get turned with your truck up on jack stands that way.

I just put a new set of cross-drilled and slotted rotors on my truck to both cure a slight wobble in the brakes, and improve my brake performance. They cost a little more, and can't be resurfaced as easy as stock rotors, but stop better in dry and wet and resist fade much better.

[CarpenterGuy]

Thats a good idea with the 2 sets of rotors.

How much were your rotors? I might look at some cross drilled rotors.

[mhevezi]

Thats a good idea with the 2 sets of rotors.

How much were your rotors? I might look at some cross drilled rotors.


I found the Cross-Drilled & slotted rotors on e-bay, and all four rotors with ceramic pads were $256, shipped to my door. Not too bad. So far, I have swapped the front rotors & pads and have noticed a difference. I didn't know the rears have the inner-drum brake for the parking brake, so I need to get some shoes for that before I do the rears.

This is the website of the company: http://stores.ebay.com/Brakemotive

I also bought some red caliper paint, just for looks. As soon as we get a long stretch of warm weather, I'll do my calipers.

Good luck.

[r76davey]

I found the Cross-Drilled & slotted rotors on e-bay, and all four rotors with ceramic pads were $256, shipped to my door. Not too bad. So far, I have swapped the front rotors & pads and have noticed a difference. I didn't know the rears have the inner-drum brake for the parking brake, so I need to get some shoes for that before I do the rears.

This is the website of the company: http://stores.ebay.com/Brakemotive

I also bought some red caliper paint, just for looks. As soon as we get a long stretch of warm weather, I'll do my calipers.

Good luck.

Glad to see you are using their Cross-Drilled & slotted rotors with good results. I am about to order a set for the front of my wife's '98 Sub, but was trying to see if the Cross-Drilled & slotted rotors were worth it for the Subs and was not sure of the quality from that company (never know who to trust on ebay!). Thanks for the good word.

[mateospeed]

The likelihood that you're looking at warped rotors is extremely low. What you're feeling is eneven deposits of brake pad material on your brake rotors, most likely caused (originally) by not bedding in your brakes properly (if you don't know what that is, don't worry, most people don't, but everyone who does their own brake work NEEDS TO).

There are 2 things to do at this point:
1) buy new new rotors, then BED IN YOUR PADS
2) have your rotors machined, then BED IN YOUR PADS. You have to be above minimum thickness on the rotors AFTER machining to safely run them, and that min thickness is stamped on the outside edges of your rotors. They vary by manufacturer.

A word of caution: Cross-drilled and slotted rotors are a waste of your time. They're a technology dating back to when rotors weren't able to properly cool themselves without help. Notadays, rotor venting is good enough to not need cross-drilling, so all the holes do is collect pad material, cause your pads to wear quicker, and make you look like an idiot for buying x-drilled rotors:-)

I'd say take them off, take them to your local machine shop, refuse to pay more than $15/rotor to have them turned, and ask them NOT to turn them if they'll be below min thickness when they're done. If they will be, it's time for new rotors.

Hope this helps!
-Matt

[CarpenterGuy]

How do you "bed in" pads? i've never heard of that.

[mateospeed]

How do you "bed in" pads? i've never heard of that.

It's quite simple, really. with fresh or freshly machined rotors (after cleaning them with soapy water or brake cleaner), take your truck out to a stretch of road where you won't encounter much traffic.
Get up to 40mph-ish, brake @~50% of max to 5-10 mph, but don't stop completely. Then accelerate moderately back up to 40mph, brake again. Repeat once more. Drive around attempting to use your brakes as little as possible for 5 minutes or so (stopping doesn't count as cool down time- they have to be spinning). Then go from 50mph, at 100% stopping power down to 5-10mph. Trigger your ABS!! This is a great time to get used to how it feels, and get used to the fact that when it's on, it's not going to hurt anything.

NOTE: If you don't have ABS, don't just stomp on your brake pedal until your tires lock up. That will just flat spot your tires, and you'll come after me with a tire iron... Brake as hard as you can without locking your brakes.

Accelerate back up to 50mph as quickly as you can (it's a truck, I know it won't get there very quickly), then stomp on the brakes again. Repeat for a total of 3 braking runs.

The point of the process is to get your brakes nice and HOT. That allows the appropriate chemical processes to occur b/w the pad and rotor so that uneven pad material deposits do not occur in the future.

WARNING: If your brakes start to smell badly (a little smell is ok, but lots is bad), stop testing. Drive around using your brakes as little as possible to cool them off. If they start smoking, you've over-done the test and need to cool off immediately.

At the conclusion of the bedding process, try to drive around for about 15 minutes without braking much in order to cool your brakes down very nicely.

When you bed pads effectively, you increase your stopping power, increase the life of the pads and rotors, and decrease the likelihood of developing uneven brakepad deposits, commonly mis-diagnosed as warped rotors.


As a side note, modern rotors EXTREMELY RARELY WARP. The only time I've ever seen rotors actually warp (I'm a brake guy, and deal with a ton of them) is when a heavy racecar come off the track hot, does not cool his brakes down, and parks the car. That allows the rotor to cool at different rates (what's not covered by the caliper cools slower), and warps the rotor. Other than that type of scenario, I invite you to TRY to warp your rotors, and let me know how it turns out. Most likely all you'll do is aggrivate your improperly-bedded pads.

:-) Have fun going fast-slow-fast-slow-fast-slow. You'll feel like a regular Camaro owner at a long stretch of stoplights! Woohoo!

-Mateo

[mateospeed]

As a side note, I love how post count determines someone as being a "master mechanic"! Glorious...

[adampaul1964]

It's quite simple, really. with fresh or freshly machined rotors (after cleaning them with soapy water or brake cleaner), take your truck out to a stretch of road where you won't encounter much traffic.
Get up to 40mph-ish, brake @~50% of max to 5-10 mph, but don't stop completely. Then accelerate moderately back up to 40mph, brake again. Repeat once more. Drive around attempting to use your brakes as little as possible for 5 minutes or so (stopping doesn't count as cool down time- they have to be spinning). Then go from 50mph, at 100% stopping power down to 5-10mph. Trigger your ABS!! This is a great time to get used to how it feels, and get used to the fact that when it's on, it's not going to hurt anything.

NOTE: If you don't have ABS, don't just stomp on your brake pedal until your tires lock up. That will just flat spot your tires, and you'll come after me with a tire iron... Brake as hard as you can without locking your brakes.

Accelerate back up to 50mph as quickly as you can (it's a truck, I know it won't get there very quickly), then stomp on the brakes again. Repeat for a total of 3 braking runs.

The point of the process is to get your brakes nice and HOT. That allows the appropriate chemical processes to occur b/w the pad and rotor so that uneven pad material deposits do not occur in the future.

WARNING: If your brakes start to smell badly (a little smell is ok, but lots is bad), stop testing. Drive around using your brakes as little as possible to cool them off. If they start smoking, you've over-done the test and need to cool off immediately.

At the conclusion of the bedding process, try to drive around for about 15 minutes without braking much in order to cool your brakes down very nicely.

When you bed pads effectively, you increase your stopping power, increase the life of the pads and rotors, and decrease the likelihood of developing uneven brakepad deposits, commonly mis-diagnosed as warped rotors.


As a side note, modern rotors EXTREMELY RARELY WARP. The only time I've ever seen rotors actually warp (I'm a brake guy, and deal with a ton of them) is when a heavy racecar come off the track hot, does not cool his brakes down, and parks the car. That allows the rotor to cool at different rates (what's not covered by the caliper cools slower), and warps the rotor. Other than that type of scenario, I invite you to TRY to warp your rotors, and let me know how it turns out. Most likely all you'll do is aggrivate your improperly-bedded pads.

:-) Have fun going fast-slow-fast-slow-fast-slow. You'll feel like a regular Camaro owner at a long stretch of stoplights! Woohoo!

-Mateo
That's a nice informative post, can't wait to try this method out.

[CarpenterGuy]

As a side note, I love how post count determines someone as being a "master mechanic"! Glorious...

haha yeah. i'm definatly not one of those.

I'm looking forward to this braking fast thing. i've never stepped on the brake completley or activated teh ABS. i'm not sure what ABS feels like. THanks for the detailed reply

[mateospeed]

haha yeah. i'm definatly not one of those.

I'm looking forward to this braking fast thing. i've never stepped on the brake completley or activated teh ABS. i'm not sure what ABS feels like. THanks for the detailed reply

If you've never gotten into the ABS, you need to! The brake pedal will pulse under your foot, and the tires will probably goes "squeak-squeak-squeak." with the ABS engaged is the quickest way to stop, so knowing how hard to you have to hit it BEFORE trying to avoid an accident will help big-time if you find yourself in a situation where you actually need it!
-Matt