Shaking after replacing rotors and pads
04-10-12, 09:04 PM
#19
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what i would do is replace all 4 rotors new unless u can get the rears from the same front u got with new break pads. If it still shakes then its something major. Or resurface all 4 rotors and get new brake pads if ur still using the old ones.
04-11-12, 04:32 AM
#20
If you had the shaking problem before. And you only replaced the fronts. And you still have the shaking problem.
Logic suggests the issue is in the rear.
Though, yeah, there should have been shims before (and after) too in the front.
So cheapest parts to throw at it is shim the front, and properly rebed the brakes. If symptoms are unchanged then probably the uneven pad transfer (that most folks misdiagnose as "warped" rotors) is in the rear and too far gone for a re-bed to fix. You could go at the rear rotors with a garnet pad at that point, or just replace em.
And again to a few folks in the thread- rotors, properly installed, don't warp.
Seriously, read the article I posted.
The guy who wrote it worked on braking systems that saw way way way more abuse and heat than any street car, and he never saw a rotor that was actually warped from it. He explains what causes most brake shuddering, and why it ain't "warped rotors" no matter what the idiot at the local brake shop tells you to sell you new rotors.
Logic suggests the issue is in the rear.
Though, yeah, there should have been shims before (and after) too in the front.
So cheapest parts to throw at it is shim the front, and properly rebed the brakes. If symptoms are unchanged then probably the uneven pad transfer (that most folks misdiagnose as "warped" rotors) is in the rear and too far gone for a re-bed to fix. You could go at the rear rotors with a garnet pad at that point, or just replace em.
And again to a few folks in the thread- rotors, properly installed, don't warp.
Seriously, read the article I posted.
The guy who wrote it worked on braking systems that saw way way way more abuse and heat than any street car, and he never saw a rotor that was actually warped from it. He explains what causes most brake shuddering, and why it ain't "warped rotors" no matter what the idiot at the local brake shop tells you to sell you new rotors.
04-11-12, 04:46 AM
#21
Before you start dumping money into this car, take it to mechanic (Tire Kingdom) usually they will check them for free. Have them do the work or if their price is too high do it at home, atleast you know what the problem is.
New or Used rotors can be warped, its always best to have the rotors turned. Napa machine shops used to turn them for a small fee.
New or Used rotors can be warped, its always best to have the rotors turned. Napa machine shops used to turn them for a small fee.
04-11-12, 06:45 AM
#22
Wow.... terrible and wrong advice.
Rotors should almost never be turned... and certainly never new ones.
All turning them generally does is waste good rotor metal.
Even vehicle OEMs have come around to understanding this-
http://www.procutinternational.com/supplier_gm.aspx
Originally Posted by GM brake procedure
New rotors SHOULD NOT be resurfaced before installation
...
Rotors are not to be resurfaced in an attempt to correct the following conditions:
Noise/squeal
Cosmetic corrosion
Routine pad replacement
Discoloration/hard spots
....
Rotor refacing during normal pad replacement is not necessary.
Rotor refacing for cosmetic corrosion is unnecessary. Clean up of braking surfaces can be accomplished by 10-15 moderate stops from 62-75 km/h (35-40 mph) with cooling time between stops.
Rotor service is ineffective in correcting brake squeal and/or premature lining wear out and should not be used to address these conditions unless specifically directed by a service bulletin.
When installing new rotors, DO NOT reface them.
...
Rotors are not to be resurfaced in an attempt to correct the following conditions:
Noise/squeal
Cosmetic corrosion
Routine pad replacement
Discoloration/hard spots
....
Rotor refacing during normal pad replacement is not necessary.
Rotor refacing for cosmetic corrosion is unnecessary. Clean up of braking surfaces can be accomplished by 10-15 moderate stops from 62-75 km/h (35-40 mph) with cooling time between stops.
Rotor service is ineffective in correcting brake squeal and/or premature lining wear out and should not be used to address these conditions unless specifically directed by a service bulletin.
When installing new rotors, DO NOT reface them.
And again, read the stoptech article, barring incorrect install, rotors do not warp.
Apart from improper install most brake pad/rotor shaking issues are caused by uneven pad transfer, which the article explains in detail, including what it is, why it happens, and how to avoid it.
Resurfacing in such a case would be a last resort if you didn't bed and use the brakes properly to begin with, and then let the problem get so bad a garnet pad couldn't clean it up.
Last edited by Kurtz; 04-11-12 at 03:25 PM.
04-11-12, 07:59 AM
#23
Since you said the car has about 80K, I would have the bearing check; chances are is that they are worn out and is causing this shaking indirectly as a result.
Had this happen to my 99 Camry before I gotten a Lexus. The car's wheel hub assembly in this case was not changed until past 160K (living way past their life span of 80K approx.). It caused my pad and rotors to wear out prematurely and the car was always somewhat shaking; it was miss-diagnosed so rotors and brakes kept being replaced. Once the root caused was found, the hub assembly was replaced. When the tech showed me the old bearings, it was unrecognizable as if it was disintegrated!!
Had this happen to my 99 Camry before I gotten a Lexus. The car's wheel hub assembly in this case was not changed until past 160K (living way past their life span of 80K approx.). It caused my pad and rotors to wear out prematurely and the car was always somewhat shaking; it was miss-diagnosed so rotors and brakes kept being replaced. Once the root caused was found, the hub assembly was replaced. When the tech showed me the old bearings, it was unrecognizable as if it was disintegrated!!
04-11-12, 03:21 PM
#26
(then again, if original owner never bedded them properly there could've been uneven transfer issues even with the right pads...)
Either way- make sure you bed em properly now and you shouldn't have the issue again.
04-11-12, 04:43 PM
#27
Tirerack also indicates that a lot of brake shaking/judder problems are misdiagnosed as warped rotors:
http://www.tirerack.com/brakes/tech/....jsp?techid=85
However, they have some other things that are inaccurate according to the info Kurtz has posted -- they say that rotors can warp with overly aggressive (high heat) bedding in techniques and that rotors should be resurfaced when installing new pads.
On that note, since it seems that manufacturers often have vastly different methods, what is the bed-in procedure for the IS350's OEM low-dust pads? Can't seem to find that anywhere. I've driven quite a bit on my new pads (~300 miles), but have yet to bed them in.
http://www.tirerack.com/brakes/tech/....jsp?techid=85
However, they have some other things that are inaccurate according to the info Kurtz has posted -- they say that rotors can warp with overly aggressive (high heat) bedding in techniques and that rotors should be resurfaced when installing new pads.
On that note, since it seems that manufacturers often have vastly different methods, what is the bed-in procedure for the IS350's OEM low-dust pads? Can't seem to find that anywhere. I've driven quite a bit on my new pads (~300 miles), but have yet to bed them in.
04-11-12, 05:06 PM
#28
I'm surprised that with all these responses nobody's brought up the biggest reason for warped like symptoms...
Lateral run-out is a big contributor to this "warped rotor" like symptom. Any run-out in excess of 0.002" can cause pedal pulsation that can also transfer to the rest of the vehicle.
Here's a scenario, you replaced your rotors with used rotors, your wheel hub is most likely not clean and flush with minimal run-out. You added used rotors that over a period of 1,000 miles conformed to the hub of another vehicle, that could most likely caused the rotor to have excessive lateral run-out that would eventually develop into vibration during braking.
So the lateral run-out of your hub, plus the existing run-out of these new rotors are causing a fine wobble that when braking it translates into violent shaking.
There's also the possibility that your front wheel hubs need to be serviced/replaced.
If you don't feel vibration in your steering wheel only the pedal and rest of the vehicle then most certainly it's going to be your rear brakes. When the rear causes vibration you can usually see a wave of material on the surface of the rotor.
In any case if the rear is the culprit you need to replace the rotors/pads, and make sure the hub surface is clean of any rust, overhaul the slide pins and you should be good to go.
Lateral run-out is a big contributor to this "warped rotor" like symptom. Any run-out in excess of 0.002" can cause pedal pulsation that can also transfer to the rest of the vehicle.
Here's a scenario, you replaced your rotors with used rotors, your wheel hub is most likely not clean and flush with minimal run-out. You added used rotors that over a period of 1,000 miles conformed to the hub of another vehicle, that could most likely caused the rotor to have excessive lateral run-out that would eventually develop into vibration during braking.
So the lateral run-out of your hub, plus the existing run-out of these new rotors are causing a fine wobble that when braking it translates into violent shaking.
There's also the possibility that your front wheel hubs need to be serviced/replaced.
If you don't feel vibration in your steering wheel only the pedal and rest of the vehicle then most certainly it's going to be your rear brakes. When the rear causes vibration you can usually see a wave of material on the surface of the rotor.
In any case if the rear is the culprit you need to replace the rotors/pads, and make sure the hub surface is clean of any rust, overhaul the slide pins and you should be good to go.
04-11-12, 05:09 PM
#29
Tirerack also indicates that a lot of brake shaking/judder problems are misdiagnosed as warped rotors:
http://www.tirerack.com/brakes/tech/....jsp?techid=85
However, they have some other things that are inaccurate according to the info Kurtz has posted -- they say that rotors can warp with overly aggressive (high heat) bedding in techniques and that rotors should be resurfaced when installing new pads.
On that note, since it seems that manufacturers often have vastly different methods, what is the bed-in procedure for the IS350's OEM low-dust pads? Can't seem to find that anywhere. I've driven quite a bit on my new pads (~300 miles), but have yet to bed them in.
http://www.tirerack.com/brakes/tech/....jsp?techid=85
However, they have some other things that are inaccurate according to the info Kurtz has posted -- they say that rotors can warp with overly aggressive (high heat) bedding in techniques and that rotors should be resurfaced when installing new pads.
On that note, since it seems that manufacturers often have vastly different methods, what is the bed-in procedure for the IS350's OEM low-dust pads? Can't seem to find that anywhere. I've driven quite a bit on my new pads (~300 miles), but have yet to bed them in.
It's pretty weird though that they spend one paragraph repeating the correct information, that most diagnosis of "warped rotors" is really uneven pad transfer... and then in the next paragraph claim hot brakes warp rotors.... Which just ain't so. Again, the author of the Stoptech article worked on brake development for cars that saw a lot more heat than street cars and rotors don't warp just by getting hot if they're installed correctly.
As to resurfacing when changing pads, certainly a waste of good rotor metal if you're going to the same type of pad.... because the (hopefully even) transfer already on the rotor is the same compound as the new pad, so a fresh bed and you're golden...
Now, if you're switching to a completely different type of pad I could maybe see a reason to resurface to remove the existing old brake compound from the rotor surface... but that's not usually what folks are doing.... and a good solid re-bed or a few days driving ought to handle that
Stoptech addresses that point here in items 4 and 5:
http://stoptech.com/technical-suppor...res/bed-in-faq
Anyway for stock OEM brakes I've used the stoptech street procedure, and I expect anything similar would work fine-
Originally Posted by Stoptech
For a typical performance brake system using street-performance pads, a series of ten partial braking events, from 60mph down to 10mph, will typically raise the temperature of the brake components sufficiently to be considered one bed-in set. Each of the ten partial braking events should achieve moderate-to-high deceleration (about 80 to 90% of the deceleration required to lock up the brakes and/or to engage the ABS), and they should be made one after the other, without allowing the brakes to cool in between.
Depending on the make-up of the pad material, the brake friction will seem to gain slightly in performance, and will then lose or fade somewhat by around the fifth stop (also about the time that a friction smell will be detectable in the passenger compartment). This does not indicate that the brakes are bedded-in. This phenomenon is known as a green fade, as it is characteristic of immature or ‘green' pads, in which the resins still need to be driven out of the pad material, at the point where the pads meet the rotors. In this circumstance, the upper temperature limit of the friction material will not yet have been reached.
As when bedding-in any set of brakes, care should be taken regarding the longer stopping distance necessary with incompletely bedded pads. This first set of stops in the bed-in process is only complete when all ten stops have been performed - not before. The system should then be allowed to cool, by driving the vehicle at the highest safe speed for the circumstances, without bringing it to a complete stop with the brakes still applied. After cooling the vehicle, a second set of ten partial braking events should be performed, followed by another cooling exercise. In some situations, a third set is beneficial, but two are normally sufficient.
Depending on the make-up of the pad material, the brake friction will seem to gain slightly in performance, and will then lose or fade somewhat by around the fifth stop (also about the time that a friction smell will be detectable in the passenger compartment). This does not indicate that the brakes are bedded-in. This phenomenon is known as a green fade, as it is characteristic of immature or ‘green' pads, in which the resins still need to be driven out of the pad material, at the point where the pads meet the rotors. In this circumstance, the upper temperature limit of the friction material will not yet have been reached.
As when bedding-in any set of brakes, care should be taken regarding the longer stopping distance necessary with incompletely bedded pads. This first set of stops in the bed-in process is only complete when all ten stops have been performed - not before. The system should then be allowed to cool, by driving the vehicle at the highest safe speed for the circumstances, without bringing it to a complete stop with the brakes still applied. After cooling the vehicle, a second set of ten partial braking events should be performed, followed by another cooling exercise. In some situations, a third set is beneficial, but two are normally sufficient.
I'm surprised that with all these responses nobody's brought up the biggest reason for warped like symptoms...
Lateral run-out is a big contributor to this "warped rotor" like symptom. Any run-out in excess of 0.002" can cause pedal pulsation that can also transfer to the rest of the vehicle.
Here's a scenario, you replaced your rotors with used rotors, your wheel hub is most likely not clean and flush with minimal run-out. You added used rotors that over a period of 1,000 miles conformed to the hub of another vehicle, that could most likely caused the rotor to have excessive lateral run-out that would eventually develop into vibration during braking.
So the lateral run-out of your hub, plus the existing run-out of these new rotors are causing a fine wobble that when braking it translates into violent shaking.
.
Lateral run-out is a big contributor to this "warped rotor" like symptom. Any run-out in excess of 0.002" can cause pedal pulsation that can also transfer to the rest of the vehicle.
Here's a scenario, you replaced your rotors with used rotors, your wheel hub is most likely not clean and flush with minimal run-out. You added used rotors that over a period of 1,000 miles conformed to the hub of another vehicle, that could most likely caused the rotor to have excessive lateral run-out that would eventually develop into vibration during braking.
So the lateral run-out of your hub, plus the existing run-out of these new rotors are causing a fine wobble that when braking it translates into violent shaking.
.
Originally Posted by Carroll Smith
With one qualifier, presuming that the hub and wheel flange are flat and in good condition and that the wheel bolts or hat mounting hardware is in good condition, installed correctly and tightened uniformly and in the correct order to the recommended torque specification, in more than 40 years of professional racing, including the Shelby/Ford GT 40s – one of the most intense brake development program in history - I have never seen a warped brake disc.
But I'd submit uneven pad transfer is a more common cause of the false warped rotor reports, because many brake places don't understand the real problem and would prefer to just keep selling folks new rotors or resurfacing labor rather than discover the real problem and tell the customer how to avoid it in the future.
Last edited by Kurtz; 04-11-12 at 05:14 PM.
04-11-12, 08:31 PM
#30
Hmmm... switching from the high-dust OEM to low-dust OEM pads isn't what would be considered switching to a "completely different" kind of pad, is it? If so, I guess I maybe should have done more to clean my rotors...
But thanks for the bedding in info. That sounds like a fairly intense procedure. I have no idea where I would even do that other than a track. Maybe on the freeway at 3:30 am? Heh.
After reading some of this, I'm slightly surprised I haven't run into any problems with my pads yet. I just slapped new pads in there, have driven a decent bit normally, and so far so good. *knock on wood*
But thanks for the bedding in info. That sounds like a fairly intense procedure. I have no idea where I would even do that other than a track. Maybe on the freeway at 3:30 am? Heh.
After reading some of this, I'm slightly surprised I haven't run into any problems with my pads yet. I just slapped new pads in there, have driven a decent bit normally, and so far so good. *knock on wood*
Last edited by RocketGuy3; 04-11-12 at 08:37 PM.