bakes pad need help
ITT
10-15-2005, 01:29 PM
I was wondering if anybody could help me with this brake problem i'm having with my 02 Ls. i when in to the dealer to get my bake and rotor replace because of the noise i'm hearing form my brake, for $800. a week or so when by the brake is make that same noise sqeeky noise again and i toke it back it in to get it check, they say is normal becuase of this new brake pads they are using. is there any thing sugguestion of how to get rit of the sqeeking noise or what type of pads i shold get?
please help
the noise is drivng me nutZZZZ :banghead:
please help
the noise is drivng me nutZZZZ :banghead:
CGGorman
10-17-2005, 10:42 AM
Seems like I've answered this before, but I couldn't find anything using the search function... Oh well.
OK...
Squealing can be caused by one or a combination of several things, so it takes some trial-n-error and/or detective work to solve this issue.
Contrary to popular belief, modern braking is accomplished through chemical means as much as mechanical means. The pads deposit a very thin layer of their material on the rotor when applied. The layer is constantly removed and reapplied as the brakes are used. The chemical bond provides much of the friction properties.
If the pads are changed and the new pad material differs from the old, the ability of the pad to transfer material onto the rotor may be impaired and cause less-than-ideal performance. Squealing can be a symptom. This is a major reason why it is recommended to turn or resurface the rotors with every pad change. Alternatively, the owner/operator can also scrub the rotor surfaces with 150-200 grit EMERY paper. Do NOT use aluminum oxide as the aluminum can also cause problems. Once the new pads are installed on clean (chemically) rotors they will need to "bed-in". This involves the pad wearing slightly so the minor surface irregularities (tiny grooves, taper, etc.) of the rotor and pad become identical and the pad material can transfer EVENLY to the rotor.
Often times, pulsating brakes are caused by uneven pad material transfer, not warped rotors. Uneven pad transfer can be caused by several things, but generally involves very hot rotors that have a pad resting against them while the car is stopped. The material adheres to the rotor more heavily in the contact area while the rotor cools.
Normally, a few hard back to back stops will redistribute pad material and correct the pulsation. This is also a quick way to bed-in new pads, but you must be careful not to overheat the brakes and risk loosing braking power completely. Bed-in can take anywhere from 50-500 miles depending on environmental factors. Under-using you brakes is worse than over-using them, as the pad never gets a chance to bed-in properly and the light pressure has tendency to scrub off the pad material transferred to the rotor.
Squealing can also be caused by loose braking system components (calipers, pistons, rotors, axles, etc.) that allow the pads to skip and chatter along the surface of the rotors.
Also, check for run-out (in and out movement as the wheel spins) at the rotor, which can cause a pulsing squeal as the rotor/pad pressure changes with the "high" and "low" spots.
When installing parts, always make sure mating surfaces are flat and clean. Remove any rust, scale, grit, etc. to ensure the pad, caliper, and rotor are all running parallel to each in the direction of travel. This helps minimize taper and, in turn, decreases bed-in time and improves overall braking performance.
Finally, correct pad material choice for your driving style/needs is important. Typically, the higher the performance level desired, the more squealing will be encounter during day-to-day driving conditions. The high performance pads often require much higher temperatures (500*F+) to operate as intended. If your driving style/requirements don't necessitate the use of high temperature pad materials, don't use them.
On my Lincoln, I run Carbon/Kevlar pads and have very minor squeal in town, but they perform well at the higher temperatures encountered during track/auto-X events. My Corvette is even more aggressive and squeals like crazy in town, but they grab like the hand of God once warmed up. I use organic pads on my truck. They are SILENT, but if they get too hot, the brake performance drops off.
OK...
Squealing can be caused by one or a combination of several things, so it takes some trial-n-error and/or detective work to solve this issue.
Contrary to popular belief, modern braking is accomplished through chemical means as much as mechanical means. The pads deposit a very thin layer of their material on the rotor when applied. The layer is constantly removed and reapplied as the brakes are used. The chemical bond provides much of the friction properties.
If the pads are changed and the new pad material differs from the old, the ability of the pad to transfer material onto the rotor may be impaired and cause less-than-ideal performance. Squealing can be a symptom. This is a major reason why it is recommended to turn or resurface the rotors with every pad change. Alternatively, the owner/operator can also scrub the rotor surfaces with 150-200 grit EMERY paper. Do NOT use aluminum oxide as the aluminum can also cause problems. Once the new pads are installed on clean (chemically) rotors they will need to "bed-in". This involves the pad wearing slightly so the minor surface irregularities (tiny grooves, taper, etc.) of the rotor and pad become identical and the pad material can transfer EVENLY to the rotor.
Often times, pulsating brakes are caused by uneven pad material transfer, not warped rotors. Uneven pad transfer can be caused by several things, but generally involves very hot rotors that have a pad resting against them while the car is stopped. The material adheres to the rotor more heavily in the contact area while the rotor cools.
Normally, a few hard back to back stops will redistribute pad material and correct the pulsation. This is also a quick way to bed-in new pads, but you must be careful not to overheat the brakes and risk loosing braking power completely. Bed-in can take anywhere from 50-500 miles depending on environmental factors. Under-using you brakes is worse than over-using them, as the pad never gets a chance to bed-in properly and the light pressure has tendency to scrub off the pad material transferred to the rotor.
Squealing can also be caused by loose braking system components (calipers, pistons, rotors, axles, etc.) that allow the pads to skip and chatter along the surface of the rotors.
Also, check for run-out (in and out movement as the wheel spins) at the rotor, which can cause a pulsing squeal as the rotor/pad pressure changes with the "high" and "low" spots.
When installing parts, always make sure mating surfaces are flat and clean. Remove any rust, scale, grit, etc. to ensure the pad, caliper, and rotor are all running parallel to each in the direction of travel. This helps minimize taper and, in turn, decreases bed-in time and improves overall braking performance.
Finally, correct pad material choice for your driving style/needs is important. Typically, the higher the performance level desired, the more squealing will be encounter during day-to-day driving conditions. The high performance pads often require much higher temperatures (500*F+) to operate as intended. If your driving style/requirements don't necessitate the use of high temperature pad materials, don't use them.
On my Lincoln, I run Carbon/Kevlar pads and have very minor squeal in town, but they perform well at the higher temperatures encountered during track/auto-X events. My Corvette is even more aggressive and squeals like crazy in town, but they grab like the hand of God once warmed up. I use organic pads on my truck. They are SILENT, but if they get too hot, the brake performance drops off.
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