2008 Lexus RX 350



October, 22, 2012 AT 12:18 AM

My brakes are making noise because of the pads. I know I need to change the pads but is it necessary that to change the brake rotor too? And is the quality of pads different from others, because I change them a lot?


6 Answers



October, 22, 2012 AT 12:21 AM

Quality? Yes. Get ceramic pads and a good set of rotors.




October, 22, 2012 AT 12:44 AM

To clarify the rotor issue, there is a published legal minimum thickness they can be and no mechanic will risk his reputation or the chance to sit in a courtroom from leaving them on the car knowing they're too thin. We all know a little bit undersize won't cause a problem but a good lawyer or insurance investigator WILL convince a jury you were partly responsible for the crash when the other guy ran the red light because you were less able to avoid the crash. We all know that's hogwash, but you can't win against lawyers.

At the very least you want to have the old rotors machined to true them up and remove any warpage. Failure to do that will result in uneven braking until the pads wear down to match the grooves that ARE worn into the rotors now. That can take a long time. I can't speak directly to a Lexus, but in general, new rotors today are so inexpensive that most shops find it less expensive for you and for them to just replace them during any brake job. When you factor in the cost of the cutting bits for the brake lathe, and the mechanic's time to measure, inspect, machine, and clean the rust and debris from the mounting surface, they save you more money in the long run by replacing them.

There are a lot of things experienced mechanics do to resolve noise issues, prevent causing noise issues, insure long life of the brake components, and avoid vibrations that most do-it-yourselfers don't know about. Many of those things involve cleaning and lubricating the rotor. Cleaning takes a lot of time and they can still miss things. That's another reason they prefer to replace them with new ones.

Be aware too that there are a lot of Chinese rotors available that usually cause a pulsation a month or two after installation. There is nothing wrong with the quality, but when we make parts out of cast iron, we let them "age" for 90 days before we do the final machining. They cast, machine, pack, and ship their rotors right away, then they age on your car. Usually one followup machining a few months later is all that's needed to solve the pulsation permanently.



October, 22, 2012 AT 7:16 AM

Generally if your changeing your pads alot and do so when you here them making noise its time for new rotors if you have a repair manual that will tell you the minimum thickness your car mfg suggests for brake rotors, why so many pads lots of intown driving? Could be your calipers are sticking causing premature brake ware.I would recomend changeing your brake fluid if you have not already done so. Old brake fluid can cause problems with brakes due to moisture and conamination. Good luck



October, 22, 2012 AT 8:00 PM

Thanks for these good points. I will get ceramic pads I would buy better pads if there are? Im still wondering what the best rotors are used longer?
Thanks again!



October, 23, 2012 AT 1:32 AM

Something to keep in mind, while there are varying quality of pads, they had better not make the car stop with less pedal effort. (Stopping in shorter distances is a product of the tires, never the brakes). The cheapest pads and shoes will already cause the wheels to lock up. You can't do any better than that. What IS more important is the "coefficient of friction" must be the same as was designed in by the manufacturer, and all aftermarket brake suppliers work really hard to match that for every car model. That's why on occasion you'll find some linings are physically smaller than the original ones. That is done to maintain the front-to-rear braking balance.

You should not notice any difference in pedal effort to stop the car with any set of pads. The difference in quality comes in when talking about squeals and fade resistance due to heat buildup. Glazing of the linings and rotors changes the friction coefficient too. Those are some of the things shrewd lawyers and insurance adjusters look for when trying to pin some of the blame on you after a crash when the other guy ran the red light. They will make a jury believe you were less able to avoid the crash.

Ceramic pads are harder so they will wear out rotors faster than regular linings. Because they are harder they also tend to squeal more, particularly when they are still cold and in humid conditions. When you hear those really high-pitched brake squeals on new cars, that tells you they came with high-quality, high-cost pads, but they do produce a lot of brake noise complaints.



October, 23, 2012 AT 12:21 PM

Those brake squeals can be eliminated with proper pad chamfering prior to installation. Bevel the edges so there are no sharp edges on the pads before you install them.

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