dkpnkc

Regarding a ’01 RX300 AWD

Note that most of my driving is in town so it’s not often that it gets on the highway.

Last November (90k miles) I took a day trip out of town & noticed when I was on the highway that if I hit the brakes while doing approx. 80mph that I had a severe brake shutter. At slower speeds the vehicle didn’t shutter but I did feel a pulsing in the brakes as if the rotor(s) were warped.

I dropped the vehicle off at Lexus & after a couple days they told me the master cylinder was shot. They also turned the rotors for free since I had a front brake job there only a few months before. I had the work done & afterwards the brakes seemed to be better.

Now fast forward to last week. I took another 500 mile day trip to pick up some wheels for my SLK & again I noticed shuttering when applying brakes at 70-80mph. Again when slower the pulsing was back. The vehicle seemed to take more to get it to stop properly. (Currently 93k)

I took it back to Lexus yesterday to find out if any of the work they did needs to be redone under warranty else I’ll take to an independent shop because I cannot afford to keep paying Lexus pricing.

Would I be correct to assume that the rotors are getting warped due to overheating when I’m driving a long distance on the highway? Could there be a problem with the brake pad or master cylinder installation?

Again they called last night & stated they had no clue what was happening & they’re calling Lexus support but I wanted to see if anyone here in this fine group had any ideas.

Thanks!

lexus114

they replaced the master cylinder?? sounds like they have a bunch of parts changers working their.to me it sounds like the rotors,if it were me,i would buy a new set of rotors and put them on myself.i would bet that is your problem.as far as it taking longer to stop,maybe their is some air in the brake lines.

whitelotus

I wouldn't take it back to the same dealer... I'd want to know if they really turned the rotors or just said they did. In my experience with Lexus, they rarely turn rotors, they either replace them or leave them alone.

I may not be the most technically inclined on this forum, but even I am suspicious that they thought it was a problem with the master cylinder!

salimshah

If the work was done in NOV, I think Lexus would fix it for free (unless they find some new things). I also think master-cylinder was an overkill, but then again they may have detected that the pressure is not held if you ride on the brake-pedal.

Since I do the work myself, I prefer replacing the rotor over turning it. Turning them does make them smooth, but takes away material and thus cause, more quicker, warping.

two thing about the post do not make full sense for me.

1. Highway driving in my mind causes less heating of the brakes. Yes when you need them they generate more heat per slow down, but the the cooling happens too. It is like mulitple burst of short heat spells (city) vs less frequent but more hot. My thinking says it is city driving that will generate heat.

2. High speed vs low speed brake pulsation due to rotor warping should only be different in frequency but the amplitude should be the same [sorry to use the scientific jargon]. The vibration in the pedal you feel should be more frequent at higher velocity but the up-down motion (stroke) should be the same. Since it is hard to explain it may be harder to tell them apart.

If the rotors are still smooth, I would look into the suspension/steering or even wheel balancing (unlikely as you would feel that in the steering column first before you sense it in the brake pedal).

I would say start with the dealer as you have already paid for it.
[I always retorque lug-nuts and once or twice, I have noticed that the dealer did not torque them properly... minimum wage worker I guess]

Salim

jrw

On a 2003. I first took it to the dealer, who said something about a recall issue involving a shim kit for the calipers. They installed, or said they installed, the shims and that took care of the shudder and pulsing for a while, but it soon came back.

So, I replace the rotors and pads myself, use ATE slotted rotors and Akebono ceramic pads. I replaced the shims behind the pads just as they were and used plenty of anti-squeal goop. That was about 6-8 months ago and everything is fine now.

I would only have the rotors turned if they're measured first to ensure there's enough metal there to keep them within specifications. Better to replace them if you're not sure. They're not that expensive.

The RX is a heavy car without a lot of braking capability. I don't think it stops very well. But, the only way rotors can warp, and I really don't believe they do warp, is from excessive heat generated by repeated hard braking. What seems like a warped rotor is really pad material deposited on the rotor, not the rotor itself deforming from the heat. In any event, that will certainly not happen in highway driving where you hardly use the brakes, and really doesn't happen around town either. Going down a mountain around lots of sharp hairpin turns could get the heat up enough, maybe.

I think replacing the master cylinder was completely bogus and was either a deliberate way to make money off you or was a clueless "let's try something" stab in the dark. I would not take the care back to that dealer.

Lexmex

I was reading the first post and also thought to myself, ...master cylinder?

I had my fair share of issues with my brakes when I lived in Mexico City, but so did everyone else regardless of vehicle. The high altitude-low oxygen environment combined heat from all the people/traffic/pollution etc. was a recipe for extreme brake use and that was even before I went to the track. I tried several different kinds of brake pads and the Akebonos I got did the best and actually worked well in bracket racing giving me a smooth braking which is necessary to that sort of competition, not a jagged hard stop.

I had my front rotors replaced once by Lexus, but they really were chewed up and that was only a few months after I started going to the track (late 2004), but then have gotten my current rotors (front and rear) machined a few times. Haven't had an issue with pad life or the rotors since I got back to the U.S. almost a year ago. I used to literally run through brake pads in Mexico at the rate of about 6 to 8 months, but my current pads have been on the vehicle to my knowledge since late 2007, right around the time I last had the rotors machined and my brake fluid flushed.

dkpnkc

Thanks for all the good feedback - I really appreciate it.

Just received a call from the dealership. They believe now that all the rotors need to be replaced & they're doing so at no cost. Have to wait until Monday though to find out if this helps.

At least I get to use their 400h loaner for a few more days.

I'll post back what I find out on Monday. Thanks again.

sktn77a

iTrader: (2)

Sounds like they're doing what they should have done in the first place.

Good deal!