Hello. My wife owns a 2017 RX 350 that is AWD. It has about 49K miles and still under Lexus Certified Warranty. We drove it to Colorado and while driving downhill, I stepped on the brakes and it vibrated aggressively. I tried this at various speeds and it consistently vibrated hard.

The catch is that after we got to a flat land and drove for about 30 minutes or longer, the vibration did not occur again. I brought this to the dealer and they could not find any problem. Accordingly, they visually inspected it and found nothing. The car computer did not show any problem code as well according to the dealer service center.

I am wondering if anyone has had the same experience with their RX 350.

 

It sounds like heat buildup. Slowing a 4500lb+ vehicle with only the brakes when driving down long mountain roads generates incredible heat, and the heat can cause pulsing and fading. I wouldn't be too concerned if it does not recur. I live in hilly WV and regularly use engine braking on long downhills to lower the heat buildup. (It's the only use I've found for the RX paddle shifters. )

 

+1

It's thermal build up in the pads and rotors. Once they cool they somewhat return to normal. They are most likely on the way out. This would fall under wear and tear, and thus wouldn't be covered under warranty.

 

The problem has been described before: https://www.clublexus.com/forums/rx-...gh-speeds.html

FWIW, my neighbor is a trained and experienced auto mechanic, and specializes in General Motors products. When I had him rotate tires on my 2015, he had me look up the lug nut torque spec, and when I told him the number (76 ft-lb), he expressed surprise, as he is accustomed to 120-140 ft-lb for cars, and higher for the trucks. So, if your average American mechanic doesn't bother to look up the spec, and rotates your wheels, it's not hard to imagine that you'll end up with over-torqued, i.e. warped rotors.

 

Fiar point, but, while toque spec is important, it is not the root cause in the source you listed. Most people had issues with brake rotors being actually warped. What I recommend when replacing pads is to never resurface rotors. Resurfacing rotors removes material making them more prone to warp in the future. Having worked in the auto industry for almost two decades, I personally have been taught to torque wheels since I was 14yo and made to do it at varying shops/dealers. Under torquing, wheels or over-torquing is better than random torque on each lug nut. You also have to remember that the torque for each car is specific to the size of the wheel stud. Torquing to 120ft-lbs could be a huge risk for far worse scenarios than warped rotors - were talking studs failing. The torque for our RX generation is 80ft-lbs which is almost nothing.

 

This thread is related as well. Short story is yes, several of us are having similar issues. https://www.clublexus.com/forums/rx-...ng-drives.html

 

Thank you for the feedback. The logic on the break is reasonable. My only exception is that the vibration occurs the first time I press the break while rolling downhill.

 

Rotors probably warped. My wifes RX jat 47k just needed brakes all around - front and rear.

 

almost 100% sure your rotors are warped. Last 5 toyota/lexus products all had rotors replaced in the 50 - 75K range. They simply arent that durable. Once I swap them out (might as well do new pads and bleed brake fluid), and yes, I oddly still use OEM products, braking is smooth as new.

 

I suspected the rotor as well. However, the lexus service center which is the only in my area said they checked it and the breaks look good and could not see any problem. What shall I do if the local Lexus dealer said they could not find anything.

 

Well, with almost 50k on it, you're probably due for pads and rotors. Either tell the dealer to do it (you'll be paying anyway), or go to a respected brake shop and have it done. IMO, stay away from chain shops.

 

Sounds like the same service center that told me my wife's RX still had 50% life in the pads when I told them I thought the pads needed replacement - two months later, metal on metal. Now I have new rotors all four which I didn't pay for

 

With the electronic parking brake, my understanding was that one needs Toyota techstream to retract the brake before replacing the pads.
Do independent brake shops have this software, or are they using a work-around method?

 

9 volt battery is all you need

search youtube

did mine a couple weeks ago, easy as pie

 

I have a steep hill on my regular route and in the past 6 years on 4 Lexus cars the answer to this problem was the same - time to replace front breaks and machine the front rotors. I do it at Toyota even for CPO RX due to lower prices. They still use OEM Lexus parts and the maintenance is reflected in electronic service history.