kojakrx

I've done some searches on this forum for the shuddering brake pedal, and while there were some reports of it last year, but nothing recently, so I thought I'd revisit it.

I have a '05 RX, with just 750 miles on it. After 400 miles, I've noticed that the brake pedal would shudder for the first 1/2 inch down during stop and go driving, mostly on streets with Stop signs. The studder was not present at every stop - I would say every 1 in 20 stops or even more. And almost never would you get two shudders in a row.

The other posts recommend getting it fixed by the dealer, with TSB-'BR004-04' referenced. Seriously, with only 750 miles on it, can this be the same thing? Or is this something that will just diminish after the break-in period? I guess what I want to know is what do I tell the dealer that this is as opposed to just giving the symptoms?

Thanks...

NeverSatisfied

Take it to the dealer and tell them exactly what you said above. That is not a symptom of the pre-break-in period.

rxdriver

I doubt it's the rotors (the subject of the TSIB you mention) as it's not consistent.

Have you noticed the problem happening at the same intersection every time? I'm thinking it's possible that you might be feeling bumps in the road. Or, is anything else consistent... amount of time braking before it happens (maybe a heat issue), the weather (wet/dry), or how fast you're going prior to pressing the brake?

Nonetheless, I agree with taking it to the dealer and describing it to them. (You paid enough money for the car!) The pads might be wearing funny for some reason. If there's any pattern at all, that might help narrow down the problem.

Lil4X

Kojak, I believe I've experienced the same shudder, usually braking from about 60 mph, fairly hard, but nowhere near getting into the anti-locks. The shudder can be pretty severe, and seems to affect only the front wheels. The problem in my case, as yours, is that it's not repeatable . . . making a trip to the dealer kinda useless.

I have noticed that if the shudder begins, releasing and reapplying the brake usually corrects it. Could that be significant?

At 750 miles your pads are probably still "green" - or at least that's what your dealer will probably tell you. After about 1000 or 1500 miles - if you can get the problem to repeat with some frequency - take it in for service. I'd certainly mention it at your 1000 mi interval service, and see what they say. Meanwhile, I've got another two weeks until my next service, so I'm paying attention to when and where it happens.

kojakrx

Thanks for all of the feedback... Really the only times I've noticed it has been on stops from low speeds - 15 mph or less, never when I slow down on an exit ramp or from highway speeds. So far, every time has been in dry weather, and it has been after the brakes have warmed up. For instance, yesterday was a 20 mile highway drive at 60mph, then stop lights for the next 5 miles. The brakes started shuddering in the last 1 mile. That would be a very interesting scenario to repeat with the mechanic - "Let's go for a 1/2 hour drive together!" MY wife who was in the car with me at the time didn't feel a thing.

It doesn't feel like ABS, as 1, the roads are dry, and 2, the pedal goes smoothly afterwards.

I doubt if it is just road bumps - as I'd expect to feel that through the suspension or steering as well. This is really just the brake pedal and for just the first 1/2 inch when I press it.

I am going to bring it in - sometime next week probably. The car still stops fine even when it shudders, but as I paid so much for it, I should. I don't think my dealer recommended/offered a 1000 mile service - but this is as good enough of a reason to get one as any.

Tammy

This Link may apply.. https://www.clublexus.com/forums/sho...ake+booster+rx

Lil4X

The shudder I've experienced is not so much a pedal pulsation as a shimmy induced into the steering wheel at about 5 cycles/sec when braking from 60 mph plus. Holding the wheel lightly on an open stretch of highway, the steering wheel alternately turns left and right about 1/2" at the rim when the brakes are applied "smartly".

This is not the anti-lock, nor is it the brake assist stepping in. It occurs when you hit the brakes with "awww nuts, I've missed my exit!" force - not the full-tilt, throw-out-the-anchor, accident avoidance mode. . . Moderately heavy braking, not stomp-the-pedal-to-the-floor braking.

It behaves like a warped rotor, except that it only occurs at 60+ mph, only on first firm application of the brake, and even then, not on every application.

Me? I'm stumped!

kojakrx

As your problem is from 60 and mine is from 15, I think they might be different issues. Have you checked the obvious things like alignment, balancing, bent rims, or even that the tire pressure is even in all your tires?

kojakrx

Driving it a bit more this weekend.. I left home and drove about 35 miles with no problems. Hit slow traffic - after 10 minutes of that, the brake shuddered once or twice. I can't predict when it will happen, but it seems that it almost is after the brake starts giving me less resistance as I push, but stops me fine anyway. Not sure if one has to do with the other... Is this just normal, hot new brake behavior? It's going to the dealer on Tuesday, just wanted to float this around first...

Thanks,
Kojak

Mark_LP

I just wanted to also reiterate what Lil4X was saying. I have an '04 rx330, Canadian made, that has a recurring severe brake shudder in that 70-60 mph braking window as well. I had the rotors replaced by the dealer under warranty at 10,000 miles. Well, I was experiencing the same thing again around 22,000 miles and again, warped rotors. The service advisor said that they were going to cover this under warranty again for me, but it seemed to be a big deal for them. Now my vehicle is having the recall on the brake booster. I can't tell if these issues are related or not. Maybe an engineer can pipe in w/ some thoughts.
The service advisor very politely reminded me not to drive with my foot on the brake and the gas. He thought this could be overheating the rotors causing them to warp. I politely let him know that I drove in no such manner. My last vehicle was a 2001 530i and I never warped brakes on that car or on any other of my previous 6 BMWs, 2 VWs, Saab or Infiniti. I have been to the dealer more times than I can even imagine with this car. I thought by buying a Lexus, I would not be at the dealer all the time. WRONG!! Lexus pease read this post and take it to heart. This is my first and last Lexus!!
As for the brake issue, I think that there will be one more issue besides the booster that is causing this problem.

lexuslover

just out of curiousity, where is your RX built and is it 2wd or awd? not to open a can of worms on japan/canada, but sometimes it helps to know if this pertains to certain types.

Mark_LP

awd and Canadian made

CK6Speed

iTrader: (1)

While I can't help yp narrow down your problem, I can say it is not normal even for new brakes that are being broken in. I never had that shudder when My RX was new, and I have never had that type of shudder on any of my cars after I change rotors or pads. The only time I personally had it happen to me is with warped rotors, but that would be all the time and not intermitent. Since yor car is so new don't hisitate to take it back to the dealer and explain the problem. Even if they don't find a solution right away because it is intermitent, at least you have documentation of your problem at the dealer in case something worse happens down the road. You can tell them "I told you so".

kojakrx

I actually did take it back to the dealer, and after checking the rotors and pads and having both the tech and the shop foreman drive it, they said that all was ok and that they couldn't duplicate it. Funny thing though is since then, I haven't been able to duplicate it either, and that was 600 miles ago, and I am now at 1600 miles. I get a much lighter resistance, but not to the same level. I'm keeping my eye on it and in case of anything, I agree, at least I have it documented.