RX 450H - Serious Brake Issue
11-03-13, 07:18 PM
#16
Racer
Optionpunk, not trying to convince you to be happy about it, just trying to explain what is happening and how best to mitigate/understand it yourself. By all means, lodge a complaint with Lexus. I know with the Prius they apparently offered a system update to improve the situation, maybe if they receive enough complaints they could do the same here for RXh owners with similar complaints. As I said, in my own experience I've found the RXh to be very satisfactory, it's only my Camry experience and previous discussions with others over the years that I am familiar with what you are experiencing (Not sure if you know, but other than system tweaks and updates the Prius, Camry, RXh, etc. systems all function conceptually nearly identically).
That said, I'll provide some mitigation to your comments. I have never experienced this issue, or heard anyone complain about it at much over 15kph. It is a phenomena, to my knowledge, typically experienced approaching a full stop, not at higher traffic speeds. At those higher speeds it is much more unlikely that the regen braking will cause as much loss of traction without the mechanical brakes already engaged and therefore not susceptible to this issue. On snowy roads, the vastly reduced traction to start with is already negating much use of the regen braking, so the mechanical brakes are likely already in play, again making it more unlikely of this issue to occur.
I suppose the solution would be for the hybrid system to be less aggressive at regen at those critical speeds approaching a stop, when it is easier for the regen braking to overcome the tire traction by itself.
Obviously if you can get Lexus to do something about it, that would be ideal, but otherwise if you understand when and why this can happen, at least you can be aware. As always, your choices are: Complain, Adapt, Sell...
Sorry it's a pain, I know experiencing problems on something like an RXh where your expectations are high and "usually" met is not nice, don't shoot the messenger... If you try the adapt route, I hope I helped. My RXh has 89,000km, but the tires are only 1 yr old, they were changed at 3 yrs. If this starts to happen to me I'm changing out the tires. I know from past experience once tires hit 3 or 4 yrs, the rubber has lost a fair bit of it's traction capabilities, regardless of tread depth. This general loss of traction occurs to any car, it's just this issue is an undesirable additional side effect for Toyota's hybrids. In either case, that is good reason to put fresh rubber on...
That said, I'll provide some mitigation to your comments. I have never experienced this issue, or heard anyone complain about it at much over 15kph. It is a phenomena, to my knowledge, typically experienced approaching a full stop, not at higher traffic speeds. At those higher speeds it is much more unlikely that the regen braking will cause as much loss of traction without the mechanical brakes already engaged and therefore not susceptible to this issue. On snowy roads, the vastly reduced traction to start with is already negating much use of the regen braking, so the mechanical brakes are likely already in play, again making it more unlikely of this issue to occur.
I suppose the solution would be for the hybrid system to be less aggressive at regen at those critical speeds approaching a stop, when it is easier for the regen braking to overcome the tire traction by itself.
Obviously if you can get Lexus to do something about it, that would be ideal, but otherwise if you understand when and why this can happen, at least you can be aware. As always, your choices are: Complain, Adapt, Sell...
Sorry it's a pain, I know experiencing problems on something like an RXh where your expectations are high and "usually" met is not nice, don't shoot the messenger... If you try the adapt route, I hope I helped. My RXh has 89,000km, but the tires are only 1 yr old, they were changed at 3 yrs. If this starts to happen to me I'm changing out the tires. I know from past experience once tires hit 3 or 4 yrs, the rubber has lost a fair bit of it's traction capabilities, regardless of tread depth. This general loss of traction occurs to any car, it's just this issue is an undesirable additional side effect for Toyota's hybrids. In either case, that is good reason to put fresh rubber on...
05-18-15, 04:18 PM
#18
Driver School Candidate
Join Date: May 2015
Location: CA
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
ES350 braking issue
This has been an ongoing complaint across all Toyota hybrids for a number of years. On my 07 Camry Hybrid this was quite noticeable on bumpy roads or paved roads covered with some dirt when coming to a stop, especially when the tires started to get old and no longer had optimum traction, or before I had put the snow tires on and the roads were very cold. If you're the type of driver that leaves no room/time to spare when breaking, yea, you're likely sooner or later to ding a bumper. If you leave a few ft of safety margin, it can be a little bit of adrenaline surge on occasion. This issue is related to the dance between ABS and regenerative braking. While the tires begin to lose traction the ABS signals the regenerative braking to ease off and mechanical breaking to take more priority. If traction drops quickly (hitting bumps, dirt) there is sometimes a momentary lag between the two, giving the feeling described. It may feel like the car speeds up, but it actually just doesn't slow down as fast as it was slowing down for a moment.
05-21-15, 07:58 AM
#19
Lexus Champion
I recently had an accident with my ES350 2007 model -when I hit a SUV in front in suddenly slowing traffic. My Lexus brakes have always been very effective even in much tighter situations. In this case I thought I had more than enough room and never felt any risk of a crash , felt that the car was not responding to the brakes for a second or two - I was about 35 MPH when braking and the impact was low speed 5 mph . The explanation above seems to describe what I went through. The spot where this happened was over a concrete road (high way overpass ) with some dirt and felt like the ABS was just slipping and the regenerative braking that normally takes place was not happening. Also after the accident the dealer inspection indicated that my brakes were soft because of a frozen brake caliper pivot. Maybe a combination of things - but lost faith in my ES350 brakes. Anybody faced similar braking issue with a non hybrid? I did ask Lexus to look at it and download the EDR data. Waiting for response.
On of sliding pins on both original calipers in my IS300 had seized-up at the age of 10.
I had one instance when I was coming on to the left turn and it wouldn't slow down for me.
I was downshifted into the second and just went for the turn anyway it at a higher speed.
It wasn't until later on when I did a full brake refresh that I figured this out.
I put brand new calipers on both sides and called it a day. I did not want to deal with rebuilding originals, which would have also needed new pistons.
08-26-15, 08:43 AM
#20
Instructor
Perhaps your problem is similar to this which seems to be affecting all Toyota hybrids. http://www.lexusownersclub.co.uk/for...braking-issue/
the OP's problem in that thread is not as severe but his situation is not that severe as his is not applying the brakes so hard. Under an emergency situation, however, I'd say he'd run into a similar problem that the OP has.
I'm still trying out the 450h for test drives myself. I have not duplicated an emergency situation with another car in front of me. Perhaps I'll try it with a cardboard box and see if I lose breaking at the last minute.
the OP's problem in that thread is not as severe but his situation is not that severe as his is not applying the brakes so hard. Under an emergency situation, however, I'd say he'd run into a similar problem that the OP has.
I'm still trying out the 450h for test drives myself. I have not duplicated an emergency situation with another car in front of me. Perhaps I'll try it with a cardboard box and see if I lose breaking at the last minute.
08-27-15, 05:58 AM
#21
Rookie
Join Date: Aug 2013
Location: Ny
Posts: 92
Likes: 0
Received 0 Likes
on
0 Posts
Perhaps your problem is similar to this which seems to be affecting all Toyota hybrids. http://www.lexusownersclub.co.uk/for...braking-issue/
the OP's problem in that thread is not as severe but his situation is not that severe as his is not applying the brakes so hard. Under an emergency situation, however, I'd say he'd run into a similar problem that the OP has.
I'm still trying out the 450h for test drives myself. I have not duplicated an emergency situation with another car in front of me. Perhaps I'll try it with a cardboard box and see if I lose breaking at the last minute.
the OP's problem in that thread is not as severe but his situation is not that severe as his is not applying the brakes so hard. Under an emergency situation, however, I'd say he'd run into a similar problem that the OP has.
I'm still trying out the 450h for test drives myself. I have not duplicated an emergency situation with another car in front of me. Perhaps I'll try it with a cardboard box and see if I lose breaking at the last minute.
08-27-15, 09:41 AM
#22
Instructor
that's is good to hear. I have a very long test drive coming up on Saturday. I'll see if I can keep the right wheels on the shoulder where there are dirt and gravel interfering with traction while keeping the left side on the clean paved road. I'll give it about 70% braking to initially slow down then yank the steering to the right at the last minute and fully depress the pedal to engage ABS and see what happens.
It seems the OPs from other threads talk about a momentary delay when going from regen/mechanical combo braking to all mechanical brake when ABS is just about to trigger. See this comment from Autoweek (the editors of there must not have attended grammar school but you can sort of make out what the author is saying).
-------------------------
2014 Lexus RX 450h
ASSOCIATE EDITOR JAKE LINGEMAN:
......... And the regenerative brakes had me a little worried, too. A driver in front of me slowed quickly, I had to give them (the brakes) a good push. It went from not slowing down to locked up on ice; I had to abandon the lane to make sure I didn't hit anybody. In fairness to the Lexus, the guy had no brake lights, so I stomped a little harder than I may have had to.
It seems the OPs from other threads talk about a momentary delay when going from regen/mechanical combo braking to all mechanical brake when ABS is just about to trigger. See this comment from Autoweek (the editors of there must not have attended grammar school but you can sort of make out what the author is saying).
-------------------------
2014 Lexus RX 450h
ASSOCIATE EDITOR JAKE LINGEMAN:
......... And the regenerative brakes had me a little worried, too. A driver in front of me slowed quickly, I had to give them (the brakes) a good push. It went from not slowing down to locked up on ice; I had to abandon the lane to make sure I didn't hit anybody. In fairness to the Lexus, the guy had no brake lights, so I stomped a little harder than I may have had to.
Last edited by MellonC00; 08-27-15 at 09:50 AM.
08-28-15, 08:46 AM
#23
Racer
If you want to test, find a place with a lot of sand or dirt on a road particularly after a bump.When transitioning from good pavement to the bump followed by loose dirt, this is prime way to replicate the cut-out of the regen without changing the brake pressure. Begin moderate braking to near max regen braking and hold steady over the bump and onto the dirt. Open your windows, you can actually hear the whine of the regen disappear over the bump.
08-28-15, 10:08 AM
#24
Instructor
If you want to test, find a place with a lot of sand or dirt on a road particularly after a bump.When transitioning from good pavement to the bump followed by loose dirt, this is prime way to replicate the cut-out of the regen without changing the brake pressure. Begin moderate braking to near max regen braking and hold steady over the bump and onto the dirt. Open your windows, you can actually hear the whine of the regen disappear over the bump.
09-01-15, 05:16 AM
#25
Rookie
Join Date: Aug 2013
Location: Ny
Posts: 92
Likes: 0
Received 0 Likes
on
0 Posts
I don't think an "emergency stop" is a relevant example of this issue. An emergency stop suggests hard on the brake pedal which results in the mechanical brakes being deployed immediately. There is no guess work here for the computer, stop fast as possible means using the mechanical brakes. The issue is primarily the result of ABS action during STEADY gentle to at most moderate breaking without changing the amount of brake pedal pressure. I don't believe trying to forcibly trigger the ABS by increasing brake pressure coupled with violent steering will have the effect you seek.
If you want to test, find a place with a lot of sand or dirt on a road particularly after a bump.When transitioning from good pavement to the bump followed by loose dirt, this is prime way to replicate the cut-out of the regen without changing the brake pressure. Begin moderate braking to near max regen braking and hold steady over the bump and onto the dirt. Open your windows, you can actually hear the whine of the regen disappear over the bump.
If you want to test, find a place with a lot of sand or dirt on a road particularly after a bump.When transitioning from good pavement to the bump followed by loose dirt, this is prime way to replicate the cut-out of the regen without changing the brake pressure. Begin moderate braking to near max regen braking and hold steady over the bump and onto the dirt. Open your windows, you can actually hear the whine of the regen disappear over the bump.
Hope this helps in your search for answers.
09-01-15, 11:16 AM
#26
Instructor
I did the test this weekend. did the braking test with the sale guy looking at me with kind of elementary school level curiosity only to be distracted with ADHD type concentration and dim wittedness. I had the window open too.
It was fine. I heard the switchover when you don't here that faint whine anymore. ABS kicked in and perhaps there was a nano second of delay or maybe not but from all perspective, no drama involved in switching over to mechanical braking.
The sad part of all this is that the dealer sold away my car. I told'em I'll be back on Monday cuz I needed to arrange some cash to write them a check. They said no problem.
On Monday morning, they said no problem again. The car is sold (for more than I negotiated for). I should have put a deposit down. It was literally loaded with every available option including ML audio.
My search continues.
It was fine. I heard the switchover when you don't here that faint whine anymore. ABS kicked in and perhaps there was a nano second of delay or maybe not but from all perspective, no drama involved in switching over to mechanical braking.
The sad part of all this is that the dealer sold away my car. I told'em I'll be back on Monday cuz I needed to arrange some cash to write them a check. They said no problem.
On Monday morning, they said no problem again. The car is sold (for more than I negotiated for). I should have put a deposit down. It was literally loaded with every available option including ML audio.
My search continues.
09-01-15, 11:47 AM
#27
Rookie
Join Date: Aug 2013
Location: Ny
Posts: 92
Likes: 0
Received 0 Likes
on
0 Posts
I did the test this weekend. did the braking test with the sale guy looking at me with kind of elementary school level curiosity only to be distracted with ADHD type concentration and dim wittedness. I had the window open too.
It was fine. I heard the switchover when you don't here that faint whine anymore. ABS kicked in and perhaps there was a nano second of delay or maybe not but from all perspective, no drama involved in switching over to mechanical braking.
The sad part of all this is that the dealer sold away my car. I told'em I'll be back on Monday cuz I needed to arrange some cash to write them a check. They said no problem.
On Monday morning, they said no problem again. The car is sold (for more than I negotiated for). I should have put a deposit down. It was literally loaded with every available option including ML audio.
My search continues.
It was fine. I heard the switchover when you don't here that faint whine anymore. ABS kicked in and perhaps there was a nano second of delay or maybe not but from all perspective, no drama involved in switching over to mechanical braking.
The sad part of all this is that the dealer sold away my car. I told'em I'll be back on Monday cuz I needed to arrange some cash to write them a check. They said no problem.
On Monday morning, they said no problem again. The car is sold (for more than I negotiated for). I should have put a deposit down. It was literally loaded with every available option including ML audio.
My search continues.
Good luck
09-02-15, 05:41 PM
#28
Didn't the dealer offer to dealer trade for one? They should be able to see every RXh in the region.
When my wife only wanted Satin Cashmere with Saddle there was only one in Florida and the next closest was Atlanta. There were none with ML audio anywhere in SE region.
When my wife only wanted Satin Cashmere with Saddle there was only one in Florida and the next closest was Atlanta. There were none with ML audio anywhere in SE region.
09-03-15, 03:41 PM
#29
Instructor
I was buying a 2013 model. I already know what's out there and what every single one has in terms of options and mileage (around 100 miles from my area). I even get updates on every single one when they have a new price or new used car gets loaded in the system. I only use the dealer to process my paper and negotiate the price. Other than that I don't really go there as I feel like I need an IQ test and prescription for Adderall from being around so many degenerates.
Thread
Thread Starter
Forum
Replies
Last Post
