Noticeable shudder/vibration when decelerating on ls600hl
06-22-16, 08:28 AM
#17
Funny you mention this, as I am actually in the midst of following up. I have re-re-opened the case, and they are back to searching for a car. Because I have a '10, they are looking for a '10-12 car, which is even more of a unicorn here on the east coast.
I am not sure that is the same issue (on the 460 AWD) as on my 600. I wonder, Vansibel, if we have the exact same issue. At any rate, I had read about the front shaft issue a long time ago and intended to raise it for consideration, just in case (in the spirit of connecting dots) - thanks for bringing it up (nice reminder!).
Very helpful and interesting info, Tec80. This reminds me of a part of the work that was done to my 460 to exorcise all the vibration demons. I am not sure it's applicable, though again, it's another factor to consider.
In my case, I either need to be braking or coasting for there to be shudder. When coasting, the fore-and-aft shudder coincides with the needle going to "charge". The second I shift to N, the car can't recover energy anymore, and the shudder disappears. FWIW, service brakes are also out of the equation (i.e., if I brake in N, braking is perfectly smooth).
So, basically, there needs to be a load on the driveline (negative torque, specifically) for there to be shudder. Remove that load, and everything is fine. The sagging you describe seems like it would trigger vibration under any/no load. Am I missing something?
I am not sure that is the same issue (on the 460 AWD) as on my 600. I wonder, Vansibel, if we have the exact same issue. At any rate, I had read about the front shaft issue a long time ago and intended to raise it for consideration, just in case (in the spirit of connecting dots) - thanks for bringing it up (nice reminder!).
Very helpful and interesting info, Tec80. This reminds me of a part of the work that was done to my 460 to exorcise all the vibration demons. I am not sure it's applicable, though again, it's another factor to consider.
In my case, I either need to be braking or coasting for there to be shudder. When coasting, the fore-and-aft shudder coincides with the needle going to "charge". The second I shift to N, the car can't recover energy anymore, and the shudder disappears. FWIW, service brakes are also out of the equation (i.e., if I brake in N, braking is perfectly smooth).
So, basically, there needs to be a load on the driveline (negative torque, specifically) for there to be shudder. Remove that load, and everything is fine. The sagging you describe seems like it would trigger vibration under any/no load. Am I missing something?
06-22-16, 09:41 AM
#18
Negative torque (car pushing the engine or wheels driving the engine) will cause the nose of the pinion to rotate downward, compressing the lower forward diff mounting cushions. If the cushions are already allowing the diff nose to sag down in the static state, the load from deceleration will make it sag further, putting it out of parallel with the transfer case rear driveshaft output. Anything past 1 degree out of parallel and you will begin to feel the vibration from the driveshaft accelerating and decelerating as it turns.
This is the opposite of axle windup under acceleration. When accelerating, the rear wheel torque creates an equal but opposite force on the diff housing, trying to rotate it backwards (nose up). The cushions prevent this. But, if the nose was too high in the static state, you'd feel vibration on acceleration as the diff nose moves up and puts the system out of parallel.
This is the opposite of axle windup under acceleration. When accelerating, the rear wheel torque creates an equal but opposite force on the diff housing, trying to rotate it backwards (nose up). The cushions prevent this. But, if the nose was too high in the static state, you'd feel vibration on acceleration as the diff nose moves up and puts the system out of parallel.
Separately, my car is very low in miles; I get that the sagging you describe could happen anyway (since gravity never stops) but imagine that wear exacerbates it.
Yes, it's what I've described: my car does this under regenerative braking - via brake pedal or when coasting.
06-22-16, 04:57 PM
#19
I paid attention going home today and I don't have any shudder coasting down from high speed.
Shudder when braking has improved significantly since dealer changed my actuator, still have some but much better than before. I don't know if this is due to regenerative braking or rotors that need resurfacing.
Shudder when braking has improved significantly since dealer changed my actuator, still have some but much better than before. I don't know if this is due to regenerative braking or rotors that need resurfacing.
01-14-18, 01:42 AM
#20
Driver School Candidate
Negative torque (car pushing the engine or wheels driving the engine) will cause the nose of the pinion to rotate downward, compressing the lower forward diff mounting cushions. If the cushions are already allowing the diff nose to sag down in the static state, the load from deceleration will make it sag further, putting it out of parallel with the transfer case rear driveshaft output. Anything past 1 degree out of parallel and you will begin to feel the vibration from the driveshaft accelerating and decelerating as it turns.
This is the opposite of axle windup under acceleration. When accelerating, the rear wheel torque creates an equal but opposite force on the diff housing, trying to rotate it backwards (nose up). The cushions prevent this. But, if the nose was too high in the static state, you'd feel vibration on acceleration as the diff nose moves up and puts the system out of parallel.
This is the opposite of axle windup under acceleration. When accelerating, the rear wheel torque creates an equal but opposite force on the diff housing, trying to rotate it backwards (nose up). The cushions prevent this. But, if the nose was too high in the static state, you'd feel vibration on acceleration as the diff nose moves up and puts the system out of parallel.
Could this be the misaligned transmission and diff housing issue?
08-11-18, 10:27 AM
#21
I recently bought a 2014 LS 460 AWD certified pre-owned and experienced the vibration issue at highway speeds but especially when coasting. The dealer replaced both front axles and front drive shaft assembly. I still feel like the vibration is there at times.
01-30-21, 08:27 PM
#22
Just started having this issue with my 600. It definitely doesn't feel like an engine or transfer case issue but definitely something in the hybrid system. Seems to have just started now that temps have dropped and seems to happen more going down hill .Wondering if it's a transmission fluid level issue since the cold fluid doesn't expand and going down hill pushes it all forward. Was there a confirmed solution for this??
02-06-21, 11:44 AM
#23
Short answer, yes! It is entirely separate from the TSIB for the transfer case for shudder when turning.
I was actually going to start a thread about this, but since I've had the car for only a few months, I've been "gathering data" for a while.
In my case, the issue seems intermittent, not in its presence (i.e., there is always some shudder, even if slight) but in its intensity. Sometimes it's tolerable; other times it gets to be annoying.
Indeed, it occurs during regenerative braking, as soon as you see the power meter go into the "Chg" zone upon letting go of the accelerator (or applying the brakes). At its worst, it can feel like a bad case of warped rotors, except it isn't the rotors.
One thing I've noticed, is that the issue surfaces when the engine is on. As the vehicle slows down (and shudders), the moment the engine turns off, the shudder virtually disappears. It's almost as if in this state, the engine is "fighting" the rest of the drivetrain.
Similarly, when I am merging into heavy traffic, letting go of the brake as the engine revs around 1000+ rpm, the car can feel jerky. If the engine is off, it's smooth as glass, again making it seem as if the engine is fighting the drivetrain.
My dealer has experienced the issue, and I opened a case with Lexus and drove the car with a Field Technical Specialist. Detailed driving snapshots of relevant parameters were sent to Lexus engineers, and so far, nothing unusual has been found. Problem is that this car is so rare, that there is nothing on the lot to compare it to. Thus, in my situation, unless something really goes wrong with the car, the next step will be to find another car to compare to and take it from there.
While this could, unfortunately, turn out to be a "characteristic" of the car (though based on others' responses, it doesn't sound like it is), I would be hard-pressed to think that it is normal. I had never owned a 600 before, but have driven plenty of RX450hs, and while they are different animals, at the end of the day, I don't see why the "flagship" would be so noticeably less smooth under regenerative braking.
I was actually going to start a thread about this, but since I've had the car for only a few months, I've been "gathering data" for a while.
In my case, the issue seems intermittent, not in its presence (i.e., there is always some shudder, even if slight) but in its intensity. Sometimes it's tolerable; other times it gets to be annoying.
Indeed, it occurs during regenerative braking, as soon as you see the power meter go into the "Chg" zone upon letting go of the accelerator (or applying the brakes). At its worst, it can feel like a bad case of warped rotors, except it isn't the rotors.
One thing I've noticed, is that the issue surfaces when the engine is on. As the vehicle slows down (and shudders), the moment the engine turns off, the shudder virtually disappears. It's almost as if in this state, the engine is "fighting" the rest of the drivetrain.
Similarly, when I am merging into heavy traffic, letting go of the brake as the engine revs around 1000+ rpm, the car can feel jerky. If the engine is off, it's smooth as glass, again making it seem as if the engine is fighting the drivetrain.
My dealer has experienced the issue, and I opened a case with Lexus and drove the car with a Field Technical Specialist. Detailed driving snapshots of relevant parameters were sent to Lexus engineers, and so far, nothing unusual has been found. Problem is that this car is so rare, that there is nothing on the lot to compare it to. Thus, in my situation, unless something really goes wrong with the car, the next step will be to find another car to compare to and take it from there.
While this could, unfortunately, turn out to be a "characteristic" of the car (though based on others' responses, it doesn't sound like it is), I would be hard-pressed to think that it is normal. I had never owned a 600 before, but have driven plenty of RX450hs, and while they are different animals, at the end of the day, I don't see why the "flagship" would be so noticeably less smooth under regenerative braking.
02-13-21, 02:25 PM
#24
Wanted to update my situation. Turns out it my issue was just terrible gasoline. Noticed the issue got better once I fueled up. I could also feel a miss at idle. Ran through that tank and gassed up again. Did 2 drain and refills on my transmission fluid wasted 6 quarts but glad it wasn't a clutch plate or anything major.
04-03-21, 07:01 PM
#25
update: shudder is back :-(
04-11-21, 05:25 PM
#26
Update for anyone curious. A week ago my car finally threw a check engine light with rich codes for both banks. A day later it went away , then came back the next day. Yesterday I replaced the air filters and cleaned the MAFs . Car has been running 10x better. No more sputtering or hesitation, electric to gas transitions are smooth again and mpg has already increased. Hopefully this fix sticks.
05-03-21, 10:49 AM
#27
Update for anyone curious. A week ago my car finally threw a check engine light with rich codes for both banks. A day later it went away , then came back the next day. Yesterday I replaced the air filters and cleaned the MAFs . Car has been running 10x better. No more sputtering or hesitation, electric to gas transitions are smooth again and mpg has already increased. Hopefully this fix sticks.
05-09-21, 05:26 PM
#28
02-23-22, 05:31 AM
#29
2nd gear
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03-27-22, 07:51 AM
#30
Intermediate
Thread Starter
After all these years I ended up at some point redoing the whole front end suspension (8 control arms, sway bar bushing, tie rod, etc) and what seems to have improved this issue the most is when I ended up replacing both front air shock. When decelerating now especially going down an incline you can feel a bit of the regenerative operation going on but it's much better and feel like normal vehicule operation now. I also suspected that the car was never aligned properly because of the compromised control arm and ended up wearing tires unevenly which made the matter worse. Now I have new tires and brand new front end suspension and it seems to have resolved the issue for me.
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