MTN4RNR
New member
Ha, then I am completely useless with no good ideas or solutions then! :whoo:
Best of luck!
vibration when accelerating on sharp turns
- Thread starter 4Runner_101
- Start date
Ha, then I am completely useless with no good ideas or solutions then! :whoo:
Best of luck!
It's probably somewhat normal. I have a 4th gen, an I notice that it vibrates if I'm turning while backing up. Sometimes it does it a little when going forward, too.
I changed the transfer case fluid earlier this year, but the old fluid that came out looked like new. I can't remember if it did it before I changed the fluid or not. The dealer might or might not have changed it a couple times before I owned the vehicle.
I don't have a very good understanding of how the Torsen diff works, but my impression is that if you are coasting it acts like an open diff. If you are accelerating (or engine braking), gearing inside it applies more torque to the slower output shaft. There's not friction material or viscous coupling to wear out. It will supposedly never wear out.
I don't know why it vibrates. There are a lot of moving parts in the Torsen diff. And when you are accelerating and turning, I think it's essentially binding up like a locked diff (though not quite as solid).
Let's say you are turning and accelerating. The front axle wants to turn faster than the rear because it follows a wider circle. The Torsen diff sees that the rear is turning slower, so it sends more torque to the rear. But the front is not free-wheeling like it would be in 2WD. It's also connected to an output of the diff, and it's not allowed to turn faster until the rear starts turning faster. I think the input torque from the engine essentially locks the diff, though it's not a solid lock. The more torque there is from the engine, the harder it is locked.
Hopefully my explanation makes sense. Look up some videos of how Torsen diffs work and it might help. I really want a model of one to play with to help understand it.
I changed the transfer case fluid earlier this year, but the old fluid that came out looked like new. I can't remember if it did it before I changed the fluid or not. The dealer might or might not have changed it a couple times before I owned the vehicle.
I don't have a very good understanding of how the Torsen diff works, but my impression is that if you are coasting it acts like an open diff. If you are accelerating (or engine braking), gearing inside it applies more torque to the slower output shaft. There's not friction material or viscous coupling to wear out. It will supposedly never wear out.
I don't know why it vibrates. There are a lot of moving parts in the Torsen diff. And when you are accelerating and turning, I think it's essentially binding up like a locked diff (though not quite as solid).
Let's say you are turning and accelerating. The front axle wants to turn faster than the rear because it follows a wider circle. The Torsen diff sees that the rear is turning slower, so it sends more torque to the rear. But the front is not free-wheeling like it would be in 2WD. It's also connected to an output of the diff, and it's not allowed to turn faster until the rear starts turning faster. I think the input torque from the engine essentially locks the diff, though it's not a solid lock. The more torque there is from the engine, the harder it is locked.
Hopefully my explanation makes sense. Look up some videos of how Torsen diffs work and it might help. I really want a model of one to play with to help understand it.
SkidPalace
Member
At the dealer right now. The techs were able to reproduce the vibration based on my description but do not know if it is normal or not. They are going to grab a new LE right now to compare.
Stay tuned...
Stay tuned...
JB.
New member
This is normal behavior from the Torsen center differential as the vibration resonates with the rear diff and is felt in the floor.
Very tight, slow speed turn, while under engine load. Everyone doesn't feel it because it's usually very subtle and apparently only crosses a certain threshold in certain vehicles.
I've periodically replied to deaf ears and skepticism about this for years on the 4th gen forum -- understandably, since I'm just a guy on the internet -- but for a while I naively over-estimated how much weight would be placed on my history of careful vetting of information -- but documentation is king, as well it should be. Unfortunately, I was always unable to find the documentation from which the info had come, until now. Guess I had just been lazy, as I found it this time with less effort than I expected. Hopefully, this will put the issue to rest or at least provide a link for instances when this will undoubtedly come up again. This is a good place for the information as the OP did a decent job of thread title construction.
See "3.6 NV performance" in this doc: http://webpages.charter.net/a7037196/misc/trasmissione.pdf
Very tight, slow speed turn, while under engine load. Everyone doesn't feel it because it's usually very subtle and apparently only crosses a certain threshold in certain vehicles.
I've periodically replied to deaf ears and skepticism about this for years on the 4th gen forum -- understandably, since I'm just a guy on the internet -- but for a while I naively over-estimated how much weight would be placed on my history of careful vetting of information -- but documentation is king, as well it should be. Unfortunately, I was always unable to find the documentation from which the info had come, until now. Guess I had just been lazy, as I found it this time with less effort than I expected. Hopefully, this will put the issue to rest or at least provide a link for instances when this will undoubtedly come up again. This is a good place for the information as the OP did a decent job of thread title construction.
See "3.6 NV performance" in this doc: http://webpages.charter.net/a7037196/misc/trasmissione.pdf
SkidPalace
Member
Certainly sounds plausible JB. I would say that you have nailed the case shut. Unfortunately for me, I have realized that I might have a separate issue. Yes, I had the low speed high differential (turning) judder and the article explains that to great detail in section 3.6.
However my issue is most noticeable cruising between 30 and 40 mph in higher gears and applying throttle to around 1500 rpm, being more pronounced when turning. And it is a vibration in the wheel, pedal and floor more than a judder in the floor per the article. I hope to find out that my truck is behaving normally, but now I am not so sure. Unfortunately the dealer had no other LEs available on the lot for driving comparison. They lubed the drive shaft hoping for a simple fix, but that made no difference. I am supposed to bring it back in and leave it for the day so they could call Toyota to troubleshoot the problem. I will probably wait to take out a new LE just to see if that vehicle makes the same vibrations before I waste a day at the dealer.
Thanks to your article, I have just now realized that my issue is a separate one. Therefore I will spin off my situation to a new thread so as to not muddy up the original OP's topic.
That does sound a bit different than the low speed turning vibration I have. I don't think I've noticed the kind of vibration you describe.
In a 4th gen V6, there will be some vibration, almost more of a low frequency sound like the thumping if you have only one window open, if the engine is at the lowest RPM before the transmission downshifts when you are going about 30-50mph. It usually happens at a specific speed in that range, but I can't remember what. I don't think the V8 does it because it is smoother at low speeds.
There's also the "rumble strip transmission" issue with some 4th gens. I don't think anyone has ever figured out a definitive cause, but there's some stuff you can put in the transmission that supposedly helps. A brand new one shouldn't need it unless something is wrong.
The fact that it gets worse when you are turning suggests it could be a CV joint, or something like that. You would probably feel that in the steering wheel more than other types of vibrations.
Higher frequency vibration, more like humming, could mean the gears in one of the diffs are not adjusted properly. But that would probably be noticeable at all speeds.
Does it go away when you lock the center diff?
In a 4th gen V6, there will be some vibration, almost more of a low frequency sound like the thumping if you have only one window open, if the engine is at the lowest RPM before the transmission downshifts when you are going about 30-50mph. It usually happens at a specific speed in that range, but I can't remember what. I don't think the V8 does it because it is smoother at low speeds.
There's also the "rumble strip transmission" issue with some 4th gens. I don't think anyone has ever figured out a definitive cause, but there's some stuff you can put in the transmission that supposedly helps. A brand new one shouldn't need it unless something is wrong.
The fact that it gets worse when you are turning suggests it could be a CV joint, or something like that. You would probably feel that in the steering wheel more than other types of vibrations.
Higher frequency vibration, more like humming, could mean the gears in one of the diffs are not adjusted properly. But that would probably be noticeable at all speeds.
Does it go away when you lock the center diff?
joshuawhite1992
New member
Does it feel like it’s binding?
Hungryhawk
Member
Have you checked the tranny ATF?
The Toyota FlexLock torque converter control solenoid in the tranny valve body locks and unlocks rapidly ( to slip the clutch,so to speak) . I am sure its sensitive to correct fluid levels.
Add Lubegard to tranny to see if it stops.
The Toyota FlexLock torque converter control solenoid in the tranny valve body locks and unlocks rapidly ( to slip the clutch,so to speak) . I am sure its sensitive to correct fluid levels.
Add Lubegard to tranny to see if it stops.
Trans fluid level is perfect.
So I had a very similar issue as OP describes in my '17 Tacoma OR. The trans fluid was about half a quart low. I initially took it to the stealership who wante to replace the whole trans. They said that it was the torque converter - they don't replace just that, so they swap the whole trans ($6500). I took it home, drained and filled the ATF and replaced the filter. I didn't notice any metal shards in what I drained, but I did neglect to cut the filter open to check inside. After I closed it and filled it back up, no more shudder. Folks on the TW forums were saying the Tacomas were coming from the factory with low ATF. Wild. Hope this helps....
