Drive shaft noise or U joint noise (LEXUS 4/06 TSB page 18) aka Driveshaft thump/bump

New drive shaft installed

Ok, just got back form the dealer with the new drive shaft installed. I did not get the full Lexus TSB installed, only the drive shaft (PN 37110-6A480). So far, no clunk. But, it's only about 3 miles between there and work with only a couple of stops. And I haven't tried it with the AC on. I'll try that on the way home tonight. I'm also planning on taking a long drive up in the mountains this weekend (Mosquito Pass) and will see how it does.

If anyone is in the Denver area, I do recommend Elway Toyota off Arapahoe Rd. My service advisor was Marshall and he was top notch. Never once questioned the clunk and he ordered the parts right away. My truck was in and out in 3 hours which included fixing an annoying squeek in the drives seat back (adjusted the track adjuster assembly).

I'll keep everyone posted with any other changes (good or bad).
 
I agree - this is a great forum for talking these things out!! [/B]
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I agree as well. I just wish I felt like the Toyota people were monitoring it.

One of the recent posts sort of answers a question I had, which is what has been the experience of the Lexus folks who have had the repair done. Did it fix the problem? We might want to find that out before we all go in demanding that it be done to ours.
 
Re: New drive shaft installed

KimoSan said:
Ok, just got back form the dealer with the new drive shaft installed. I did not get the full Lexus TSB installed, only the drive shaft (PN 37110-6A480). So far, no clunk. But, it's only about 3 miles between there and work with only a couple of stops. And I haven't tried it with the AC on. I'll try that on the way home tonight. I'm also planning on taking a long drive up in the mountains this weekend (Mosquito Pass) and will see how it does.

If anyone is in the Denver area, I do recommend Elway Toyota off Arapahoe Rd. My service advisor was Marshall and he was top notch. Never once questioned the clunk and he ordered the parts right away. My truck was in and out in 3 hours which included fixing an annoying squeek in the drives seat back (adjusted the track adjuster assembly).

I'll keep everyone posted with any other changes (good or bad).
Click to expand...
Awesome! Let us know how it turns out. I used to live close to that dealership but someone told me that Burt on Broadway was better....NOT. Don't ever use Burt on Broadway...
 
After a couple days of close observation, I'm now convinced that the clunk is due to the cycling of the A/C compressor while stopped with the trans in a forward gear. I haven't completely figured out the decision-making process for the computer to turn off the compressor, but when it does, clunk!
For me, it's most noticable when stopping at a light after going 40+ MPH. A second or two after I stop, the RPM drops from about 800 to 500 when the A/C compressor shuts off. Apparently there's an instant in time where the compressor is off but the idle is still higher, so there's suddenly more torque available to the drivetrain, and the truck wants to scoot forward, but only a tiny bit. Greasing the joints on the driveshaft must give it enough play to absorb that slight movement without actually trying to turn the wheels. I have also confirmed an earlier finding I made that holding the brake pedal down harder does lessen the effect, anticipating that momentary burst of power.
It makes perfect sense that this clunk is present on both V6 and V8, but it seems to be a bigger deal on the V8. Bigger motor, more torque!
And you would still notice the clunk in the winter, all the way down to 32 deg. F, because the auto climate control uses the A/C as a dehumidifier in the winter. As long as it's above freezing outside, it will run the compressor as it deems necessary.
All this time we've been looking for some magical release of energy from a wound-up driveshaft or loose rear axle suspension. If I'm correct, this might actually be fixable with software for the engine ECU to change the sequence of events surrounding the cutoff of the compressor. Bring the idle down before shutting it off, or maybe wait longer to shut it off. The computer shuts it off as a paranoid precaution to prevent overheating of the engine. If you wait 2-3 mintes to make that decision, the light will have turned green!
 
toto said:
After a couple days of close observation, I'm now convinced that the clunk is due to the cycling of the A/C compressor while stopped with the trans in a forward gear. I haven't completely figured out the decision-making process for the computer to turn off the compressor, but when it does, clunk!
For me, it's most noticable when stopping at a light after going 40+ MPH. A second or two after I stop, the RPM drops from about 800 to 500 when the A/C compressor shuts off. Apparently there's an instant in time where the compressor is off but the idle is still higher, so there's suddenly more torque available to the drivetrain, and the truck wants to scoot forward, but only a tiny bit. Greasing the joints on the driveshaft must give it enough play to absorb that slight movement without actually trying to turn the wheels. I have also confirmed an earlier finding I made that holding the brake pedal down harder does lessen the effect, anticipating that momentary burst of power.
It makes perfect sense that this clunk is present on both V6 and V8, but it seems to be a bigger deal on the V8. Bigger motor, more torque!
And you would still notice the clunk in the winter, all the way down to 32 deg. F, because the auto climate control uses the A/C as a dehumidifier in the winter. As long as it's above freezing outside, it will run the compressor as it deems necessary.
All this time we've been looking for some magical release of energy from a wound-up driveshaft or loose rear axle suspension. If I'm correct, this might actually be fixable with software for the engine ECU to change the sequence of events surrounding the cutoff of the compressor. Bring the idle down before shutting it off, or maybe wait longer to shut it off. The computer shuts it off as a paranoid precaution to prevent overheating of the engine. If you wait 2-3 mintes to make that decision, the light will have turned green!
Click to expand...
Sure sounds reasonable... if your theory is correct you should charge Toyota........ lol...
 
Ok, I tested and watched my tach on the way home last night and my 30 minute drive last night to and from my parents house. AC on. I see it at 800RPM when I come to a stop. Then it dropped to 500 and stayed there. Now the thud doesn't happen every single time, but when it did the tach was at 500 and there for a few seconds and then a THUD. I can't say that I ever felt the thud when the tach jumped from 800 to 500 on Q rather it dropped to 500, sat there for a few seconds then hit the thud. Now without the AC on but AUTO still on, I didn't feel any thuds. It either isn't as noticeable or not present.
 
There has also been talk that the thud is caused by the transmission shifting into 1. I remember reading on the board that the tranny shifts down to 2 coming to a stop and then after your stopped, it drops down to 1. This to could be corrected with a reflash of the CPU.
 
I tend to agree with the downshift theory. I have been living with this clunk on my 04 SE for 2 1/2 years. I tried to analyze it many times. This is what I experience;

Drive 40+ mph
make a quick stop
keep foot firmly on the brake after coming to a complete stop
I can sit there for as long as I want with my foot on the brake
as soon as I release the brake and start to roll, I get a clunk like someone hit me in the rear bumper.

In my case, the downshift theory makes sense, almost like it was never able to roll long enough to downshift all the way to first. once I start to roll, it finishes the downshift and make the clunk.

Anybody else have a similar experience?
 
MurrayTheCat said:
I tend to agree with the downshift theory. I have been living with this clunk on my 04 SE for 2 1/2 years. I tried to analyze it many times. This is what I experience;

Drive 40+ mph
make a quick stop
keep foot firmly on the brake after coming to a complete stop
I can sit there for as long as I want with my foot on the brake
as soon as I release the brake and start to roll, I get a clunk like someone hit me in the rear bumper.

In my case, the downshift theory makes sense, almost like it was never able to roll long enough to downshift all the way to first. once I start to roll, it finishes the downshift and make the clunk.

Anybody else have a similar experience?
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I checked my 05 today.. and that's almost exactly what happens.
 
The only thing I question about this theory is that my 04 V6 has the 4 speed tranny, and I believe the V8 (and never V6's) have the 5 speed tranny. Would it be odd for both transmissions to have the same downshift problem?
 
You know, I get that when I am sitting and waiting for the light as well without moving forward at all. But yes, 99% of the time you need to drive over X speed and come to a stop and as you release the brake THUMP.

Also, I have put the car in gear and raised and lower the rear and this will cause the thump as well.

Could it be that under harder braking the rear end raises up, binds and then as you release the brakes and apply gas the klunk is the rear end coming down to the proper(normal level)? Or when the A/C kicks off the added torque also brings the rear end down just enough to free the binding parts? Just a thought.

I also agree that the A/C cycling makes the klunk more pronounced and frequent.
 
further thought....

or is wieght/torque allowing the transmssion to shift into 1st? The prospect of such a hard shift coming from the gear box, or this beeing a transmission issue is disconcerting!
 
I need to try some of these 40mph+ runs. I also notice when I release the brake I feel a thud, smaller than the normal come to a stop then 30 seconds later get the "hit from behind" thud. Now I feel that thud with or without the AC on. They should be able to reprogram the transmission shift points. I know I had my GTO's tranny tuned and they firmed up the shifts by increasing the line pressure and changed all the shifting characteristics for performance so I see no reason why they couldn't reflash these CPUs to change the way the tranny shifts making it softer. Wonder if they brake assist has anything to do with it? Like when you are going down hill and you brake and it shifts down to assist? Just another thought. It is sad we have to do the Toyota engineer's jobs.
 
I disagree with you all.... the transmission theory was my first thought but if you manually shift the tranny down, you are still able to reproduce the thud with the cycling of the A/C....

Count the gears... you can feel the truck shift.... so you know exactly what gear the vehicle is in.... I don't believe it has anything to do with the transmission.... more of a torque issue ....

Just makes me wanna :beer:
 
I read the trans idea this morning and was looking for that while driving today. Now I'm hyper-sensitive to any little vibration... watching the tach while I'm braking. I've got to be a menace to anyone else on the road. :)

I still can't reproduce the clunk without the A/C being on. And with it a little warmer here than it has been for the last few days, the A/C was cycling quite a bit today. Even just sitting and waiting to make a left turn for a couple of minutes, it cycled and clunked twice!

I feel better now that I know what it is, at least with my truck. There could very well be two issues here exhibiting the same symptoms. But I don't believe I have any issues with the trans. I know what it is, I am fairly confident replacing the driveshaft would not fix it long-term, and it's not causing any harm.

So I won't worry about it any more! :beer:
 
claydoctor said:
They lubed the driveshaft??? Did you come in late or something? Read the previous 200+ posts
Click to expand...


Yeah I read the previous posts! I am just saying, that even my toyota dealer knows about the problem and most will do you a favor and lube it for free. wow
 
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