What Is "the Clunk"? Options

[Gravity]

What exactly is “the clunk”? I read a good portion of the pinned post on the issue but I can’t seem to find what it is and when it happens.

I have an 07 so I’m guessing that it isn’t an issue with this model year.

One thing I do experience is this. As I slowly pull up to a stop sign or red light and just before the vehicle comes to a complete stop it feels like something releases. The truck kind of lets go of something like the transmission is going into neutral.

I don’t hear a clunk so I’m assuming it’s something else.

G

[GX 470 law]

What exactly is “the clunk”? I read a good portion of the pinned post on the issue but I can’t seem to find what it is and when it happens.

I have an 07 so I’m guessing that it isn’t an issue with this model year.

One thing I do experience is this. As I slowly pull up to a stop sign or red light and just before the vehicle comes to a complete stop it feels like something releases. The truck kind of lets go of something like the transmission is going into neutral.

I don’t hear a clunk so I’m assuming it’s something else.

G

Unfortunately, the clunk affects 2003- 2007 AND, even the 2008, as I have come to learn. The Clunk is felt when you are slowing down or when you come to a stop, 1-2 seconds later, you feel a lovetap or a slight "clunk" from the rear. There's a technical service bulletin for this from Lexus and they will change the driveshaft and control arms for 2003-2007. As far as I know, it's just an annoyance and no safety implications.

[Omegaman]

The clunk is related to the dynamic height control system. The GX470 dynamically adjusts the height of the back end of the vehicle based on road conditions and how it is being driven, in order to give a smoother ride. When you come to a stop, the height adjustment system will lower or raise itself to place the height at its normal position. When this happens, the driveshaft is going to move forward or aft and the arms are going to experience more or less force/strain. Because of the design of the driveshaft, and its lack of grease, it has heated up and thus now has a tighter fit. When the driveshaft is being forced to move by the height changing it has less friction in the rotational sphere then in the forward/backward directions and then it turns until it seats itself, i.e. relieves the forces or stabilizes. This is what causes the sense of being pushed forward, because in affect you are.

Given the above explanation of what is happening, anything under the vehicle, especially in the back or that is part of the drive train, can have an effect on how much or little you feel the “clunk”. The new driveshaft has been changed to give it extra play forward and back so that it will move more freely in those directions rather than rotating, without causing enough play to cause other noise or functional problems. This is also why keeping it greased helps a great deal. Grease provides less friction as well as keeping the shaft cooler, which also reduces friction. The new arms have been changed to be able to better handle the forces placed on them by the height control system, as well as all the forces present in any vehicle.

Omegaman

[Gravity]

Great explanation O-man !!

Thanks. I think I have experienced this sensationn a few times. I'm getting a hitch installed next week so I'll have them check for this TSB on mine.

G

[scanboy]

Will they send you letter telling you to go to a dealer to fix it, or nothing will be done unless you complain?

[The G Man]

Nothing will be done unless you complain.

[Carol]

I have almost 25000 miles on my 06 now and have been hearing and feeling that "klunk" recently. It's not really that bothersome to me but I don't want to let it go either. Any input on if I should get it taken care of right away or not worry and let it wait a bit. I will be having service very soon. How long does it take to have it fixed and they will do it free of charge I assume? Thanks......

[The G Man]

It takes about 2 to 3 hours to fix the clunk, no charge since its a warranty issue. Ask the dealer if he has the parts and ask for a loaner car.

[2klx470]

It takes about 2 to 3 hours to fix the clunk, no charge since its a warranty issue. Ask the dealer if he has the parts and ask for a loaner car.

I read somewhere that this is covered under the powertrain warranty, which I believe is 7 years or 70k miles (whichever comes first).

Is this accurate information as far as the "clunk" getting repaired at no charge (warranty)?

[denslexusgx470]

Honestly, I forgot to ask where the clunk would fall into what warranty category. I would PRESUME it's powertrain, but don't quote me on that. Ask your Lexus dealer for details. It took my dealer about 6-8 hours of labor to fix mine so I got a loaner car on the day I had mine done.

And YES the clunk should be covered under warranty, so it should be fixed for NO CHARGE if you do have the defect and if you still have warranty left.

[mkupchyk]

http://www.lexustsb.com/index.php?action=a...&artlang=en

Link to the actual TSB

I heard that the Driveshaft/Propeller shaft is covered under the 70k powertrain warranty, but the Suspension Control Arms are not. I am unsure if that is really true & people that had the fix did not report being charged for the arms. (I think the labor for everything would be covered, but maybe only some of the parts.)

[Jimi James]

First post as I'm doing some homework on my upcoming purchase.....I'm just about to purchase an 07 GX later this week so I'll be listening for this for sure. I assume that this problem is fixed at n/c in Canada as well.....somebody please let me know if you know different.

Also, does anyone know if this also affects the 4Runner? My dad owns an 04 4runner with the self leveling rear end option and his does the same thing just before he comes to a stop. We were talking about it just the other day wondering what it was.

Thanks.

[The G Man]

Yeah, the 4runner has the same problem. The difference is that Toyota will not fix the problem for the 4runner.

[eugene.s]

The clunk is related to the dynamic height control system. The GX470 dynamically adjusts the height of the back end of the vehicle based on road conditions and how it is being driven, in order to give a smoother ride. When you come to a stop, the height adjustment system will lower or raise itself to place the height at its normal position. When this happens, the driveshaft is going to move forward or aft and the arms are going to experience more or less force/strain. Because of the design of the driveshaft, and its lack of grease, it has heated up and thus now has a tighter fit. When the driveshaft is being forced to move by the height changing it has less friction in the rotational sphere then in the forward/backward directions and then it turns until it seats itself, i.e. relieves the forces or stabilizes. This is what causes the sense of being pushed forward, because in affect you are.

Given the above explanation of what is happening, anything under the vehicle, especially in the back or that is part of the drive train, can have an effect on how much or little you feel the “clunk”. The new driveshaft has been changed to give it extra play forward and back so that it will move more freely in those directions rather than rotating, without causing enough play to cause other noise or functional problems. This is also why keeping it greased helps a great deal. Grease provides less friction as well as keeping the shaft cooler, which also reduces friction. The new arms have been changed to be able to better handle the forces placed on them by the height control system, as well as all the forces present in any vehicle.

Omegaman

I would assume if you turn off the dynamic suspension system (or how its called) using the "off" button by the stern up/down controls, it would be a good short-term solution?

[The G Man]

The rear height air system cannot be turn off.