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Confirmed: Driveshaft In 08 Is Still "pnm5"


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Hey everyone,

So, I crawled underneath the car ('08 GX470, Manufacture Date - 2/08) yesterday and saw the sticker on the driveshaft. It has the designation "PNM5" on it, so it's the same driveshaft as on the '03 to the '07's. I don't know why in the world Lexus would not simply put in the updated driveshaft in the TSB which is "PNMO."

Yet, the Lexus service/parts people at my dealership confirm that the "new" driveshaft is already in the '08's.

Can anyone shed some light on this?

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Hey everyone,

So, I crawled underneath the car ('08 GX470, Manufacture Date - 2/08) yesterday and saw the sticker on the driveshaft. It has the designation "PNM5" on it, so it's the same driveshaft as on the '03 to the '07's. I don't know why in the world Lexus would not simply put in the updated driveshaft in the TSB which is "PNMO."

Yet, the Lexus service/parts people at my dealership confirm that the "new" driveshaft is already in the '08's.

Can anyone shed some light on this?

I took my 2008 GX470 (purchased in late March, 2008) to the dealer yesterday to change the plastic piece that covers the speedometer/tach/etc (because of scratches on the back/inside side, for the second time), and the clunk issue came up (I brought it up). They had no problem making the changes (TSB). The service manager, without hesitation, said, and I quote “I would be glad to complete the TSB” (which only technically goes through 2007), and said he would check to see if he had the parts. He did. They began to complete the TSB right then (same day), but, corporate said no, claiming my 2008 should already have the new parts. My dealer argued with them, stating that their customer had experienced the clunk (I experienced it only two times (1400 miles), and this is what I told him). They (corporate) agreed to allow the dealer to change the driveshaft, but not the arms (upper/lower, two sets of two). My dealer changed the driveshaft. My dealer said that the driveshafts were, without question, different, but they could see no visible difference in the arms (note that they did not really look closely (measure them), so there may really be some difference; I have read that the new ones are larger in diameter but do not know if mine has the new or the old). The dealer (service manager) also said that the numbers on the driveshaft don't mean much. They use the part numbers specified in the TSB, and the numbers on the driveshaft may not be the same when ordering the driveshaft by the part number in the TSB.

The service manager and I spent at least 1/2 hour looking for some mention of the VIN regarding the clunk issue. We could not find any. There seems to be nothing in the VIN that would tell them/you if or if not the clunk TSB is included. The bottom line is that the dealer has no easy way to determine if you have or not the new driveshaft and arms. They just go by complaints. If you complain, and based only on the complaint, they (the dealer) should/may apply the TSB, but corporate may prevent them from doing the entire TSB, or any of it depending on the vehicle and how strongly the dealer is willing to argue with them on your behalf. When I say prevent, I mean of course, they will not pay for it.

I have not driven the vehicle long enough to see if the clunk is gone. I have not experienced it yet, but hardly did before. Since I have only driven 40 miles since the driveshaft change (due to my three recent surgeries) I really don’t know if it is fixed. I cannot really tell any difference except that it may shift a little smoother. One last note, the service manager said that the biggest part of the clunk problem is lack of grease in the drive shaft (the end that goes into the transmission, I think, and which has no grease fitting). He grease mine up when he installed it. The other end has a grease fitting but since it is not mentioned in the dealer prep documentation only experienced techs will know to grease this as part of the prep before sale. He said, as the driveshaft gets drier and drier (grease melts or thins out) the worse the clunk will be. He gets his 2007 GX470 greased (the driveshaft) at every oil change, and we agreed that he would do the same to mine at every oil change.

Omegaman

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Hey everyone,

So, I crawled underneath the car ('08 GX470, Manufacture Date - 2/08) yesterday and saw the sticker on the driveshaft. It has the designation "PNM5" on it, so it's the same driveshaft as on the '03 to the '07's. I don't know why in the world Lexus would not simply put in the updated driveshaft in the TSB which is "PNMO."

Yet, the Lexus service/parts people at my dealership confirm that the "new" driveshaft is already in the '08's.

Can anyone shed some light on this?

I took my 2008 GX470 (purchased in late March, 2008) to the dealer yesterday to change the plastic piece that covers the speedometer/tach/etc (because of scratches on the back/inside side, for the second time), and the clunk issue came up (I brought it up). They had no problem making the changes (TSB). The service manager, without hesitation, said, and I quote “I would be glad to complete the TSB” (which only technically goes through 2007), and said he would check to see if he had the parts. He did. They began to complete the TSB right then (same day), but, corporate said no, claiming my 2008 should already have the new parts. My dealer argued with them, stating that their customer had experienced the clunk (I experienced it only two times (1400 miles), and this is what I told him). They (corporate) agreed to allow the dealer to change the driveshaft, but not the arms (upper/lower, two sets of two). My dealer changed the driveshaft. My dealer said that the driveshafts were, without question, different, but they could see no visible difference in the arms (note that they did not really look closely (measure them), so there may really be some difference; I have read that the new ones are larger in diameter but do not know if mine has the new or the old). The dealer (service manager) also said that the numbers on the driveshaft don't mean much. They use the part numbers specified in the TSB, and the numbers on the driveshaft may not be the same when ordering the driveshaft by the part number in the TSB.

The service manager and I spent at least 1/2 hour looking for some mention of the VIN regarding the clunk issue. We could not find any. There seems to be nothing in the VIN that would tell them/you if or if not the clunk TSB is included. The bottom line is that the dealer has no easy way to determine if you have or not the new driveshaft and arms. They just go by complaints. If you complain, and based only on the complaint, they (the dealer) should/may apply the TSB, but corporate may prevent them from doing the entire TSB, or any of it depending on the vehicle and how strongly the dealer is willing to argue with them on your behalf. When I say prevent, I mean of course, they will not pay for it.

I have not driven the vehicle long enough to see if the clunk is gone. I have not experienced it yet, but hardly did before. Since I have only driven 40 miles since the driveshaft change (due to my three recent surgeries) I really don’t know if it is fixed. I cannot really tell any difference except that it may shift a little smoother. One last note, the service manager said that the biggest part of the clunk problem is lack of grease in the drive shaft (the end that goes into the transmission, I think, and which has no grease fitting). He grease mine up when he installed it. The other end has a grease fitting but since it is not mentioned in the dealer prep documentation only experienced techs will know to grease this as part of the prep before sale. He said, as the driveshaft gets drier and drier (grease melts or thins out) the worse the clunk will be. He gets his 2007 GX470 greased (the driveshaft) at every oil change, and we agreed that he would do the same to mine at every oil change.

Omegaman

Thanks for the information - - I'm going to follow up with my dealership sooner or later on this and although I don't feel the "clunk" when stopping, it's a different story when I have my A/C on. When the A/C cycles on, my rpms go up a bit for a brief second or two and sometimes, I feel a little push from behind. I think it may be the increase in rpm. Does this happen to you? Not many '08 owners here yet, so figured you may have experienced this as well?

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Hey everyone,

So, I crawled underneath the car ('08 GX470, Manufacture Date - 2/08) yesterday and saw the sticker on the driveshaft. It has the designation "PNM5" on it, so it's the same driveshaft as on the '03 to the '07's. I don't know why in the world Lexus would not simply put in the updated driveshaft in the TSB which is "PNMO."

Yet, the Lexus service/parts people at my dealership confirm that the "new" driveshaft is already in the '08's.

Can anyone shed some light on this?

I took my 2008 GX470 (purchased in late March, 2008) to the dealer yesterday to change the plastic piece that covers the speedometer/tach/etc (because of scratches on the back/inside side, for the second time), and the clunk issue came up (I brought it up). They had no problem making the changes (TSB). The service manager, without hesitation, said, and I quote “I would be glad to complete the TSB” (which only technically goes through 2007), and said he would check to see if he had the parts. He did. They began to complete the TSB right then (same day), but, corporate said no, claiming my 2008 should already have the new parts. My dealer argued with them, stating that their customer had experienced the clunk (I experienced it only two times (1400 miles), and this is what I told him). They (corporate) agreed to allow the dealer to change the driveshaft, but not the arms (upper/lower, two sets of two). My dealer changed the driveshaft. My dealer said that the driveshafts were, without question, different, but they could see no visible difference in the arms (note that they did not really look closely (measure them), so there may really be some difference; I have read that the new ones are larger in diameter but do not know if mine has the new or the old). The dealer (service manager) also said that the numbers on the driveshaft don't mean much. They use the part numbers specified in the TSB, and the numbers on the driveshaft may not be the same when ordering the driveshaft by the part number in the TSB.

The service manager and I spent at least 1/2 hour looking for some mention of the VIN regarding the clunk issue. We could not find any. There seems to be nothing in the VIN that would tell them/you if or if not the clunk TSB is included. The bottom line is that the dealer has no easy way to determine if you have or not the new driveshaft and arms. They just go by complaints. If you complain, and based only on the complaint, they (the dealer) should/may apply the TSB, but corporate may prevent them from doing the entire TSB, or any of it depending on the vehicle and how strongly the dealer is willing to argue with them on your behalf. When I say prevent, I mean of course, they will not pay for it.

I have not driven the vehicle long enough to see if the clunk is gone. I have not experienced it yet, but hardly did before. Since I have only driven 40 miles since the driveshaft change (due to my three recent surgeries) I really don’t know if it is fixed. I cannot really tell any difference except that it may shift a little smoother. One last note, the service manager said that the biggest part of the clunk problem is lack of grease in the drive shaft (the end that goes into the transmission, I think, and which has no grease fitting). He grease mine up when he installed it. The other end has a grease fitting but since it is not mentioned in the dealer prep documentation only experienced techs will know to grease this as part of the prep before sale. He said, as the driveshaft gets drier and drier (grease melts or thins out) the worse the clunk will be. He gets his 2007 GX470 greased (the driveshaft) at every oil change, and we agreed that he would do the same to mine at every oil change.

Omegaman

Thanks for the information - - I'm going to follow up with my dealership sooner or later on this and although I don't feel the "clunk" when stopping, it's a different story when I have my A/C on. When the A/C cycles on, my rpms go up a bit for a brief second or two and sometimes, I feel a little push from behind. I think it may be the increase in rpm. Does this happen to you? Not many '08 owners here yet, so figured you may have experienced this as well?

No, I have not had that happen to me that I noticed. I will let you know if I do. I only experienced the "clunk" twice, so it did not happen very often, in my case. I do have a little more information that explains, and helps at least me to understand, what is happening with the “clunk” –

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.

About the A/C, it is normal for the RPM to go up for a second or two when the A/C engages. This is to compensate for the extra load placed on the engine when the pump is started. The question is; can the A/C cause the “clunk”. I do not know for sure. One way that it could would be if the increase in RPM causes the hydraulic system that raises and lowers the back of the vehicle to do so faster i.e. increase the pressure. This increase in pressure could put more force/strain on the driveshaft, causing it to turn to seat itself. My suggestion would be to pay particular attention when stopping and see if you ever experience the “clunk” when the A/C does not come on, or is off altogether. If it does, it doesn’t prove the A/C cannot cause the “clunk”, but does prove that the A/C is not the only cause of the clunk. In my case, I saw no correlation between the “clunk” and the A/C. My opinion is that the A/C is not the root cause of the problem, but may have some affect on how often, and/or how much, the “clunk” happens and you feel it.

Finally; the most important thing to remember is that the hotter the components (driveshaft) gets, and the more the height control system has to adjust to find normal, the more often/likely the “clunk” is to occur. This implies that a hotter day, longer driving period before a stop, hard driving, fast starts and stops, etc. should cause the problem to occur much more often. I should add that if not firmly holding the brake when the RPM goes up, the vehicle could/would move forward. This could be in combination with, or entirely separate from, the clunk.

Omegaman

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