i have a 2005 350Z enthusiast model with auto trans. when in manual shift mode, i experience a thump(as defined by nissan) noise from the rear axle. after 3 trips to the dealership and a complaint to nissan corp, nissan's position is it's a normal operation.

if anyone else experience the same problem, please advise.

ps - i've noticed there's a service bulletin for 2003 & 2004 on rear axle noise. but nissan is adimant it's not the same problem.

 

if your talking about a thump when you shift under wot then its normal. its one of two things. either the torque converter or the differential recieving a surge in power through the drive shaft. in any case its totally normal and happens in most manual trans. car also.

 

i realize on a manual transmission car, if the clutch is dropped too fast, then one can hear the thump as power is tranferred to the rear axle. however, on a auto with manual shift mode, shouldn't that not happen? is there something wrong with the torque converter??

please advise.

 

I bet its the 2nd to 3rd gear shift. Lots of people have it and many have asked the dealer and all have come back as normal. I have a grounding kit and it has helped eliminate most of it. If you shift over 3k, it happens much less.

 

no, nothing is wrong with your converter. it shouldn't make the thumping from the rear unless your shifting at wot in manual mode. mine never makes the thumping from the differential unless i shift while i have it floored (and really only occurs when shifting from 1st to 2nd or 2nd to 3rd). i'd say that it's caused by the blades in the tranny spinning faster after giving it some gas and that increased motion transfers from their to the drive shaft and into the differential. when that sudden surge of power hits the differential the axles resist and thumping noise is produced. just a theory though.

 

thanks for all your inputs. the thump noise in my car is only heard from 2nd to 3rd gear, regardless of rpm. this is my 1st auto with manual shift car. nissan's customer service regarding this problem is definitely a joke, at best. i am in california and thinking about getting an attorney for lemon car claim.

 

Honestly, if that is your only gripe, then may not have much of a case. As I said before, many people have this for their manumatic (not the majority, but a significant amount). This has been brought up in the G35 forums too and none who have this problem has ever reported their tranny going bad. One person had their technician describe it to them and they referred to it as a "torque slap". I have the thump between 2nd to 3rd and it has gone mostly away by getting a grounding kit (a good one) and shifting a little over 3k (although if I am at WOT and short shift, it sometimes still thumps). Either way, good luck and let me know how things go with the lemon law route.