mistaboosta

iTrader: (1)

The question is, as the rpms rise there is a noticable vibration at the car. You dont feel it normally but if you hold the shift know as the rpms are rising you can feel it. It is like this from the first day i bought this car (i bought new). Does anyone know why that could be ? Do you have the same issue with your Z? Maybe it is the way VQ35 is working and i'm just not used to it.

mistaboosta

iTrader: (1)

the car is bone stock btw

g356gear

iTrader: (12)

Taken it to the dealer yet?? Could be many things. Flywheel problem, driveshaft problem, loose motor mount.........

Z BOY

iTrader: (41)

i have noticed vibration/rattling in the rear of my z with high speeds and high rpms.

mistaboosta

iTrader: (1)

my vibration is not due to driveshaft coz the vibration increases as the RPMs rise, not the speed. Could be a flywheel problem thats right, but i feel like it's something about the engine.

FCallender

If you can, put the car on a lift and look at the setup on the exhaust pipes after the manifold. A Y brace attaches with a bolt to each side and is attached in the center to the transmission case. Here some rubber grommets are used. The result of this setup is that when you reach higher rpms, say 6600, there is a lot of vibration from those pipes being transmitted to that Y brace. When you shift from 5th to 6th and slide the lever along the side of the tranny to avoid 4th the vibration goes all the way up to your shoulder. My first time on a track with the Z was at Road America where sixth gear can be used. Drove me nuts. others have felt the problem on roads like, say US 50 through Nevada.
The good news(?) is that the torque band for the VQ35 is from about 3900 to 5000 so there is rarely a need to go over 6000.
I tried putting rubber grommets on the attachments to the cats and they did have some effect, but not through the full range. Had them on for a few weeks and they seemed to handle the heat ok. Also tried removing the brace. This is probably not a good idea as it is certainly there for a reason, like chassis stiffness and torsional rigidity. Properly reducing or eliminating the problem without totally removing the brace would require sophisticated chassis tuning equipment at Nissan

mistaboosta

iTrader: (1)

Zrock,
thanks for the nice info, i need to get over this problem coz i'm willing to spin more than current redline with FI and this vibration is annoying me. I'll let u guys know if i can make out a solution.