Hi guys,

I'm from Australia, the car is imported from Japan so please bear with me when I say driver side is opposite from you.

Last week I purchased a 2008 V36 Sedan 370GT 7 speed Auto. Bought from a dealer at 56000kms. From day one I have been hearing this low frequency pulsating vibration and the faster I go the quicker the sound cycles. I'll be brief but descriptive here so I hope someone here can shine a light to this as I am totally stumped. The car still has the 3 months stat warranty but as everybody know dealer screws you around unless you pin point what the problem is.

Car is completely stock

The sound:

1. Low frequency (i.e when you drive over the fairly gapped ripple strip as you approach a toll gate)
2. Gets more frequent the faster you go - gets you nuts at 100km/h
3. It pulsates - loud none loud none
4. If I swerve the car to the left (all the weight on the driver side) the sound amplifies
5. It is felt through the car body
6. Steering does NOT shake at any speed (not wheel balancing)
7. Steering does NOT shake whilst braking (not warped discs)
8. Sound is irrelevant to engine RPM (I dropped gears at 100km/h or put it in neutral and the sound is still there)

What I have tried to rule out few possibilities:

1. Tyres - I originally thought it is because of the cheap chinese brand new tyres they put on during compliance. However, just then, I fitted another oem nissan same size wheels all round with michelin tyres that have NO issues. Sound is STILL there.

2. Re-check all suspension related bolts including tail shaft bolts, none were loose. Sound is STILL there

3. Wheel bearing - now this could be the debatable culprit. I checked for play, there was NO play. However I read online that even if there is no play the wheel bearing, it could still be in the early stages of failing.

4. Bushings - Car was on hoist, I checked all bushings for signs of wear or cracks. Nothing, everything was good.

5. Stuck caliper - Whilst the car still up, I spun all the wheels. Both rears has slight resistance (due to the drive train) but nothing was abnormal. Also been driving for a week, I would of noticed if the pads were cooking.


I pretty much did what a normal mechanic would do, bringing it to the dealer they would end up doing the same thing and do the catch 22 on me UNLESS I can sort of pin point where the problem is. Pretty stumped, please help! T.T

Cheers.

 

Welcome. Pretty thorough analysis. I can see you are trying hard.

Can you jack the car up and run it in gear with both wheels spinning? My thought is, you will SEE the vibration area at that point. Bent axle? Driveshaft? Both of them are speed (not engine) dependent.

I'd hoist it on jackstands or a lift, and see what gives.

Coop

 

Yeah, I would guess driveshaft or axle is somehow out of balance. I'm assuming the axles are stock? If not, maybe one was replaced by a cheap third party manufacturer. Or CV joints going bad? Play in the output shaft of the transmission? Or play on the front side of the driveshaft that connects to the tranny?

 

Tire cupping or feathering?

 

Could also be the pulley or the belt around it. You may be right by it being the wheel bearing. You need to lift up the car and put it in gear. Have you checked the rear differential oil too maybe it's a lubrication problem.