Ve v6 Strange shaking at highway speeds

[bfhoon]

Hi Everyone

I know this is going to be a hard to answer question as there is so many variables but maybe this has happened to someone before or someone may have some good starting points.

My Ve drives perfect trouble free under about 90klms per hour. Once I hot above 90 to 110 the car shakes a bit like something is a miss. I notice it as soon as I get on the highway and hit 110. I usually set cruise control and you dont actually feel it through the steering wheel but the car shakes like the seat im sitting in you can feel shaking vibrations in it andif you have a bottle of water sitting in the cup holder it shakes pretty bad. I have tried going quicker and the shaking is still there. But just driving around 80klms per hour no shaking whatsoever. It seems to sometimes on the highway go away for a bit but then comes back. When i hit the brakes its fine no shaking on the steering etc it just has me worried as im doing a 12 hour drive next week and the shaking the whole way is really going to piss me off. Both tyres on the front 80 per cent tread rears are worn down pretty bad just above legal limit plan on getting new tyres on the rears on my return. I dont think it would be tyres. Could bad wheel bearings make the car shake a bit like this im guessing if its wheel bearings though wouldnt you feel it through the steering


Thanks

 

[MYVESSV8]

, rear balance, centre bearing, front wheel alignment, to name a few

 

[UFO]

The fact you dont feel the shaking through the steering wheel but from underneath your seat, tells me its drivetrain related... so I'd concentrate on that for the time being.

First thing I'd try to work out if it's selected gear related, or rev related, or consistent regardless of gear or revs.
Is your car auto or manual out of curiosity?

You said it only happens above 90, and gets more noticeable at 110. At what revs does it occur and in what gear?
Does it only occur in that gear, or does it go away if selecting a different gear at those speeds.
If you select a different gear and then go at 90 to 110 (forcing the engine to use a higher or lower rev range) does the problem still occur at the same speeds?
If so, you can eliminate particular gears as the problem and work back.
It could be the final drive gear of the gearbox, or the driveshaft itself.

When the shaking occurs, is it only under load or does it do it even when coasting?
Does slipping it into neutral at 110 and coasting down to 90 cause the shaking to stop or is it still there?

Any unusual noise associated with the shaking? Whirring? If so is it high pitched or low?

Unlike electronic issues, mechanical issues in cars like this can be narrowed down pretty quickly when you try and replicate the problem under different scenarios.

Give me answers to the above and we'll try and at least narrow it down a bit.

How many k's has your VE done?
Has it had any major work done to it? New engine, new gearbox/drivetrain components, or major work due to prangs?

I'm leaning towards it being a driveshaft issue, but this normally doesnt happen on its own. Any work done on drivetrain recently?

 

[ModySLR]

I think I know what your car is doing. I had the same issue with mine (2009 Commodore V - V6 - Auto-4spd.). I have spent a lot of time to diagnose the bloody thing. Replaced Rotors (worn-out anyway), rear left and right spindles, and balancing the tires. Still did nothing to the vibrations. Until I checked the suspension bushings, and I found that rear upper-inner suspension bushing, it appeared like there was nothing wrong with it until I removed the arm. It was torn inside! I replcaed it and voilla! the car is smooth again.

What I would suggest is checking all the bushings first, as mine did that at 80K.

 

[bfhoon]

I think I know what your car is doing. I had the same issue with mine (2009 Commodore V - V6 - Auto-4spd.). I have spent a lot of time to diagnose the bloody thing. Replaced Rotors (worn-out anyway), rear left and right spindles, and balancing the tires. Still did nothing to the vibrations. Until I checked the suspension bushings, and I found that rear upper-inner suspension bushing, it appeared like there was nothing wrong with it until I removed the arm. It was torn inside! I replcaed it and voilla! the car is smooth again.

What I would suggest is checking all the bushings first, as mine did that at 80K.

Hi

Thanks for the info maybe that is it car has done 220,000 klms and when I firt got it the l/h front rotor was uneven replaced that which stopped vibration when braking. Im not the best around naming suspension components any chance you could link me to a photo of what I should be looking at.

Cheers

 

[ModySLR]

Hi

Thanks for the info maybe that is it car has done 220,000 klms and when I firt got it the l/h front rotor was uneven replaced that which stopped vibration when braking. Im not the best around naming suspension components any chance you could link me to a photo of what I should be looking at.

Cheers

Hi.
The first picture is for the bushing that solved the issue for me. The second one is for the diagram of the location. Look at number 2. If the one you found in your car is the same as the picture, that means that you have iron suspension. If it was different, then it is an aluminium suspension.