Huge vibration 80km +

[JKruges]

Hey
When i go over 80km an hour, there are random spots where the car vibrates. it doesn't last long if i keep accelerating, but if i get to the vibration spot and keep the RPM constant it will stay.
its been happening for a few months now, and i think it may be happening more often.
the vibration is the equivalent of driving on the outer white lines that make the car vibrate on the freeway etc.. (sorry, i do not know the name.)

I had a wheel alignment a month or 2 ago, for an unrelated reason. and i am changing the uni joint on the weekend.
it would be great if you guys had any advice.

[PanthaVS]

Hey
When i go over 80km an hour, there are random spots where the car vibrates. it doesn't last long if i keep accelerating, but if i get to the vibration spot and keep the RPM constant it will stay.
its been happening for a few months now, and i think it may be happening more often.
the vibration is the equivalent of driving on the outer white lines that make the car vibrate on the freeway etc.. (sorry, i do not know the name.)

I had a wheel alignment a month or 2 ago, for an unrelated reason. and i am changing the uni joint on the weekend.
it would be great if you guys had any advice.

That should fix it... since youll have your tailshaft out... check your centre bearing as well while youre at it... it doesnt cost much, and if it's a little flogged.. change it too!

[Hangman]

Could also be a wheel out of balance.

[SP00KSTER]

+1 for the wheel balance. but it could also be the centre bearing

[hako]

First try swapping front tyres with rear ones....costs nothing.

[JKruges]

Thanks for the advice guys. i will change the uni joint and check the centre bearing, see how it goes, any more troubles and i will swap the front and back tyres. and most likely get a wheel balance.

one more unrelated question, is it safe to swap the sides of the car the tyres are on?

[seq4x4]

Am i the only one thinking torque converter? If you hold the RPMs itll shutter from the post you said. However when you drop back a gear and hold at 80km/h does it go away? Does it only happen on slight acceleration or no matter the RPM?

[shadetreemechanic]

Yeah torque converter clutch trying to lockup...happens just past 80 and holding it there will vibrate like all hell
I'm not sure if it's a great thing keeping it there so I try to either be under or over that spot. Maybe someone who knows autos can give more advice but mine works ok except for this issue (you can even disable the TCC to stop it locking but you'll lose fuel economy on highways and also generate more heat in the box since only the fluid coupling will be driving it)

[seq4x4]

Yeah torque converter clutch trying to lockup...happens just past 80 and holding it there will vibrate like all hell
I'm not sure if it's a great thing keeping it there so I try to either be under or over that spot. Maybe someone who knows autos can give more advice but mine works ok except for this issue (you can even disable the TCC to stop it locking but you'll lose fuel economy on highways and also generate more heat in the box since only the fluid coupling will be driving it)

This is quoted form my post here: East Coast Commodores

The idea of this is that you can drive around town with no TCC lock up if you wanted to. Good for dyno runs too. Instead of doing 1900RPM in a 110km/h zone you will be doing 3000RPM, if you have decided not to the the TC lock up. Which is why theres a switch.
Locate the the switch near the top of the brake pedal arm (You know that white one). It should have a pink/black wire and a purple wire connected to the switch. Follow the Purple wire and select a good place to splice a (12v) switch into it. When this switch is in the "off" condition the TCC will not engange at all.

[JKruges]

Am i the only one thinking torque converter? If you hold the RPMs itll shutter from the post you said. However when you drop back a gear and hold at 80km/h does it go away? Does it only happen on slight acceleration or no matter the RPM?

I will go for a drive soon and confirm this.

Maybe someone who knows autos can give more advice but mine works ok except for this issue (you can even disable the TCC to stop it locking but you'll lose fuel economy on highways and also generate more heat in the box since only the fluid coupling will be driving it)

i cannot afford to lose fuel economy, my car goes through a tank in 300km already.



thanks for the reply's guys

[Bizmark]

Might also pay to check the condition of all your wheel studs. I had a couple snap on one wheel a while back, massive vibration if maintaining speed or decelerating at highway and freeway speeds.

[JKruges]

Am i the only one thinking torque converter? If you hold the RPMs itll shutter from the post you said. However when you drop back a gear and hold at 80km/h does it go away? Does it only happen on slight acceleration or no matter the RPM?

I think it is only slight acceleration, arround 2000rpm.

[seq4x4]

To me it sounds like the torque converter and or related solenoids. But will need someone elses opinion to either back this up or deny it.

[Holden94]

It does'nt hurt changing ur wheels from side to side, front left to back right, front right to back left, but if they are directional treat you can only go from front to back on either side, front left to back left, front right to back right, but it does sound like ur torque converter. My old man statesman does the same thing, and as you say just go under or over the shaking. How many K's has your car done?

[H3SH]

I had the exact same problem, however mine is at around 90Km/h. Did you hit a curb hard while you were driving by any chance? I think it could be a damaged rim.

I let my mum drive my car one day, and she calls up saying that there was a flat tyre. Found out she hit the curb after coming out of a round-about and both passenger side wheels were gone. Front one was flat the rear was intact but heavily damaged. LESSON LEARNT .... "Don't let the mum drive your car" :P:P

I smacked on a new set of tyres and I started getting this issue at 90KM/h. Did my wheel balancing, wheel alignment ... still the same issue. I finally got my new 20" wheels and it was fine after that.

[hako]

This is quoted form my post here: East Coast Commodores

Unfortunately access is denied unless you join. I guess that what you suggest to disable the TC lockup is to trick the ECU into thinking the brake pedal is depressed...correct me if I'm wrong, but this will probably prevent the cruise control from working as well.
However, reading what the OP says again I reckon it could be one or more of his coils breaking down which causes slight missing at this speed due to the engine fuel supply leaning out for economy. The resultant lean fuel mixture requires a higher voltage at the spark plug tip to fire the plug - this puts extra strain on the coils and if they are not 100% they can breakdown. A cheapscate way of checking if this is the case is to simply gap the spark plugs down to 1.0mm...this makes them easier to fire and cannot do any harm. If the vibration goes away you will know it"s ignition related.