Vibrating only in 5th geat at 100ks, but no other gear

[mitweiler]

Hey guys,

Quick question, maybe somebody has experienced this.

I have had my wheels balanced and alignment done a few times during the time I have owned my VY. But ever since I purchased it, when traveling on free way at 100ks in 5th gear my car vibrates. If I decelerate to 80ks or accelerate to 120ks it no longer vibrates in 5th. If I put it in 4th or 6th gear at 100ks it doesn't vibrates.

Some people have suggested getting tail shaft balanced and replacing the uni-joint/donuts what ever you call them.

 

[rambunctious]

Does it feel like it is coming and going like a harmonic vibration, not the harmonic balancer, but a vibration like something is out of harmony with something else in the drive train, just like you get if you have 2 cars side by side at the lights revving.
If so, then you should look at replacing engine and gearbox mounts with genuine holden mounts from a gmh dealer, not genuine from repco or anywhere else, but only from a dealer.
Tailshaft would be the next thing of course.
I have known a lot of V8's to do this even back to HZ monaro.

 

[mitweiler]

Does it feel like it is coming and going like a harmonic vibration, not the harmonic balancer, but a vibration like something is out of harmony with something else in the drive train, just like you get if you have 2 cars side by side at the lights revving.
If so, then you should look at replacing engine and gearbox mounts with genuine holden mounts from a gmh dealer, not genuine from repco or anywhere else, but only from a dealer.
Tailshaft would be the next thing of course.
I have known a lot of V8's to do this even back to HZ monaro.

Hey Rambunctious,

Thanks for reply. No it doesn't feel like it's coming and going,, once i'm around 100ks its just vibrating/shaky and makes a vibrating noise. The clubby is nearly at 300,000ks I might just do the engine and gearbox mounts now that i think about it. They probs have never been done.

Is that something I can do myself on jack stands and a small jack or will i need a hoist?

I'v done my VS Calais back in the day (engine mount) wasn't to difficult.

 

[rambunctious]

Last set I did was a VL 5 litre, and I put the front on ramps then used a trolly jack with timber on top to lift the engine.
I have not done any on the later cars as yet.

 

[mitweiler]

Last set I did was a VL 5 litre, and I put the front on ramps then used a trolly jack with timber on top to lift the engine.
I have not done any on the later cars as yet.

I'll have a good and see what ends up fixing the problem and update this post. In case anybody else runs into the same issue.

 

[SavVYute]

Could be something basic like a slight misfire causing it...a coil breaking down when under load or corrosion on/or loose plug lead.