High Speed Shudder

[NZBen]

I was at Hampton Downs the other week and found that at high speed - over 170kph, the car starts to shudder severely, the shudder continues till speed has dropped to below 130. It possibly gets slightly more severe if brake are applied but not certain. I know my diff bush is stuffed. The car is an 09 G6Et. Has anyone come across this before? Not sure if it's driveshaft, brakes, wheels or something else.

Thx

[Wilko16]

Tailshaft !! Centre bearing most likely

Or even worse a loose wheel

[Bizkets is Drunk?]

My diff bushes are average and control are bushes are shot tail shaft takes a caning daily and this morning I hit 200+ and no wobble.

Wheels need balancing maybe?

[Wilko16]

Haha I love reading how much you flog the piss out of it [emoji106]

Great Job

[Ralph Wiggum]

I was at Hampton Downs the other week and found that at high speed - over 170kph, the car starts to shudder severely, the shudder continues till speed has dropped to below 130. It possibly gets slightly more severe if brake are applied but not certain. I know my diff bush is stuffed. The car is an 09 G6Et. Has anyone come across this before? Not sure if it's driveshaft, brakes, wheels or something else.

Thx

Under power? Under brakes? Or coasting

[NZBen]

It happens under power accelerating, then coasting or braking back down till abt 130

[NZBen]

I might spin it up on a hoist and isolate any drivetrain issue

[Wilko16]

Good idea... Just remember te suspension is hanging on a hoist and could hide a driveshaft problem.

Could lower the back control arms down onto jack stands to simulate sitting on the ground and see how you go spinning it up

[Bulletime]

Tailshaft !! Centre bearing most likely

Or even worse a loose wheel

this^^^ had nine replaced recently with vibration under load more noticeable up hill so I'd imagine 170 would do it! Check for excessive play.

[Ralph Wiggum]

I'd suggest tail shaft as well given the speed range.

Increase under braking could be another issue.