VT Shudder at 100 kph

[C-change]

After some advice if anyone has had something similar.

My old 98 VT V6 wagon with 280,000k's had been running great until recently. It has always been very smooth and comfortable to drive and I've had it since 30,000 k's. Anyway now when I drive at 90-120kph I get this annoying shudder through the steering and then the whole car does it. It only starts at 90 k and gets worse the faster I go. Its minor, nothing violent and can be tolerated on the 20 min drive to work but a few hours on the Hume Hwy or the F3 and it drives me mad.

Here is what I have had replaced, fixed in the last 6 months.

New steering rack, lower control arm bushes (front right), left tie rod, new brakes and rotors all around plus 4 new tyres.

When it first started I thought the old tyres were the problem. Mech thought so too but with new tyres there is no change to the shudder. I've had the new tyres balanced 3 times in 3 weeks and no change.

Got me stuffed, any ideas ?

 

[mustafa76]

it could be universal joint or center bearing in the drive shaft

 

[jafo]

wheel and camber alignment might help
or as mustafa76 said

 

[vy-346]

Sounds like a problem with one of your rims, I just had a similiar thing in my VY at xmas after driving through a shitload of mud on hols, and it dried onto my rims and put them way out of balance. Are your rims just the factory steelies or are they Alloys, maybe try borrow or get a cheap set of chaser rims and whack them on and see if it changes anything.

 

[jazza15]

I have the same problem, this has come up on a few other threads, very similar/same symptoms and people have tried very similar/the same things to try and fix it to no avail.
I have replaced every bush in the front suspension, the steering rack and one of the first things i replaced was a tie rod end.
I started my VY IRS conversion today and currently have the whole IRS out of the car. Before i did this i had the rear wheels off and ran the car in 5th to see if i could see anything wrong. The rear left brake was making a bit of a noise, but my mate said it probably isn't it. Seeing as you replaced all of your rotors, i'd probably say it isn't it too.
More interestingly i found that my left side outer cradle mount bush was completely torn upon removing it. I doubt that i could have done that while removing it and the right side one was pretty much fine. This could be sending that vibration through to the steering wheel.
My other possible option is a bent half shaft (diff to trailing arm), but i didn't see anything of significance during my 'diagnostic test'.
Only other possibility is my front left wheel bearing as it has been gone for some time now.
Good luck with it and let us know how you go, as will I

 

[C-change]

Thanks all for the suggestions, I'll work through them starting with the cheapest first. Going to take the mech for a ride next week to prove I'm not mad and then go from there.

I was worried that the new rotors might be warped but they reckon thats not it and all suspension components seemed fine when they checked last week. I feels like its coming from all four wheels which makes me think thats where the problem is. Even the kids in the back were complaining about the "shaking" today and that was on the new Dunmore section of the Princes Hwy near Shellharbour. Considering this road only opened a couple of months ago, it must be one fo the smoothest bits of road in NSW and it still shook its arse off. The biggest hassle is the cars age and mileage. I don't want to spent a fortune on it, but I would like it to run like it did a few months ago.

I'll let you know how I get on next week.

 

[GenOktOniA]

my brother inlaws VX did the same thing, he just got a wheel alignment and that sorted it out, i recomend starting there

 

[holden_calais_VT_1999]

i am not 100% sure but maybe take it to a suspension specialest in sted of ur normall mechanic and let him take it for a drive. thats what i did he he new what it was straight up. just a surgestion hope it helps cheers

oh and sorry cant remember what the excat problem was

 

[jazza15]

Thought I'd just update you's on how mines going. Just finished rear suspension overhaul, now every suspension bush, bar stab bar bushes has been replaced.
I will be finally getting a cradle alignment and 4 wheel alignment tomorrow. I believe things like wheel alignments (and new radius rod bushes) will only help dull the symptoms, not fix the actual problem.
I mentioned earlier that my rear left rotor was making noise, I switched it over to the right side, same noise, it has to be warped. I think that's the source of my problem, not much of a surprise as they are getting along a bit, have a fair lip and this particular one has some scoring on it from when i put a brake pad in the wrong way one time :~
A while back when I hijacked someone else's thread about the same sort of problem, someone came up with a general rule of thumb that below 80km/hr it is the front brakes, above 80km/hr it is the rears. Turned out to be a good rule for me I reckon.
One thing you can try doing if you have the equipment is jack your car up and put it on axle stands. I ran mine in fifth moving the wheels at around 40km/hr at idle speed (i figured using the accelerator could get a little bit dangerous), so with an auto you might want to come up with something a bit ifferent to test it.

 

[50LTRv8]

When you brake, do you feel a vibration through your shifter?