AU drivetrain vibration

[macman]

I had the transmission in my AU TE50 (5.0 auto) rebuilt as it had lost reverse, had a leak from the rear extension and wouldn't hold a gear when manually downshifting.

Got the car back and the transmission now feels great. That said, I still don't think it's holding gears when downshifting quite as it used to when I first bought the car but I'm not 100% sure as it's been a long time since I've been able to downshift!

BUT my main problem:

When at operating temperature, I can induce a quite noticeable droning vibration.

Only occurs between 80-100km/h and only when the torque convertor is locked in 4th and you apply light acceleration.

I took the car back to my transmission builder who told me that he didn't believe it was TC vibration or any issue with the transmission and that it was more likely an issue in the motor (pinging under load or something similar).

So, I've owned this car for over 6 years and have definitely had previous issues with pinging, mostly resolved now. But this feels nothing like what I've experienced and it certainly has never done this previous to the transmission being rebuilt. I've said all this to my transmission builder, he seemed to sympathise and didn't seem to be trying to get rid of me so to speak, but has told me he believes there's some other issue elsewhere.

Searching the forums I've read that using the wrong transmission fluid can cause this sort of thing, but there's no way he'd use the wrong fluid as he is a Falcon transmission specialist!

At this stage, I think I'm going to take the car to another transmission specialist for a second opinion but I'd like to know if anyone has any suggestions.

[Maka]

I had my transmission rebuilt in my i6 AU Futura about 55,000k ago, had to take it back a few times to get it working properly too, but all good now. Definitely get a second opinion & maybe see if it dropped a code. Its still under warranty, so maybe drive it it bit more then see if the vibration goes away once the transmission settles down. Good luck!

cheer's, Maka

[mik]

can you where the vibe is coming from ? , through the floor, rear vision mirror shake ? tbar vibrating ?
its always a bugger having done work on a limo and somethings not right, my own general procedure is to go over every nut and bolt and see if have over looked something.

my brother had an auto fixed at a tranny place some years ago, after picking up the car which drove nicely at that moment after driving over the other side of town a knocking/ nasty rattling noise started and continued to get worse, my bro found the torque convertor bolts where loose.
good idea to have a look over work done again, i would look at the tail shaft too.

[mcfly94]

Agree on second opinion to be sure, there is no harm.
Tailshaft not bent?
No bent wheels?
Tyres all balanced up and in shape?
Exhaust is standard?
Engine and trans mounts good?
All wheel bearings good?
Theres a lot of different things that can cause a vibration.

[macman]

Thanks heaps for the comments folks.

The vibration just resonates through the whole car, feels like it's from front to back top to bottom, just a moaning/droning vibration like something shuddering or resonating, almost like the road just becomes rough underneath you.

Some country roads have those noisy strips on the white lines, when you run over them - think it's to try and wake people up when they start crossing off the road - sounds just like running over that stuff.

The thing is that it only comes about as you apply light acceleration and only when the TC is locked in 4th.

I might need to take note if it's a certain rev range?

Looks like a second opinion is the general consensus.