Mopar Muscle Association UK

Going from your statement the vibration is intense...

What have you changed on the car / engine ?

Have you changed the flex plate ?

Was the flex plate a good fit, any slack/ovality in the bolt holes ?

What condition is the harmonic balancer in, is it the original ?

Has the vibration always been there since you have had the car ?

Has it appeared after you have done some work ?

I think you need to do a process of elimination to determine if the vibration is; Engine, Gearbox/Converter/Flex plate/Converter, Prop, etc

1st step & as you have the car on axle stands, I would remove the prop, to eliminate the prop from the equation & to see if the vibration is present.

At least then it will help narrow down the focus areas. if it is still present, I would be double checking the flex plate/converter.

A mate of mine fitted his flex plate incorrectly, due to there being too much wear in the holes, normally this cant happen. This was the cause of his severe vibration....

Cheers Mark,
Balancer seemed good & a tight fit.

I've hardly done any miles in her over 60mph so don't know when it started or if it was there from day 1.

I have a funny feeling there was an issue with 2 of the bolts on the flex plate.
I'll take a look.

See of its still there in nuetal.That will eliminatie tailshaft

Terry I tried that but as I said in an earlier post when I put it in nuetral it still accelerated is if it was still in drive!

Sinny, if it accelerated it couldn't be in neutral, could it?
I haven't read every post, but I take it the UJs are good and that the pinion bearing in the diff is not loose?

sinny wrote:Terry I tried that but as I said in an earlier post when I put it in nuetral it still accelerated is if it was still in drive!

If there's no load, the fluid drag in the trans will turn the wheels.
Wit the parking brake on and/or the trans in Park, the wheels won't turn unless summat's seriously wrong with your trans!

The UJ's are good, the vibration doesn't seem to be coming from the diff or prop hence me thinking fex plate, torque converter, harmonic balancer or something worse in the trans!

Got her upto 65mph up on jack stands, shifted into neutral & pressed the accelerator & the speed climbed just as if it was still in drive. (vibration still there)

I'm going to pull the flex plate & check for issues.

I would double check the Damper and ancillaries first as it is easy......apart from checking the Flexplate bolts (did you Loctite them??) then it is either Engine out or Gearbox out. Lots of work so rule out all other options first.....

Trying to rule out possible causes: The vibration is at over 60mph which is about 3k rpm so I Revved her in park up to 4k rpm & no sign of vibration so that says to me the harmonic balancer & flexplate are ok or am I wrong?

How can I check the torque converter?

The prop angle is almost dead straight.

I had the same problem and it turned out to be the rear tyres were out of balance. Try it in gear without the rear wheels on.

They are brand new wheels & tyres & I had them balanced before being fitted.
But it's worth a shot so have pulled them off but don't want to wind the neighbours up so will test it tomorrow. But will also get the wheels re-balanced tomorrow too.

Mine were brand new wheels and tyres, I guess the balancer was out. Vibration was gone when I fitted new tyres.

sinny wrote:Got her upto 65mph up on jack stands, shifted into neutral & pressed the accelerator & the speed climbed just as if it was still in drive. (vibration still there)

as DB said could be fluid drag in the trans

test it in Neutral with the parking brake on and/or wheels on the ground, that will isolate anything from the trans backwards

process of elimination

if it still vibrates in Neutral must be something between the balancer and the trans

if the vibration stops, looks like it's something from the trans backwards

Just had the wheels balanced again & they were well out. 50g on one & 45g on the other so we may have found the issue!

(not to take this thread off track)

I'm currently getting a similar problem and I've not nailed down the issue yet, my tyres on the rear came with the car and could well be out of balance but with my problem I can rev to 5k in N with no ill effect. In drive it is speed dependant, fine from 0 -55 ish then past that 'hold on fast' (the car feels like its going to go in any direction).

Pete will hopefully find something this week.

Good luck, I'm watching this to see what you find out on yours.

Jon


edit, two minutes ago looks like you might have found the problem!!! GREAT NEWS.