Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: JamesW74 on 04 April 2015, 21:57:32

Title: Regular thud at 20mph - nightmare wobble at 60+!😢
Post by: JamesW74 on 04 April 2015, 21:57:32
Hi. I've tried not to bother everyone but after having had non Omega mechanics diagnose everything from control arm bushes (not convinced) to brake discs (problem is not always present) I'm convinced it can only be something peculiar to the Omega.
Usually in the morning or from cold, pulling away down the road, I can feel a regular light thud through the floor at low speeds for about a mile (like the drivers side wheels are going along the broken White lines in the road). It then goes until the next time I'm coasting at <30mph and it comes back until power is reapplied. The car happily wafts through 40mph zones without showing the fault.
Now the car has become awful to drive on the m/way as over 50mph comes the 'tyres out of balance' vibration.  I can't drive through it, it just gets worse especially near 80mph. All tyres front and back have been balanced and discs and pads changed. Any advice where to start with this would really be appreciated? (52 plate 2.6 v6 with 65K miles.)
Title: Re: Regular thud at 20mph - nightmare wobble at 60+!😢
Post by: kevinp58 on 04 April 2015, 22:02:42
when were the discs and pads changed did they seat them fully and what about wheels come lose  :-\ can you feel it through the brake pedal
Title: Re: Regular thud at 20mph - nightmare wobble at 60+!😢
Post by: 05omegav6 on 04 April 2015, 22:11:58
Wheel boots first... Check all of them. Now.

Otherwise check propshaft connections...

What gearbox?

Incidentally, the thump and wheel wobble might not be related...
Title: Re: Regular thud at 20mph - nightmare wobble at 60+!😢
Post by: JamesW74 on 04 April 2015, 22:14:06
Thanks for your quick reply - Brakes and pads (front done last August) rears done in November. Will check the fronts again tomorrow. Can't feel it thought the brake pedal - it's just usually through the footrest/ floor
Title: Re: Regular thud at 20mph - nightmare wobble at 60+!😢
Post by: 05omegav6 on 04 April 2015, 22:15:21
Saloon or estate, but check wheel bolts now ;)
Title: Re: Regular thud at 20mph - nightmare wobble at 60+!😢
Post by: JamesW74 on 04 April 2015, 22:16:40
I know the prop shaft is ok. Had it on a ramp last week. Will check boots. 'Box is auto - thanks
Title: Re: Regular thud at 20mph - nightmare wobble at 60+!😢
Post by: JamesW74 on 04 April 2015, 22:29:28
Saloon. Will check bolts in the morning. Hope my local garage hasn't been trying to kill me! ???
Title: Re: Regular thud at 20mph - nightmare wobble at 60+!😢
Post by: chrisgixer on 04 April 2015, 22:29:41
What's the stearing doing when it happens ?

Any wobble, fluid rather than a banging, like a tank slapper,is almost always wishbone bushes. It's random but often within a speed range. So not always present.

So
A vibration on the brakes is brakes.

A vibration at speed, in a certain  range, reliably, is wheel balance.

Beyond that. And I think that's where you are with this from what you said...
Omegas usually either
knock,( if car is level mostly drop links which don't affect handling, or rarely wishbones which do)
Flap (wishbone bushes)
Or the comical car goes be way, stearing hoes the other. Wishbones or steering idler.

There is a guide in faq to test all these things. I'd bet on idler or wishbones. Personally.

Title: Re: Regular thud at 20mph - nightmare wobble at 60+!😢
Post by: JamesW74 on 04 April 2015, 22:50:51
Sometimes there's an odd but very light jerkiness through the steering wheel at the same time which you can see as half inch wobbles.
Best description is the going over freshly painted white lines down the centre of the road, seems like if you weren't  feeling it, you'd almost hear it.
Will check wheel bolts and wishbones. I know the bushes are worn but didn't think the problem would show as intermittent.
Are Quinton Hazell wishbones okay, or do you recommend genuine all the way?
Title: Re: Regular thud at 20mph - nightmare wobble at 60+!😢
Post by: chrisgixer on 04 April 2015, 22:56:33
QH don't have a good rep on here.


So it's in time with wheel speed?
Title: Re: Regular thud at 20mph - nightmare wobble at 60+!😢
Post by: JamesW74 on 04 April 2015, 23:01:29
QH don't have a good rep on here.


So it's in time with wheel speed?
Does seem to be in time BUT doesn't seem to increase with acceleration however it disappears at about 30, so hard to say
Title: Re: Regular thud at 20mph - nightmare wobble at 60+!😢
Post by: Andy H on 04 April 2015, 23:03:44
QH don't have a good rep on here.


So it's in time with wheel speed?
Maybe a buckled wheel as well as knackered wishbone (AKA control arm) bushes.

Whoever balanced the wheels should have noticed a buckled rim though :-\
Title: Re: Regular thud at 20mph - nightmare wobble at 60+!😢
Post by: Andy B on 04 April 2015, 23:11:01
Radcliffe Tyres & Exhausts on Radcliffe Moor Road opposite the Sparking Clogg, aren't bad ....... Tony used to have an Omega many moons ago.  ;)
Title: Re: Regular thud at 20mph - nightmare wobble at 60+!😢
Post by: ffcgary1 on 04 April 2015, 23:11:15
With ref to the wishbones, i would be looking to rebush with polybushes if the lower ball joint is ok, easy enough to do the maintanence section has a guide for this.
check the steering idler arm located on the passenger side front footwell area for play or slop.
Then check all the wheel nuts and bolts on the struts.
Drop links will give you the sound of a knock going over rough road surfaces.
Top mountings on the front shocks have a knack of giving a knock sound so dont rule these out either.
Post up any findings
Gary
Title: Re: Regular thud at 20mph - nightmare wobble at 60+!😢
Post by: JamesW74 on 04 April 2015, 23:28:37

Post up any findings
Gary
Will do, thanks Gary and everyone who's replied! :)
Title: Re: Regular thud at 20mph - nightmare wobble at 60+!😢
Post by: 05omegav6 on 05 April 2015, 01:33:32
Wheel bolts. Wheel bolts. Wheel bolts.

Especially if it's getting progressively worse and at ever lower speeds.

Did I mention wheel bolts?
Title: Re: Regular thud at 20mph - nightmare wobble at 60+!😢
Post by: chrisgixer on 05 April 2015, 02:44:15
Wheel bolts. Wheel bolts. Wheel bolts.

Especially if it's getting progressively worse and at ever lower speeds.

Did I mention wheel bolts?

Seems you have a t shirt that I don't Al, and might very we'll have a point.

Iirc TB has that t shirt as well. Although the reason why escapes me for some reason. ::) ;D
Title: Re: Regular thud at 20mph - nightmare wobble at 60+!😢
Post by: 05omegav6 on 05 April 2015, 03:44:27
TBs experience was probably caused by the invisible gravel fiend ;D
Title: Re: Regular thud at 20mph - nightmare wobble at 60+!😢
Post by: YZ250 on 05 April 2015, 08:05:28
Wheel bolts. Wheel bolts. Wheel bolts.

Especially if it's getting progressively worse and at ever lower speeds.

Did I mention wheel bolts?

Agreed, definitely first place to check.  :y  Having witnessed this on my brother-in-laws van, the wheels clonked on rotation as the lower side takes the weight and the top slaps as it moves the slack. By the time he asked me to look at it the wheel bolt holes had worn oval.  :o :o
Propshaft can certainly transmit a clonk as the worn UJ's weight drops on rotation at very low speeds, then centres itself at mid speed, then causes unbearable vibration at higher speed.  :-\

Edit: Just noticed the mileage, too low for propshaft wear I'd have thought, so back to wheel related.   :)
Title: Re: Regular thud at 20mph - nightmare wobble at 60+!😢
Post by: 05omegav6 on 05 April 2015, 10:41:58
Oval wheel bolt holes are more of an issue on steel wheels due to the material thickness (or lack of)... had this happen to an old Volvo 245... got a puncture halfway through a three week trip to Orkney... popped the spare on, had the puncture dealt with and didn't swap the wheels back. The next 1500 miles were spent trying to identify the source of a definite speed related clonk, found to be loose wheel nuts, tightened them, and 100 miles later the wheel came off... car was fully laden at the time, and if anyone knows the A283, it came off just before the double bends as you head south towards Northchapel, at 50mph :o Only warning was the clonk as the wheel came off.

More recently I have suffered the similar with the black estate, had it pegged as failed/failing propshaft donuts... actually both rear wheels were loose...  :-[