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Author Topic: twitchy backend  (Read 8629 times)

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pauls

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twitchy backend
« on: 29 January 2017, 19:42:09 »
Dont know how else to explain it. When its wet the backend always feels a lot less planted. It feels like it wants to let go also seems to be a bit more jumpy. Any ideas please.

car history 3.2 auto back end has police springs with b4 shocks also doughnuts are poly,ed tyres are dunlop maxx rts 235/40/18.  Fronts are police springs standard shocks poly wishbones and 235/40/18 dunlop maxx rt2
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Doctor Gollum

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Re: twitchy backend
« Reply #1 on: 29 January 2017, 19:53:08 »
Possibly failed diffmounts or the poly donuts need refitting... both easy enough to check, weather permitting  :y
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STEMO

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Re: twitchy backend
« Reply #2 on: 29 January 2017, 20:58:32 »
Omegas are twitchy, end of.
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X30XE

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Re: twitchy backend
« Reply #3 on: 29 January 2017, 21:50:08 »
Quote from: pauls on 29 January 2017, 19:42:09
Dont know how else to explain it. When its wet the backend always feels a lot less planted. It feels like it wants to let go also seems to be a bit more jumpy. Any ideas please.

car history 3.2 auto back end has police springs with b4 shocks also doughnuts are poly,ed tyres are dunlop maxx rts 235/40/18.  Fronts are police springs standard shocks poly wishbones and 235/40/18 dunlop maxx rt2

It's RWD... the springs are over stiff unless you carry 250kg of clobber all the time, the bilstiens are stiff as a wedding prick, the polybushes have no give, dunlop aren't the stickiest of tyres and you have a limited slip diff presumably...  Little wonder really.
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Re: twitchy backend
« Reply #4 on: 29 January 2017, 22:16:04 »
Quote from: X30XE on 29 January 2017, 21:50:08
Quote from: pauls on 29 January 2017, 19:42:09
Dont know how else to explain it. When its wet the backend always feels a lot less planted. It feels like it wants to let go also seems to be a bit more jumpy. Any ideas please.

car history 3.2 auto back end has police springs with b4 shocks also doughnuts are poly,ed tyres are dunlop maxx rts 235/40/18.  Fronts are police springs standard shocks poly wishbones and 235/40/18 dunlop maxx rt2

It's RWD... the springs are over stiff unless you carry 250kg of clobber all the time, the bilstiens are stiff as a wedding prick, the polybushes have no give, dunlop aren't the stickiest of tyres and you have a limited slip diff presumably...  Little wonder really.
Car is otherwise standard Elite. Springs were fitted to replace overly soft Elite ones and to lift the back end slightly, as its arse was on the floor. Shocks were replaced as were leaking. No lsd either.

Car drove fine with the above set up, and from my experience with plod springs/polybushes/rigid diff mounts on my old estate is anything to go by, twitchy isn't a word I would associate with the handling...

Suspect failed diff mount...
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X30XE

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Re: twitchy backend
« Reply #5 on: 29 January 2017, 23:35:49 »
What's more surprising is that the useless soup heater mushbox ar35 is able to transfer enough torque to the rear wheels to achieve twichty-ness.  :P
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Kevin Wood

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Re: twitchy backend
« Reply #6 on: 29 January 2017, 23:48:31 »
I can't say the rear end of mine has ever been anything other than completely planted so yes, I'd say something's amiss. Probably one or other of the bushes as the rest has been eliminated.
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mandula

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Re: twitchy backend
« Reply #7 on: 30 January 2017, 05:28:19 »
http://www.omegaowners.com/forum/index.php?topic=136126.msg1746023#msg1746023

^That's how I solved my rear subframe rear busing issue. No wobbling after those also changed to polys  :y
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Magwheels

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Re: twitchy backend
« Reply #8 on: 30 January 2017, 17:52:07 »
Seeing as the car is IRS then I fail to see how the diff mount would add to any rigidity in the back end. My first look (especially if the car was running low for any length of time would be the subframe mounts or the trailing arm bushes, both add (or not) locational strength to the rear end.
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TheBoy

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Re: twitchy backend
« Reply #9 on: 30 January 2017, 19:18:25 »
How worn are the rear tyres? Dunlop RT's grip levels fall off a cliff when worn (about 3mm)
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Doctor Gollum

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Re: twitchy backend
« Reply #10 on: 30 January 2017, 19:50:23 »
Quote from: Magwheels on 30 January 2017, 17:52:07
Seeing as the car is IRS then I fail to see how the diff mount would add to any rigidity in the back end. My first look (especially if the car was running low for any length of time would be the subframe mounts or the trailing arm bushes, both add (or not) locational strength to the rear end.
Unbolt one, either will do, take the car for a spirited drive with some roundabouts thrown in for good measure and report back...

... I'll say "I told you so" now, just to.get it out of the way ;)
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pauls

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Re: twitchy backend
« Reply #11 on: 30 January 2017, 20:03:19 »
Quote from: TheBoy on 30 January 2017, 19:18:25
How worn are the rear tyres? Dunlop RT's grip levels fall off a cliff when worn (about 3mm)

Not sure but i can spin them up very easy in the damp. Will have to check
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zirk

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Re: twitchy backend
« Reply #12 on: 30 January 2017, 20:25:40 »
Stupid question I know but I take it your TC is working.
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pauls

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Re: twitchy backend
« Reply #13 on: 30 January 2017, 20:28:23 »
Quote from: zirk on 30 January 2017, 20:25:40
Stupid question I know but I take it your TC is working.

Yes it works fine
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VXL V6

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Re: twitchy backend
« Reply #14 on: 30 January 2017, 20:46:57 »
Quote from: pauls on 30 January 2017, 20:03:19
Quote from: TheBoy on 30 January 2017, 19:18:25
How worn are the rear tyres? Dunlop RT's grip levels fall off a cliff when worn (about 3mm)

Not sure but i can spin them up very easy in the damp. Will have to check

My experience of RT2's is that they lack the grip of RT's in the wet. Appreciate you have RT's on the back. As TB asks, how many MM on them? If they're less than 4mm they become a totally different tyre....
« Last Edit: 30 January 2017, 20:48:40 by VXL V6 »
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