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[05omegav6]

The Omega arrangement allows a certain amount of waftability rather than outright control... To drive there's a definite line between soft/wallowy and precision. Noticeable when you drive around a familiar bend at a sedate pace, and then attack the same bend at a far higher pace.

Sedately the car will waft around the bend with no fuss, but press on and the suspension loads up and the car tucks in and gets on with it (tyres permitting of course)

[chrisgixer]

Thanks Chris. I would have designed it with both bolts horizontal and in line, that would have allowed normal wishbone motion with no yaw, been easier to make and easier to change. There is some cunning plot in the present design and I don't understand it.

That rearward bush is, IMO, a shit idea. But then, when considering the design, and what a suspension joint has to do in a passenger car Ie pivot AND damp out vibration while STILL giving an acceptable level of precision to the driver and be cheap to produce, there's only one outcome.

The bush as genetic item is, like suspension itself, is infinitely tunable. They can have oil bladders, and voids and insets to limit and control comfort and movement  in various directions.

Welcome to the world of compromise.

Next car will have a double wishbone front set up. Hopefully. Worst thing about omega suspension is the lack of control of camber throughout the suspension stroke. Hence the shoulder wear etc. handling degrades far too quickly as the tyres wear as a result.

...and through driving other members cars I see on my drive for suspension work, that's not as a result of driving style either.

[chrisgixer]

I can assure you though, a twin horizontal bush will be MUCH harder as far as ride goes. It's a set up that offers far less give. (Or much needed control in front wheel drive cars for example)

[berserkerboy]

There is no WIM near enough for me SA19 8LS to visit. I've recently done a wishbone and drop link change and my tracking needs looking at. Local ish ATS have the equipment to do 4 wheel alignment. If I take it to them what settings should I ask them to do with the car unloaded?

[terry paget]

Thanks for all thoughts Chris. I wonder now if the vertical rear wishbone pin may be responsible for the tyre wear pattern on Omegas. Perhaps under braking both front wheels toe out and scrub off the inner tyre edges. If so no amount of careful setting up will correct it.
Do any other cars have vertical rear wishbone pins?  If so, I wonder how their front tyres wear.

[chrisgixer]

Thanks for all thoughts Chris. I wonder now if the vertical rear wishbone pin may be responsible for the tyre wear pattern on Omegas. Perhaps under braking both front wheels toe out and scrub off the inner tyre edges. If so no amount of careful setting up will correct it.
Do any other cars have vertical rear wishbone pins?  If so, I wonder how their front tyres wear.

Tyre wear issues on a well set up omega with oe suspension relate to a long (comfortable) suspension stroke, single wishbone suspension (cost), and a soft (again, comfortable ) front bush.
 Poly FRONT bushes go a long way to Improve accuracy for the driver. Both in stearing and stability in a straight line, and most effectively on the brakes which gives much less darting about as the road imperfections pull the road wheel about due to a soft front bush. This with a slightly firmer FEEL to the front suspension. (It's not actually firmer, but is caused by the slightly lesser damping ability of poly over the oil bladders in the front rubber bush designed to damp out high frequency vibration)

The rearward vertical bush affects stearing feel far more, (apart from steering idler etc) as its part of the two parallel lines that must be constant in the steering set up. 1 the line of the steering tie rods obviously, but also 2, the line of the suspension (ignoring the hole in the subframe for the engine to sit in) that hold the hub and steering pin on the wishbone in position. Pin no play>wishbone no flex>Bush no play or tears but still allowing a pivot without transmitting vibration>bolt tightening must be correct>subframe>ditto the other side etc

But, and heres the thing Terry....we can't really criticise the  tyre wear  on the standard set up, when we have such (comparatively)  vast inaccuracies in the diy set up methods used, as described here.  ....Especially given the refusal to set the car set up correctly via a hunter hawk eye rig for full geometric set up. Castor, camber, toe at the front. Camber, toe and the all important thrust angle at the rear.
 While I admire your desire to understand and replicate the correct ideals, I repeat, it is NOT possible to confirm without doubt that the settings are correct going by anything seen here. So given that fact, one can't tell if any tyre wear or handling issue is down to set up or design, component failure, or whatever, when not starting from the same "bible" as any other car here.

From experience it is very difficult to keep an omega on, what I would call, a straight line(although I am fussy in that regard over others here). There are way too many variables from tyre size and design, through set up and interpretation of those figures even with the correct gear, to component quality and wear.

Get it set up correctly. Then go from there.

Rule no 1 in development of any machine. Achieve the manufacturers spec FIRST. OOF has achieved that over the years AND gone on to further refine those figures with the help of wheels in motion to the point that the standard figures in Haynes are now considered completely obsolete as a result. So the problems you have are;
Working to obsolete data
Working with too many variables on that data
Working with inaccurate methods

The best anyone can hope to achieve AND CONFIRM as correct with diy is to minimise tyre wear prior to set up on a hunter rig. Or there is a risk of premature tyre wear as you are quite rightly concerned about.


Having said all that though, that's not to say we shouldn't try, and have a go. So hats off to you Terry. I hope this isn't taken as overly negative, but more of a pointer as to what we are  actually up against.