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[terry paget]

Hi Anthony. I reset the camber on X168 , your old car, yesterday, to -1.1 degrees both sides, from -0.7 left and +0.3 right. It sounds like you are having a suspension shop replace all your front suspension components, and they have an optical alignment machine needing set up data. Advice here is camber setting of -1.1 degrees. I set my camber to -1.1 degrees front seats empty, then had the wife clamber into the car, reading did not change; so setting is not very load sensitive.

[ajsphead]

I've got accelerated tyre wear on the inner edge both sides, hence the replacement. It's getting MV6 replacement springs from Germany (NOS) so I'm going -1.15 with toe at + 0.05 +/- 05'. If it's not so weight dependent I might tell the shop to calibrate with 70kgs either side, then leave the weights out allowing for future sag as it ages and settles.
Terry,  that's interesting as it looks like it had shifted from where I had it set (-1.10) by the local WIM agent.

Rear has also been lowered with NOS MV6 so for thrust angle and camber, is rear toe best set at 0.00 ?

[05omegav6]

Rear toe and camber both set by one adjustment, so they are always a compromise... usually 1°0.35' camber and 0°005/6 toe in. Critical rear measurement is that the thrust angle is 0° regardless of what the other measurements are

Front toe I always get set to 0°, although my car has poly vertical bushes too...

[ajsphead]

Rear toe and camber both set by one adjustment, so they are always a compromise... usually 1°0.35' camber and 0°005/6 toe in. Critical rear measurement is that the thrust angle is 0° regardless of what the other measurements are

Front toe I always get set to 0°, although my car has poly vertical bushes too...

Thanks

Take that's a -1.35 camber

[Shackeng]

Rear toe and camber both set by one adjustment, so they are always a compromise... usually 1°0.35' camber and 0°005/6 toe in. Critical rear measurement is that the thrust angle is 0° regardless of what the other measurements are

Front toe I always get set to 0°, although my car has poly vertical bushes too...

Interesting. For any particular reason Al?

[TheBoy]

Rear toe and camber both set by one adjustment, so they are always a compromise... usually 1°0.35' camber and 0°005/6 toe in. Critical rear measurement is that the thrust angle is 0° regardless of what the other measurements are

Front toe I always get set to 0°, although my car has poly vertical bushes too...

Interesting. For any particular reason Al?

A few of us have tried them, for a combination of reduce maintenance and better handling, with varying degrees of success.

Mine handled fantastically when first installed, but destroyed themselves within days, so I went back to GM.

[Shackeng]

Thanks. I've often wondered why we don't.

[05omegav6]

Rear toe and camber both set by one adjustment, so they are always a compromise... usually 1°0.35' camber and 0°005/6 toe in. Critical rear measurement is that the thrust angle is 0° regardless of what the other measurements are

Front toe I always get set to 0°, although my car has poly vertical bushes too...

Interesting. For any particular reason Al?

If the fronts can be made to last the life of the car, then why shouldn't the rears?

Those with less success were basically using milled lumps of almost solid poly, which generally causes the welds and/or wishbone to fail, and gave a bone shaking ride.

My solution isn't perfect, taking alot of trial and error, not to mention tyre wear, to reach... but a little low speed vagueness/stiffness is a very small price to pay for missile precision when pressing on.

There is an underlying concern regarding wishbone fatigue, which is why they're generally not recommended, but this is looking to be unfounded as my bushes are four layers rather than a single lump, thereby allowing some (limited) slip

[terry paget]

I've got accelerated tyre wear on the inner edge both sides, hence the replacement. It's getting MV6 replacement springs from Germany (NOS) so I'm going -1.15 with toe at + 0.05 +/- 05'. If it's not so weight dependent I might tell the shop to calibrate with 70kgs either side, then leave the weights out allowing for future sag as it ages and settles.
Terry,  that's interesting as it looks like it had shifted from where I had it set (-1.10) by the local WIM agent.

Rear has also been lowered with NOS MV6 so for thrust angle and camber, is rear toe best set at 0.00 ?

I found your set up by Fcm wheel alignment documentation 07/08/2012 £50 total (sounds cheap to me) and they reset it from L-2.00 R-0.5 fo 1.1 both sides. It may be my rotten measurement, hope not. I did the first car using the brake discs, realised there was scope for error so did the second car (X168) on the wheel screw hole flanges.

[chrisgixer]

Thanks. I've often wondered why we don't.

It's not currently easily possible to make a balljoint type bush, which is what the oe bush is, without either moulding or using a lump/block of poly that stresses the arms. Al's attempted solution is the best I've seen so far, but I wouldn't fit it. Sorry but no way.

A metal ball joint could be pressed in, if it could be sealed from the elements and not rust, but that would also be so harsh it's not worth the trouble.

At the other end Of the scale we have Al's solution. A combination of poly and a ball joint will be needed IMO. With a seal to keep the gall joint greased. Not so straightforward.

So, for me. Back to GM bushes.

[terry paget]

I struggle to understand the intended behaviour of the Omega wishbone. The front rubber joint allows primarily rotation round the horizontal bolt; the rear joint allows the wishbone to rotate around the vertical bolt and also up and down motion as dictated by the front joint. The vertical pivot rotation in turn requires the front joint to yield sideways. I am sure Adam Opel knew what he was doing, and am surprised that the rubbers can be replaced with polythene bushes behaving differently.

Is this arrangement common to other Mcpherson strut rubber mounted wishbone layouts?

[chrisgixer]

I struggle to understand the intended behaviour of the Omega wishbone. The front rubber joint allows primarily rotation round the horizontal bolt; the rear joint allows the wishbone to rotate around the vertical bolt and also up and down motion as dictated by the front joint. The vertical pivot rotation in turn requires the front joint to yield sideways. I am sure Adam Opel knew what he was doing, and am surprised that the rubbers can be replaced with polythene bushes behaving differently.

Is this arrangement common to other Mcpherson strut rubber mounted wishbone layouts?

Suspension movement, and toe in/out due to braking.

[terry paget]

I struggle to understand the intended behaviour of the Omega wishbone. The front rubber joint allows primarily rotation round the horizontal bolt; the rear joint allows the wishbone to rotate around the vertical bolt and also up and down motion as dictated by the front joint. The vertical pivot rotation in turn requires the front joint to yield sideways. I am sure Adam Opel knew what he was doing, and am surprised that the rubbers can be replaced with polythene bushes behaving differently.

Is this arrangement common to other Mcpherson strut rubber mounted wishbone layouts?

Suspension movement, and toe in/out due to braking.

On braking the wishbones will rotate about the rear vertical bushes, limited by the front bushes. I imagine  the track rods will then cause the front wheels to toe-in, as Opel intended. If the front bushes are polythene, this will not happen. Am I right?

[chrisgixer]

I struggle to understand the intended behaviour of the Omega wishbone. The front rubber joint allows primarily rotation round the horizontal bolt; the rear joint allows the wishbone to rotate around the vertical bolt and also up and down motion as dictated by the front joint. The vertical pivot rotation in turn requires the front joint to yield sideways. I am sure Adam Opel knew what he was doing, and am surprised that the rubbers can be replaced with polythene bushes behaving differently.

Is this arrangement common to other Mcpherson strut rubber mounted wishbone layouts?

Suspension movement, and toe in/out due to braking.

On braking the wishbones will rotate about the rear vertical bushes, limited by the front bushes. I imagine  the track rods will then cause the front wheels to toe-in, as Opel intended. If the front bushes are polythene, this will not happen. Am I right?

Braking causes toe out. Hence the static toe setting is a minus figure. -0.05 each side, -0.10 combined. Ime polyurethane bushes allow a nearer zero setting before they go positive. So less scrub (minimal already) and better stability in theory.

Obviously this is different for front wheel drive, as the front wheels pull ahead of the car as well as being pulled to the rear on the brakes.

Wishbone Yaw is the main (effective) concern on the rear bush. Poly helps minimise this over the softer rubber oe bushes. Suspension set up affects vertical wear. So softer suspension driven hard will give the rearward bush a much harder time.

[terry paget]

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.