Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: vexorg on 26 July 2010, 22:27:28
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As title, where can I find an exploded diagram of the rear end suspension?
Is it the same for all models? or is there some difference between early/late or 4cyl/v6?
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all Omegas are same (though springs/shocks may vary with age/model)
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Higher models have more sensors / looms for self leveling, but all have same basic setup. What are you looking to do?
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What are you looking to do?
Just some mad idea right now... ;)
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steering rack position - that's what's going to kill the idea ;)
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steering rack position - that's what's going to kill the idea ;)
That's another on-going project :) angle-grinder at the ready
I noticed the trailing arms look almost identical to the calibra, but you have camber adjustment. And the camber is a killer on lowered calibras.
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yes, that's possible.
you'll need to pay attention to the rear mounting - I can't just remember what that is on the Calibra.
It may be that your best starting point is an Omega A subframe, as it's more likely that you have the same rear mountings. BUT, make it a post-facelift Omega A 24V non-estate, as these are the only ones that have the camber adjustment. then there's also the 4 stud / 5 stud issue.
Om Omega B, the camber adjustment isn't really that - its part of the rear steer mechanism. The cars have a stiff outer bush in the semi-trailing arm and a weak ( axially-compliant ) inner bush. The extra link ensures that as the wheel moves up and down through its arc of travel, there is some camber and toe-in imparted - the result is better handling.
The flip side is that this only works with the vehicle at normal ride height - if it has been lowered at all, then the handling will be worse, possibly to the extent that the suspension will partially bind up. It also only works if you have the "weak" inner bush.
so, to summarise, If you're after imparting Omega B - style handling to your car, then go for it. If you're after realigning the camber after you've lowered your car, then this won't help you at all.
to get the mod, you'll need :-
subframe and semi-trailing arms from Carlton GSi 24V or Senator 24V
hubs if you already have 4 stud wheels
springs to give you "standard" ride height
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That's not so good, carlton gsi's aren't so easy to find.
Mine are both 5 stud cars.
On the omega B, there's the big adjusting bar, you're saying that will change the toe in as well as camber. Is there a pivot point on the hub itself?
Might be easier just getting a hold of one to see, I've only had a brief look under a car to see it. Difficult to see where all the bits were connected.
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Yes - as far as I'm aware, the rear adjustment is finding a happy compromise between camber and toe. If you are trying to correct camber on an excessively lowered car, you would probably therefore end up with toe being way out.
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That's not so good, carlton gsi's aren't so easy to find.
Mine are both 5 stud cars.
On the omega B, there's the big adjusting bar, you're saying that will change the toe in as well as camber. Is there a pivot point on the hub itself?
Might be easier just getting a hold of one to see, I've only had a brief look under a car to see it. Difficult to see where all the bits were connected.
I have spare.... ;)
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Was there a diagram of the suspension? Having similar mad ideas......thinking of putting mine into a mini!!!!!
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Yes - as far as I'm aware, the rear adjustment is finding a happy compromise between camber and toe. If you are trying to correct camber on an excessively lowered car, you would probably therefore end up with toe being way out.
That is my understanding as well, toe for main adjustment but also affects camber so a compromise to be found.
Interesting comments re suspension tying up at lower ride hights. I presume the tie rod adjuster pulls the rear suspension trailing arm within rubber "play" of the trailing arm bushes, and might explain why an mv6 with irmscher suspension,30 mill lower, would appear to have less play or movement in the rubber trailing arm bush than a newer model elite at stock ride hight....?
This was noticed at Ashridge meet when comparing my wayward handling elite with The Boys prefacelift mv6. problems with my car latter blamed solely on the falcon 912 tyres.
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Yes - as far as I'm aware, the rear adjustment is finding a happy compromise between camber and toe. If you are trying to correct camber on an excessively lowered car, you would probably therefore end up with toe being way out.
That is my understanding as well, toe for main adjustment but also affects camber so a compromise to be found.
Interesting comments re suspension tying up at lower ride hights. I presume the tie rod adjuster pulls the rear suspension trailing arm within rubber "play" of the trailing arm bushes, and might explain why an mv6 with irmscher suspension,30 mill lower, would appear to have less play or movement in the rubber trailing arm bush than a newer model elite at stock ride hight....?
This was noticed at Ashridge meet when comparing my wayward handling elite with The Boys prefacelift mv6. problems with my car latter blamed solely on the falcon 912 tyres.
.....and also presumed that the position of the trailing arm pivot points gives some camber as it's compressed as the inner trailing arm pivot point is set rearward of the outer pivot....? (iirc)
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you're sort of there....
the whole idea is to get the outer rear wheel to toe in on corners, and for this system to be easily adapted to the Omega A suspension.
the semi-trailing arm isn't pivoted straight across the car, or level for that matter. This is deliberate to get a compromise between roll centre and camber and to get a little toe-in on corners. In order to do this, the attitude of the arm to the car is absolutely critical.
now, for the system with the extra link, when the wheel moves up, like it would in a corner, the semi-trailing arm pivots around both the centreline of the bushes, but also about the outer stiff bush, allowing it to toe-in some more - it's a sort of 3D movement.
the problem comes when a car is lowered - the amount of extra toe-in will increase, even if the static toe has been corrected, so you'll be in a position where you'll have unknown toe-in variations to both sides in addition to the negative effects of moving the roll centre.
almost certainly, this will result in a lower car handling worse.
for interest, the case for the front suspension is more clear cut - lowering this WILL worsen the handling.
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Fascinating stuff all this, trouble is I don't understand it as well written down as when it's in front of me, I need to see it, does anyone have the above mentioned diag ? Must admit I looked on the net a while back and couldn't find much.
:(
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?
http://www.google.co.uk/imgres?imgurl=http://inlinethumb51.webshots.com/30194/2629721800048927869S500x500Q85.jpg&imgrefurl=http://www.cadillacforums.com/forums/cadillac-catera-cimarron-forum/137056-aftermarket-suspension-bushings-2.html&usg=__oTGMxIVZ0gp7y_DiOEQBvH8lL0Y=&h=500&w=375&sz=45&hl=en&start=10&um=1&itbs=1&tbnid=bxKUlejwxUjXPM:&tbnh=130&tbnw=98&prev=/images%3Fq%3DOmega%2Brear%2Bsuspension%26um%3D1%26hl%3Den%26sa%3DN%26tbs%3Disch:1
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Interesting - looking at that thread then reading into it further, looks like you can get aftermarket eccentric rear trailing arm bushes (for pontic GTO or Holden Commodore but will fit Omega) that allow for extra camber adjustment, especially for lowered cars. Might be just what the OP is after, assuming he can fit the right bits to his calibra.
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The shocks and springs are not because it isn't much to explode :)
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You do get eccentric bushes for the calibra too, however, if you drop the body by say 40mm, then youd need 40mm at the pivot point to maintain the camber. That's bigger than the bush.
How does the hub part pivot?
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Interesting - looking at that thread then reading into it further, looks like you can get aftermarket eccentric rear trailing arm bushes (for pontic GTO or Holden Commodore but will fit Omega) that allow for extra camber adjustment, especially for lowered cars. Might be just what the OP is after, assuming he can fit the right bits to his calibra.
Ooh now, seem to remember one of Tonys lads at wim bemoaning camber adjustable bushes. Might ask Tony to comment, see if he's had any dealings with them.
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You do get eccentric bushes for the calibra too, however, if you drop the body by say 40mm, then youd need 40mm at the pivot point to maintain the camber. That's bigger than the bush.
Er, doesn't work like that :-? Dropping 40mm will put probably an unwanted degree or so of camber on. That could be taken out by a trailing arm bush with only a few mm of eccentricity.
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Er, doesn't work like that :-? Dropping 40mm will put probably an unwanted degree or so of camber on. That could be taken out by a trailing arm bush with only a few mm of eccentricity.
I thought that at first, but having fitted them to another car, there just wasn't the range.
The trailing arm is a fixed unit to the hub, for the camber to remain the same then the angle of the arm also must remain the same, and the pivot point will still be at the same height relative to the ground. Or is my logic wrong there?
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The idea of the eccentric bushes is not to restore your trailing arm pivot points back to where they were (relative to the ground) before the lowering, and hence get your trailing arm to the original angle. That would work, but of course as you realise is impossible - to really do that you'd need to raise all your suspension pivots the same amount you were lowering the car!
What these eccentric bushes are actually doing is allowing you to tilt the trailing arm and directly adjust the camber. Depending on the kit you get (various seem to be available), you might just replace the outer bush with an eccentric allowing you to move the outer pivot downwards, or you might replace both outer and inner bushes, in which case you'd move the outer pivot downwards and the inner pivot upwards to get even more camber adjustment (how much you could actually do the latter would depend on how much spare space there is in the bracket between the inner end of the trailing arm and the subframe itself). In either case you are essentially tilting the axis of the trailing arm directly altering the camber. The eccentricity would only be of the order of a few mm to allow you to loose the extra camber you've gained from lowering.
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don't forget - eccentric bushes not compatible with the extra camber-toe adjusting bar.
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I would have thought, at least in principle, you should be OK just replacing the outer bush with an eccentric and keeping the compliant inner bush that allows the toe control bar to do its thing. Have stiff eccentric bushes both inner and outer, and the suspension will probably bind up. In fact in some of the threads i was reading, GTO owners were reporting having removed the toe-control bar all together after fitting eccentric bushes to correct camber. I suppose they'll be more likely to end up pointing backwards on the road, but i guess no more than in a car that has 'normal' semi-trailing arms without the extra toe-bar in the first place.
Going back to the OP's plan, I think we can probably conclude that if correcting excessive camber due to lowering is your intention, trying to incorporate the omega's toe-control bar into your rear suspension isn't going to help. Eccentric trailing arm bushes, on the other hand, seem to be available for exactly that application and should help if you understand what they are doing and install them correctly i.e. outer pivot down and inner pivot up.