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[terry paget]

Sorry chaps, I have not mastered the quote and editing system
Hi Ex Taxi Al, the pitman arm and the idler arm are two sides of a parallelogram, the other two being the central steering rod and and the chassis. So they should jolly well be parallel.

Hi Chris, obviously the support must be under the wheel end so that the spring bears the load. I think I achieve that the way I support the wishbone.

I did say, you must free both track rods at the outset.

To have the geometry reset at Chesham, I should have to fit new two wishbones, replace or free both front and rear track rods, and the idler arm. Then Chesham man would have to measure and reset front toe in, rear toe in, camber angles both sides and king pin inclinations both sides. I should want to watch him do it, not just accept his computer print out. I have had tyre shops do similar tasks in the past, and all they do is place the front wheels on greased pads, find a track rod that will turn a bit, reset the toe-in and call it a day.

This thread began with OmegaMan2.2 enquiring how he could get his steering wheel straight when the car was going in a straight line. I have told him.

[Webby the Bear]

imo and what I've experienced at school...

there isn't a place on the suspension you cant jack up on. not saying its technically right, but I have seen all sorts done by the kids there  and no breakages.

having said that, on my own car/customers car i personally wouldn't just in case

[Webby the Bear]

which reminds me...

out of curiosity has anyone ever seen a problem when jacking up a rear diff?

[tunnie]

which reminds me...

out of curiosity has anyone ever seen a problem when jacking up a rear diff?

You mean jacking the entire car up on the diff? Not something i'd do, think there are better places 

[Webby the Bear]

which reminds me...

out of curiosity has anyone ever seen a problem when jacking up a rear diff?

You mean jacking the entire car up on the diff? Not something i'd do, think there are better places 

Yeah jacking the entire car up. Watching lots of videos and having done it myself I haven't encountered a problem. Just wondered if there was any actual evidence of someone jacking up on the diff and having it cave in or something lol

[05omegav6]

Sorry chaps, I have not mastered the quote and editing system
Hi Ex Taxi Al, the pitman arm and the idler arm are two sides of a parallelogram, the other two being the central steering rod and and the chassis. So they should jolly well be parallel.

They need to be parallel to the chassis rails. Nothing else. If the pitman arm is not parallel to the offside rail, then the box is not centred.

WIM at Chesham start by measuring, then they set the REAR geometry to ensure the correct thrust angle. Then and only then do they start the front end, which can include tweaking the subframe.

And as for jacking the Omega up by the diff, you need 6" more lift than you think you do, as it goes a looong way before it reaches the floor, by which time the diff mounts are fubar

[chrisgixer]

Sorry chaps, I have not mastered the quote and editing system
Hi Ex Taxi Al, the pitman arm and the idler arm are two sides of a parallelogram, the other two being the central steering rod and and the chassis. So they should jolly well be parallel.

Hi Chris, obviously the support must be under the wheel end so that the spring bears the load. I think I achieve that the way I support the wishbone.

I did say, you must free both track rods at the outset.

To have the geometry reset at Chesham, I should have to fit new two wishbones, replace or free both front and rear track rods, and the idler arm. Then Chesham man would have to measure and reset front toe in, rear toe in, camber angles both sides and king pin inclinations both sides. I should want to watch him do it, not just accept his computer print out. I have had tyre shops do similar tasks in the past, and all they do is place the front wheels on greased pads, find a track rod that will turn a bit, reset the toe-in and call it a day.

This thread began with OmegaMan2.2 enquiring how he could get his steering wheel straight when the car was going in a straight line. I have told him.

But there is no explanation how to jack on the wheel end so the springs are loaded, with the wheel fitted?


Webby, don't jack on the did on an omega. It will separate the rear dif bushes/subframe to body. They are a cup/horse shoe shape, basically, jacking the dif will lift the rubber out of the cup.

Other models may differ. (Haha, differ )

[Webby the Bear]

Sorry chaps, I have not mastered the quote and editing system
Hi Ex Taxi Al, the pitman arm and the idler arm are two sides of a parallelogram, the other two being the central steering rod and and the chassis. So they should jolly well be parallel.

Hi Chris, obviously the support must be under the wheel end so that the spring bears the load. I think I achieve that the way I support the wishbone.

I did say, you must free both track rods at the outset.

To have the geometry reset at Chesham, I should have to fit new two wishbones, replace or free both front and rear track rods, and the idler arm. Then Chesham man would have to measure and reset front toe in, rear toe in, camber angles both sides and king pin inclinations both sides. I should want to watch him do it, not just accept his computer print out. I have had tyre shops do similar tasks in the past, and all they do is place the front wheels on greased pads, find a track rod that will turn a bit, reset the toe-in and call it a day.

This thread began with OmegaMan2.2 enquiring how he could get his steering wheel straight when the car was going in a straight line. I have told him.

But there is no explanation how to jack on the wheel end so the springs are loaded, with the wheel fitted?


Webby, don't jack on the did on an omega. It will separate the rear dif bushes/subframe to body. They are a cup/horse shoe shape, basically, jacking the dif will lift the rubber out of the cup.
Other models may differ. (Haha, differ )

 

[terry paget]

Hi Chris,
           don't quite understand the question, but I simply jacked up each side in turn, trolley jack plus wood block under the front side jacking point, then lowered it gently on to axle stand plus wood block under wheel end of wishbone. Takes less time to do than describe.

[05omegav6]

The issue is that the outer end of the wishbone isn't designed to take a vertical load. Its sole purposeis to locate the wheel laterally

[terry paget]

Let's not have a row about it, but the purpose of the wishbone is to locate the bottom ball joint laterally and fore and aft. Other cars I have had (Minis, Morris 1100s) had separate suspension items to bear those forces. The Mcpherson strut bears the vertical load.  The forces on the wishbone are large under braking and when cornering. The wishbone is a strong assembly of pressed steel components, and will come to no harm supported as I described.

[Mr.OmegaMan]

The new "tyre debate thread" is now the tracking for the tyres 

I appreciate all the replies.

Will update next week what I decide to do.

 

[chrisgixer]

Let's not have a row about it, but the purpose of the wishbone is to locate the bottom ball joint laterally and fore and aft. Other cars I have had (Minis, Morris 1100s) had separate suspension items to bear those forces. The Mcpherson strut bears the vertical load.  The forces on the wishbone are large under braking and when cornering. The wishbone is a strong assembly of pressed steel components, and will come to no harm supported as I described.

It also bends quite easily, in a vertical direction just outboard of the bolts, when pushed into a kerb by a range rover. Var clobbered a kerb effectively. So, given that its not possible to place a stand on the ball joint end while the road wheel is fitted, the stand will have to be placed inboard of the ball joint! Nearer the crumple zone of the wishbone, and away from the strut.

So there's a real danger of bending the arm, and incorrect ride height when measuring/setting. If I understand your post correctly...?

Please advise, because if there's an easier way of setting the toe, i'm all ears.

[TheBoy]

The reason I would still recommend a full geo check in this scenario is that the car most likely hasn't had one for a while (if ever).

At 10+ years old, everything would have fallen out, though the big killer for Omegas is the way the front camber falls out of (even GMs piss poor) spec, though other stuff will be out as well.

If the rear is out, everything is out. 4 wheel alignment/laser alignment and just guff does not set the rear, only use it as a reference point for the front...  ...so if the rear is out, they will bugger up the front by adjusting it.


After years of suffering chronic tyre wear and pulls on my first Omega (the Silver Bullet), it now gets an annual WIM check, along with every subsequent Omega I've had.  Other cars I've had I tend to only get WIM'd once, as they don't appear to fall out of adjustment like the Omega does.

I would also add, the Silver Bullet, despite its 204k, is one of the straightest, sure footed cars I've ever driven (shame I'm struggling to get TBE to the same level, but its getting there), followed 2nd by Tractor, which also had regular WIM visits.


There are DIY ways of getting it close, if its only one setting you've disturbed, and the car's geo was bang on before (only known if you have recently had it checked), but they are very fiddly. I believe they are more for getting it "near enough" so as to be drivable, and not wreck the rubber, until you can get it done properly.


For an Omega, I would always class any form of tracking/4wheel alignment as a waste of money, as its the wrong service for what the car needs.


As to 2nd hand TREs. *sigh*. They are only £20ish from GM. The GM ones are by far the most durable. I think the trash that Autovaux sell as genuine GM (and clearly aren't, the lying 'tards) are probably the worse I've seen, not lasting the warranty period. 2nd hand is just a tad daft IMHO.

[TheBoy]

Supporting the weight of the car on the wishbone, the only place I'd say thats possible it right under the balljoint (so wheels off). The wishbone is not designed to withstand the forces exerted in that direction if you support anywhere else.