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[chrisgixer]

I'm reasonably happy with mine currently so no biggies here, but I was wondering, not wandering , in the car today....

We know the steering link rods, tre's and centre tie bar, and the wishbones need to work very closely together without play or movement in their parallel planes (ish) to give a normal sensation of feel at the steering wheel. Trust me, we do. So that's all fine, we have polys to take out play there, we know a solid idler is key, no ball joint play, rear bushes sound etc. That all works as a unit. Mounted on the subframe. It's all fairly independent from there.

But then we have the steering box and column. These are mounted to the body. Now you may or may not have noticed, but when you jack one corner of the car, the drivers door doesn't close as well as it would normally. So obviously there is an element of body flex there, probably understandably though.

So, question 1
... is it reasonable to assume that if there is an element of flex in the body, and the body has the box mounted to it, that body flex could pull the steering box slightly over giving a slight pull? One corner of the car would need to be higher or lower for this to happen. Think table with a short leg and a flexible top. So to speak. 


Further up the system there's often talk of a dead spot in the steering box in the straight ahead position. Re this I often think there's an element of delay in slight steering adjustments that's not present when more steering lock is dialled in. Actually I'm not sure about that but certainly dead ahead is a bit vague. Only a bit mind if all else is as it should be.
But, question 2
... If you accept the dead spot theory exists, how could a delay in steering input occur? The dead spot as its often described. An example of this, dead straight, motorway speeds, no dramas. Wiggle the steering half inch either way, very little response. But steer a half inch one way, and the car does eventually respond. But it's not instant.
 Is it the steering box?
Is it the possible body flex?
Is it servo tronic?
Or... What about the the flexi joint at the base of the column, that connects the column to the box. It's quite a hard piece of rubber, but could it develop play with age. Or go soft(er) over time. Might allow the delay sensation to occur, as the shaft turns but the damping effect of the rubber takes a fraction longer to actually turn the steering box.

Just some ramblings. Any RELEVANT thoughts?

[Nick W]

I'll play, but I do think you're rambling. These are opinions.

Flex in the body: it's inevitable, as your door example shows. But I doubt it affects the steering box if you consider the part of the body it's bolted to. The join of the bulkhead, inner wings, strut towers and chassis rails are further braced by the subframe and have got to be the most rigid area of the structure. The steering linkage is designed to accommodate the suspension movement, which is vast compared to any likely flex.

Your 'delay' in the steering is common to ALL boxes, powered or not. The cause is interesting at 02:00 until I get to sleep. I think it's just something you have to accept as a characteristic, and learn to live with.

[05omegav6]

The only way to remove slack from the steering box is to pack the balls in a liquid poly, so that they have no slop.

If you turn the wheel one turn to the left, then a quarter turn to the right, then a quarter turn to the left, there will be slack in the steering feel at each change of direction. As Nick says, this is a natural characteristic of the design.

You either accept it, or you fit a rack... although a worn rack will give the same feel/symptons 

[omega3000]

Your door hinges are bent and worn 

[chrisgixer]

I'll play, but I do think you're rambling. These are opinions.

Flex in the body: it's inevitable, as your door example shows. But I doubt it affects the steering box if you consider the part of the body it's bolted to. The join of the bulkhead, inner wings, strut towers and chassis rails are further braced by the subframe and have got to be the most rigid area of the structure. The steering linkage is designed to accommodate the suspension movement, which is vast compared to any likely flex.

Your 'delay' in the steering is common to ALL boxes, powered or not. The cause is interesting at 02:00 until I get to sleep. I think it's just something you have to accept as a characteristic, and learn to live with.

Take your point on suspension movement in relation to the wobbly table. But as you say flex is inevitable. But what to do about it?

Don't get me wrong there's no big issue, I 'd quite happily live with it as is, but why wouldn't we want to improve it? If possible?

 Thinking head on cross section, we have the two triangular shapes made by the the pivot points of the suspension, ie top mounts, wishbone pivot point, and wishbone ball joint.

             /|engine|\
  Wheel/_| void   |_\wheel     
               ______

There's a massive structure at the bottom bracing the engine, a subframe.

So the only thing I can think of to help would be one of those nasty chavy strut brace things. That should get that chav TB going

But to be fair the ones I've seen involve drilling the metalwork around the top mounts. Opps that

[chrisgixer]

The only way to remove slack from the steering box is to pack the balls in a liquid poly, so that they have no slop.

If you turn the wheel one turn to the left, then a quarter turn to the right, then a quarter turn to the left, there will be slack in the steering feel at each change of direction. As Nick says, this is a natural characteristic of the design.

You either accept it, or you fit a rack... although a worn rack will give the same feel/symptons 

Steering box is all metal parts. What's damping out the harshness? Hydrolics maybe? Or the rubber block in the rack to box connection?

[biggriffin]

If you want to remove the flex

fully seam Weld the shell, put reinforcement plates on the crumble panels, then fit a fully triangulation cage,made from t45, and as its a road car,fill the hollow chassis legs with expanding foam. Then any thing that is rubber mounted or bushed, use a poly bush or a spherical joint.

[chrisgixer]

If you want to remove the flex

fully seam Weld the shell, put reinforcement plates on the crumble panels, then fit a fully triangulation cage,made from t45, and as its a road car,fill the hollow chassis legs with expanding foam. Then any thing that is rubber mounted or bushed, use a poly bush or a spherical joint.

No I don't want to remove all the flex.

[Field Marshal Dr. Opti]

My MV6 just feels 'right'......and far nicer to drive than my CLS 500.

[Nick W]

Strut braces work when the struts are fitted in the middle of an unsupported panel. Ford were good at this, just look at a Capri or Escort. Extra bracing on those is easy to do, and effective. I lashed up a Capri strut brace out of an old school-desk one Sunday afternoon, which eliminated the wobble the car always had. A similar brace across the anti-rollbar mounts is even easier to make, and also makes a noticeable improvement.

Bracing the Omega is much harder due to the method of attaching the strut and the engine being in the way. And if you look at the strut tower, it's already reasonably well braced against the bulkhead, so any improvement is likely to be minimal.

[Nick W]

While I think about it, the much vaunted steering rack is hardly a paragon of stiffness either. How can it be? A metre long assembly of tubes, sliding and\or articulated joints, gears and bushes that are only attached in a couple of places is going to be a pretty floppy thing.

I improved the steering feel on my Avenger by machining a solid clamp for the 'floating' passenger side out 1" aluminium square bar. Rally cars use a much longer part that wraps around the rack tube to prevent it splitting!

Some slack in the steering is a necessary component for a comfortable, easy to drive roadcar. The gokart like steering on  Seven type car, or quick-rack equipped car gets tiresome very quickly.

[05omegav6]

The only way to remove slack from the steering box is to pack the balls in a liquid poly, so that they have no slop.

If you turn the wheel one turn to the left, then a quarter turn to the right, then a quarter turn to the left, there will be slack in the steering feel at each change of direction. As Nick says, this is a natural characteristic of the design.

You either accept it, or you fit a rack... although a worn rack will give the same feel/symptons 

Steering box is all metal parts. What's damping out the harshness? Hydrolics maybe? Or the rubber block in the rack to box connection?

The hydraulics mostly don't forget, the box is essentially part of the chassis, so any further damping is done by the tyres/ball joints/suspension...

The rubber connection is there for crash purposes, ie if you bend the car enough to move the box, the rubber will deform more effectively than a metal UJ. This means you're less likely to A) lose your lower legs, and B) end up with the steering column attached to your spine... both of which might otherwise be quite unpleasant...

This is summat that might be worthy of consideration when fitting a rack to the V8

[05omegav6]

If you want to remove the flex

fully seam Weld the shell, put reinforcement plates on the crumble panels, then fit a fully triangulation cage,made from t45, and as its a road car,fill the hollow chassis legs with expanding foam. Then any thing that is rubber mounted or bushed, use a poly bush or a spherical joint.

No I don't want to remove all the flex.

Only filling all the box sections/cavaties with expanding foam could be a good compromise... you might find that it increases stress loads where the flat panels meet the boxes, so seam welding is probably a must. Without the bracing the shell will still have a degree of flex. It will change the crash dynamics of the car as well because the box sections won't deform at all, making any prang that much harder.

I don't know what basic crash testing costs, but you could buy a couple of scrap Omegas and fill the cavaties with foam and get them crash tested to compare the impact results.

Doesn't affect the steering though...

[chrisgixer]

Hmmm. ...I wonder could I get a govt grant? Might save in heating bills. Solar panels in the roof maybe? Hybrid power? Yeah, that'd work

[chrisgixer]

While I think about it, the much vaunted steering rack is hardly a paragon of stiffness either. How can it be? A metre long assembly of tubes, sliding and\or articulated joints, gears and bushes that are only attached in a couple of places is going to be a pretty floppy thing.

I improved the steering feel on my Avenger by machining a solid clamp for the 'floating' passenger side out 1" aluminium square bar. Rally cars use a much longer part that wraps around the rack tube to prevent it splitting!

Some slack in the steering is a necessary component for a comfortable, easy to drive roadcar. The gokart like steering on  Seven type car, or quick-rack equipped car gets tiresome very quickly.

Getting warmer, as the rack would be mounted to the same structure of the subframe, rather than a separate structure of the body, in this example at least. Omega doesn't lend itself to a front axle mounted rack too well. So rear mounted is more likely, but that leads to quite an acute angle for the u.j. to negotiate. and then no need for this particular design of rubber block damper for crash protection as it will fold up naturally anyway.

Rack also eliminates the steering idler obviously, mounted to the other wing.

So two points of contact moved from the body to the subframe where all the business happens. Also removes the rearward arc of the idler and pitman arm. So thinking aloud, does that mean a rack needs to be mounted rear most point of that arc to get the lock angle on the hubs?