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[Webby the Bear]

Chris, when you say 'feedback' what are we talking about? A vibration?

Obviously you've forgotten more than I have to learn but if it is... vibrations from what I've learned are something ''not being round''.... so that would indicate tyres, alloys and bearings.

like when I was looking for a dodgy tire could it simply be one if those 3....obviously if we're talking about a vibration if not then feel free to tell me to shut up 

[Andy H]

Wanderlust? (that's what he usually complains is happening)

[wheels-inmotion]

But an out of line thrust centre(combined rear toe) can. (Make the car crab)

So given the desired rolling toe setting is zero, that's alot of rolling resistance to give +0.10 mins static. Would poly give less deflection from rolling resistance? Given the comparatively soft oe bushes.

Yes polly's or rose joints would be set to a static zero toe front and rear.

[wheels-inmotion]

+1.

Very informative.... especially regarding the toe as I was led to believe it's this that is the most aggressive tyre wearing angle! And also that it can't create pull! 

That's the tyre industry talking to you.... Reality is the toe displacement offers lateral scrub to the tyres. In the event to toe position is wildly out then you as a driver would definitely know with the car bolting on/ off bump and white lines.

The front toe is the only angle that's shared between the front wheels. Since it's shared it's also symmetrical so of an equal force... Can't pull.

[Webby the Bear]

so whilst youre on can I ask how much youd charge to correctly align my car based on the image of my current readings? pm me if you prefer

[wheels-inmotion]

Chris has raised some good, valuable points that members need to heed before spending a penny on wheel alignment.

Let's try this..... There you are in the tyre shop wanting the front wheel alignment checked/ adjusted would you dare to ask what they are aligning the front wheels to?

I bet my left nut they say each-other......"WRONG!"

The front wheels don't actually know where forward is, is it \ \ there or / / or | |? The front wheels point of reference is the middle of the rear, called the Thrust angle.

The Thrust angle is a geometric law despite the drive formate. The Thrust position is generated by each rear toe position. In an ideal world both rear wheels would have the exact toe position and within the tolerances permitted, but it's not an ideal world.

Globally a tolerance displacement of the thrust is 10', this has been downgraded from the 30' permitted some years back. The Thrust position establishes an imaginary centre line that's projected to the front wheels forward direction. From that data each front wheel can be adjusted to the forward direction born from that reference point.

It's from that i say to you "front wheel alignment" is a con, reason i say this is on it's own there's no reference point so.... What are they aligning the wheels to?

[wheels-inmotion]

so whilst youre on can I ask how much youd charge to correctly align my car based on the image of my current readings? pm me if you prefer

I need to be careful here because the forum has given me great leverage over the years but in this case i feel a real image of realistic pricing might help members know what to expect elsewhere.

I can't quote for the entire country but i would like to offer a smattering of knowledge....

If you are told a "free alignment/ geometry check" then that's hook so ask what is any adjustment fee in advance?

MD will offer a total fee. This is regardless of the corrections made so top dollar.

We offer members a worst-case fee of £60+ vat including adjustments assuming the front subframe doesn't need moving, if it does then it's £95+ vat ( worst case )

Now in my tiny little mind the adjustability of the Omega doesn't command more than the normal discounted £60+ vat. Data positions are established so to me the calibration is fire-and-forget type of thing.

Thank TheBoy for this because he is the one who's helped me maintain the price structure without change for the last five years.... Think i might need to send him a letter bomb for Xmas 

[05omegav6]

Some bricks would suffice

Joking aside, finding someone prepared to offer an actual solution rather than a mere 'Green is fine' approach is a rare thing, and much appreciated 

[chrisgixer]

Chris, when you say 'feedback' what are we talking about? A vibration?

Obviously you've forgotten more than I have to learn but if it is... vibrations from what I've learned are something ''not being round''.... so that would indicate tyres, alloys and bearings.

like when I was looking for a dodgy tire could it simply be one if those 3....obviously if we're talking about a vibration if not then feel free to tell me to shut up 

Feedback is unwanted sensations from the road surface "feeding back" to the driver through the steering. Ime the most common starting point for this degrading of handling towards "wonderlust" is, pulling up to a set of traffic lights with wheel depressions in the road surface from heavy traffic, busses trucks and cars etc, commonly known as tramlines.
 You slow down to the line to stop, the slower you go the more the pull on the steering increases, the more you have to turn into the pull to keep the car on line. Similarly having stopped, creep up a few feet with no hands on the steering wheel, and you can observe the steering wheel turning on its own, due to ruts in the road. As if there was a mechanic or a little gremlin working on the road wheel pulling on a spanner. The driver feels that leverage on the steering wheel.
 In effect, the road is steering the car, not the driver. As the road is causing an uneven contact patch, or, an uneven contact patch in relation to the steering axis centre line of the front wheel.
 This is the same as a worn tyre as far as the steering feedback to the driver goes. Except its only present during contact with poor road surface. Tyre wear if present, is active all the time so the car becomes twitchy to the driver, rather than that one piece of bad road surface at the lights.
 The tyre wear in conjunction with poor road surface conspire to pull the steering, and feedback to the driver.

Poor road surface alone should not pull so much as give mild sensation mostly through the suspension.
Poor road surface and tyre wear however, and your into correcting the steering due to feedback, and the worse it gets as the tyres wear more.
Poor road surface, tyre wear, AND braking increases the feedback again. To the point that an emergency stop/severe inside shoulder wear/badly rutted road from a poor road repair, can see the car violently dart off line into the face of oncoming traffic. As I had with those Audi rated sc3. Luckily I was able to keep the car from crossing the white line, but the other driver coming the other way wasn't so convinced.

[05omegav6]

How likely is the thrust angle to change if the rear subframe bushes are poly?

[chrisgixer]

But an out of line thrust centre(combined rear toe) can. (Make the car crab)

So given the desired rolling toe setting is zero, that's alot of rolling resistance to give +0.10 mins static. Would poly give less deflection from rolling resistance? Given the comparatively soft oe bushes.

Yes polly's or rose joints would be set to a static zero toe front and rear.

We hear talk of tyre slip angles... Presumably aiding tyre grip by generating heat. I presume that's not desirable in a road car? Or with road tyres?

Personally I find it difficult to see how slip angle in tyres can be helpful.

[chrisgixer]

How likely is the thrust angle to change if the rear subframe bushes are poly?

Do you mean a before and after change in angle due to fitting? Or during use of poly?

Both seem to be zero chance going by TB's before and after settings when poly where fitted. Poly have no voids like oe, so there's little chance for the rear subframe to articulate with poly.

[chrisgixer]

Although the rear trailing arm bushes are still rubber, so a level of deflection is still possible there.

[05omegav6]

If the car is set up after the polys are fitted, will the thrust angle setting degrade over time?

[chrisgixer]

If the car is set up after the polys are fitted, will the thrust angle setting degrade over time?

Due to poly bush in the subframe to body, no.

Due to to track rod wear(extremely rare), spring sag, trailing arm bush wear, all effecting the combined toe/camber setting... Yes