Wheel Alignment the big con!

[KenONeill]

The only swap that's easily possible with directional tyres is front to back on the same side. If you suspect a tyre issue, that would be enough to confirm it, as the vibration etc will move.

OTOH if your issues are coming and going that quick, then unless there's something loose inside the tyre, it's not a wheel/tyre issue; I'd suspect an out of balance driveshaft (possibly a loose balance weight).

[NikBorton]

Naturally, because I picked a stupid car a front-back swap isn't possible - 7.5in at the front, 8.5in at the back; the fronts will go on the back, the backs won't go on the front!

All ideas are good ammunition for taking to the garage though! In the accident, the sidewall and edge of the rim (which was been tried on the other side immediately after) did take part of the wallop, though not enough to noticeably deform or crack it; it still balanced fairly simply after tyre fitment. As a result I've always had worries of damage to the hub or diff (it's an LSD, albeit a "bomb-proof" M one) at the back of my mind. And tried vainly to dismiss them!

There's a guy in the other building with an E36 323 convertible, I'm starting to get tempted to beg a temporary swap of fronts and/or backs one lunchtime.

Edited 26 February, 2009 by NikBorton

[ultra_joel88]

I've noticed today that my N/S rear wheel is wearing more quickly on the outside edge than the inside.

I've looked at the all the other tyres and they seem to wearing relatively evenly.

Would a binding brake caliper cause this?

[wheels-inmotion]

I've noticed today that my N/S rear wheel is wearing more quickly on the outside edge than the inside.

I've looked at the all the other tyres and they seem to wearing relatively evenly.

Would a binding brake caliper cause this?

No.... the brakes cannot influence the wear.

[ultra_joel88]

What on earth would cause the outside of the tyre to wear faster than the inside, and only on one wheel? The fronts seem to be wearing evenly.

Looking at my specs, I seem to have slightly too much positive camber on that wheel, I thought lowering the car would cause more negative camber, any ideas?

[wheels-inmotion]

What on earth would cause the outside of the tyre to wear faster than the inside, and only on one wheel? The fronts seem to be wearing evenly.

Looking at my specs, I seem to have slightly too much positive camber on that wheel, I thought lowering the car would cause more negative camber, any ideas?

Depending on the suspensions configuration lowering doesn't always deepen the camber at the rear, if you had "near" to positive positions before then it's probable you still have.

As for the wear, there are two main reasons for this...

1: On a turn each wheel has a different radius, obviously the left turn encompasses the smallest radius impacting scrub on the NS tyres. This scrub would agitate the NSR because unlike the front there is no Ackermann angle to assist.

2: On a right turn/ bend the suspension is subjected to transitional loads, these loads produce roll front and rear and a roll couple, the rear outer wheels camber position should migrate under lateral compression forcing a more aggressive negative camber position and maintain the tyres saturation grip limits. This is all good and fine assuming the static camber position is correct, seemingly on your car it's not.

[KenONeill]

On a Furbie, lowering shouldn't affect rear camber; it's got a trailing beam.

Joel, have you taken actions to reduce understeer?

[ultra_joel88]

I have a rear anti roll bar fitted, I'm I read that these reduce understeer, what would you suggest?

I'm considering shimming the offending wheel

[wheels-inmotion]

I have a rear anti roll bar fitted, I'm I read that these reduce understeer, what would you suggest?

I'm considering shimming the offending wheel

Historically to invite oversteer you would increase the torsional rate at the front and reduce it at the rear, it's not uncommon on various marques that they remove the rear arb, obviously i don't recommend this but it gives an idea of how the arb controls the roll centres during transition.

If the cars lifting a paw on cornering it would be better to source a "anti-lift" kit?.... this allows the front castor angle to sweep further during cornering, belaying lateral rigidity to some extent.

[Interphase]

I'm going to have to have a full alignment done on my Octy soon as the pull to the left is just silly - switching to SWMBO's micra (which used to be mine) leaves me drifting to the right because of the countercorrection I've learned to apply. The steering wheel is also a good 5 degrees or so offset to the right when the car is travelling straight which is irritating.

Seems my closest centre in Leicester according to the site given here is the main Parkers on Scudamore Road. Anyone used them and know what they're like? I've only dealt with the parts side of the business before, and they've very good.

Ah, one more thing - there's a bit of play in the steering which I was informed by a main dealer was caused by wear on the inner track rod arm bushes. They quoted over £390 to do the job, which seems excessive - I take it just the bushes can't be replaced so they've quoting for replacement arms? I'll need to get that sorted before I take it for the alignment, so have to factor in the overall costs.

[ultra_joel88]

I have just re-fitted the rear adjuster in my coilovers, as the rear was sitting slightly (few mm) lower than the front.

The car now seems to be a lot more stable.

[wheels-inmotion]

I'm going to have to have a full alignment done on my Octy soon as the pull to the left is just silly - switching to SWMBO's micra (which used to be mine) leaves me drifting to the right because of the countercorrection I've learned to apply. The steering wheel is also a good 5 degrees or so offset to the right when the car is travelling straight which is irritating.

Seems my closest centre in Leicester according to the site given here is the main Parkers on Scudamore Road. Anyone used them and know what they're like? I've only dealt with the parts side of the business before, and they've very good.

Ah, one more thing - there's a bit of play in the steering which I was informed by a main dealer was caused by wear on the inner track rod arm bushes. They quoted over £390 to do the job, which seems excessive - I take it just the bushes can't be replaced so they've quoting for replacement arms? I'll need to get that sorted before I take it for the alignment, so have to factor in the overall costs.

If the wear is in the steering arms knuckle then yes it needs to be replaced.... It's a non-mechanical part so i fail to justify the price quoted.... This sort of part normally sells for around £80+ each.

[Interphase]

Cheers for that, I did think it was a bit excessive - they justified the cost on the ground of 'having to drop the steering rack out', which would then be multiplied by main dealer labour costs. I'm not sure how long such a job would take and if they'd have to do a rudimentary alignment as well, inviting extra costs and labour charges.

What are the odds that the techs at Parkers would have received training up to the same level as anyone else in using that particular alignment kit? Is there a standard process to go through before they've authorised to advertise the service?

[KenONeill]

Cheers for that, I did think it was a bit excessive - they justified the cost on the ground of 'having to drop the steering rack out', which would then be multiplied by main dealer labour costs. I'm not sure how long such a job would take and if they'd have to do a rudimentary alignment as well, inviting extra costs and labour charges.

There's no obvious (other than model specific) reason beyond better access why you'd need to drop the rack to change the TCAs. Of course, dropping the rack does afford the opportunity to give it an inspection.

[wheels-inmotion]

Cheers for that, I did think it was a bit excessive - they justified the cost on the ground of 'having to drop the steering rack out', which would then be multiplied by main dealer labour costs. I'm not sure how long such a job would take and if they'd have to do a rudimentary alignment as well, inviting extra costs and labour charges.

What are the odds that the techs at Parkers would have received training up to the same level as anyone else in using that particular alignment kit? Is there a standard process to go through before they've authorised to advertise the service?

The rubber gaiters on the steering rack eventually need changing, this is done without removing the rack, well the steering arm anchor point is under the gaiter.

Alignment centres and technicians are totally unregulated, anyone can set the chassis. The people who install the machine only train them on the procedure not the theory of chassis dynamics, this was one of the reasons i built the wheels-inmotion webby years ago, just so the public can get a little "heads up" before letting fast fit loose on their car.

[ultra_joel88]

I've been keeping an eye on my left rear wheel and the outside of the tyre is wearing down very quickly and there are now very small cracks appearing at the top of the sidewall, as in the type you get on tyres that are aging.

I am going to hazard a guess and say its down to the too much positive camber on this wheel - this only seems to have come about AFTER fitting coilovers?

What are the causes of this?

Worn rear beam bush on that side?

Bent beam when fitting coilovers?

Is the ONLY way to correct it with a plastic shim?

Help.

Edited 29 March, 2009 by ultra_joel88

[wheels-inmotion]

Very unlikely the camber position is to blame... Is it possible you can display an image of the wear or email it to me [email protected] , i'll be able to tell at a glance what's causing this.

[ultra_joel88]

I've got some pictures but its hard to capture on a camera?

I can get more if these are useless.

The outer most tread indicator has about 2mm left on it and the inner most about 4 or 5

[disco-barry]

Are you sure there is such a big differance? Also has the tyre ever been elsewhere on the car??

[wheels-inmotion]

The wear is lateral, look at the tread blocks you can see a feathered pattern of wear, camber's unable to do that.

If your running stock positions then these need to be changed to suit your driving style/ area.... Point to remember the positions offered by the manufacture are "suggestions" not law.

[KenONeill]

Joel, how does the car feel when cornering hard? Understeer, oversteer (real oversteer where it turns tighter than commanded, not just rear-wheel skids), neutral? I've seen a wear pattern like this before, but it doesn't normally appear on the back of an FWD car.

[ultra_joel88]

Tyre has always been there and has covered about 15k now.

Car seems to corner fine, some understeer but I guess thats normal on a big diesel, I dont really push it enough to make the tyres squeel.

car is lowered on coilovers. but not "stupidly" low, can still fit two fingers between tyre and arch.

any ideas?

[KenONeill]

If it's understeering, it's not what I thought it might be.

[ultra_joel88]

well I've had a closer look all around the tyre, and on the outer edge some patches are wearing more quickly than others, for example one indicator in the outer tread is at about 2mm, whilst another has around 5mm.

Strange.

]

Tyre is a Toyo T1R, and I keep the pressures at about 36 psi

[wheels-inmotion]

well I've had a closer look all around the tyre, and on the outer edge some patches are wearing more quickly than others, for example one indicator in the outer tread is at about 2mm, whilst another has around 5mm.

Strange.

]

Tyre is a Toyo T1R, and I keep the pressures at about 36 psi

That pattern of wear is common on directional tyres, the actual reason for it is open to debate between the car manufacturer and the tyre manufacturer.

I wrote a white paper on this topic in an arbitrary position for a conflict over the pond... if anyone is interested i'll post the paper?