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Full Geometry


Parthiban
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Just a quickie while on the subject. Do you need all even tyres to have the geometry set up correctly? Reason I ask is because I have 3 nearly new tyres and one about half worn on my std lexus 17's. What im asking really is, once its set, can I then put new 18" wheels and tyres on without needing it doing again?

If that makes any sense? :mat:

Cheers.

the tyre condition will not effect the geometry, in fact on some machines you don't even need a wheel? the geometry position is dependent on the wheel size so if you intend to upsize the wheel then thats the time to have the geometry set..

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wow! did i miss the point or what? i am so sorry.. this week i have been building the site for the jan upload, replying to distressed email and nipping in and out of the forum, the situation with your car by mistake i confused with Scorpions car sorry! Scorpions castor angle is fine, your's is not. yes the castor can cause vibration but the effect will increase with speed. the attitude of Lexus regarding your problem is comforting and i am sure many people in this forum welcome the outcome. myself included.

No worries mate, although from your first post, I thought you were making a joke that I couldn't figure out at all! :lol:

Thanks, will keep you posted.

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  • 3 weeks later...

Tony ( wheels in motion ) can you tell me anybody in the West Midlands who has the kit to do this full geometry check? I have read your website ( first few pages ) and can appreciate the benefit of doing it properly when I am about to replace four tyres ( 18 inch wheels ) that have worn in 17k miles. Also I get a railing affect on some roads where the road is trying to steer me ( tried a courtesy car on 17 inch wheels and that's OK ).

Any assitance, even if you can't persoanlly recommend them, would be appreciated.

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Tony ( wheels in motion ) can you tell me anybody in the West Midlands who has the kit to do this full geometry check? I have read your website ( first few pages ) and can appreciate the benefit of doing it properly when I am about to replace four tyres ( 18 inch wheels ) that have worn in 17k miles. Also I get a railing affect on some roads where the road is trying to steer me ( tried a courtesy car on 17 inch wheels and that's OK ).

Any assitance, even if you can't persoanlly recommend them, would be appreciated.

I have had my full alignment done and have a printout of the results, they couldnt get two things in the spec (front caster and rear camber) and i still get that 'railling effect' you are talking about, I was wodering if it was something more serious such as a shock or a ball joint or something thats has gone? (I dont get any creaking or clunking) but sometimes (especially at speed on the motorway) the car seems to want to steer one way almost like the wind is suddenly taking it or something (and no it wasnt windy) also when I go around one corner in particular it seems as if the back wheels are bouncing or something

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Colin, have you got the uprated anti roll bars on your car as that sounds exactly like you have?

Plus sure I read somewhere that the cars on 18's do tramline more than those on 17 - can't remember the topic though....

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Tony ( wheels in motion ) can you tell me anybody in the West Midlands who has the kit to do this full geometry check? I have read your website ( first few pages ) and can appreciate the benefit of doing it properly when I am about to replace four tyres ( 18 inch wheels ) that have worn in 17k miles. Also I get a railing affect on some roads where the road is trying to steer me ( tried a courtesy car on 17 inch wheels and that's OK ).

Any assitance, even if you can't persoanlly recommend them, would be appreciated.

I get this on my 17's

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i'm gonna be off to see tony beginning of feb hopefully for a full check up, bit of a trek for me but well worth it i reckon! hear nothing but great things!

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Colin, my car reacts loads faster to wind on the motorway and bumps on the road than it used to since I put the full uprated suspension on, I find the benefits outweigh the negatives but if it's windy you really do need to be concentrating all the time as the car gives you that much feedback you can adjust the instant it starts to go, never really noticed it that much with standard anti rolls and springs...

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yea, i suppose i'll just deal with it.

just wanted to make sure nothing was 'seriously' wrong and that i wasn't going to have my tyres replaced again after 10.000 miles, especially now they are 18's!

I think i'll pay tony a visit though next time i'm around that area.

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This is the print out I got for my alignment

http://www.imagehosting.us/imagehosting/sh....jpg/?id=151251

The car is on 18s and standard sport suspension - any comments welcomed.

Does this cover full geometry?

Being from N.Ireland, Watford wouldn't really be economically viable.

the settings are OK, but where are the figures for KPI and included angle? a bigger wheel offers different load on the tyre, the KPI/ included angle would help with the final settings for the camber, im not saying they are wrong just inconclusive....

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the settings are OK, but where are the figures for KPI and included angle? a bigger wheel offers different load on the tyre, the KPI/ included angle would help with the final settings for the camber, im not saying they are wrong just inconclusive....

Thanks for the feedback - at least now I know it's not full geometry. But at least it's better than just tracking. Does 1 hour seem like a reasonable time to set up the geometry.

I'll have to have a look around for some one who knows about KPI and incuded angle next time. :)

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the settings are OK, but where are the figures for KPI and included angle? a bigger wheel offers different load on the tyre, the KPI/ included angle would help with the final settings for the camber, im not saying they are wrong just inconclusive....

Thanks for the feedback - at least now I know it's not full geometry. But at least it's better than just tracking. Does 1 hour seem like a reasonable time to set up the geometry.

I'll have to have a look around for some one who knows about KPI and incuded angle next time. :)

sorry i don't think i have explained myself properly, you have had a full geometry? but they haven't assessed the full report, hence the missing KPI and Included angle data. your camber and toe settings are fine, to be true with the IS200 30' neg front camber tends to still wear the inners, but the position is by the book without applied IS theory, in addition dont worry about the osf castor, have a look at my site www.wheels-inmotion.co.uk the KPI and Included angles are explained in full, from basic knowledge to full theory depending on your flavour, that my help and costs nothing...

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sorry i don't think i have explained myself properly, you have had a full geometry? but they haven't assessed the full report, hence the missing KPI and Included angle data. your camber and toe settings are fine, to be true with the IS200 30' neg front camber tends to still wear the inners, but the position is by the book without applied IS theory, in addition dont worry about the osf castor, have a look at my site www.wheels-inmotion.co.uk the KPI and Included angles are explained in full, from basic knowledge to full theory depending on your flavour, that my help and costs nothing...

Yeah, thanks, I had a look at your site - I think I'd need some pointing and hand gestures around suspension to get a grip of the theory of KPI.

So next time, should I ask the technician to add some negative camber, to improve the handling? - or will the bigger wheel already be making the camber more negative than normal?

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OK, I'm trying to get my head around KPI and I understand what it is (I've even been out under the car with a torch), but I'm not sure of it's function.

The only thing I can think of is that as a wheel turns away from straight on, the force across the tread becomes more concentrated on the edge of the tyre, but at the same time the angle of the KPI causes pressure to counter that force, hence making the tyre sit flatter on the road in a corner. - am I even luke warm?

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Tony ( wheels in motion ) can you tell me anybody in the West Midlands who has the kit to do this full geometry check? I have read your website ( first few pages ) and can appreciate the benefit of doing it properly when I am about to replace four tyres ( 18 inch wheels ) that have worn in 17k miles. Also I get a railing affect on some roads where the road is trying to steer me ( tried a courtesy car on 17 inch wheels and that's OK ).

Any assitance, even if you can't persoanlly recommend them, would be appreciated.

I have had my full alignment done and have a printout of the results, they couldnt get two things in the spec (front caster and rear camber) and i still get that 'railling effect' you are talking about, I was wodering if it was something more serious such as a shock or a ball joint or something thats has gone? (I dont get any creaking or clunking) but sometimes (especially at speed on the motorway) the car seems to want to steer one way almost like the wind is suddenly taking it or something (and no it wasnt windy) also when I go around one corner in particular it seems as if the back wheels are bouncing or something

i'm a bit concerned that the camber adjusters are max'd out!! the castor angle pre-set on the IS200 will be affected by the rear camber position ( ? ) you may think, the explination is long and will make my fingers bleed, can you post here or email me the geometry report..

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OK, I'm trying to get my head around KPI and I understand what it is (I've even been out under the car with a torch), but I'm not sure of it's function.

The only thing I can think of is that as a wheel turns away from straight on, the force across the tread becomes more concentrated on the edge of the tyre, but at the same time the angle of the KPI causes pressure to counter that force, hence making the tyre sit flatter on the road in a corner.  - am I even luke warm?

very warm.. KPI is one of the hardest angles i have when training students, the KPI is three dimentional, and involves many factors within the geometry.

The KPI/ CASTOR/ and INCLUDED ANGLE tend to be the ones that are missing on most geometry reports since they are the hardest to understand and explain....

let me address one area of KPI which is the most common complaint ( pulling ) please dont get the impression it's the only reason why a car can pull..

Effect: the KPI in a straight needs to be rested and even, the inclination lets say on the IS200 9 degrees ( not pos/ not neg ) just an angle, if you attempt to deviate from the straight line, lets say to the left, the ns KPI will decrease in the angular value to 8 degrees 30', os increase to 9 degrees 30', this means that the ns KPI wants to push it's self down, this is not possible so the body of the car has to rise up, now equilibrium between the angles are unbalanced, the weight if the car will want to pull back down to the rested state and return to the rested 9 degrees, if the KPI is uneven and not rested in straight line travel it will pull toward the lower figure, test the effect yourself? drive straight, move the steering wheel slightly left/ right, that resistance you feel is the KPI.

I must add this as a personal note, today i have setup the geometry on one of the cars for the Drift Acadeny UK, www.driftacademy.co.uk, go there, go sideways.

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