Author Topic: Chassis, suspension and aerodynamics, the modified car!!  (Read 16350 times)

Offline wheels-inmotion

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Chassis, suspension and aerodynamics, the modified car!!
« on: August 03, 2010, 10:02:39 PM »
Hi peeps, i've only recently joined the club and i'm not intending to teach anyone how to suck eggs, although if you remove the shell they are much better....

The MK5 is a target car for modifications, albeit lowering or adding a few HP, this is not belittling the build, more like perfecting it, nothing is perfect. If you have driven down this modified road i salute you but are you getting the best from your modifications?

I want to take you down a simple journey that exposes how you have been conned into the form of measurement taken and the level of understanding of those taking the measurement's.

At this point you may be thinking "FFS" do i really need this chap preaching on about bloody wheel alignment!! Well in actual fact yes you do and here's the first installment for why.

Various methods are described to encourage you to resolve tyre wear or handling issues, additionally members in forums are keen to advise but often fall victim to the same miss-information, read carefully and stay ahead of 'alignment the big con'

Tracking/Alignment
Is linear, this measurement shows no concern for any other angle. This form of measurement is the most common in the World and the most damaging.
Angles measured 1

Four wheel Alignment
Uses the rear wheels as a scale to centre the steering rack.... then the front toe..... this is better but is assuming the rear is centred.
Angles measured 2

Four wheel Laser Alignment
Same as above.... be wise!

Geometry/Primary
Will image the exact rear centre line to permit a centred steering wheel.. additionally the front and rear camber positions will be measured. This is the most common form of Geometry and i consider this as 'basic'
Angles measured 8

Full Geometry/primary and Secondary
Is absolute but harder to understand. Few places even with the equipment measure the Secondary angles, these include...
Castor
KPI/SJI/SAI
Scrub radius
included angle
TOOT/Ackerman
Delta curve
and so on

Most areas that involve rapid tyre wear or handling issues need to be read from the 'Secondary' data, even more important if the car has been modified or for diagnostics after an accident.
Angles measured 15+

Not easy reading indeed, millions of pounds change hands every day for 'Alignment', a need to be wise could save you £ssss

One more thing to make the 'blood boil'.. The Primary and secondary Geometry has a customer destination?

1: Primary is the 'dumb' customer version
2: Secondary is with held unless requested and named the 'Technicians version.






Offline stu_no_1

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Re: Chassis, suspension and aerodynamics, the modified car!!
« Reply #1 on: August 03, 2010, 10:25:12 PM »
i got my wheel alignment done today at a specialist in edinburgh called clcm wheel alignment i was recomended to this guy by quite a few ppl including a guy who works for porsche it cost me £40 but the guy said if everything needed adjusted it would have been £68 have you heard about this garage are they any good i dont want my new tyres getting uneven wear like my last ones they were back to the canvas before i noticed. I got a print out of primary and secondary angles so the guy seemed to check loads do u think this was the technical version or just an expensive one

Offline stealthwolf

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Re: Chassis, suspension and aerodynamics, the modified car!!
« Reply #2 on: August 04, 2010, 06:30:35 PM »
Is there a list of companies who could do a full geometry set up? Bucks is a bit far for me.

The GTI isn't just a machine. It's very much a living, breathing thing.

Offline vRS Carl

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Re: Chassis, suspension and aerodynamics, the modified car!!
« Reply #3 on: August 04, 2010, 07:01:17 PM »
I went to WIM last year and was quite surprised how far out my car was after it had so called been aligned.

It was without doubt the best £100 i ever spent. It may be a bit far to travel (2 hours for me) but i was quite happy doing so knowing the car would be done properly :happy2:

Offline wheels-inmotion

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Re: Chassis, suspension and aerodynamics, the modified car!!
« Reply #4 on: August 06, 2010, 09:07:01 PM »
Is there a list of companies who could do a full geometry set up? Bucks is a bit far for me.

Here is a list i have evaluated and trained> http://www.wheels-inmotion.co.uk/tyre-fitting-centres.php

Offline gazbutS3

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Re: Chassis, suspension and aerodynamics, the modified car!!
« Reply #5 on: August 06, 2010, 09:13:15 PM »
Is there a list of companies who could do a full geometry set up? Bucks is a bit far for me.

Here is a list i have evaluated and trained> http://www.wheels-inmotion.co.uk/tyre-fitting-centres.php

smashin, one of them is round the corner from me :happy2:

Offline stealthwolf

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Re: Chassis, suspension and aerodynamics, the modified car!!
« Reply #6 on: August 06, 2010, 09:39:27 PM »
"john hall tyres" - they don't seem to advertise geometry set ups on their website? is it worth popping down?

The GTI isn't just a machine. It's very much a living, breathing thing.

Offline wheels-inmotion

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Re: Chassis, suspension and aerodynamics, the modified car!!
« Reply #7 on: August 06, 2010, 09:47:19 PM »
i got my wheel alignment done today at a specialist in edinburgh called clcm wheel alignment i was recomended to this guy by quite a few ppl including a guy who works for porsche it cost me £40 but the guy said if everything needed adjusted it would have been £68 have you heard about this garage are they any good i dont want my new tyres getting uneven wear like my last ones they were back to the canvas before i noticed. I got a print out of primary and secondary angles so the guy seemed to check loads do u think this was the technical version or just an expensive one

£40-£68 is to cheap?... If the tyre wear was about 10% of the total tyre width then the problem is camber. On the MK5 the camber adjustment is achieved by moving the subframe, this "optimizes" the positions and justifies a fee higher than £68.

It reads to me your car is lowered, if this is the case the pattern of wear is a done deal unless you can find additional camber adjusters.

Offline RedRobin

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Re: Chassis, suspension and aerodynamics, the modified car!!
« Reply #8 on: August 06, 2010, 10:23:23 PM »
.
This thread makes interesting reading  :happy2:

Very technical though and somewhat over my simple head.
« Last Edit: August 07, 2010, 10:51:53 AM by RedRobin »


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Throbbin' Red Mk5 GTI DSG with too many mods to list - Have Fun but Safe Journeys!

Offline stu_no_1

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Re: Chassis, suspension and aerodynamics, the modified car!!
« Reply #9 on: August 07, 2010, 07:31:21 AM »
My car has standard suspension

Offline wheels-inmotion

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Re: Chassis, suspension and aerodynamics, the modified car!!
« Reply #10 on: August 08, 2010, 12:35:23 PM »
My car has standard suspension

How many miles has it done and are there any other modifications?

Offline stu_no_1

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Re: Chassis, suspension and aerodynamics, the modified car!!
« Reply #11 on: August 08, 2010, 01:53:34 PM »
70k miles no other mods just a stage 1 remap but i just done that last week

Offline wheels-inmotion

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Re: Chassis, suspension and aerodynamics, the modified car!!
« Reply #12 on: August 09, 2010, 08:43:38 PM »
Tricky one.... Assuming all mechanical defects has been resolved and you are on stock wheels (off-sets) and both front tyres are wearing the same, then the likely criminal is the coil springs. Over time as these sag the camber angle migrates with it.

Offline stu_no_1

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Re: Chassis, suspension and aerodynamics, the modified car!!
« Reply #13 on: August 09, 2010, 09:14:22 PM »
the car is on standard wheels i dont know if the springs are worn it passed an mot before i got it im thinking about putting Eibach Sportline springs on it have you any good advice on these springs

Offline xxx_mojo_xxx

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Re: Chassis, suspension and aerodynamics, the modified car!!
« Reply #14 on: August 09, 2010, 09:19:05 PM »
I thought the standard GTi setup only allowed simple alignment...?