MK5 Golf GTI

All Things Mk5 => Modifications & Technical Area => Technical Workshop => Topic started by: wheels-inmotion on August 06, 2010, 09:51:17 pm

Title: Geometry calibration, what is it and why?
Post by: wheels-inmotion on August 06, 2010, 09:51:17 pm
 What is it?
Simply put Geometry is the X,Y,Z axis that forms a dynamic realm expressed by the suspension, steering and the cars parallelograms.

Why have it?
The actual tyre contact patch is about 1/3 of the total tyre width. During the suspensions transitions there is a need to maintain the position of the contact patch without distortion or saturation but still allow for comfort and indeed tyre preservation.

How?
Geometry has two areas that concern us after the mechanical engineers offer the final product.
Static:- This is the inert position of X,Y,Z measured during a calibration.
Dynamic:- This is the "expected" gains of X,Y,Z whilst in motion.

The true realm of Geometry is dynamic, a fluid 3D environment applying Geometric forces that are dependable during Yaw, maintaining the contact patch..... The holey grail of chassis calibration is realizing the gains whilst the cars chassis is static... Not an easy task.

The angles and forces
Of the many angles we will just concentrate on three.

Camber:- Is the vertical position of the wheel, it's duty is to position the cars weight to the correct area of the tyre contact patch. If the vertical position is incorrect then the vehicular weight will be disproportionate and accelerate tyre wear.

Camber force:- The tilt of the camber deforms the circumference of the tyre sidewall, this forces the tyre into a conical profile that wants to roll into it's conical centre...... So if i were to describe the camber force it would be "compressive".

Toe:- Is the longitudinal position of the tyre relative to the direction of travel. In a straight line a need to calculate the type of momentum albeit front-rear or four wheel drive -V- the actual rolling resistance generated between the tyre contact patch and the road makes Toe an infinitesimally difficult position to exact outside of the theoretical.... Nevertheless the ultimate aim for all drives is a dynamic 0 toe.

Toe force:- Toe exerts no force unless aggressively displaced, then the car will feel unstable off the bump.... Toe cannot make a car pull.

Castor: Is an extension of the front wheels steer axis... By design the lower steer axis is off-set to the wheel centre and the upper rotational axis.

If an imaginary line was drawn through the pivotal points it would fall in front of the tyre this is called the "trial distance", by design the tyre has no option other then to follow the trail unless interrupted by Yaw.

Castor force:- Is compressive adding weight to the steering feel.... My best description is the castors energy is gyroscopic resiting any attempts to deviate from dead ahead.

Time to turn
Now we have a basic understanding of the angles lets see what happens when you turn....This explanation will not include inertia or transfer properties.

Example taken at the front wheels on a 10 degree right lock
At 10 degrees the front camber positions will change from / \ to / / the near side castor will reduce and the offside will extend.

This action lowers the cars upper parallelogram on the offside corner, diagonally modifying the camber contact patch, the castor trail and the acceptance of toe on the inner wheel.

Most believe the recovery of the lock is due to the castor extension or gyroscopic laws, in fact this is not true?

During any lock transition the cars upper parallelogram is supported by the lower King-pins (lower swivels) as the inner castor sweeps forward the inclination of the king-pins is off-set so that the inner offside front is more vertical than the relaxed nearside front.

Since the position of the king-pin is perpendicular a higher position holds more vehicular weight and since the kingpins are connected via the steering rack a natural equilibrium insists the steering will be returned.

Those settings
All manufacturers offer a static setting range, this allows for wear since the driven car is subject to road trauma and progressive deterioration of the suspension, so we have a range.

On a fully adjustable chassis a range means nothing... Optimum positions can be achieved and you should expect nothing less if you want to experience the true splendor of the chassis.

That's it..... I hope my explanation made some sense and offers a little understanding for you and what to expect at the shop from the Geometry calibration.

Thank you
Tony


User's Signature
Title: Re: Geometry calibration, what is it and why?
Post by: stealthwolf on August 06, 2010, 09:54:09 pm
Can't help but feel pics/diagrams would greatly benefit your otherwise informative post.
Title: Re: Geometry calibration, what is it and why?
Post by: RedRobin on August 06, 2010, 10:27:45 pm

Can't help but feel pics/diagrams would greatly benefit your otherwise informative post.


.... x 2

(https://www.mk5golfgti.co.uk/forum/proxy.php?request=http%3A%2F%2Fdaz.co%2Fmedia%2FRedRobin_05%2FRED_INK%2FAspirinHeadache.jpg&hash=229c2ea5963c0e3d468cf9a0002f0ec842152251)

^ Though to be fair, this applies more to your other technical post. Not everyone here is so technically minded.
Title: Re: Geometry calibration, what is it and why?
Post by: wheels-inmotion on August 08, 2010, 09:56:46 am
Can't help but feel pics/diagrams would greatly benefit your otherwise informative post.

Agreed, is there a "how to guide" here you can point me to?
Title: Re: Geometry calibration, what is it and why?
Post by: stealthwolf on August 08, 2010, 10:00:55 am
Agreed, is there a "how to guide" here you can point me to?

You mean with uploading pictures? This websitr doesn't have the facility to upload them. You need an accout with sAy photobucket (free). Upload the pics there and it gives you the address to copy and paste. As long as it has
Code: [Select]
[img][/img] tags, you'll be fine.
Title: Re: Geometry calibration, what is it and why?
Post by: wheels-inmotion on August 08, 2010, 12:33:50 pm
Reads like a lot of work.... Maybe i'll be more explicit in the posts and allow members imagination to do the rest.
Title: Re: Geometry calibration, what is it and why?
Post by: Teutonic_Tamer on August 30, 2010, 02:12:44 pm
I understand it all . . . .   :P

So what kind of prices are we talking about for you to do a full check and adjust?  :smiley:
Title: Re: Geometry calibration, what is it and why?
Post by: RedRobin on August 30, 2010, 03:18:06 pm

I understand it all . . . .   :P


....Hello smart arse! :evilgrin: - Good to see you back, buddy  :drinking:
Title: Re: Geometry calibration, what is it and why?
Post by: stealthwolf on August 30, 2010, 11:12:20 pm
+1. T_T's back in town! :pomppomp:
Title: Re: Geometry calibration, what is it and why?
Post by: the bruce on January 10, 2011, 12:36:35 pm
+1. T_T's back in town! :pomppomp:


T O E

(https://www.mk5golfgti.co.uk/forum/proxy.php?request=http%3A%2F%2Fwww.golf5gti.com%2Fupload%2Favatars%2Futool_f_1291507325_3041.jpg&hash=0a92792ff3cc855a32000609c45c537754623c2a)

Toe in (= positive); toe out (= negative)


C A M B E R

(https://www.mk5golfgti.co.uk/forum/proxy.php?request=http%3A%2F%2Fwww.golfvigti.com%2Fupload%2Favatars%2Futool_f_1291509663_14.jpg&hash=1a1bb136d42d02141a3d7af12662e864a6523db4)

Stock - 1° front and - 1°40' rear. 1° is 60 minutes (' ). 1.5° = 1°30'.


C A S T O R

(https://www.mk5golfgti.co.uk/forum/proxy.php?request=http%3A%2F%2Fwww.golfvigti.com%2Fupload%2Favatars%2Futool_f_1291510472_14.jpg&hash=c52136bd7f6e6785388b33678d24662c2f286f15)



sorry, I don't know the english word for 'Spreizung'

(https://www.mk5golfgti.co.uk/forum/proxy.php?request=http%3A%2F%2Fwww.golfvigti.com%2Fupload%2Favatars%2Futool_f_1291903700_14.jpg&hash=7ce53a907eb68e7de6cb83fb7c70f8e282cdba73)


again, I don't know the correct word for 'Lenkrollradius'

(https://www.mk5golfgti.co.uk/forum/proxy.php?request=http%3A%2F%2Fwww.golfvigti.com%2Fupload%2Favatars%2Futool_f_1291904006_14.jpg&hash=fb871406ee0d16cb79df2a034daf131496f5159a)



C E N T E R  O F  R O L L

(https://www.mk5golfgti.co.uk/forum/proxy.php?request=http%3A%2F%2Fwww.golfvigti.com%2Fupload%2Favatars%2Futool_f_1291904512_14.gif&hash=5dfd3374bddfd7649ac4f6566385ad951d50ba75)
(https://www.mk5golfgti.co.uk/forum/proxy.php?request=http%3A%2F%2Fwww.golfvigti.com%2Fupload%2Favatars%2Futool_f_1291904541_14.gif&hash=77631392d9a41de35a2cc88d94131bcc05b90ead)
Title: Re: Geometry calibration, what is it and why?
Post by: Kiwi on January 10, 2011, 06:04:31 pm
 :signIWS: What he said.
Title: Re: Geometry calibration, what is it and why?
Post by: s2martyn on February 26, 2011, 01:03:39 pm
can anyone point me in the direction of the front track settings please..done a search to no avail..car will be set up on supertracker(in mm not degrees)thaks in advance martyn
Title: Re: Geometry calibration, what is it and why?
Post by: RedRobin on February 26, 2011, 03:03:36 pm
^^^^
Don't know if this info will help, but here goes:

If you are having a laser alignment on say a Hunter rig, one of the presets is called: "Volkswagen : Golf V 2004-09 : Sport Suspension GTI (G08/1JE)".

Ranges are:

FRONT : LEFT & RIGHT

Camber: -1º14' - -0º14'
Caster: 7º17' - 8º17'
Toe: 0º00' - 0º10'


Title: Re: Geometry calibration, what is it and why?
Post by: rich83 on February 26, 2011, 03:05:10 pm
oops.. i think i got the USA setting by accident!  :popcornsoda:
Title: Re: Geometry calibration, what is it and why?
Post by: Teutonic_Tamer on February 03, 2012, 11:38:19 am
sorry, I don't know the english word for 'Spreizung'

(https://www.mk5golfgti.co.uk/forum/proxy.php?request=http%3A%2F%2Fwww.golfvigti.com%2Fupload%2Favatars%2Futool_f_1291903700_14.jpg&hash=7ce53a907eb68e7de6cb83fb7c70f8e282cdba73)
'Spreizung' is German for 'steering axis inclination' (SAI) - basically the modern term for the old skool 'king pin axis inclination' (KPI).  The blue line is just the vertical plane (as measured at the centre line of the roadwheel/tyre), the red line is the steering axis inclination, and the degree of angle between the vertical (blue) and the SAI (red) is the value.


again, I don't know the correct word for 'Lenkrollradius'

(https://www.mk5golfgti.co.uk/forum/proxy.php?request=http%3A%2F%2Fwww.golfvigti.com%2Fupload%2Favatars%2Futool_f_1291904006_14.jpg&hash=fb871406ee0d16cb79df2a034daf131496f5159a)
'Lenkrollradius' means 'steering roll radius' - no normally measured.  Using the upper picture, this is measured as the distance from the road surface to where the vertical (blue) crosses the SAI (red).

There is a final measurement (again, not normally stipulated) - the distance widthwise on the road surface between where the vertical and the SAI 'touch' the road.  From the deepest bowels of my memory, I think this is called something like 'scrub offset'.


Its interesting to note that no one has actually discussed the actual effect each setting does . . .  :booty:
Title: Re: Geometry calibration, what is it and why?
Post by: the bruce on February 03, 2012, 11:53:33 am
 :happy2: :wink:
Title: Re: Geometry calibration, what is it and why?
Post by: Cij84 on February 03, 2012, 04:29:01 pm
I know Tony from Lexus Owners Club, he has worked wonders for the IS200's as they came from the dealership how to say it...."not right" he has from what i have seen a fantastic set up in his garage, and able to perform and show you exactly what he is doing to your cars geometry whilst setting it up!!

Chris
Title: Re: Geometry calibration, what is it and why?
Post by: Teutonic_Tamer on February 03, 2012, 05:49:20 pm
I know Tony from Lexus Owners Club, he has worked wonders for the IS200's as they came from the dealership how to say it...."not right" he has from what i have seen a fantastic set up in his garage, and able to perform and show you exactly what he is doing to your cars geometry whilst setting it up!!

Chris
MANY main stealers completely fook up geometry settings . . .

IMVHO, you should never let a stealer loose on alignments.  I had my previous S4 done by an official Audi garage (Huntingdon Audi), and they messed it up so badly I had two monster blowouts at three figure speeds on the Autoroute in the south of France!  Thankfully Michelin France came to my rescue . . .
Title: Re: Geometry calibration, what is it and why?
Post by: majinvash on October 09, 2012, 09:53:21 am
^^^^
Don't know if this info will help, but here goes:

If you are having a laser alignment on say a Hunter rig, one of the presets is called: "Volkswagen : Golf V 2004-09 : Sport Suspension GTI (G08/1JE)".

Ranges are:

FRONT : LEFT & RIGHT

Camber: -1º14' - -0º14'
Caster: 7º17' - 8º17'


Toe: 0º00' - 0º10'




Hi

Heading up to a local trusted garage to have the geometry on my car sorted. ( Denmead Tyres )

They have a hunters rig.
Are the above settings the ones you would recommend getting or would I be much better with getting another "fast road" setting put on?

Cheers

Mat
Title: Re: Geometry calibration, what is it and why?
Post by: RedRobin on October 09, 2012, 10:32:01 am
Hi

Heading up to a local trusted garage to have the geometry on my car sorted. ( Denmead Tyres )

They have a hunters rig.
Are the above settings the ones you would recommend getting or would I be much better with getting another "fast road" setting put on?

Cheers

Mat

....Hi Mat, and a Warm Welcome to the forum  :happy2:

I have used Denmead twice (via JKM). I would take their advice as it might be influenced by how your car is individually already set up. My suspension was set up by VWR but yours may never have been specifically set up.

It will be interesting to compare our Denmead Hunter settings.
Title: Re: Geometry calibration, what is it and why?
Post by: majinvash on October 09, 2012, 10:57:21 am
Cheers Bud.

I am pretty sure its not been done since It was new or at best by main stealer's.

Getting a set of F1 Eagles soon, so going to get it all done at the same time. £480 fitted :D

Trying to decide weather to get the WALK and the relevant front bushings to support that done at the same time.

Coming from a 350bhp Scooby I am really missing being able to put the power I have down.
Title: Re: Geometry calibration, what is it and why?
Post by: RedRobin on October 09, 2012, 12:07:09 pm

Trying to decide weather to get the WALK and the relevant front bushings to support that done at the same time.


....As soon as you've had WALK and bushings I think you'll need alignment done. So you might be going for an alignment twice in fairly quick succession.

If you are definite about the WALK and bushings (all fronts or just arm to balance WALK), then I would leave the alignment until they are installed and put up with the new tyres without up-to-date alignment as long as as it's not too long.

I've changed tyres plenty of times without alignment every time.
Title: Re: Geometry calibration, what is it and why?
Post by: majinvash on October 09, 2012, 12:11:32 pm
From reading the reviews on this site.

I think its these that I need?

   Front Wishbone Inner Bush (Front)   2   1   PFF85-501   
Ex. VAT:     £18.65
Inc. VAT:     £22.38
   Front Wishbone Inner Bush (Rear)   2   2   PFF85-502   
Ex. VAT:     £24.15
Inc. VAT:     £28.98


Annoyingly the pricing on the Powerflex site is half that I can find on the net from suppliers.. I am wondering if the main site is actually listing the trade pricing?
Title: Re: Geometry calibration, what is it and why?
Post by: RedRobin on October 09, 2012, 12:18:25 pm
^^^^
I don't know the part #'s on mine but they are installed as shown (purple):

(https://www.mk5golfgti.co.uk/forum/proxy.php?request=http%3A%2F%2Fdaz.co%2Fmedia%2FRedRobin_05%2FMods%2FVWR_WishboneBushWALK.jpg&hash=3513d5f682a497ec76d6e8a2721820877b48ab6d)

(https://www.mk5golfgti.co.uk/forum/proxy.php?request=http%3A%2F%2Fdaz.co%2Fmedia%2FRedRobin_05%2FMods%2FVWR_WishboneBushes.jpg&hash=18b07a7651b64a34da1ac75966e401f104314cfd)

^ Powerflex.
Title: Re: Geometry calibration, what is it and why?
Post by: the bruce on October 09, 2012, 03:01:40 pm
I'd go for the SuperPro or Whiteline front bushes that have a pattern to keep
some grease.

 :wink:

For spirited driving get the rear camber reduced to a value close to front camber
and front toe slightly increased (+10' to +15) while having rear toe close to zero
(0' to 5'). The car will turn better.

The main problems with most shops are:

- get both sides as equal as possible (VW allows huge tolerances)
- they often "forget" to reduce rear camber after lowering
Title: Re: Geometry calibration, what is it and why?
Post by: Hedge on October 09, 2012, 03:12:25 pm
For spirited driving get the rear camber reduced to a value close to front camber
and front toe slightly increased (+10' to +15) while having rear toe close to zero
(0' to 5'). The car will turn better.

Is that Toe in or Toe out?
Title: Re: Geometry calibration, what is it and why?
Post by: RedRobin on October 09, 2012, 04:11:34 pm
^^^^
My Toe, both front and rear is 0º07' on both Left and Right.

I remember that VWR slightly increased my rear camber a fraction after lowering on KW=V3's.
Title: Re: Geometry calibration, what is it and why?
Post by: the bruce on October 09, 2012, 08:19:39 pm
Is that Toe in or Toe out?


Toe in as almost always on a street car.  :wink:
Title: Re: Geometry calibration, what is it and why?
Post by: Hedge on October 09, 2012, 09:07:25 pm
Is that Toe in or Toe out?


Toe in as almost always on a street car.  :wink:

Thanks Bruce.  :happy2:
Title: Re: Geometry calibration, what is it and why?
Post by: the bruce on October 09, 2012, 09:28:26 pm
To make things more clear when you read alignment data:

Positive toe values are 'toe in', negative numbers are 'toe out'.

Keep in mind reducing rear toe in (or even toe out) wil help turning, but at the same time unsettle
the rear end. Toe out on rear is too dangerous at higher speeds, so not recommended on street.
A slight increase of toe in on front will help turn in and steering response. Again: Don't overdo it.
Stop at +15'.

Guess I don't need to explain positive and negative camber as almost anyone knows stock cars
run zero to few negative camber and increasing negative camber helps cornering speeds greatly.
Title: Re: Geometry calibration, what is it and why?
Post by: Lollylauren on October 09, 2013, 08:26:52 pm
Nice bit of light reading  :rolleye:
Title: Re: Geometry calibration, what is it and why?
Post by: Donx22 on December 11, 2013, 05:01:13 pm
I will be performing a full alighnment after centering the subframe next week once I get a  free second at work as at the moment there is nearly a 30 minute split betweek left and right catser and its doing my head in!

I had planned to do a full guide once I have taken some pictures to make it easier to explain and try relate this as to what you feel on the road/track if anyone would like me to?
Title: Re: Geometry calibration, what is it and why?
Post by: edd30 on November 18, 2014, 11:08:43 am
Donx did you get your alignment sorted in the end ?
What settings did you end up with ?
Title: Re: Geometry calibration, what is it and why?
Post by: JENKO on July 30, 2015, 01:03:09 pm
Hi Red Robin, you seem to be the goto jedi for alignment queries, I am running eibach prokit and fsd on my mk5 gti so will be slightly lower than stock - are you running lowered springs as I was after the settings for a decent alignment - can you help out?
thanks


^^^^
Don't know if this info will help, but here goes:

If you are having a laser alignment on say a Hunter rig, one of the presets is called: "Volkswagen : Golf V 2004-09 : Sport Suspension GTI (G08/1JE)".



Ranges are:

FRONT : LEFT & RIGHT

Camber: -1º14' - -0º14'
Caster: 7º17' - 8º17'
Toe: 0º00' - 0º10'
Title: Re: Geometry calibration, what is it and why?
Post by: the bruce on August 26, 2015, 11:35:01 pm
No need for "special" alignment settings. There's even no "magic numbers".
Just get stock settings. It's that simple. Take care they correct the (due to
lowering) increased rear camber back to -1°30' or -1°45'. Stock toe is fine
for street (both front and rear about +0°10' = 10 minutes). That's about it.
Title: Re: Geometry calibration, what is it and why?
Post by: BlackR32 on October 10, 2018, 07:14:59 pm
Can any share the R32 geo settings? Will get mine checked when I change the tyres.

Thanks
Title: Re: Geometry calibration, what is it and why?
Post by: colesey on October 11, 2018, 02:47:23 pm
The geo people should have a database of stock settings however you might find the following website useful for making any adjustments from the standard settings to tune the handling for individual preferences https://motorsportessentials.co.uk/blogs/car-setup

Title: Re: Geometry calibration, what is it and why?
Post by: pudding on October 12, 2018, 11:36:29 am
Without trawling through my War & Peace sized stack of paperwork, I remember the rear being in the -1.30 region for camber, and tiny amounts of +toe.

The front is more tricky.  Stock camber is -0.50 to -0.60 and zero toe, but because of the subframe shonkiness (small bolt, big hole) you will often see MK5s showing -0.55 on one side, and -1.25 on the other.   Not a major issue as you can't really feel that discrepancy on the road, but for OCD folk, it's nice to see a perfect match on each axle.

I recommend a 'start from scratch' and 'do it once' approach to get it all perfectly even.  To do this, you will need:

TyrolSport Deadset or equivalent (not the VAG 'spacer washer' temporary fix).
SuperPro adjustable ball joints.
Someone who knows what they are doing on a Hunter or VAG Biessbarth alignment rig.

Step 1:

Hook up VCDS and log into the Steering controller module, and go to the angle block.  Confirm 0 degrees reflects a perfectly straight steering wheel visually.  If not, someone has moved the wheel around a notch or more, which is very WRONG with angle sensing PAS modules as it can bugger up the ESP/TC behaviour.

Step 2:

Fit the Deadset kit.  An utter, utter ball ache that no balls have ever suffered before, but well worth it as it physically aligns and locks the subframe dead straight.  It also relieves your ears of the annoying clicking/clacking/crunching noises during slow, heavy steering angle manoeuvres.

Step 3:

Fit the SuperPro BJs.

Step 4:

Take the car do a Hunter or Biessbarth equipped alignment shop.  Dealers use the latter.

Step 5:

Have them set the steering wheel alignment to 0 on the diagnostics screen, hold the wheel still with a clamp and THEN adjust the ball joints and toe until it's all equal.   I suggest setting the camber to -1.3

So many cheaper places adjust the hardware and then tweak the wheel round a few splines.  This is not what you want.

After doing that, you will be stunned at the difference, and also how consistent it feels corner after corner, month after month, year after year  :happy2:




Title: Geometry calibration what is it and why
Post by: SharonSot on April 21, 2019, 12:44:43 pm
I am thinking on putting splitrims on i have plenty of those. Small and wide

Handy to fix your flat in the field.   
What kind of thread they used factory off on the tires  all terrain  or did they use whatever was at hand

___
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