Best track alignment set up?

[laurent.d]

Hi,

I wondering which set up you guys who use your car on track could advice.

I go to track only on the Nürburgring, I use road Pirelli P ZERO MO.
I'm easily around 8'40'' on this track.

My car was aligned by VWR, handling was fine and fun but quiet agressive.

I checked out alignement because I thought it as to much rear-and negative camber and I found out this:

Front:

Caster     L 7°41'    R 7°52'
Camber   L -2°14'   R -2°04'
Toe         L -0°09'    R +0°13'

Rear:

Camber   L -2°38'   R -2°45'
Toe         L -0°16'    R +0°06'

Rear camber is higher than front so we lowered it.
Toe front should have been 0°15' (both side) and rear 0°05' (both side) I dont know why it is not like that. Break in bushes or mistake, any way this is not my point.

After aligment we found out:

Front:

Caster     L 7°46'    R 7°57'
Camber   L -2°14'   R -2°05'
Toe         L +0°07'    R +0°07'

Rear:

Camber   L -2°01'   R -1°56'
Toe         L +0°10'    R +0°12'

So less camber at the rear, more even Toe ant toe in instead of out.

The car is more stable, far less agressive, maybe a bite more efficient but I miss the rear which turn around the corner.

So my question is which alignment do you advise?

Front Toe L +0 ° 15 ' R +0 ° 15'
Rear Toe +0 °05 'R +0 °05'

As VWR said it should be, or smothing else.

[gillm]

i run all my cars to the factory settings (they spent ages setting them up !) i messed around with my mk1 for years and it was a battle between staright line stability and floaty corners , so i now run it very close to std apart fro 2 degrees front camber

[laurent.d]

Thanks for your reply GILLM.
Any other advice? Hurby? Tony Danza?

[Janner_Sy]

take it to a specialist chassis tuning place like centregravity or wheelsinmotion.  you tell them how you want it and thy do it.

I thought adding more rear camber would increase the rear grip in cornering, so if your running more rear camber tha the front, you should find it will be less likely to loose the back end as it 'should' understeer before over steer

[laurent.d]

Thanks VRSY,

But I live in France, so I can't go to centregravity or wheelsinmotion, otherwise I would go bake to VWR.

I went to a chassis specialiste in France but they work on any cars and are not specialist on MK5 platform.

My main concerne is about toe.

Do I stay close to OEM : 5' each side Front and 10' each sideRear
or 15' each side Front and 5' each side Rear as claim VWR and Jonny'c had on his Golf?

[laurent.d]

No more advice?!!

My car is going to be aligned this week while I'll change the tyres.

As:
VWR claim                                                                     15' each side Front and 5' each side Rear.
Jonny'c said he hade                                       1,5mm  (11')each side Front and 0' each side Rear.
NeilM hade hes car aligned by Center Gravity Limited  11' each side Front and 5' each side Rear.
So I'm going to fit about 13' each Front and 5' each Rear.
So, I think I can't be wrong.

[laurent.d]

So I have my car aligned last week.

Now it is:

Front:

Caster     L 7°35'    R 7°41'
Camber   L -2°17'   R -2°04'
Toe         L +0°10'    R +0°10'

Rear:

Camber   L -1°56'   R -1°51'
Toe         L +0°05'    R +0°05'

They didn't want to go over the OEM front spec Toe which is 10'

As they didn't want to spend some time to balance my front camber for only 10', I think I will do it my self and then proceed to the alignment myself with the old school method (string alignment)

I will found out within 10 days at the Ring how it handle.

To exonerate VWR, we had the surprise that front alignment was wrong again while it have been done only a few weeks ago.
We found out that explanation comes from tyre wear.

Between VWR alignment and previus alignment in France the tyres have been permuted and were about 21000 km old. Since, previus alignment and last one, we just fited brand new tyres all around.


So no VWR mistake and no break in bushes.

[danishmkvgti]

any updates on this??   

[tony_danza]

I can't remember the exact numbers, but I had this:

Rear.

1/2degree less camber than the fronts
Parallel toe

Front.

As much caster as you can get
Your preferred camber, 2 degrees is ideal IMO.
1.5 combined toe in

It'll feel like the rear is a bit alive and loose, but loose is fast.

[the bruce]

So my question is which alignment do you advise?

Front Toe L +0 ° 15 ' R +0 ° 15'
Rear Toe +0 °05 'R +0 °05'

As VWR said it should be, or smothing else.

I just found this topic today.


I'd prefer the VWR recommendation (nice to see they recommend similar adjustments like I do).

If you like to have more camber don't be afraid to adjust more toe in as well.

1. rule is:
The more camber the more toe in you'll need to have proper tyre wear.

2. rule:
More toe in on front gives quicker turn in, more toe in on rear provides more stability.


 

[_Nathan_]

Are you sure more toe in on the front gives better turn in? It is the exact opposite to what I'd have expected based upon setting up my other car. On that toe out makes the turn in miles better. Unless FWD is that much different? If so do you know the physics behind why it is so different?

Agree on toe in at the rear for stability though!

[the bruce]

Yes, guess I do know.  

I don't which kind of car your other one is (I guess rwd?).
It depends a bit on ackermann geometry (like road cars) or not (like true race cars).

But generally toe in on front improves turn in.

Why?

The reason is dynamic weight distribution.
When cornering weight moves to the outer wheels.

Imagine first you'd have toe out on front:

When you turn your steering wheel a bit the inner wheel turns in first, the outer
wheel is just directed out or straight. This causes in the moment when the weight
goes to the outer wheel the 'turn in' is slowed. If you turn the steering wheel even
more the cars turns in.

Now with toe in on front:

When you start turning the steering wheel the weight goes to the outer wheel
which is already slightly 'turned in' and so this helps for quick turn in. This gives
usually a much better steering feel.

You got it?

Toe out on front has a stabilizing character. That's why bumping in causes the
Golf front axle to toe out esp. when braking hard.

One more reason for even more toe in on front:

For low tyre wear the front steering kinematic needs to be according to Ackermann.
This means both wheels follow the same center poit with their own radius.
That's good for road cars used in narrow cities.

Unfortunately driving fast through corners requires more steering angle on the
wheel that has more weight. This is the outer wheel!
That's why true race cars' steering systems are desgned 'anti-Ackermann', so their
outer wheel turns more than the inner wheel.

Retrofitting this on a street car isn't easily possible. But more toe in helps coming
closer to this. So more grip and less understeer as well.

Porsches have a neutral steering. No Ackermann, no anti-Ackermann.  

 

Last not least a third reason:

It is common knowledge that if you increase (negative) camber you have to increase
toe in as well to provide even tyre wear.


edit:

Even more, the VAG PQ35/36 platform front suspension goes to massive toe out
when bumping in (you can see it when lowering your car before alignment).
So the outer wheel will do so when turning. The softer the bushes the more.
This helps to stabilize the car when an unskilled driver needs to brake and/or
needs to turn in an emergency situation cos this causes understeer and slowes
the steering. On track or for fast raod applications we don't want this behaviour
or at least less of it. We want less understeer.

http://tesis-dynaware.com/fileadmin/Downloads/Referenzen/VW_ATZ_Messdatenbasierte_Fahrdynamiksimulation.pdf

[_Nathan_]

Yes, RWD, It is based on a road car though rather than a proper single seater race car. That was my question really - why is it different for the golf platform compared to other platforms (including other FWD platforms that would run toe out for better turn in).

[the bruce]

- edited last post -

 

[_Nathan_]

When does the weight transfer happen relative to when you want the car to turn?

What are the slip angles of inner and outer wheels during that initial turn in phase? Which wheel needs to describe a tighter radius at this point?

I have spoken to a couple of race engineers that run FWD cars, and both say on a race car they'd be running some tow out for better turn in (one mentioned 4mm out on a modern hot hatch), neither run the golf platform though, I'll read that PDF later.

I believe toe out under bump is pretty common, certainly seems to be the case for a lot of McPherson strut cars, that is what happens on my car too and we still run static toe out along with 4.25 degrees of camber, perfectly even tyre wear, 4 hours from a set of tyres which is on the money.

Maybe the above isn't valid due to the fact that race cars will have less weight transfer so the static values must be higher?

PS. Milliken & Milliken suggests adding toe out as you add negative camber, appreciate this is biased towards performance and not tyre wear but still interesting.

PPS. Thanks for the info, not disagreeing with you as I have no experience of the Golf platform on track, just trying to understand, last FWD car I used on track was years and years ago and was running race suspension and slicks so trying to get my head around setting up a softer car is interesting for me :)