Go Back   FMUK > Forza Motorsport 4 > The Workshop



Register Now for FREE!
Our records show you have not yet registered. To sign up and get instant access to all our features, simply fill out the form below.

Username: Password: Confirm Password: E-Mail: Confirm E-Mail:
 
Image Verification
  I agree to forum rules 

Notices

Reply
 
Thread Tools Display Modes
Old 03-04-2012, 10:51 AM   #1
Raggist
Banned

Rep
154
Joined
Jan 2012
Posts
302
vCash
4775
Tuning ARBs - how do You do it?

I find tuning ARBs quite tricky, therefore when I saw @Screaming posting this in another thread I was very interested:

Originally Posted by Screaming View Post
What i do know is that with front engine you need a stiffer front and softer rear because you have more weight over the front wheels adding mechanical grip, the opposite is true with mid or rear engined cars.

As a couple of examples, i'd set up the ARB's and springs roughly as follows:

Mid engine: Front ARB soft, about 10.00, Rear ARB harder, about double so 20.00
springs would be similar, with a lightweight car front springs can range from 260-360 depending on if it bottoms out (check telemetry) rear would be around 360-450.

Front engine: Front ARB stiff maybe 20.00 - 25.00, rear arb very soft 4.00-10.00 theres nothing heavy like an engine holding the back end down so we need to create our own mechanical grip, some would argue aero holds the back end down, but not really in slow corners, roughly the same ratio for springs.

In the past I have used various methods to determine the correct ARB setting for any car; one being tyre temperature difference across the same axle and the other being a "magic formula". I haven't found either to be satisfactory.

The tyre temperature difference is also very dependent upon the circuit and so unreliable.

The magic formula is (A-B)C+B=X, where A is the max ARB setting, B is the min, and C is the percentage of weight distribution to the front of the car. Well, A-B is always going to be 39 and B will always be 1. If the front weight % is 53 then X would be 39*53%= 20.67, then +1 gives 21.7 for the front. To get the rear you simply use the rear weight % which would be 47% in this case. It all sounds very technical and clever, but in practice it really isn't. If you try it on a Ferrari 312P with 32% front weight, it is ridiculous.

What I thought to be the case was that the stiffest ARB will "push" in a corner. Therefore, if you have a very stiff front ARB on a FWD car and a soft one at the rear it will understeer bigtime. Similarly on RWD soft front and stiff rear will encourage oversteer - however, I am prepared to be completely mistaken about that.

You can check the telemetry to see if you are lifting the inside wheel in corners or if the front outside wheel is pushing away from the apex, but aside from that what else gives clues to the ARBs? Driving the car with different settings obviously gives a "feel" and you can normally tell if the front ARB is too tight as the steering goes very lose.

I would be very interested to hear the methods that others use to set ARBs.

Raggist is offline  
Reply With Quote
Old 03-04-2012, 11:32 AM   #2
MzR liquidator96
Mechanic

Location
Leicester
Gamertag
Liquidator96
Rep
59
Joined
Feb 2012
Posts
250
vCash
1150
You know my formula mate, stiff as a..........board, I don't know what else you were thinking.
liquidator96 is offline  
Reply With Quote
Old 03-04-2012, 11:56 AM   #3
Screaming
Test Driver

Location
Nottingham, UK
Rep
1174
Joined
Dec 2011
Posts
855
vCash
100
Another trick which can be a bit hit and miss, set rear ARB to maximum, then increase front until the back end grips properly, end up with a nice and stiff car that changes direction really well without tank slappers.
__________________
Borderline Personality Disorder
Screaming is offline  
Reply With Quote
Old 03-04-2012, 12:10 PM   #4
TfR JohnG
Race Driver

Location
Swindon
Gamertag
TfR JohnG
Rep
1278
Joined
Nov 2011
Posts
1,845
vCash
100
Twitter Profile
Send a message via MSN to JohnG
Depending on drive train.....

Fwd:

Increased rear stiffness increases turn in. Increased front helps exit speed. But, too much rear or not enough front will cause you to loose traction mid corner.
I generally have rear 10% softer than front, and around 90% of stiffness!

Rwd, pretty much the same, but softening the rear can reduce exit oversteer.

Mid engine, about the same, but compensate the engine weight by stiffening the rear more than normal.

Hope that helps!

Sent from my HTC EVO 3D X515m using Tapatalk
__________________
XBL= TfR JohnG
JohnG is offline  
Reply With Quote
Old 03-04-2012, 07:13 PM   #5
TfR Spiny Anteater
Race Team Manager
 
Spiny Anteater's Avatar
Location
Herts
Gamertag
Spiny Anteater
Rep
3715
Joined
Jun 2009
Posts
5,967
vCash
39405
Awards
Photocomp Winner Photocomp Winner 
Originally Posted by Raggist View Post

What I thought to be the case was that the stiffest ARB will "push" in a corner. Therefore, if you have a very stiff front ARB on a FWD car and a soft one at the rear it will understeer bigtime. Similarly on RWD soft front and stiff rear will encourage oversteer - however, I am prepared to be completely mistaken about that.


Yep, that's pretty much it, but for all drive trains.

Typically I start with a 50/50 split then go for a test drive and adjust until I'm happy with the steady state cornering of the car (stiffen front/soften rear to cure oversteer and vice versa). Corner entry and exit behaviour I deal with through the damping.
__________________
Clubman GT Winner (only 'cos Jamesy got pished)

We all learn from our mistakes. I am very well educated...

RIP Stuart (Hoonta). Gone. Not Forgotten.
Spiny Anteater is offline  
Reply With Quote
Old 04-04-2012, 08:48 AM   #6
Raggist
Banned

Rep
154
Joined
Jan 2012
Posts
302
vCash
4775
Thread Starter
@Spiny Anteater - I was really hoping you would contribute to this.

Much appreciated

So no magic formula, just tweakit and see. I use the big right hander on Catalunya GP as a good workout for ARBs meself.
Raggist is offline  
Reply With Quote
Old 04-04-2012, 06:37 PM   #7
TfR Spiny Anteater
Race Team Manager
 
Spiny Anteater's Avatar
Location
Herts
Gamertag
Spiny Anteater
Rep
3715
Joined
Jun 2009
Posts
5,967
vCash
39405
Awards
Photocomp Winner Photocomp Winner 
Originally Posted by Raggist View Post
@Spiny Anteater - I was really hoping you would contribute to this.

Much appreciated

So no magic formula, just tweakit and see. I use the big right hander on Catalunya GP as a good workout for ARBs meself.

I think that's going to be the final stage for tuning every setting. It always helps to have a robust set of default settings, but the final dialling in is going to need you to see how the car feels. That's where understanding what each bit does comes in handy.

For example, I'll start with the ARBs evenly balanced as that's usually not far off unless the settings are quite severe. Then, while test driving, I'll try to notice unwanted effects. For example, with ARBs I might feel that the car understeers mid-corner. The best way to cure that is to soften the front ARB and/or the front springs or stiffen the rears. It's up to you which you go for, but usually if the car feels skittish I'll soften the front; if it feels a bit wallowy I'll stiffen the back.
__________________
Clubman GT Winner (only 'cos Jamesy got pished)

We all learn from our mistakes. I am very well educated...

RIP Stuart (Hoonta). Gone. Not Forgotten.
Spiny Anteater is offline  
Reply With Quote
Reply

Tags
big, cars, correct, driving, engine, final, happy, king, practice, rwd, settings, steering, tapatalk, tuning

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Tuning 101 Milton The Workshop 31 07-10-2011 09:51 PM
tuning groups tuning comp. A Senna Competitions Forum 2 20-07-2011 08:46 PM


All times are GMT +1. The time now is 12:24 PM.


Powered by vBulletin® Version 3.8.6
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
tracert