Tuning for Dummies - help needed!

pmgolf · Mar 30, 2005

I hope I am not alone in this... Reading page after page of tuning techno-babble does not give me the answers I need. For me, its like trying to determine that the coefficient to the hydro-steetsis of the encephilo-kerplexis needs to be inverse to the splado-amismaxis in order to reduce understeer. It is difficult enough to keep the meanings of understeer and oversteer straight in my mind!

Also, I am not mechanical or skilled enough to drive each lap exactly the same as the previous one, much less five laps, so doing five laps somewhere to test each and every miniscule handling change I make does not give me the answers I need. Having lap time as my only guide does not work. Instead, it would greatly help if someone could provide answers in simple terms ("KISS" Principle) to my basic questions:

Springs:

If you make the number higher, are you making the springs stiffer?
If you LOWER the spring rate front and rear, what do you look for to see if it improves handling?
Same for lowered rate in front and raised rate in rear? Same for raised rate in front and lowered rate in rear?

Ride height:

What to look for when testing the the 4 combinations (both higher, both lower, front higher than rear, front lower than rear). For example: if my car is bottoming out (ex. 'ring), how can I tell?

Shock bound and rebound:

How do you test for this? I see crazy combinations like 1/7 front with 8/9 rear and 5/6 front with 4/10 rear that work great and I wonder how in the heck does someone come up with numbers like that?

Camber, Toe: What to look for when testing.

Stabilizers: Low front - high rear, high front - low rear, both low, both high. What to look for when testing.

Brakes: Front and rear the same, front higher than rear, front lower than rear, rear lower than front. What to look for when testing.

When is weight reduction called for? When is rollcage stiffness called for? (Refresher Plan is obvious - IMO)

How can frontend dive-down and raise-up be reduced?
If you want to improve the ability of a car to turn while accelerating, what should you do?
How can you improve a cars ability to stay stable through S-turns?
If your car goes crazy when cresting a hill at high speed, causing a crash, what are some things you can try to fix it?

These are basic things I would like to understand better so I can make some intelligent choices when trying to tune cars on my own. Hopefully, other people feel the same way! If anyone else has questions along these lines, please post them!

Thanks, Pete.

tm2003 · Mar 30, 2005

This Is a Fabulous Idea, I't Would be a good thing to sticky, if people like ///M-Power & grey Post Here, This Will Be a Jem Of Information& will prevent alot of useless posts . So Lets Have It Technically Minded GTP's help us with our jargon, If you wouldnt mind, helping us with those topics, maybe writing out the question then putting your answer, and that way, this can be linked into a form of database,

Thanks TM

dunn0 · Mar 30, 2005

this might seem like a bit of an overstatement but its completely true, i feel EXACTLY the same way as you, all i ask is for someone to give a brief few sentences explaining the following for each piece of equipment:
-what the thing does, eg: loweing ride hight reduces the centre of gravity therefore improving handling
-what increasing and decreasing does
-a guide line to say wether the modification has worked or not
-and how to understand wether the modifications are suited for pure handling, pure speed or for a good balance etc
-a setup for a good overall setup for cornering AND speed/acceleration
-then with our newly learnt skills and pieces of knowledge we can adjust the 'good overall setup' accordingly for whatever we require from the car.

PLEASE NOTE: a whole page of information is not appealing and is very hard to take in
thanks

Duke · Mar 30, 2005

dunn0
this might seem like a bit of an overstatement but its completely true, i feel EXACTLY the same way as you, all i ask is for someone to give a brief few sentences explaining the following for each piece of equipment:
-what the thing does, eg: loweing ride hight reduces the centre of gravity therefore improving handling
-what increasing and decreasing does
-a guide line to say wether the modification has worked or not
-and how to understand wether the modifications are suited for pure handling, pure speed or for a good balance etc
-a setup for a good overall setup for cornering AND speed/acceleration
-then with our newly learnt skills and pieces of knowledge we can adjust the 'good overall setup' accordingly for whatever we require from the car.

PLEASE NOTE: a whole page of information is not appealing and is very hard to take in
thanks

Well, I hate to break it to you, but suspension tuning is a complex, interrelated topic, and there's not much further it can be simplified without becoming useless. If you can't work your way through ///M-Spec's (not ///M-Power) Tuning Guide, you're really going to have to keep at it.

We'll do our best to answer questions, but there are simply too many factors involved to make a one-liner for each item, particularly since so many factors affect the response of a car to control inputs.

If you read through the Is suspension tuning backwards? thread, you'll also see that there is not a clear understanding of how the GT4 suspension tuning works yet.

tm2003 · Mar 30, 2005

Duke
Well, I hate to break it to you, but suspension tuning is a complex, interrelated topic, and there's not much further it can be simplified without becoming useless. If you can't work your way through ///M-Spec's (not ///M-Power) Tuning Guide, you're really going to have to keep at it.

We'll do our best to answer questions, but there are simply too many factors involved to make a one-liner for each item, particularly since so many factors affect the response of a car to control inputs.

If you read through the Is suspension tuning backwards? thread, you'll also see that there is not a clear understanding of how the GT4 suspension tuning works yet.

yay, Duke, Remember Me, Mate, Does BoomBexus Still Post,
aint been here In ages 👍

sukerkin · Mar 30, 2005

Beat me to it Duke :lol:

.

I'm afraid gentlemen that the posts you find here on the Planet are the simple and straightforward answers.

The real thing is much more complicated and involve you getting your hands dirty and banging your head on the underside of the car whilst you try to measure distances and angles before you get to work through all the equations you need ... :cries:.

'Techno babble' is a phrase used for meaningless but scientific sounding speach - I'm afraid when people are talking in the jargon of their profession it might sound the same but it most assuredly is not. It's probably not the best idea to say such a thing to a race mechanics face - unless you really want to see how far a torque wrench can be ... well you get the idea

.

All in all, as with many technical things in life, if you don't understand it either don't touch it or mess with it 'till it breaks and then figure out how to fix it (that's how I first learned about computers back in the early '80's and it's a very effective instructional technique).

That said, however, Mr. Golf's questions are good ones in the main:

Springs:

If you make the number higher, are you making the springs stiffer? Yes

If you LOWER the spring rate front and rear, what do you look for to see if it improves handling?
Same for lowered rate in front and raised rate in rear? Same for raised rate in front and lowered rate in rear?

Having Higher Spring Rates at the back is normally reckoned to give you a more oversteer prone car and Higher Spring Rates at the front a more understeer prone car. That is a very large approximation but it'll do for now.

What you're looking for depends on what you wanted in the first place but generally you encourage oversteer to get a car to turn into a corner more easily and enable you to apply power sooner on the way out. You only want to encourage understeer in a race car using the springs if the backend kicks out uncontrollably on turn in or in a (usually vain) attempt to quell power oversteer (not advisable).

Ride height:

What to look for when testing the the 4 combinations (both higher, both lower, front higher than rear, front lower than rear). For example: if my car is bottoming out (ex. 'ring), how can I tell?

I don't usually advise having anything other than a level ride height in a car as it's what I term an 'always on' change i.e. it colours the behaviour of the car all the time (accelerating, braking and turning) usually meaning that you get some effect you don't want. If your car is bottoming out you can soon tell as your braking distances will be huge (front tyres sliding) or you will get sudden and unexpected direction changes over rough ground.

Shock bound and rebound:

How do you test for this? I see crazy combinations like 1/7 front with 8/9 rear and 5/6 front with 4/10 rear that work great and I wonder how in the heck does someone come up with numbers like that?

This is the primary tool I recommend for adjusting the cornering performance of your car as the changes only affect transitions and so don't upset the balance elsewhere. In GT3 I would say that most of the time a Bound setting of 5/4 and a Rebound of 9/8 would serve you well on the majority of FR cars. In GT4 I don't yet know but the principles should be the same. In essence (again massively simplified) increasing Bound is only necessary to the point at which gross 'mushiness' in the handling is dismissed. The Rebound is then used to fine tune the balance by increasing it at the end you want to 'stick' more i.e. if the Rear Rebound is lower than the Front then you'll get more of an 'oversteery' feel.

There are a number of threads in the GT3 Settings and Tunings forum that cover dampers. I suggest reading and reading and reading different explainations until you understand.

Camber, Toe: What to look for when testing.

Camber - increasing Front relative to Rear gives oversteer and vice versa. Testing for this in-game is a nightmare tho' and I trully wouldn't bother changing from stock if you can't run consistently enough to tell if your camber settings are giving you faster times or not.

As for Toe - there's a whole thread just about this right here on this forum. Read and enjoy - just don't let the contradictions confuse you. Either run it at stock 0/0 or for an FR/MR car put it at -0.5/+1.5 (ish) which is what real world touring cars run. It can work wonders or make a complete mess of your handling (as well as hiding bad settings elsewhere). Twitch your toes at your peril

Stabilizers: Low front - high rear, high front - low rear, both low, both high. What to look for when testing.

By all accounts, the Stabs have been neutered in GT4 but generally run it at equal, Front two clicks lower than Rear for Oversteer or Front one click higher than Rear for more stability.

Brakes: Front and rear the same, front higher than rear, front lower than rear, rear lower than front. What to look for when testing.

Generally, you want to run the Fronts a little softer than the Rears but equal is fine. It all depends on whether you want to stop quicker or be able to turn in under braking (which brings the LSD into the story so lets not go there). Essentially, tweak the Front force downwards and keep testing to see how your braking distances vary (try watching the replays to see if you can observe wheels locking up).

When is weight reduction called for?

Always.

When is rollcage stiffness called for? (Refresher Plan is obvious - IMO)

So far I haven't come across any evidence that applying it is detrimental but time will tell. For now I have to say that, in GT4, dunno.

How can frontend dive-down and raise-up be reduced?

Simple answer is Stiffer Front Bound and Rebound. There's more but I'm (desperately) trying to keep it simple.

If you want to improve the ability of a car to turn while accelerating, what should you do?

See comments about Oversteer in the above notes.

How can you improve a cars ability to stay stable through S-turns?

Stiffer springs and Stabalisers

If your car goes crazy when cresting a hill at high speed, causing a crash, what are some things you can try to fix it?

Seriously, go slower. It essentially means your wheels are leaving the road. You can try various other things but they will compromise handlig in other circumstances.

I hope the above helps a bit. Bear in mind that I've simplified a great deal and have left out a lot (particularly with regard to component interactions). Other tuners may have different takes on some things (and may speak up with their views).

I'm about typed out anyhow. If you want to learn how to tune then I'm afraid that there's no substitute for education and experience. Learn the principles, familiarise yourself with the maths and try to put the theory into practice. That last step is the one where individual driving traits come to the fore and why it is that you can have all the computer models and engineering qualifications in the world but the final arbiter of setting up a car is it's drivers bum.

pmgolf · Mar 30, 2005

Duke, thanks for your response. From what you stated though ("...suspension tuning is a complex, interrelated topic, and there's not much further it can be simplified without becoming useless. If you can't work your way through ///M-Spec's ... Tuning Guide, you're really going to have to keep at it.
"), it sounds like you may not possess the ability to reduce your knowledge to terms and descriptions that are more easily understood. NP, my friend, not everyone possesses such skill or in-depth knowledge.

What I am looking for here is someone who does possess such skill. Someone who can answer simple questions, like:

1. When you raise your spring rate number, are you stiffening the springs? For the lay-person, it is NOT self-explanatory.

2. Shock Bound - is that where the shock absorber is being compressed? If you reduce the number, are you making it more difficult for the shock to be compressed? Is that "stiffening" the shock, or would "stiffening" involve both Bound and Rebound?

3. Toe Angle - is minus pointing outward or inward?

And surely there is someone who can explain suspension changes and effects in more simple terms than what is explained in M-Spec's writeup. Even some of the basics about suspension changes and WHAT TO LOOK FOR when testing changes would help. Telling someone to "read the manual" does not help when there isn't a teacher around to explain the manual or answer questions!

Thanks, Pete.

sukerkin · Mar 30, 2005

pmgolf
What I am looking for here is someone who does possess such skill. Someone who can answer simple questions, like:

1. When you raise your spring rate number, are you stiffening the springs? For the lay-person, it is NOT self-explanatory.

Yes

pmgolf
2. Shock Bound - is that where the shock absorber is being compressed?

Yes

pmgolf
If you reduce the number, are you making it more difficult for the shock to be compressed?

No

pmgolf
Is that "stiffening" the shock, or would "stiffening" involve both Bound and Rebound?

In GT4, you are allowed to alter the Bound and Rebound independently (which is not always the case in real life). Higher numbers are 'stiffer' i.e. the shocks resist the compression or expansion of the spring more.

pmgolf
3. Toe Angle - is minus pointing outward or inward?

As far as I am concerned, negative numbers mean the wheels point outwards and positive points them inward.

pmgolf
And surely there is someone who can explain suspension changes and effects in more simple terms than what is explained in M-Spec's writeup. Even some of the basics about suspension changes and WHAT TO LOOK FOR when testing changes would help. Telling someone to "read the manual" does not help when there isn't a teacher around to explain the manual or answer questions!

I'm afraid, Pete, that it really isn't a simple subject. M-Specs guide is pretty plainly written (as opposed to deliberately obtuse) and is the distillation of years of game experience from a lot of us as well as real life experience and research. Read everything you can on all the various components and sift out what it is that you can't get your head around and ask questions from there.

I don't mean to be rude so please don't take this the wrong way but there is no substitute for working it out for yourself. Getting assistance is one thing but having it handed to you will teach you nothing in the long run as you won't have really understood what is behind the tweaks and twirls.

hippo0422 · Mar 30, 2005

ok...i'm new here....But here is what i found out...

I just like lowering my cars all the way...or almost all the way... ^_^
and i like stable linear driving...no tailwhipping and the such... i found out that if you set up the suspension to this equation

(Original Rate)/(Original Height) = (Amount to raise rate by)/((Original Height) - (Desired Height))

would give you a pretty stable and good suspension setting
HOWEVER this works best with the "Original" Suspension upgrade from the tuners upgrade section....and works okay with the fully customizable...

and i think it works best on tuned street cars...cause my friend tried this with the race cars and didn't get too good results...or he didn't like em...but then again he only play's b-spec...

oh yeah just change the spring rate and ride height.... everything else should be left the same... the spring rate really determins almost everything...i think

pmgolf · Mar 30, 2005

Sukerkin and Duke - Thanks for responding. Please take this as nothing more than an opposing view to yours...

[ Example - on my own I have found that increasing "Limited-slip Acceleration" helps when the car gets uncontrollable at high speeds on a straightaway. Increasing "Limited-slip Deceleration" helps when a car gets uncontrollable while braking from high speed on a straightaway. If someone had told me that info before I spent my time discovering it, I would have been appreciative for the time-saving. I am a computer programmer, not a race mechanic. Maybe you race mechanic types may know so much about the subject that you just can't explain it in simple terms. Before you dismiss the possibility of anyone being able to provide simpler explanations, how about giving other folks a chance to try - ok? ]

IF you ask what the differences are between the CICS Command Level language and the CICS Macro Level language, I could hand you both of the IBM Reference Manuals and say "read these", or I could go a step further and tell you that CICS Macro Level provides you with access to more detailed commands and also provides an entry to data storage areas that Command level can not reach, and I could offer to explain the commands and storage areas. If you are a beginning programmer, you could read those manuals 'til you are blue in the face, and you still won't totally understand the differences! That's why the world has teacher-types. They know how to explain things.

I understand you experts saying that it can't be explained any better. But if I can make some discoveries as stated above, then surely others can make such discoveries. This can be a thread where we share them. I had much rather spend my time playing the game (to me - it IS a game) than spend hour upon hour studying the physics of racing.

Thanks, Pete.

ps. Sorry Sukerkin about posting questions that you had already answered. You posted the answers while I was typing my response. Also, truthfully, I really don't care to spend time understanding the physics behind the "tweaks and twirls" - I just want to play the game!

ZoomZoom · Mar 30, 2005

My guide to suspension tuning:

Understeer = difficult to turn-in and/or come out of a corner
Oversteer = car likes to turn more than you desire

Springs

The higher the number, the stiffer they are... The higher the number, the more responsive they are... Stiffer ain't always good; if your too stiff your tires can lose grip...

Ride Height:

The lower the number, the more you lower your center of gravity which allows you to corner faster... That is a very good thing until you start to run out of suspension travel and hit your bumpstops while cornering which will cause your car to behave/handle erratically.

Camber:

Your tires VERTICAL angle to the ground; e.g. / \... Camber (negative) helps your car corner by keeping the tires in contact with the road more while cornering... gt4 & gt3 mentions 3-4 degrees is where you start to have too much camber and start to see too much tire wear...

Toe:

Positive toe is toe-out, negative is toe-in despite what others say...

A little negative toe (toe-in) is what I recommend for cars that are difficult to handle, positive toe (toe-out) is recommended for vehicles that are difficult to turn...

Negative toe (toe-in) in both the front & rear will cause some understeer while positive toe (toe-out) will cause oversteer...

Brake Balance:

Setting the front slightly lower will help you turn while cornering... I find I like to set the rear value at 8 and adjust from there... Settings these too high will actually decrease your cars braking ability...

Stabilizers:

Also known as anti-roll bars, raising these will cause your car to seem "stiffer"... Increasing the front will cause a bit of understeer while increasing the rear a bit will cause oversteer...

Rollcage:

I like this in most all production cars, exception being heavy cars that understeer and those wrong-wheel, err front-wheel drivers. Even then, a lot of fwd cars will benefit from this...

This stiffens up the chassis considerably though will induce a bit of understeer...

Weight reduction:

I'd recommend weight reduction for any and all vehicles... Not only does weight reduction help a cars acceleration, it helps its cornering & braking as well...

Depending on the vehicle it might induce a little oversteer...

Downforce:

Helps your car "stick" to the road better, especially at high speeds... The drawback is you lose acceleration & top-speed due to aerodynamic drag...

Raising the front will cause oversteer, raising the rear will cause understeer...

Limited-slip:

Acceleration: - The higher the number, the more traction you'll have while coming out of a corner. Also helps with straight-line stability... Increasing this will also increase understeer a little, thus makes it a little more difficult to turn...

Deceleration: - The higher the number, the more traction you'll have while braking and slowing down... If you like to "drift" around corners, a lower value is recommended... Like acceleration, increasing this increases understeer and will make the car a little more difficult to turn while braking...

-

Hopefully someone else can touch on the bound/rebound settings. Not quite as knowledgeable about them despite me having success with settings I've used from others...

You'll probably find this is quite similar to other guides posted online and in these forums. If you have any questions after understanding this guide, feel free to ask away

dunn0 · Mar 30, 2005

theres arealy simple (ish) site, not sure exactly what it is called but its something like www.howstuffworks.com, it will have everything on there and then apply that knowledge to the game....thats how im learning

Duke · Mar 30, 2005

pmgolf, I didn't mean to imply that anybody was unworthy of the effort, or anything like that. Speaking of effort, I see by your "Last edited..." tag above that you take the time to proofread and correct your posts. That is sincerely appreciated.

We are capable of explaining in more simplified terms. The problem is that suspension adjustment is literally a black art of compromise, and any attempt to find a panacea solution invariably creates or aggravates some other undesireable condition.

For instance, it's perfectly possible (and quite common) for a given car to oversteer on corner entry and understeer on corner exit... or worse, vice versa. So correcting one problem will likely make the other worse. This truly makes it difficult to make flat generalized recommendations.

Some questions can certainly be answered as sukerkin did above. But, for instance, while it is universally agreed that increasing the number of the BOUND setting makes the damper more resistant to compression, there is no similar consensus about the REBOUND setting. I'm of the opinion that the larger REBOUND number means that the damper returns to static position more quickly (ie is LESS resistant to extension). In other words, high numbers mean that the wheel is more resistant to being moved away from static position, and quicker to return to static position when it does move. Sukerkin believes (or did last time I checked) that the higher number means more reistance to movement in BOTH directions.

So there may not be a simple answer to some questions.

I'll also suggest that you look into threads on the OLR School board in the Online Racing Forum. This is an underutilized resource that for some reason has never taken off. Hopefully we can make it a useful thing that gets more action.

One last thing to bear in mind with this is that individual driving styles have a big effect upon settings. It's commonly agreed among more practiced drivers that one person's settings rarely translate directly to another person. The same physical truths are obviously valid, so settings can be used as grounds for common discussion and starting points, but again it is another obstacle in the way of achieving ultimate universal settings.

[edit] And here we run into another problem of universality. ZoomZoom, not so single you out or pick on you, but you are wrong about toe settings. At least in the North American / European GT4 version, toe IN is POSITIVE and toe OUT is NEGATIVE at both ends of the car.

ZoomZoom · Mar 30, 2005

"not so single you out or pick on you, but you are wrong about toe settings."

I'm extremely confident that I'm correct... I autocross my Miata nearly every other weekend and know how it behaves with changes to toe-in, toe-out, etc...

I recommend as I said in the other discussion to test-drive (in gt4) a Miata which is very sensitive to suspension tuning and experiement with toe settings...

You'll find that positive toe will make your Miata oversteer, twitchy and a little tough to handle...

Now experiment with negative toe; you'll see a Miata that oversteers less (but may still oversteer) and is easier to control...

Experiment front & rear seperately.

Duke · Mar 30, 2005

Well, I came to my conclusion based on A) GT3 experience - which admittedly may or may not translate to GT4; B) real life experience; and C) experimentation with my GT4 RX-7 FD, which oversteered under most conditions and was very unstable on high-speed straights until I added some POSITIVE toe to the rear.

pmgolf · Mar 30, 2005

It is helpful seeing both sides of a discussion. Thanks to all of you for joining in with your posts. I hope more folks will join in with their opinions and tuning ideas.!

Pete.

Greyout · Mar 31, 2005

sukerkin
The Rebound is then used to fine tune the balance by increasing it at the end you want to 'stick' more i.e. if the Rear Rebound is lower than the Front then you'll get more of an 'oversteery' feel.

obviously one has to think twice now before applying real world facts to GT4, but if the game is accurate, I disagree with the above statement.

A Stiff rebound in the rear will increase oversteer during both lateral and longitudinal transitions.

As the inside of the chassis lifts in a corner, the suspension must droop to maintain contact with the ground. The stiffer the rebound setting of the damper, the slower the suspension will droop. If the droop movement is slow, the inside tire will be temporarily unloaded, reducing the rear's grip, until the spring moves the suspension to its new position, and steady-state cornering dynamics takes over.

A stiff rebound in the rear will also unload the rear temporarily when lifting off the throttle in a corner. As the weight shifts foward, the body pitches foward. The rear suspension must droop to maintain contact with the ground... if the rebound is overly stiff, the load on the rear tires will lighten temporarily, reducing traction in the rear... not only do you reduce the rear grip, but when this happens, BOTH fronts are loaded more, increasing their maximum combined grip... hence the front tucks in, and the back steps out.

Rx3 · Mar 31, 2005

If you really want to understand suspension tuning, go to your library/ Barnes and Nobles/ Borders/ Walden Books/ whatever and start reading books on suspension setup, and how it affects cars.

tm2003
This Is a Fabulous Idea, I't Would be a good thing to sticky, if people like ///M-Power & grey Post Here, This Will Be a Jem Of Information& will prevent alot of useless posts .

Not really, because no one would read it, and then they would still post up useless posts. Then everyone will *****

sukerkin · Mar 31, 2005

I'm not going to argue with you, Greyout. Your description is accurate of how a damper will act in isolation.

What I was attempting was to keep it simple and say how the car would 'feel' with weight transfers and alterations in the CoG in progress.

sukerkin · Mar 31, 2005

To elaborate a lot further and show how complicated things can get even when dealing with just dampers, the following is probably one of the best and most succinct coverages of the subject available out there in webland (it's for GP2 and I suspect it to have initially been lifted from a great article I've been linking for years but is nontheless valid):

ENTRY type 1 : Increasing braking + increasing steering
This phase is the first part of a fast decreasing radius turn. This phase will not occur at all if you get all your braking done *before* you turn-in. Since weight is being transferred both forward and outboard, the outside front damper moves in bump and the inside rear damper moves in rebound. these are the dominant two dampers in this phase of turn-in. The other two have minimal effects during this phase.
ENTRY type 2 : Decreasing braking + increasing steering
This is the turn-in phase of a slow corner. This phase may or may not occur depending on the type of turn or driving technique. Weight is being transferred outboard and to the rear, so the outboard rear damper moves in bump and the inside front damper moves in rebound. The other two dampers are considered stationary.
ENTRY type 3 : Increasing steering at constant throttle
This phase can be a chicane turn-in (GP2 has a lot of these!) or a turn entry taken at *full* throttle. Weight is being transferred outboard only, so *both* outside dampers are moving in bump and *both* inside dampers are moving in rebound.
MID-CORNER TRANSITION : Decreasing steering back to zero at constant throttle
This is really the opposite of a type 3 entry. It's what happens in the middle of a chicane, as you flick the steering back away from the current cornering direction. As soon as the lateral acceleration passes back through zero, the turn reverts to a type 3 entry again.
EXIT : Decreasing steering + increasing throttle (or decreasing braking)
This is the apex_to_exit phase. Weight is being transferred inboard and to the rear. The outside front damper moves in rebound and the inside rear moves in bump. The others are considered stationary.
Here's a chart to help understand low speed damper adjustments:

Code:

 CORNERING PHASE        MORE UNDERSTEER         MORE OVERSTEER

  Entry Type1            F bump +                 F bump -
                         R rebound -              R rebound +
 
  Entry Type2            F rebound +              F rebound -
                         R bump -                 R bump +
 
  Entry Type3            F bump +                 F bump -
                         F rebound +              F rebound -
                            or                       or
                         R bump -                 R bump +
                         R rebound -              R rebound +
 
  Mid-corner             F bump -                 F bump +
  Transition             F rebound -              F bump +
                            or                       or
                         R bump +                 R bump -
                         R rebound +              R rebound -
 
  Exit                   F rebound -              F rebound +
                         R bump +                 R bump -
 
                          + = increase adj.
                          - = decrease adj.
                          F = front
                          R = rear

For reference, here is what I suspect to have been the 'source' article:

http://www.smithees-racetech.com.au/theory/shocktune1.html

rk · Mar 31, 2005

sukerkin
To elaborate a lot further...

Is it enough of a 👍 and thanks to tell you that I am printing this post and hanging it on the wall over my Farrah Fawcett poster? (She was popular when the Chapparral's were.) You should know that if you withdraw from participating as you implied in another post, The Planet will be less for it.

sukerkin · Mar 31, 2005

Many thanks for the kudos, Aarque. It's always nice to have something appreciated and be of use to another.

As to the reference to my remark in the 'Backwards' thread, I didn't mean to imply that I would stop nipping in and helping out with testing or theorising, just that, for me, the question was pretty much answered and I didn't feel I had anything more to add that wasn't repetitious.

I'm afraid you'll have to put up with my laboured pedantry a while longer :scared:

Duke · Mar 31, 2005

sukerkin
I'm not going to argue with you, Greyout. Your description is accurate of how a damper will act in isolation.

What I was attempting was to keep it simple and say how the car would 'feel' with weight transfers and alterations in the CoG in progress.

And hence, my original post about how it is nearly impossible to provide a non-technical discussion on this subject that has any meaning at all.

mrnelson · Mar 31, 2005

Question for clarification:

Does the setting for bound affect how the damper compresses and rebound affect how the damper decompresses?

Suspension is something I'm desperately trying to get my head around, and I feel i'm almost there if I can just figure out how everthing hangs together I feel I'll be able to understand what I'm actually doing to the bits when I'm adjusting them....

sukerkin · Mar 31, 2005

@Duke

Needless to say I agree entirely.

I tried to winnow away all the 'what ifs', 'unless's', 'also's' etc etc etc that go with the suspension tuning territory and give a 'seat of the pants' feel for what a setting would do.

The problem is it means you leave a lot out of the explaination and anyone with some technical knowledge who looks at it instantly goes "That's not right"

.

Still, I think that as far as Dampers go (my favourite tuning tool) the table I posted up is a clear enough guide for most people to have a twirl of the spanner with some degree of success (hopefully)

.

@Mr Nelson - The Bound is indeed the resistance to compression of the shock (and hence the springs speed of response) whilst the Rebound is the resistance to expansion.

In (very) rough terms, the Front Bound and the Rear Rebound affect corner entry whilst the Rear Bound and Front Rebound affect corner exit.

Nelsy · Mar 31, 2005

learn something new everyday...
didn't know that about dampers. but now i do...

i thought bound affects entry and rebound affect exit..
didn't know it was a combination of the two...

thanks for clearing that up.

rk · Apr 1, 2005

A bit of trivia from my ancient "Suspension Tuners Handbook" may help a lot of understanding about the role and function of the dampers.
(According to the book) when engineers design or consider suspension components, they paraphrase from one of Newtons basic laws. The vehicle, to these engineers, is motionless in the center of "perfect" space; but a very rough, very fast moving plane continually intrudes into this space, it is the job of the suspension to prevent these intrusions from displacing the vehicle from it's position of "rest." When you view the situation this way, you can see what a bump really means to a suspension, it is basically a big pile of energy. As this pile of energy hits our hapless vehicle, the compression dampers convert some of that energy, through friction, into heat, which is allowed to bleed into the passing air. They can only absorb a small fraction though, lest they become too restrictive and fail their job of not disturbing the vehicle. The remainder of the energy is stored in the springs, which continue to compress.
The passage of the bump begins the most crucial phase of suspension travel, the extension or rebound stroke. The dampers must convert all the remaining energy in the spring into heat by restricting the extension of the spring. If they try too hard to convert heat, the spring may still be extending when the next bump comes, a condition that will quickly overload and disable a suspension if the terrain is rough. If they don't convert enough heat, they leave the car dangerously vulnerable to loss of traction through unweighting as the springs pogo their energy away.

Airey · Apr 5, 2005

I found another good guide by kwixx~

http://db.gamefaqs.com/console/ps2/file/gran_turismo_4_tuning_a.txt

Greyout · Apr 5, 2005

Airey
I found another good guide by kwixx~
http://db.gamefaqs.com/console/ps2/file/gran_turismo_4_tuning_a.txt

I'm reading it right now... so far, I'm not impressed.

When he explains the parts, he simply says that the next level up is better for no reason.

"1 way LSD is ok, but you really should get the higher ones. 1.5 is a little better, but 2 way is the best"

and thats it.

great.

we'll see what he has to say about the tuning.

edit: he also says the higher the brake balance setting, the faster the car will stop.... haha

a lot of these insightful writeups are useless

dnomarz · Apr 6, 2005

pmgolf
Duke, thanks for your response. From what you stated though ("...suspension tuning is a complex, interrelated topic, and there's not much further it can be simplified without becoming useless. If you can't work your way through ///M-Spec's ... Tuning Guide, you're really going to have to keep at it.
"), it sounds like you may not possess the ability to reduce your knowledge to terms and descriptions that are more easily understood. NP, my friend, not everyone possesses such skill or in-depth knowledge.

What I am looking for here is someone who does possess such skill. Someone who can answer simple questions, like:

1. When you raise your spring rate number, are you stiffening the springs? For the lay-person, it is NOT self-explanatory.

2. Shock Bound - is that where the shock absorber is being compressed? If you reduce the number, are you making it more difficult for the shock to be compressed? Is that "stiffening" the shock, or would "stiffening" involve both Bound and Rebound?

3. Toe Angle - is minus pointing outward or inward?

And surely there is someone who can explain suspension changes and effects in more simple terms than what is explained in M-Spec's writeup. Even some of the basics about suspension changes and WHAT TO LOOK FOR when testing changes would help. Telling someone to "read the manual" does not help when there isn't a teacher around to explain the manual or answer questions!

Thanks, Pete.

Have you tried reading the scrolling message (at the bottom of the screen) when you are highlighting or clicking on to one of these components, i.e., if you go to the suspension menu and want to fidget with the springs, you go to the spring setting and click on it. Once you do, there will be a scrolling message at the bottom of that screen which describes the part and what it does and what it will do if you mess around with it!!!
I am no mechanic but using the scrolling messages helped me out for tuning my cars...........I even tune my LMP and F1 racers with great and advantageous effects!!
Being able to tune your car, suspension-wise, is what makes the GT series so great.........
So read the scrolling messages regarding all the parts and have fun adjusting your car's suspension..............it only costs you 5 credits to take your adjusted car to any unlocked tracks and take it for a spin and see what you did wrong or right.

Tuning for Dummies - help needed!

pmgolf

tm2003

dunn0

Duke

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tm2003

sukerkin

pmgolf

sukerkin

hippo0422

pmgolf

ZoomZoom

dunn0

Duke

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ZoomZoom

Duke

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pmgolf

Greyout

Rx3

sukerkin

sukerkin

rk

sukerkin

Duke

Keep 'em separated

mrnelson

sukerkin

Nelsy

rk

Airey

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