Suspension Theory/Chat Thread

[Sirbelch]

ok so, what do you run for the rear camber on the street an what are the toe settings you use for the street as well?

[Highrev1]

Well I have been through 4 sets of tires in 22xxx miles I am not a good example of what to follow.

I run about 1/16th of toe out all around.
And about -1degree in the rear. I am probably gonna up this to -1.5 to -2 but also up the front at the same time:) I want is SICK SICK SICK.

MY settings are NOT ones to follow. In incliment weather my car is almost scary, I won't even let my fiance drive my car cause its that aggressive.

[Sirbelch]

my woman has only driven my car once so as long as i don't get hammered at a bar or something, i'll be fine. I only have 11xxx miles on my car but only 2000 on the current set of tires because i bet the rims on my old set. The old set was gonna go like 5000 more max before it needed to be replaced and thats on a stock alignment (i like to play) But, i would rather spend my money on other parts than fried tires. So I'll just stick with 0 toe.

Do you know what caster you are running? I've read that positive caster is good for handling but i dont know why.

[Highrev1]

http://www.ozebiz.com.au/racetech/theory/align.html
Start reading
Basically more caster is free negitive camber as you turn the wheels.

I amout for tonight Later.

[Highrev1]

BUMP, this is agreat thread and want to continue the discusiions about real suspesnions, NO WILL this RUB in here please....

Lets discuss some other suspension ideas....I have been grilled by BELCH about the LSD causing oversteer....Lets get another debate going...ANYONE got anything

[Sirbelch]

's advocate. Softer spirngs can't handle better than stiffer springs. The stock springs are soft and uping the rates ups the limit of the car. How come you say run the softest spring you can?

[Highrev1]

Originally Posted by Sirbelch

's advocate. Softer spirngs can't handle better than stiffer springs. The stock springs are soft and uping the rates ups the limit of the car. How come you say run the softest spring you can?

I thought you were my friend

The higher the suspension frequency grip decreases. Well this frequencey is a measure of how many cyles per minute or in a second, the car would go through and bounce up and down on springs alone. This matters greatly to you because the stiffer the suspenion is the less contact pactch will be touching the ground over rough surfaces, and if the tires in the air your not gaining traction or grip. The more grip your tires can make, the more force your putting into the car so you will need to up the resistance to body roll to keep it at an acceptable level. Race tires need a much stiffer suspension than a street tire.

[Sirbelch]

I’m just trying to get the party started. Have you done any testing in which you tried to find and ideal spring rate?

[Highrev1]

I got one for you...I know the answer I want to see how well I am doing

Which would be better the slightly better dampers that come with the HFP kit or the more aggressive alignment you will be able to get with the addition of the rear camber kit?

Anyone have an extra set of HFP dampers so I can get a SHock dyno on them? I am gonna do the stock ones one day :)

Full story here
Which is the best suspension setup?

[Sirbelch]

Well increasing rear camber and not increasing front camber at the same time would cause the car to push even more than it already does. So, I'd have to say, the HFP over the rear camber kit. But wait, if you set the rear camber to 0 or even go positive, that should get more rotation out of the car that the HFP. So, in light of that revelation, I'd have to change my answer to the camber kit. If you get a front camber and a rear camber (we'll say 300 for the set) as apposed to 600 for the HFP, you would see and even bigger difference in handling with the camber kits over the HFP.

[Mitch]

I love this thread.

[Sirbelch]

How does compression and rebound effect the way a car handles on a track and how does changing both compression and rebound effect handling?

[aki]

Originally Posted by Sirbelch

How does compression and rebound effect the way a car handles on a track and how does changing both compression and rebound effect handling?

The idea is similar to spring rates. You want the compression/rebound at a rate where you don't lose traction over bumps/rough sections in the road. Excessively high compression/rebound makes the car skittish. In other words, you want a balance. Without rebound the car would endless jump up and down. Too much rebound damping and the rebound speed is reduced to a point where it doesn't react quick enough to a rough patch, say a bump on the road.

Too much compression damping and the wheel bounces off bumps. Too little compression and the car takes a dive when hitting bumps.

Aside from bumps, where damping settings come into play in corners is the weight transition. Excessively stiff rebound dampening, for example, means the weight doesn't transfer quick enough from inside to outside, possibly lifting the inner wheel. Insufficient dampening means it transfer too quickly. Hence body roll is also in part dictated by rebound dampening. This ties into a point about roll bars, and how ppl get locked into a mentality of "stiffer is better": just because race cars have less body roll doesn't mean they're using insanely gigantic anti-roll bars. It likely has to do with their compression/rebound dampening settings as well.

The two go hand in hand--changing compression has to be compensated with rebound damping. Basically, you want a happy medium where there's just enough stiffness that the wheel won't lift, and where there's always optimal load on each tire (outside and inside).

Going back to body roll, stiffer rear sways can be deceptive--when you're not at the limit, the setup will feel more aggressive, as though it's on rails... but at the limit it could have lost traction. So even though stiffer sways could "feel better," in reality you don't know until you've thoroughly tested on the track. You could always use a smaller sway up front, which could increase front traction... as opposed to lessening rear traction with a bigger rear sway bar.

I disagree with Highrev's semantics of wanting the "softest" spring setup (although his point is still valid, and he could kick my butt on the track). You want something not too soft, not too hard. Soft enough where it can do its job of compressing, hard enough where it doesn't make the suspension hit the bumpstops on every corner. Everything is about a happy medium--and to some extent, preference.

Edit: to cover my butt, a lot of what i've said are simplifications and general rules of thumbs. Stiffer rear sways doesn't necessarily "reduce" traction as much as softer fronts don't necessarily increase traction. My point is overdoing settings always have their downsides.

[Sirbelch]

When Revy says softest, he doesn't mean literally the softest springs you can run. He means the stiffest spring you can run and still keep the tires on the ground which will still be much softer than the stiffest springs the car can handle.

I thought the more rebound you ran the quicker the weight transfer happens. Too quick of weight transfer will overwhelm the outside tires in a corner, thus lowering grip levels.

[Highrev1]

Bump does have the tendency to "fake" spring rates but that is only in transitions, The doesn't mean it can do it for steady state turns, A long sweeper will need the acutal rate rather than "fake" one from the additional bump valving...

I have yet to read AKI's post I will...Getting in trouble here though

[Highrev1]

For optimal performance You SHOULD be running as soft of a spring that you can get away with. What you can run generally is determined by what tires you run. Really stiff springs are only helpful when you run say an R-compund tire. Otherwise you end up increasing your Suspension frequency for no reason and you decrease the acutal traction your car can make...

When I speak I speak of acutal people who drive their cars to the limit on the track. When we discuss driving on the street, were talking about "feel" rather than acutal tuning. FOr example the Chassi bracing thread. For the average street driver this is a waste cause you will never know if it is better or not.

Any way, As long as you are happy with your selection thats all that matters.

Valving, stiffer valving means that wight will transfer faster. Faster transfer means that the car WILL respond quicker. Thats why the average street driver equates stiffer to better handling. Faster response does not mean better handling.

Ok with that said, why will a real person tuning thier car be happier to be able to adjust how load gets transfered front vs rear rather than just stiffer? Beacuase that allows you to determine which end of the car gets loaded first, which helps you for corner entry and exit. As I have said Weight being transfered=less traction as we all know how a tire makes traction, given this this allows you to adjust oversteer/understeer of your car.

"In the whole, why would some one want a single adjustible damper to only adjust Rebound rather then Bump and rebound at the same time... well, that deals more with ride quality and how the car reacts to rough surfaces and impacts (FIA curbs any one?). See, bump valving has a much bigger influence on how the car reacts to impacts then rebound... It could be said that stiffer bump valving sort of Fakes a higher spring rate (One reason why alot of Stock Autocross drivers run double adjsutible dampers). The problem with that is, since they have the side effect of "faking" a stiffer spring, you are also "faking" a higher suspension frequency.... meaning the car will have less traction over bumps and rough surfaces. so, with a damper that adjusts bump and rebound at the same time, you end up running in to an issue of "I need stiffer valving to get the car to handle and respond the way I want, but I cant run to high of a bump valving with out making the car unstable in turns that arnt perfectly smooth". Alternatly, and this is why I say single adjustible dampers that adjust both bump and rebound are great for the street, is that because you can influence ride quality a lot more with bump valving the rebound, you can tune the car to ride much softer, then if you had a damper that only adjusted rebound. In the grand scheme of things, I'd personally much rather have a double adjustible damper then a single adjustible where both bump and rebound adjusted, but in the single adjustible damper world, performance wise your probably better off with a damper that only adjusts rebound vs one that adjusts bump and rebound." A ZZ quote

Roll Resistance is determined by these basic items......

1. TIRES...any rubber that grips will require stiffer suspension, as compared to someone who is running a stock tire cause then you can run a softer spring, and still maintain adequate levels of body roll.

2. CAMBER...The degree of camber you run is dependent on how much body roll you can accept. I run close to -2 daily, I can accept more body roll than someone with a stock alignment and 0 degrees of camber. This also means I can run a softer suspension.

3. Ride height...This is more complicated, and why we suggest not to go toooo low. Lower means a stiffer ride as to reduce bottoming out, but also if you go too low as the suspension compresses you can lose -camber. Lower car means more roll resistance than one that is higher..

No matter what doen't beleiev me Read books, Do some testing and autox;s, and track days and make your own conclusion...But basically run as soft a suspension as you can without allowing the negatives of a soft suspension to come forward.

[aki]

Originally Posted by Highrev1

But basically run as soft a suspension as you can without allowing the negatives of a soft suspension to come forward.

My point is that it's semantics. I can say the exact same thing as seemingly the opposite--ie, "Run as hard of a suspension as you can without allowing the negatives of a hard suspension to come forward."

[Highrev1]

OK yes you can say that butt..more ideally softer IS better cause I would rather run softer as it is easier to diagnose than too stiff..NO? Too much body roll and camber loss is easier to see and diagnose than too stiff NO? :)