[Dezoris]

I see so many questions about springs, as which is better, and what shocks to use, although I really don't get tired of helping I do think that many people have no clue what your springs and shocks are doing, nor the whole idea of what modding your suspension does, in the big picture. So this post or article is designed to provide a basic understanding of the major components in your suspension, and a checklist of what you can do to achieve your suspension goals.

So here are the main reasons I see people mod their suspension.
Section 1

1.)To just reduce fender gap, or have that lowered look
2.)To get better performance, as far as handling, and maintain good ride
3.)To go all performance with racing in mind

I think most of us fall in the middle somewhere.[FONT]

So lets start with the most important question of all.

What is the cheapest way to get my car to handle better, should I get springs?

Answer The common misconception primarily spouted by magazines and much of the industry is to throw on some lowering springs, to reduce your center of gravity, and reduce roll. While this is in part true, it hardly is the first step in creating a better handling condition.

So here is an example to thing about look at this picture-

Now if you can imaging yourself in that vehicle what would be the most noticable thing to you, (besides being thrown to one side of the car)
Now look at the picture again, there is roll, and also what else would you feell or hear? Ah ha, yes the tires!! You probably would hear them screaming if they are not a sporty or soft compound tire.
So if you got in your car and drove up to 50 MPH or 90 kmh and decided that you wanted to just take a hard 90 degree turn, your first worry would be, "am I going too fat to make it." Which would result in you sliding, or spinning.

Now ask yourself this, is this sliding condition caused by the body roll?
And would having lowering springs help you from sliding?

Well the answer lies here- When you are turning the wieght of the vehicle is shifting form one side to another and that weight is being placed on the tires to maintain the cars contact with the road, which keeps you one the road, or maybe not depending on conditions.

section 2

This is what we will look at now.
[b]
1.)What brand and model tire does your car currently have?
2.)Do you currently Have suspension mods? (if so see section 4)
3.)What size is it? (Not sure read below here)
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An example of tire size would be 205/65/15

Here is a detailed explanation for those who care, provided by tirerack.
If this information is not important to you skip to section 3

Calculating Tire Dimensions
The first number is the width of the tire in millimeters, measured from sidewall to sidewall. To convert to inches, divide by 25.4 In the example above, the width is 185mm or 7.28".

The second number is the aspect ratio. This is a ratio of sidewall height to width. In the example above, the tire is 7.28" wide, multiply that by the aspect ratio to find the height of one sidewall. In this case, 185x0.60=111mm or 7.28"x0.60=4.36".

The last number is the diameter of the wheel in inches.

To figure the outside diameter of a tire, take the sidewall height and multiply by 2,(remember that the diameter is made up of 2 sidewalls, the one above the wheel, and the one below the wheel) and add the diameter of the wheel to get your answer.

Example...185/60R14 85H or 185/60HR14

185mm x .60=111mm x 2=222mm + 355.6mm(14")= 577.6mm or 22.74"

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section 3
Ok so if you have a vehicle that was just bought, you should now know your tire size, now the only question is what size do you have.
Upgrading your tires is the first step in getting more grip.

If you have a 14" rim (example tire size 185-65-14-------that means you have 14" rims)
You are limited from aquiring a true performance tire, but you do have some strong choices, and getting more grip will be cheap in this size, here are some recommended tires and prices per size.

I mention tread wear and traction rating as a consideration here is the explanation for that please read!
http://www.tirerack.com/tires/tiretech/general/utqg.htm

Size:185/65-14

1.)Bridgestone
Potenza RE92
utqg=160 Traction rating=AA
Price=$60 a tire

The RE92s are the best tire as far as dry grip and wet handling you can get on a 14" rim for a street tire, I have tested this tire on a Saturn SL2 which going from the stock rubber was amazing. The wet handling and braking were so improved it shocked me. The road holding with these tires make the car feel sure footed and turned the car from a messy squealing pig to a quiet stable, and grippy machine. I swear that you would think from driving it that there were major suspension mods that had occured. The main thing is these tires were quiet!!! And well balanced in wet and dry, where the other tires fail this tire wins, stiff side wall and well balanced

The bad part here is that the treadwear rating is less than 1/2 of the other two tires I recommend, and it is more money at about 60$ a tire.
But this is the best tire if you can't afford a rim tire upgrade or wheel tire and suspension mods.

2.)Yokohama
Avid H4
utqg=360 Traction rating=AA
Price=$50 a tire

I went from the stock Firestones on my Honda Civic to these, and although they are not nearly as quiet and composed as the RE92s they have held up through torturous conditions, bad alignments and many tests after tuning and modifying my suspension. The treadwear rating is higher. The tires make some noise when you get on them, but not excessive, you know when you are reaching your limits with these tires
Dry grip is its stronger point, where in rain they tend to hydroplane more than the RE92s, although nothing uncommon and still much better than the stock tires. These tires will roll over more than the RE92s the side wall is not reinforced as much as the RE92s, but the rolling really only disrupts higher speed manuvers where you can feel tire rolling over. On slower speed runs in a parking lot course, they roll but grip very well, until moisture comes into play. I recommend these tires to those looking for longer tire life a good dry traction.

3.)Dunlop SP Sport A2
utqg=420 Traction rating=AA
Price=$52 a tire

I finally had the chance to test these tires, on a ford focus.
These are really a nice quiet and smooth riding tire. I can't say they impressed me as far as performance goes. They were noisier than the H4s and the RE92, they gripped well, but just screamed at me. The wet traction was ok very similar if not a little better than the H4s, in damp conditions, resisted hydroplane better, but was not as grippy as the H4s and no where near as stable as the RE92s. This tire would be good if you want want a long lasting tire, but really just looking for a replacement for your stock tires with slightly more grip.

4.)Falken Azenis RS
These are fairly new tires but in the higher sizes are excellent, this would be a tire for track use, although drivable on the street, its dry drip is better than all the above, but its soft compound would take a beating for the daily driver, although providing the best dry traction here without going with a race tire. This tire comes in 195-60-14 so you may have to consider strongly if you wanted to throw this on your stock rims in 14" do to some issues with speedometer readings do the the lessened diameter of the tire, but I throw this out there for someone who just wants to go auto crossing and just needs some race tires that will not bump you out of your street class. This is a tire that will not resist hydroplaning very well the evacuation design is not that hot, although this is debated, between a few people.



Now if you have 15-18" rims then the world opens up to you as far as tire sizes, which if you want opions feel free to ask. Some quick recommendations are.

Bridgestone highest performance from top to bottom
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Potenza S03 Pole Position


Potenza S-02


Potenza RE730


Potenza RE-950





Kuhmo
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ECSTA Supra 712



Yokohama
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AVS Sport


AVS Intermediate


A520



Sumitomo
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HTR Z II


Falken
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Azenis RS


Any questions on sizing and tire recommendations based on driving style and goal please post.
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section 4

If you have a modified suspension and you already have a so called good tire. Then there is more at play here than just tires.

I would still consider upgrading tires before you considering these steps below if you suspect wear or you are riding on your average all season tires.

Tires that I have tested that I feel are not adequate, for a modified suspension

Toyo FZ4
Toyo T1S (Dry Only)
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Nitto NT555R (drag only)
Nitto NT555 (drag only)
Nitto NT505 (street dry only)

Not many people who are looking for handling like the Nitto tire line do to its bad balance of wet/dry capabilities and poor tire life.

If you are a racer and would like to add to this list of tires not cut out for autox or good balance that are supposed high performance tires please post.
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If you have dropped your car then you have a few things to look at.

1.)Springs
Springs control the cars loading and unloading.
They are the load bearing members in a doublewishbone suspension and in a suspension using Macpherson struts.
What this means that the the springs on your car have a specific rate at how they compress or control load.

Lets say your springs have a spring rate of 300, this would mean for every 300lbs of load they compress 1 inch. The higher the spring rate the stiffer more resistand to compression the spring is.
Your lower rate springs are usually longer using a typical shock or strut to dampen them, for a softer ride. When you hear that phrase, this car has improved handling do to higher spring rates.... now you know what it is.

Here is a detailed explanation of spring rates by IntegraR0064

What a spring rate is can be seen by hooke's law: F = kx. F is the force pushing/pulling on the spring, k is the spring rate, and x is how much the spring is stretched/compressed from it's natural length. After your basic algebra, you get that spring rate = F/x ...or force required to deform the spring by a unit length. A typical spring rate might be 300 lb/in, meaning if you push on the spring with a 300 lb force, it'll compress one inch. If you push with 600 lbs, it'll compress two inches, etc.

In summary.... a larger spring rate means you have to push or pull on the spring harder to get it to deform.

If you had an infinitely high spring rate, it'd be like you just had an indeformable steel bar for a spring. When you hit a bump, the suspension would not absorb any shock...the entire car (and you) would. If you had a really really low spring rate.....the spring would compress all the way just from the weight of the car....and you'd just be riding on your bumpstops all the time....getting the same effect.

With real available spring rates for your car....a really low one means that your car would bounce a lot on every little bump. Higher ones (i.e. those pesky cheap coilover sleeves) can get to the point where your suspension barely bounces over anything.

Higher spring rates need more dampening too....if you run typical coilover sleeves with your stock shocks, your shocks will blow.

If you're talking about tuning your car's handling behavior by messing with having different spring rates in front and rear... some people do it, but it's not really something I'd recommend. It's a little unpredictable and tuning oversteer/understeer is better left to sway bars and such, as well as your shocks.

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1.)Shocks/Struts
As quoted By Texan
SHOCK ABSORBER
This is what controls spring movement. What is almost always used on our cars are mono-tube hydrolic shocks, so you don't need to know about anything else. A shock absorber's job is to absorb shock (duh!), which means that it dissipates spring energy. Hydrolic shocks do this by moving a small piston with orifices in it through a viscous oil, providing the energy damping needed to control spring movement. The size of the orifices determines the resistance to movement the shock will have, and adjustable shocks have adjustable sized orifices to offer a range of resistance to motion. Since a car's coil spring can be likened to a big slinky, you can imagine that the same way a slinky bounces off one step and jumps to another, where it compresses again and then jumps away once more. A spring will do this just the same, causing the suspension to compress & rebound over and over again after hitting a single bump. The primary job of the shock absorber is to prevent this cycle, and if it's properly matched to the spring's rate it will only allow this to happen once. This is what keeps the tire in good contact with the ground, so you can imagine the importance of getting the shock stiffness right for your springs. The secondary job of the shock is to add some resistance to motion in the suspension, much like the spring does. There's no need to get deep into that yet, just know the shock has an effect on both ride quality and performance.

ADJUSTABLE SHOCK ABSORBER
Adjustable shocks allow you to change their stiffness. Now that you know how important it is to match the shock settings to the spring in order to keep the tire in good contact with the ground, you can also understand how it's control over the spring movement will affect ride quality. Since the shock absorber has some level of control over how quickly the suspension can be compressed (because it adds additional resistance to the whole system), you can imagine that making the shock stiffer will have the same overall effect on ride quality as stiffening the spring. There are two main types of adjustable shocks: those that adjust stiffness of the compression stroke only and those that adjust stiffness on both compression and rebound strokes. It's not important to go over the different types of desgins here, but know that most shocks either only adjust compression stiffness (called single-adjustable shocks) or they adjust both compression & rebound at the same time (called double-adjustable shocks). This means that there is no way to adjust the bias between compression & rebound stiffness on double-adjustables, which is of principle design concern to shock manufacturers because it's so easy to get the bias wrong. There are indepently double-adjustable shocks which allow you to change this bias, but I wouldn't recommend them for the average enthusiast. You will probably just end up making the suspension damping worse than it was stock. Recommendations here are usually to get the double adjustable shocks that control both compression & rebound (but not independently), and that's probably the best idea for the average enthusiast.

COILOVER SUSPENSION
a coilover suspension is simply one that has the shock body located within the space inside the coil spring (as installed on the car). This is the best design possible because the shock is moving in the same plane as the spring, which ensures that it can most accurately control spring movement, plus it's usually the lightest. In our double wishbone suspension systems, the shock's only job is to control spring movement, so it makes sense that Honda equips all of their performance cars with coilover systems. The popular catch phrase "coilover" is only applied to systems that are sold complete with both shocks & springs (and sometimes upper mounts), but the truth is that every spring or shock you install on the car will function in a coilover system. Here's the basic breakdown as far as you are concerned: Honda uses almost exclusively the coilover setup on their current cars. Aftermarket spring manufacturers like Ground Control simply one-up their design by adding height adjustability to the system. This comes in the form of threaded shock bodies and adjustable spring perches, we generally refer to them as "sleeved springs". There are also shock manufacturers like Koni who one-up Honda in the shock absorber department by offering adjustable shocks, which are adjusted usually by a knob somewhere on the shock body or rod. Then at the top shelf of coilover designs, you have companies like Tein who one-up everybody else by offering a complete & ready to install coilover package that is adjustable in several different ways (height adjust, rebound adjust, compression adjust, whatever they throw in) and comes as a properly matched system. These are the systems we refer to as "true" or "complete" coilovers. Usually these shocks are rebuildable and offer custom valving options, and the company usually has a variety of spring rates available for you. If these are the best systems, it's simply because they are the most complete. The only system that offers a better garaunteed match between spring & shock are usually the stock units (which of course are not stiff enough and have no adjustability). What I am getting at here is that just because you get springs from one manufacturer and shocks from another does not mean that you won't have a kickass ride, it just means that there is more possiblity of mismatching one part to another. As we have pointed out many times, the simple Eibach Pro Kit & Koni adj. shocks combo seems to whoop ass on many other street setups without costing an arm and a leg (relatively speaking).
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Holy Shit!!!! You tired yet?

Ok so the main difference between shocks and struts? Really, not much they really are the same things dampers, the only really difference is in what application they are used. In a double wishbone suspension shocks dampen the springs and the springs do the load bearing.

In a Macpherson setup the strut will so some of the load bearing as well as dampening the spring.

People commonly ask "why can't I use lowering springs with higher rates on stock shocks?"

If you have learned anything from this lesson, you will now know that the stock shock is valved to dampen a specfic spring rate usually that spring it was designed to work with, by puting a high rate shorter spring on it, it causes two major problems resulting in failure.

1.)Decreased travel (The shock no longer can travel up and down,"compression-rebound" to dampen the spring properly which means you shock is useless, and is the spring is just bouncing up and down.

2.)Over work (the shocks oil inside and valving cause it just bounce and thrash about causing bubbling of the oil and extensive pressure usually causing leaky seals. Since the shock was not valved to dampen a higher rate spring, it just is working many times harder. Basically certain shocks are tuned on a shock dyno to effectively tune them for specific spring rates, our general recommendations on shock spring combos are based off of this. Combos that will play togther and, where the shock is designed to control the springs movment. When the shock cant control the movement of the spring we can see shock failure. which means you are driving a car without shocks This is why we STRESS USE AFTERMARKET SHOCKS WITH LOWERING SPRINGS!
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Ok now the most important part of setting up a modified suspension is alignments.

section 5

Just for all of you, who wonder


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"Should I get an alignment or not after lowering, or any other suspension mods."
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Well some will argue, that some drops don't effect the camber, or toe. So you don't need to get one.

Lowering the car does the following
1.)creates more negative camber
2.)Can change your toe angle (usually toe in)
Putting on a wider tread width tire on (195 to 205) will
1.)Change Toe angles

Now there is a specified range for these readings.
Such as the Civic for example (factory ranges)
Front camber can be from +1 degree to -1 degree
Rear camber can be from 0 degree to -2 degrees
So who knows what the factory reading were?
What if they were on the borderline lets say the front camber was at
-.8 degree, that would mean lowering it a fraction, 1", would put it over
-1 degree. Then on the other hand is could work to your advantage.
But usually your toe is messed up to which can cause very odd handling problems, and is harder to notice.
So I hope you can see my point.
So when the alignment guy asks what settings you want, you would normally say
"within factory specs"
Well for all you Civic riders here is a modified range, something I did not have when I did my alignment.

Front Camber/TOE Range for modified suspension
Front Camber(in degrees)
Range (-1.8 degrees to 0 degree) the 0 setting will offer longer tire life
Front Toe
Range (-0.02 to 0.08)

Rear Camber/TOE Range for modified suspension
Rear Camber(in degrees)
Range (-2.0 to -.5)(Tire wear is a consideration when more negative camber is added (see below)
Rear Toe
Range (+0.04 degrees to -0.15)
So the point? At least have your alignment checked after suspension mods.

These ranges have been created for the tuner who wants a balance of performance and practicality.
These setting are also for the hard street driver and semi-autoxers not for people slamming their car. Those dropping their car more than three inches
may need more camber, depending on the offset of the rims, so rubbing does not occur, but camber out of those ranges
supplied can cause premature tirewear. These settings take in account the factory range while giving the alignment tech
a new guidline, instead of the one he looks at for a stock suspension.
These settings are still withing factory spec, so treawear is not a consideration.


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What's toe in toe out?
These pictures are very extreme, usually toe in/out is not visable by the eye, even then it can cause odd handling and poor tire wear.

With the wheel center the wheel toes inward away from the centerline.


With the wheel center the wheel toes outward away from the centerline.
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What is camber?

Camber is illustrated by this picture, where this picture shows a positive angle. the reverse angle would be a negative angle, and these angles are best measured and ajusted professionally.

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What is Caster?

here is a piece from Motor Age describing it perfectly-


Caster refers to the tilt angle of the front spindles, as viewed from the side of the vehicle. It involves the relationship between the top of the spindle and the bottom of the spindle at its attachment and pivot points. Imagine a front suspension with upper and lower control arms. As viewed from the side of the vehicle, the caster angle refers to the location of the upper ball joint to that of the lower ball joint. If you draw an imaginary line from the lower ball joint to the upper ball joint, that angle represents caster. In the case of a strut-equipped front suspension, you can imagine a line drawn from the lower ball joint to the top of the strut tower.

When the top of the spindle is set back (placing the upper ball joint closer to the rear of the vehicle, with the lower ball joint closer to the front of the vehicle), this is called a positive caster angle. All vehicles use a positive caster angle.

The caster angle -- the reason we have an offset angle between upper and lower spindle points -- exists to allow optimum steering and handling for a given vehicle. A positive caster angle is used to allow predictable steering of the vehicle. If the caster was zero with the upper ball joint exactly above the lower ball joint, steering would be erratic, the vehicle would be very hard to control and the front wheels would wander all over the road. By creating a backward 'lean' (a positive caster angle), the vertical travel of the front wheels is 'dampened.' The more positive the caster angle, the more controllable the vehicle is at higher speeds. As caster is lessened (closer to zero), the vehicle's front wheels will react faster to steering input, but highway stability will be decreased.

Caster settings on many vehicles are fixed and can't be easily adjusted independently. Replacement of damaged parts is commonly required in some cases. Front double-A-arm suspensions allow easy caster adjustment at the upper control arm fulcrum shaft with the use of shims. Strut suspensions may be adjusted through use of camber/caster top tower plates.
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Here are some frequently asked questions

Q"you mentioned these specs are also for the autocrosser and street enthusiest but the question is
are these settings practical for street driving? how about tire wear? "
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A:These settings are still within factory spec, so tire wear is not that much of
a consideration. But, having an allignment before and after every autox can be hard so these settings are the best for both worlds.
Now of course you can go with -3 degrees in the rear and -2 in the front, which is
more extreme, more suited for autox but on the street you will wear down your tires.
So that is why the settings i posted are optimal for both, the "middle ground" for most Hondas. Please check your factory alignments, and post up if you want recommendations

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Q"i have a question while we r on the subject of suspension. anyone who can clarify for me please do.
when u go to a dealer service shop or a shop in general and have an alignment,
it is my understanding they are adjusting your camber. so if they were not good at their job they
could mess up your camber, and it can be corrected. so what is the purpose of a camber correction kit
when u get lowering springs. why can't you just have your camber corrected
through an alignment from shop? i apologize if this is stupid, but it just makes sense to me. "
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A:Camber, kits are generally for those who have modified suspensions, namely for those that have their car dropped.
When this occurs (lowering) the factory adjustment may no longer get the vehicles camber and toe within desired range.

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Q"so ok you do'nt need a kit to adjust TOE in/out on all four wheels right??? BUT for the camber.. you must buy a kit.. or at least only for the front..
the rear you can kind of shim it out with some washers to some extent right?????So here's my big question... the factory camber specs on a factory
non-lowered 2000 civic (or 96+) i seen that the rear actually has negative camber
... and the front is basically straight. so does it mean we have to set the rear
to have "some" negative camber when we lower it?? like don't get rid of all
the negative camber in the rear since the rear had it at stock?"
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A:Yes the stock settings for the rear can be from 0 degrees to -2 degrees,
so if you drop it you have to watch for the tires going over that 2 degree mark.
You can effectively adjust toe regardless of lowering (w/ or w/o a kit)
You can use washers in the rear, that is true, many do it with good results,
but it is nice to have a kit that can be easy to work with that takes the guess work out of,
say "we need three more washers" Caster is something that can't be messed with unless using a plate on top of the shock tower to adjust it.
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Part 2 will cover adjustable suspensions and corner weighing the suspension.

If you need any shock/spring combo recommendations please post.