Thread: Suspension 101 (basic)

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  1. #1 Suspension 101 (basic) 
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    little quick write up i did

    Suspension 101

    The suspension is a critical aspect of your car. It will help put the power down and more importantly keep you on the road. Many people overlook the necessity of these components and many only buy the bare minimum parts. In this thread I will try to cover some of the major areas and some of the major questions that have been asked. I am not an expert on these but I have done lots of research and will write everything I know to my knowledge. If any information is incorrect or I leave something out, please feel free to email me or post up the mistake.

    I think it is very important to understand how the actual suspension works. This may seems basic, but I know there are some “noob’s” out there who don’t know much and looking for the very basic’s so I will start there and try to define and explain the main parts of suspension.


    Stabilizer bars/Anti-roll bars:

    These bars are used to keep the car stable throughout a turn. Think about it this way. If you are driving and go around a turn, the car will “roll” to the outside of the turn. Therefore a lot of weight is being placed on the tires on the outside side of the corner, and the inside wheels have less weight on them. This causes a loss in traction, steering may be compromised greatly, and the car can even flip over if to much roll is involved. These anti-sway bars help reduce that “roll”. So how do they work? These bars are connected to the frame of the car. They are attached with bushings allowing them to move when the car is cornering. When the car goes into a turn one side of the cars suspension will compress down and take most of the weight. This roll bar is connected to the suspension unit and when the suspension is compressed on one side the bar has a tension placed on it. This causes the other side of the bar to rise and compress that sides suspension component. Therefore both sides of the suspension compress and keep the car more level throughout the turn.

    Corner Weighting a Car:

    This process if very beneficial but can be very expensive. The only downside to this technique is only adjustable suspensions (coilovers) can benefit from this. Like tuning a turbo the suspension can be tuned. You can move the weight of the car to where ever you want it. Corner weighting allows the drive to place a set weight ratio to the car (i.e. 50/50, 40/60, etc.)

    Strut Bars:

    These bars made the cars frame more rigid. They are metal bars that are placed from the top or the strut towers (front to front and rear to rear). Then the car enters a turn the body of the car tends to twists. These bars make the frame more rigid and less prone to twist.

    Struts:

    The strut is a very important part of the suspension setup. Struts are also commonly called dampeners. They purpose of these is to compress and absorb energy when going into a turn or going over a bump. When you go into a turn the strut compresses. Many of the struts out there are full adjustable. This means a person can set it to either a full stiff, full soft, or various places in-between. But what does a full stiff/soft mean and how does it work? Picture this. You place 5 of the plastic Dixie cups on top of one another. Then you compress them together. Now picture 5 coke cans on top of one another and you compress them. Which will be stiffer? There is no real answer to the perfect setting. There are too many variable involved such as, the car, the drivers driving style, etc.

    Springs:

    The spring is what pushes the wheel back to the road. As the strut compresses and the wheel is compressed, there must be a part to keep the wheel back on the road. You may have heard of spring rates, but you might now know exactly what they are. The higher the spring rates the stiffer the spring/ride of the car. The stiffer they are the more likely they are to stay contacted to the ground rather than being compressed more easily. Usually a spring setup rides a little nicer and is softer than a coil over setup. I have attached a list of spring rates (for Civics) I have researched and compiled (mostly from Clubsi.com).

    Camber:

    When you lower a car the camber changes. Camber refers to the vertical movement of the tires. Negative camber is when the top of the tire leans towards the inside of the wheel well. If you were at the front of the car looking down the right side (your right side) of the car, the wheel would have this lean “/_/”.
    Positive camber is when the bottom of the tire is leaned into the wheel well/car. Looking from the same position as above the tire would appear to have an angle like “\_\”. If you don’t understand my picture let me know and I will make a diagram.

    Some ask, “Why do a lot of people run negative camber?” Negative camber has its pros and its cons. First the cons. If you are and avid drag racer and don’t car about turns then a 0 degree camber would be beneficial (on the drive wheels). This allows for maximum contact patch with the pavement. If you love to autocross or drive in the twists then negative camber is for you. When a car enters a turn the car tends to roll and the tire will usually roll some also. When you have negative camber the car and tire will virtually roll onto itself. Since the camber is at an angle the car tilts at an angle and then creates a nice flat patch of tire to keep traction with. If you don’t understand this picture either let me know. These theories are hard to put in words and much easier to diagram.\

    Ok so what is the perfect suspension setup?

    There is no answer to that. It is all about what car you have, how you want the car to respond, etc. The Civic is notorious for having loads of under steer. There are many variations to cure this problem. One must understand that by adding a anti sway bar or new coilovers, will not make the car invincible. The car will have its limits and more likely than not, the car will react differently then before the part was placed on it. Learning to dive a Civic with large amounts of over steer takes some getting use to. There will be times when you need to get on the gas when you natural instincts will tell you to brake. This will only cause you to go into an uncontrollable spin.
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  2. #2  
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    good info..
    camber also helps the car look better when running super wide wheels to tuck )
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  3. #3  
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    my contribution... prolly a bunch of repeated stuff but theres some other info as well.


    The Suspension Thread: Things Everyone Should Know

    --------------------------------------------------------------------------------

    Well, I've said I would post this about 1000 times....so here goes....

    The following is a basic list, though a long one, of things you guys should know before you go spending money on suspension parts and/or slamming you car to the ground because you want to rid your toy of "wheel gap" or look "jdm tyte."

    Basic Terms:

    coilover - COIL spring OVER shock.

    adjustable coilover - height and/or preload adjustable system of coilover suspension that usually matched a good stiff/firm spring with an appropriately valved shock.

    camber - the tilt of the wheel/tire in relation to vertical alignment. more NEGATIVE camber makes for better grip while turning, however too much negative camber will causes your straight-line braking to suffer because of lack of contact patch.

    caster - think of it as camber's friend...seriously. caster is the angle of the steering pivot axis to vertical alignment. basically, if you ADD caster, your coilover will be angled forward at the lower control arm because the tension rod pulls it toward the front of the car.

    toe in - picture your car overhead. now, look at the front wheels/tires. if the FRONT of the tires (closest to the nose of the car) are point toward each other, that is TOE IN.
    toe out - same as above, but with the front tire facing away from each other equals TOE OUT.

    tie rod - the inner tie rod connects the tie rod end to the steering rack. the beefier this item is, the better as they can warp easily under pressure. the tie rod end is a tough SOB. the bushings on them however, usually suck, and blow out which makes for a lovely popping noise when turning the steering wheel. solution - get tie rod ends with heim joints and spherical bearing. no bushing = great idea.

    LCA - lower control arm
    RUCA - rear upper control arm
    t/c rod - tension (compression) rod
    coils - coilover
    CG - center of gravity

    Other Important Stuff:

    roll center - this is the angle of your suspension arms in relation to one another at the middle point of your chassis (facing the front/rear of your car). over lowering (slamming) your car without replacing the proper arms with adjustable ones decreases the handling ability of your car because the control arms are not the proper length to give your it's original wheel base, nor are they at the proper angle to pivot (compress) during cornering.

    sway bars - little bars that are formed to connect to your chassis at 2 points, and to your suspension (usually on the LCA) to help handle weight transitions. unlike popular belief, thicker bars control weight transitions better, but do not decrease the transitioning weight (that would be impossible unless you do weight reductions to the car itself). sway bars also tighten up the front/rear suspension if they are adjustable.

    camber plates - plates used on the front suspension to adjust camber at the shock tower (MacPherson strut suspension only).

    unsprung weight - the weight of all parts supported by the suspension, as well as all suspension parts. less unsprung weight = mucho better handling and performance.

    bumpsteer - when you lower your car too much, you get this sensation where the wheel likes to jerk back a bit in the opposite direction it is being turned. it sucks. to eliminate it, the tie rod end must have a spacer between the heim joint and the spindle that adjusts the angle of the tie rod to be level with the ground. no bumpsteer = happy steering rack.

    Special Notes:

    Contrary to popular belief, the lowest offset is not always the best for any car. Suspension geometry includes the position of the wheel/tire in relation to all other parts in order to make for a good handling car. In short, the best thing you can do is fit as much wheel/tire under your fenders as possible. However, this is truly only beneficial to guys who need the power/grip to autoX/drift/road race. It's not as important to drag racers.
    Basically, 17x8 -5 is pointless compared to 17x9 +22. Lower offsets also increase steering heft...which sucks when you could fit more wheel/tire and make more grip.

    When it comes to lowering your car, there are a number of things to think about. To start with, don't SLAM your car if you don't ATLEAST HAVE ways to adjust camber/toe/bumpsteer. Proper suspension geometry = a better handling/performing car = more fun.

    As far as the mistaken drift/autoX suspension setups, there's a lot to it that people over look...
    Drifters require a large amount of camber (up front) to maintain more grip on the forward most (inside) wheel during cornering. Stretching tires serves the purpose of more accurate handling. It makes traction breakaway much more predictable as the stretched tire can't flex back and worth. Tires are also over-inflated a bit, but still within safety specs of the tire's air capacity to allow for easier breakaway to initiate a slide at the right time. When it comes down to wheels, the wider the better. However, in order to maintain a predictable car (depending on power) a wider track is helpful. Wide wheels are also preferable because of the need for stretched tires. After all, what good is a 255 in the rear on a 9" wheel when a 245 on a 10 works much better?
    Autocrossers however, are very different. For one, depending on the course used for the particular event, the right alignment specs along with the account of sway bar size must be taken into account. If you are running a thicker rear bar than stock, a bit more camber in the rear makes for a much grippier car through turns than a tail-happy one. Camber on the front wheels is usually nothing beyond 3* so that the outside wheel doesn't lose too much contact patch since it is handling the majority of the grip load. Caster for most cars is usually maxed out or set to something around 8* or more. You won't see many that are slammed either though, as the alignment settings are set to maximze performance, and a roll center lowered beyond the vehicle's center of gravity just doesn't work well in this case. When it comes to wheels, properly sized (rarely if ever stretched) tires are put on the properly sized wheels to maximize grip. Remember that stretched tires are used to minimize sidewall flex, however that also changes the maximum grip each tire can hold.

    More Useful Info:

    It has been brought to my attention by a local buddy that the Suspension Techniques sway bars are a bit oversteerish. Well, there's a simple solution for this....camber. Guys who run upgraded (aftermarket) matched bars often find that the front or rear bar is too thick or thin. Adding a bit of camber to the rear, or decreasing it can solve this issue of breaking away too easy if you're trying to grip well through a corner. And while alignments aren't cheap and aren't fun to sit and wait on, they're worth every penny.
    Another issue that needs attention for a lot of us track whores is tire wear since most of us only have one car. Many find that their tires wear unevenly or too quickly, and instantly blame this on camber. While that might be part of the problem, it's not everything. Too much toe-in or out can kill tires like a taco fart can kill a first date. Get your toe set as minimal as possible, and you will see longer life. Also ROTATE them bitches with every oil change. I do it on my Miata every other oil change, but that's because I'm lazy...lol
    Sway bars were brought up somewhere above, but I think they need a bit more attention/clarification. Sway bars function JUST LIKE springs. They control the weight transition. If you run uber stiff coilovers, you probably might not need a rear sway bar, but I would only say you should remove it if your rear springs are something like 10kg/mm and you're having some traction issues on rougher surfaces. However, removal of the rear bar can cause understeer if your front spring rates are too stiff in proportion to your rears. Remember that a lot of track cars (not so much for drifting, but Solo1 and 2 events mainly) run stiff front and rear springs, but use fairly thin sway bars as they do not need anything stiffer to maintain the desired grip.

    Ah, strut bars, shock tower braces, and all those little things that make your engine bay look just a bit more performance oriented. While they all look cool, they don't always work like you want them to. The bars I see on Ebay are ok, not great, but the brackets are the problem usually, not the brace itself. When looking at these braces, remember that its only as strong as the brackets at each end of the bar. 3pt shock tower braces rock too. While decreasing the play between the shock towers of your engine bay, the cross bars still allow the chassis to flex horizontally, which is no good for good steering response. 3 point bars remove this problem by adding a bracing point at the firewall to eleviate (sp? lol) that horizontal flex. Rear STB's are also helpful, sometimes more-so than front ones as the rear of many cars is left somewhat "flimsy" behind the rear seats to help allow more trunk space or create some understeer, which is what most NORMAL drivers are used to. Well, understeer sucks. Pick up a rear brace first. You won't regret it.
    Also, I've seen those POS "subframe braces" that come in combos with the front and rear STB's on Ebay. Throw that thing away. It is useless. It will help you about as much as "racing chip" in terms of performance.

    I'll probably add-on more to this as time goes on, but I lost the WORD file on my laptop, and thats all I feel like typing for now...and comments or criticisms are welcome. I know this stuff very well, but finals have fried my brain.
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  4. #4  
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    I am going to leave this till i get bored.....(waits 10 secs.) ok time to read


    Quote Originally Posted by ~The_Duke~ View Post
    Well then yes you do drift cas there was most def a gaurd rail involved...

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  5. #5  
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    Credit for the info in my post goes to Raen over at 240sxforums.com. Our local non 240 owning suspension guru.
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  6. #6  
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    I have a question. If i were to get coilovers what other parts would i also want to have?

    To correct the rear camber is it the RUCAs? or LCA?

    As for the front do I want tension rods or tie rods? tie rod ends?

    I'm new to these parts and would like to know what each part does what job. I'd appreciate it if anyone can clarify this for me.

    knowledge bump for the night.

    btw i did search NICO before posting and came up with nothing so don't hate.
    Last edited by Nisxsz; 03-17-2008 at 01:34 AM. Reason: Automerged Doublepost
    bitches b burnin'
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  7. #7  
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    if you get coilovers you might as well get camber plates.
    the ruca is the camber for the 240 the rear trailing arms or rear steering push rods (use in chevys and toyotas) you already have tie rod ends hope that helps
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  8. #8  
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    Quote Originally Posted by supraz240 View Post
    if you get coilovers you might as well get camber plates.
    the ruca is the camber for the 240 the rear trailing arms or rear steering push rods (use in chevys and toyotas) you already have tie rod ends hope that helps
    thnx but i already found out the info. reps?
    bitches b burnin'
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  9. #9  
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    what reps?
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  10. #10  
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    Quote Originally Posted by supraz240 View Post
    what reps?
    nvm. i meant reps. i gotcha.
    bitches b burnin'
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