Suspension mods:
Courtesy of
RoadSpike &
EGbeater
Coil Overs:
Coil overs are by definition are an aftermarket item that combines both the spring and shock absorber in one adjustable unit. The adjustments a typical coilover will allow you to make are ride height with the form of adjustable nuts around the coilover and an adjustment to compression/rebound. The rebound/compression nob usually found on the top of the coil overs adjust how stiff your ride will be the lower you put the car the stiffer the ride must become or you will risk bottoming out the car and perhaps causing damage.
Anti-sway/roll stabilizer Bars:
Anti-sway bars (also known as anti-roll bars) are used along with shock absorbers or struts to give a moving automobile additional stability. An anti-sway bar is a metal rod that spans the entire axle and effectively joins each side of the suspension together. When the suspension at one wheel moves up and down, the anti-sway bar transfers movement to the other wheel. This creates a more level ride and reduces vehicle sway.
If you don't have a stabilizer bar, you tend to have a lot of trouble with body roll in a turn. If you have too much stabilizer bar, you tend to lose independence between the suspension members on both sides of the car. When one wheel hits a bump, the stabilizer bar transmits the bump to the other side of the car as well, which is not what you want. The ideal is to find a setting that reduces body roll but does not hurt the independence of the tires.
Stiffeners:
Upper and lower braces help to stiffen up the front end of the chassis. Believe it or not a car is not as solid as you think. Through corners, acceleration and braking chassis flex and twist due to forces applied on the car at these times. In a race car a chassis will be as stiff as possible to help it corner well, in a road car there is less support. The reason for this is that its expensive to fully stiffen a chassis and in an average road car the extra rigidity is not needed as the forces applied are not as great as they are in a race car.
Upper and lower braces are designed to stiffen the chassis and basically work as a bar, tying together two points to hold them together to make sure they don’t move. The upper strut brace attaches to the top mounts on the front suspension mounts (can be seen when opening the bonnet). The lower brace attaches to the bottom of the suspension assembly on the underneath of the car. Fitting these will stiffen up the front end of the car, which helps to keep the car rigid through corners. This will be noticeable as cornering will become more stable and more predictable, which in turn gives the driver more confidence. They also help to give the car better turn-in through corners too. The upper strut brace looks great too under the bonnet.
Both the upper and lower braces can be fitted separately or together, but work better together.
Alignment:
As with most cars, Evos respond extremely well to aggressive alignments. Getting a proper alignment is arguably the cheapest mod to your car that you can do that will net noticeable, real-world benefits in your car's handling or your lap times. Your Evo offers OEM adjustments for toe front and rear as well as camber adjustment (albeit only a simplistic +/- one degree adjustment in the front via an eccentric strut fixing bolt).
To minimize understeer (yes, your stock Evo WILL understeer, especially at lower speeds), set your rear toe to zero or up to 1/8" total toe out. Front toe settings can also be ideal between zero to 1/8" total toe out.
Toe in tends to make a car more stable, but reduces its ability to rotate and slows initial turn-in response. Toe out helps a car to turn aggressively and can make it more nimble, but can lead to unwanted oversteer. NOTE: no matter what your alignment settings are, your Evo can still understeer AND oversteer. Your inputs to the steering, brakes and throttle determine handling response as much as any vehicle factor.
Once you add coilovers to your Evo, you will likely have adjustable camber plates that allow you to increase the negative camber of your front tires. Increasing negative camber up front will helps the front tires to be planted more squarely to the road surface under cornering loads, which increases grip and reduces the car's inherent understeer.
"Ideal" camber settings for handling are somewhere between 2 and 3.5 degrees negative for the front, and about 1.2 to 1.5 degrees negative in the rear. However, read on to get the "no free lunch" disclaimer about setting your alignment outside of what Mitsubishi intended.
Ride height:
For many of us, a lower Evo is a better-looking Evo. Admittedly, it looks like a monster truck from the factory. However, when you lower an Evo based purely on your desired aesthetics, you can actually make it handle WORSE.
This is because when you lower the Evo more than about 1" from its stock ride height, you risk lowering your car's roll center below the ground under compression, which will actually REDUCE grip and induce understeer. Also, if your front suspension bottoms out on the bump stops under load, your spring rate will go to infinity (i.e., no spring at all), and then the result is again terminal understeer. Basically, there's much more to optimizing handling than just minimizing your center of gravity by lowering the car.
A very simplified way to determine if your Evo is too low is by checking the orientation of your lower control arms. If they are angled "downhill" towards the centerline of the car - i.e., the pivot point/fixing bolt at the wheels is noticeably HIGHER than at the other end - your car is probably too low.
Also, the higher your spring rate, the lower you can go with your ride height, because your suspension won't compress as much under load.
For more detailed information on optimizing your car for ideal handling, taking roll center, ride height, rake, alignment, spring rate and ride height into consideration, check out this thread:
Another Ride Height Thread (Input Needed)
Spring Rate:
Evos come with fairly soft spring rates from the factory (180#/in. F, 225#/in. R). While the Evo is of course an amazingly competent car as is, there is still a lot of room for improvement, and a lot of this improvement can be achieved through higher spring rates.
Higher spring rates reduce left-to-right body roll, as well as offering more controlled front-to-rear weight transfer (something that anti-sway bars CANNOT do), but more importantly, they allow for higher overall grip, assuming that your tires are sticky enough to achieve these increased cornering limits.
The spring rate that is appropriate for your Evo depends on your intended purpose (autox, track days/road racing, etc) and what type and size of tires you are using. Generally speaking, the stickier the tire, the more benefit to higher spring rates, assuming your dampers are up to the task of controlling that spring.
Most people who want a neutral-handling Evo will run 150-200# stiffer springs in the rear; however, if you are using aftermarket sway bars, this changes the F/R spring rate equation significantly.
Also, softer spring rates are appropriate for rougher or more slippery surfaces (e.g., Heartland Park's sandy asphalt vs. Forbes Field's weathered concrete).
The main downside to increasing the spring rates under your Evo is a harsher ride. Your ride height, damper settings (if adjustable), and type/quality of damper will also affect this to some extent. What is "still acceptable" for street driving is highly subjective - some people think that 600#F/800#R is fine for a daily driver, while others would think they're crazy.
Keep in mind that someone who enjoys smooth roads in Florida or California will think that his setup is still "totally streetable," but he'd probably change his mind real quick if he lived in Detroit or Chicago.
Final Thoughts:
There is no free lunch when it comes to alignment or suspension mods. A change that is better for one thing is typically worse for another. When you start getting serious about improving your Evo for handling - lowering ride height, increasing spring rate, altering your alignment settings, replacing rubber bushings with urethane versions or spherical bearings, using "pillow mounts" with spherical bearings as opposed to the OEM rubber bushings - you will typically degrade ride quality... increasing noise/vibration/harshness (what automotive engineers call NVH), tire wear and how sensitive the car is to unsmooth/grooved pavement.
Having toe-in, toe-out or negative camber will all contribute to an advanced rate of tire wear. This is because instead of the tire rolling perfectly straight forward and with its tread square to the pavement surface, you're actually "dragging" the tire across the surface slightly as your car drives forward.
Some people think that negative camber is the main factor the causes fast inner edge tire wear, but in actuality it is a result of a toe-in or toe-out setting combined with negative camber. Bottom line: if you lower/raise your Evo with aftermarket suspension parts, GET IT ALIGNED.
There is no "optimal" alignment setting for both handling and minimal tire wear... it's a compromise that you will have to decide upon.
Also, having a lot of negative camber up front in an attempt to increase cornering grip will reduce the contact patch of the tire for straight-line braking. There is definitely such a thing as too much negative camber, even if you only care about performance, but what that exact figure is depends largely on the type of tires you are running, your ride height, your spring rates, etc etc.
General Clutch Information:
Courtesy of
RoadSpike
For the installl go here:
EVO Clutch Install, includes t-case removal and service manual links
or here:
http://evomoto.com/tech_info.php?tec...79d88430d2c833
If you want opinions on what clutch is the "best" you better just search around. Everyone has an opinion why twin disk A is better than 6 puck B..
Clutch Types:
Single organic:
Its a disk almost always sprung with an organic/carbon friction material in it usually with some kind of binding fibers pressed into it. Most people call these "street" clutches but it really just means easy to drive and low torque holding.
Racing Clutches (with pucks):
What is a puck? Well it looks like a brake pad stuck to a metal plate mostly made with something like a ceramic composite. It grabs HARD and does not have a real friendly slip pressure like an organic clutch. To compensate for this revving the engine a little more before slipping engagement seems to help with the take off. These kind of clutches hold lots of power and can come in sprung or unsprung.
Multi-disk:
So what do you do when you run out of surface area for friction on a clutch? Well you make more surface area by stacking clutches on top of themselves. Thus the really crude idea behind a multi disk clutch is that simple.
Sprung:
Means simply you have a set of big springs connecting the friction plate to the shaft. Its supposed to prevent the shaft splines from being damaged on hard launches but honestly all its seemed to do for me is create clutch chatter on take off..
Unsprung:
In evo aftermarket clutches it seems to prevent take off chatter having a solid clutch. Of course you run the risk of spline damage instead.
Pressure Plates:
Pedal pressure bothering you? Perhaps your clutch manufacturer thought instead of making the friction material better they'd just slap another 1000lbs of force on the clutch instead. Unless you like light switch like feel try to avoid extreme pressure plates and go for something more sensible.
Flywheels:
Lighter flywheel means you will probably have to gas it on take off or risk a stall. Rev matching is somewhat easier since the engine will spin more freely.
Braided line:
Did I feel the difference? Well... no but it looks cool!
flywheel/pressure plate/clutch disc - overview and information
Transmission Specific:
Courtesy of
EGbeater
Transfer Case:
The transfer case on the Evo 8/9 is under a lot of stress. It gets very hot because the downpipe runs right next to it. This is especially true if you run your car hard regularly at track days or even autocross events.
There are more than one opinion on what the "best" fluid to use is, but the OEM Diaqueen fluid is a good choice for a daily driver. Not a bad idea to change the transfer case fluid every other oil change, despite this being a shorter interval than what the factory recommends.
IMPORTANT: Getting the right amount (i.e., enough) fluid back in can be tricky, especially on Evos with ACD (Active Center Diff). Here are two how-tos on refilling the T-case:
http://www.teamrip.com/transfer_case...tion_info.html
http://www.jackstransmissions.com/pages/t-case-filling
Just like with engine oil, it doesn't really matter how awesome the fluid is, or how clean or dirty it is, if you are 50% low on the AMOUNT of the oil, so properly refilling your transfer case is of utmost importance.
Keep in mind that the oil in the transfer case doesn't just provide lubrication; it also plays an essential role in controlling heat. When the transfer case is low on fluid, it also gets much hotter than it's supposed to, which further compounds the abuse on an already highly-stressed component. The transfer case is expensive to rebuild or replace, plus it's not fun to remove/reinstall, so you need to prioritize taking good care of it.
Rear Differential:
The Evo comes with an OEM rear LSD (limited slip differential). As compared to an open differential, it does a better job of putting down power when the car is cornering and the inside tire has less weight on it. However, the OEM diff will quickly wear out with use, especially if you've upped the power output of your Evo substantially.
If you're using your Evo for autocross or track driving, you can make a substantial improvement in the car's ability to power out of corners (and therefore not understeer as badly) by having your rear differential rebuild or upgraded. If you're mostly drag racing, the rear diff doesn't have as hard of a job, since the car squats and puts an almost-equal amount of weight on both rear tires, but you might still see improvements with a rear diff upgrade. You can also replace the OEM differential with an aftermarket unit, but this is a more expensive option.
Two place to have your rear diff rebuilt:
http://www.teamrip.com/EVOLUTION%20R...20SERVICE.html
http://www.sheptrans.com/diffservice/index.htm
Once you have your rear diff upgraded, you can further finetune its performance with the fluid you use in it. Believe it or not, this makes a HUGE difference in the lockup characteristics of the diff. Using Redline 80w-140 NS (as Jon @ TRE recommends for drag junkies, trackday whoring or autocross warrior use) will make a night and day difference in how much the rear diff locks as compared to using OEM Diaqueen fluid. The fluid also directly affects how much noise the diff will make. More locking = more noise. Sorry, can't have your cake and eat it too.
There is a ton of useful (and thought-provoking) information about Evo drivetrains at the two websites below:
http://www.teamrip.com/faq.htm
http://www.jackstransmissions.com/pages/faq
Obviously, some of what is stated here are opinions, not irrefutable fact. However, I think it's fair to say since these statements and opinions are from two very experienced drivetrain shops, they are at least informed opinions with direct, real-world experience behind them. So to me, that's worth a lot. But I'm sure there are plenty of people who would disagree with some of their statements or recommendations.
