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Discussion Starter #1
Thought I would post some things about the Megan set of coilovers and compare both the WRX and STi
Common for both: Adjustments, both height and dampening are nicely done. Spring rates are not affected even with height adjustments. Dampening levels are numerous and noticeable at the same time. Dampers are of similar construction for both units.
Not so common: Rates softer and staggered for WRX 8k/6k Stiffer and consistent for STi 10k/10k
This was all basic info.
On to driving impressions. Tests done in a closed canyon road to test dampening qualities and driveability in many different situations. Camber set at stock rear front to -1.5 VDC off
WRX Hatch: Fun to drive, the rear end was a bit too soft on the uphill as the rear weight shift caused massive understeer during off and on throttle situations. Entering hot and trailbraking was the only solution to this but may not be viable to beginners. Downhilling was great with the softer rear end letting you get on the throttle earlier and maintaining stability. However, once dampers were dialed-in, I think this could be replicated with damper adjustments even with a stiffer spring rate.
WRX Sedan: The rear suspension on the sedan traveled more than the hatch and accenuated more of the understeer on the uphill like the hatch, downhilling, you could pretty much go full throttle as the rear was planted nicely. Something I still think could be dialed in with the dampers.
STi: Agressively set up to attack on the get go. Front camber -2.25 rear stock. DCCD Full Rear
Uphill: Jumpy jumpy. readjusted for the dampers 2 clicks lower front 3 rear much better. Uphill was good and there was plenty of rear end slippage to compensate for the understeer. Downhill for its purposes the way it was setup was also fine for the downhill. Deciding to do a better run we changed settings one more click softer rear and one stiffer for the front. Also lowered the rear a bit. This let us get on the gas much more quickly and provided alot of stability when on throttle.
 

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Discussion Starter #2
Re: Megan Racing Tests

Next was changing out the OEM tires for some grippy Azenis ones (for WRX sedan only STi was felt to be fine already for everyday anyways and the Hatch could be adjusted easily because the sedan was harder to dial-in). 225 width also.
Camber adjusted to -2.25 Stiffened every setting up 2 notches for the increased tire grip.
I drove for awhile and didn't like the way the rear end and suspension travel was not consistent with the front. Moved rates up to 8k rear also. First run needed to stiffen up all corners again. Grip is great isn't it?
The car felt much better with 8k 8k and the better tires. I think that the car can and should go 10k and set the dampers softer to compensate but I am now under the assumption that the Megan rates were made for the OE tire set.
With the increased grip and being able to adjust for it. This car felt much faster in the corners. Stability was way up. Uphill, the stiffer springs in the rear helped with the understeer. Downhill, the car was very stable, more so by the damper adjustment.
Pretty happy at this point. Given no DCCD or LSD the car was great.

I would recommend to definitely change out the tires and increase rear spring rate for the WRX
 

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Discussion Starter #3
Re: Megan Racing Tests

Consistency notes:
Springs were preloaded and not altered no increased or decreased compression.
Corner balancing not done. Just height leveling.
All vehicles experienced much higher entry speeds and the braking abilities were increased dramatically.
Front nose dive reduced and rear brakes felt like they were working better because of it.
3 wheeling happened in high speed bumps in all cars but was still pretty stable when landing and suspension compression qualities didn't let it bottom out either.
This was just basic feedback. We decided just for kicks to compare the 3 cars.
Thought it would be fun and we wondered why the 2 sets had different rates.
 

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amazing review....
hope it was fun! how were you able to test all three cars with megans? sponsorship or volunteered?
 

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doest the hatch have a shorter wheelbase than the sedan or is the overall length just shorther?
 

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Discussion Starter #7
amazing review....
hope it was fun! how were you able to test all three cars with megans? sponsorship or volunteered?
I test drive a bunch of cars to dial them in over here. This time around was just for fun as the company that had asked is under development for new parts for the vehicle. The test fitment vehicles had the coilovers already installed and we had the opportunity to test how these sets performed on the 3 different bases. I am now curious to know how they perform on the 09. ;D

Sorry to be so broad butyou know non-disclosure blah blah
 

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Discussion Starter #8
doest the hatch have a shorter wheelbase than the sedan or is the overall length just shorther?
The STi has a slightly longer wheelbase at 103.3 inches vs. 103.1 for both WRXs
Overall length for hatch is 173.8 and the sedan 180.3
 

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did the coilovers really tighten things up or was there still some of that "push" that the wrx's seem to have?
 

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Discussion Starter #10
did the coilovers really tighten things up or was there still some of that "push" that the wrx's seem to have?
Please define "push." But the suspension did definitely change the overall handling characteristics of the vehicle. There was much better steering response and the turn in was much sharper as well. Depending on how the rear end was set up, this generally adjusted how much throttle control the driver needed to have when cornering. The rear squat of the vehicle at the different dampening levels and higher spring rate had a big difference as to how much uplift the front end had at the corner exits. The short stroke design of the vehicle also limited this as the front end did not float at high speeds, keeping the car more stable and steering sharp even when accelerating during a corner. This was independent of the change of tires which benefitted the car further.
 

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sorry touge.. I meant Mush. like driving on pillows. and also when you turn the wheel it seems to rotate a significant amount before the car actually turns like the steering wheel is not connected

sorry if that makes no sense, I have been at the hospital for hours. :p
 

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Discussion Starter #12
Makes perfect sense but whoa did you just open pandora's box.... I think I'm gonna have to do this in increments. Ok, the basic point of the suspension on a car is to devise a way to effectively shift weight and traction away from the direction that g forces naturally go to the contact points between the car and the road during cornering, accel, or decel. The good way to describe this is to explain why there are tires at each of the 4 corners of the vehicle. This allows lateral and longitudnal forces to be taken into account along with a mixture of both. You could essentially have the tires on each of the sides of the car but this setup would fail to be effective during a mixture of lat and long forces i.e. trailbraking situations. The corners allow more effective physics to apply to a vehicle. It is also most effective to have the supported weight to be in the middle of these corners because that is the neutral gravitational position given lat and long force exertion. Hence why corner balancing is effective.
Why is a long wheelbase good? During accel or decel the weight shifts to front or back so the opposing side loses traction. The longer the wheelbase, the more force it takes to lift up the opposing side, hence the opposing side still maintains traction (see why I said earlier that the suspension should channel the g forces away from the natural direction? Its so that all 4 tires can be used.) Imaging lifting up a long bar. Lifting from the front is easy but if you extend it in front of you while holding on to the back, th elonger the bar, the harder to lift the opposing side right?
Why is width good? Apply the same reasoning above but with lateral movements.
 

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Discussion Starter #13
Part 2. If this is the case why have springs struts etc? theoretically speaking, with unlimited tire traction and mirror smooth surfaces, this would not be needed. Instantaneous weight shift would occur, with no rolling, so dampening etc etc... jsut direct feedback from steering to contact point. However we know this is not the case, so these devices are added to compensate for the differences in road surfaces while still trying to maintain the principle of keeping the gs away from their intended direction. The softer the suspension, technically, the less quick this weight shift and traction response would occur. (one part of your question)

Why lower the car? The weight of the car is most easily controlled and shifted if its center of gravity equals that of the wheels. Hence why F1 cars have wheels that are almost the same height of the car. the closer you get to this, the less the stress of the weight shift is on the traction points. If gravitational forces of both the wheel and the body are exactly the same, theoretically speaking you have no traction loss and the tires are not doing anything. But because of differences in weights, densities etc, this is impossible, hence why we need friction to be caused by our tires. The closer you get to this though, the less of the tires gripping potential you use, hence you can increase cornering speeds.

Why increase the spring rates, dampening, swap sway bars etc? This allows us to get closer to that "ideal" situation of a "solid suspension" with instantaneous responsiveness while still being able to compensate with changing road conditions.
Spring rates reduce the bound rate, keeping the weight more towards the opposite side of g forces. Sway bars try to keep the body level so the weight does not shift so much towards the side of g forces.

Dampers control bound and rebound rates similar to the springs but also takes rebounding so the opposing g side does not lift as quickly if only springs were attached.

Part 3 later tonight....
 

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Discussion Starter #14
Part 3 Why camber corrections? This is actually something of a compromise as you would want as much contact patch and tire friction as possible during cornering, accel and decel situations. f1 cars as they are so light and low to the ground, focus on more total balance under braking and cornering loads. For us, typically we compromise for braking and accel for cornering speeds as our centers of gravity are higher and the cars pitch and roll in corners. As the car rolls, the tire geometry angle changes so we compensate by adding camber so that we get more contact to the tire who has the most stress. At this point, the tire with less stress also has less contact patch. Also it is teh case that braking and accel are compromised somewhat since their contact patches have been compromised.

Why bushings and braces? These stiffen up the weaker links of the suspension and stiffen up the chassis from flex. Bringing it once again towards the "ideal" solid structure. A bar that bends is easier to lift by one end than one that does not. Hence more weight away from the natural g side.

When is stiff too stiff? This is actually focused on several things. In terms of increasing the suspension/ chassis rigidity, this can happen if the suspension is too good for the tires. The tires have a limited amount of gripping potential and if the suspension and body exceed its limitations all it will do is slide while the body is still super stable. At this point a bit of softening will ease the weight shift towards natural tendencies (the outer tires when cornering) physically increasing grip on the tires and letting them do their job.

Another situation is when in when in bumps and the body/ suspension is so stiff that there is excessive wheel hop. It cannot rebound fast enough to keep the tires stable on the ground.

I think the major points are ok so I can answer the question now. :)

The coilovers adjust the height, spring rate, bound and rebound rates of the vehicle.
 

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Discussion Starter #15
Part 4 That being said, yes, the reaction time will be greatly increased as height, dampening, stiffness, camber can all be adjusted toward the ideal instantaneous responsiveness situation.

How well it does it and to what degree it does it well is up to you to decide. I think that a rebound adjustment would be beneficial ;)
You guys gotta be the one to dial it in for your personal driving preferences.

There is much more to suspension dynamics but hey at least its a starting point right? ;)

Forgot to add: for the WRX the setup did reach the level where the tires were insufficient so you may feel the whole "my car isnt changing its heading" thing but it might be because you have exceeded the tires gripping potential while you felt the suspension was still just cruising along.

For steering responsie sole improvement. Since the rack and pinion and all the steering linkages also somewhat dampen the transfer of energy from your hands to the whels, this also negates some response time. Stiffening up these links and joints allows for more positive feedback from teh steering system and is also the purpose of the PSRS.
 

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Touge, you are the man.... 8)

thanks for such an in depth response...its great to have you around this board. thank you for helping me understand suspensions better. ;D
 

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Discussion Starter #17
Anytime :)
 

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i have the megan racing COs on my wrx hatch right now ...

what dampering settings would you recomend for canyon runs like what you did and daily driving?

and when you adjusted your clicks were they are full hard or full soft or in the middle when you said you turned one softer click and one harder click
 

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Discussion Starter #20
i have the megan racing COs on my wrx hatch right now ...
what dampering settings would you recomend for canyon runs like what you did and daily driving
and when you adjusted your clicks were they are full hard or full soft or in the middle when you said you turned one softer click and one harder click
We started off at setting 10, 12 for the STi all around and worked from there. ( It was like this when we did the initial drives, I figure it would give a good tuning base depending on how each individual felt their car was performing, like a rough estimate on how many clicks it'll take to make a significant difference)
As far as the damper settings, it really depends on the stage you are running. We tested on a pretty steep incline so we could get dialed in for total balance with the extremities included. It had a nice variety of small and big bumps but not alot. If there were alot we would have softened up the dampers a bit more.
Also do you want to get dialed in for downhill, uphill, or just get a nice all around setting? This might also require height adjustments depending on the side of dominant weight shift.

As for me, I definitely go for "total" balance take a look at my sig. To me, thats what it's all about. We aren't on the track so we need to be pretty much ready for anything. This being the case. Once I dial in, I leave the settings for the street until I either go to the track or add another component to the vehicle that changes the balance.

For the WRX, I thought that the softer spring rates made the car understeer too much for my preference. You shuld be able to alleviate this with a stiffer rear sway bar, this will increase the total effective spring rate. We chose to increase the spring rate itself.
 
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