josh's ep3

This thread of course will be a work in progress and anyone that would has good information, facts, developments, or anything for that matter that this thread should include, please feel free to PM me or any other moderator to have the info. added to the thread.

Most of the information in here so far, is right out of our current FAQ thread that most people can't seem to go through before they post their questions. Now hopefully, with this thread right at the top of the page, hopefully anyone with a suspension related question will be able to get their answer here on their own.

Here is a list of useful links containing common knowledge about our MacPherson Strut suspension design...

Suspension Tuning Basics and other Important Information
https://honda-tech.com/forums/showthread.php?t=2665976

MacPherson Strut as told by Wikipedia...
http://en.wikipedia.org/wiki/MacPherson_strut

Lowering the RSX/EP3...How low is too low?]
https://honda-tech.com/zerothread?id=1775290

A-Spec Suspension Threads and Other Information…
https://honda-tech.com/zerothread/1856479
https://honda-tech.com/forums/acura-rsx-dc5-honda-civic-ep3-32/rsx-spec-suspension-1856479/

More about running the RSX/EP3 too low…
https://honda-tech.com/zerothread/1995016

RSX/EP3...other suspension issues…
https://honda-tech.com/zerothread/1984600

Video: Spoon Sports' Ichishima Tatsuru talking about the DC5R Suspension…
https://honda-tech.com/zerothread/2414044

RSX/EP3 Suspension thread for those who want to AutoX/HPDE or time trials…
https://honda-tech.com/zerothread/2008855

Problems with the RSX/EP3 Suspension design…
https://honda-tech.com/zerothread/2156562

Another RSX/EP3 suspension thread with info on how to fix…
https://honda-tech.com/zerothread/2297884

Information about the Spoon DC5 (suspension, etc)…
https://honda-tech.com/zerothread/2028344

EM2/EP3/RSX Suspension Differences…
https://honda-tech.com/zerothread/1715937

02-04 RSX springs are not directly interchangeable with the 05-06 version of the RSX. Unless, you convert to the 05-06 shock bodies and hats.

Here is a list of common spring rates for various suspension manufacturers...

[Springs]

Stock EP3: Spring Rate: (248 Front/440 Rear)
Stock RSX: Spring Rate: (279 Front/458 Rear)
-
Dropzone: Spring Rate: (? Front/? Rear) - Drop: (2in all around)
Eibach Pro-kit: Spring Rate: (15-20% more than stock) - Drop: (1in Front/1.1in rear)
Eibach Sportline: Spring Rate: (20-25% more than stock) - Drop: (1.4in Front/1.5in Rear)
GoldLine Springs - Spring Rate: (?) - Drop: (2in all around)
H&R Sport: Spring Rate: (25-30% more than stock) - Drop: (2in all around)
Neupseed Race: Spring Rate: (200 Front/280 Rear) - Drop: (2in all around)
Neupseed Sport: Spring Rate: (200 Front/280 Rear) - Drop: (1.5in Front/1.5in Rear)
Progress: Spring Rate: (280 Front/500 Rear) - Drop: (1.8in Front/1.5in Rear)
Sprint: Spring Rate: (20-25% more than stock) - Drop: (2in all around)
Spoon Progressive: Spring Rate: (413 Front / 458 Rear) - Drop: (1.5-1.7in all around)
Tanabe df210: Spring Rate: (10-15% more than stock) Drop: (2in Front/2.3in Rear)
Tanabe nf210: Spring Rate: (10-15% more than stock) Drop: (1.5in all around)
Tanabe gf210: Spring Rate: (20-30% more than stock) Drop: (1.3in Front/1.5in Rear)
Tein H Tech: Spring Rate: (257 Front/476 Rear) Drop: (.8in Front/.7in Rear)
Tein S Tech: Spring Rate: (280 Front/515 Rear) Drop: (1.4in Front/1.3in Rear)

[Ground Controls]
Dropzone: Spring Rate: (? Front/? Rear)
Ground Control EP3 kit: Spring Rate: (375 Front/450 Rear)
Skunk2 Coil-overs: Spring Rate: (440 Front/330 Rear)

[Full Coil-overs] Spring & Shock (fixed height)
Mugen: Spring Rate: (283 Front/439 Rear) Drop: (1.4in all around)
Honda Factory Performance: Spring Rate: (? Front/? Rear) Drop: (?in all around) - very similar to the mugen kit, awaiting specs

[Full Coil-overs] Spring & Shock (adj height)
Megan Racing Street w/Straight Arm 32-way adj.(447 Front/559 Rear)
Buddy Club Racing Spec: Spring Rate (559 Front/894 Rear) (Adj ?? min - ?? max)
D2 Racing: Spring Rate (447 Front/559Rear) (Adj ?? min - ?? max)
JIC FLT-A2: Spring Rate: (504 Front/560 Rear) Drop: (Adj stock - 3.5in max)
KW V2: Spring Rate: (340 Front/515 Rear) Drop: (Adj 1.4in min - 2.6in max)
Omni Street: Spring Rate: (559 Front/445 Rear) Drop: (Adj 0in min - 4in max)
Omni Sport: Spring Rate: (670Front/559Rear) Drop: (Adj 0in min - 4in max)
Progress C1: Spring Rate: (350 Front/640 Rear) Drop: (Adj 1in min - 4in max)
Tein Basic: Spring Rate: (336 Front/448 Rear) Drop: (Adj ?? min - ?? max
Tein Type Flex: Spring Rate: (448 Front/559 Rear) Drop: (Adj ?? min - ?? max)
LSR: Spring Rate: (550 Front/450 Rear) Drop: (Adj 4 min - 4max) 12-way adj

[Conversion Rates]
1 kg/mm = 55.88 lb/in
1 N/mm = 5.588 lb/in

Please keep in mind that custom spring rates are available from many of these manufacturers upon request...

[What is Progressive Spring Rate?]
Progressive rate springs are likely “all-in one” solutions. They are often used on performance aftermarket kits like Eibach or others, and they are good for daily performance street driving. They help you achieve the highest performance when driving hard, while providing a smooth, comfortable drive the rest of the time.

[What is Linear Spring Rate?]
Linear springs are more often used in drag racing, road racing, track and races that require a “high spring rate”, in which a constant spring rate is more important than a smooth ride. They are still popular because they are:

1. Easier to produce and can be made to lower a car beyond the point of progressive rate springs.
2. Easy to work with, because the spring rate never changes, allowing quick chassis set-up.
3. Inexpensive, allowing most race teams to use several different sets depending on track conditions


Again, if you have any updated information to add to this thread please PM me to have it added to this thread.

mustclime

The following is a look at how to "tune" the ep3/dc5 suspension from a design point of view. First I would like you to really look at the front suspnsion......




First, look at the top pic, that is looking at the stock suspension from the rear. You will notice the LCA is angled down from center of the car. The tie rod is angled up from the center of the car. The suspension design is greatly effected by ride hight . What does that mean? Well, look at the top pic again. As you lower the the suspension the LCA goes flat and then past one inch of drop it starts to angle up. This is very bad for the suspension when you look at side loads( cornering forces). If the LCA is angled up and the weight of the car pushing side ways while the tire is trying to stick to the road, this force will "tend" to push the LCA up more and cause the suspension to blow through its travel. If the LCA is flat or angled down, the cornering loads are directed down the LCA in to the sub frame.
Cliff notes: LCA angled up from the center of the car = you blow through your suspension travel and get lots of under steer. So do not lower the car more than one inch.

Next issue to look at with the top pic is camber......Camber is a term used to describe what angle the tire is set at with regard to the road. In stock form, camber is not adjustable and the stock suspension is set for about zero degrees camber. This is great for drag racing and making tires last for 60,000 miles but it sucks for generating grip in turns. Having a couple degrees of negative camber helps the outside tire to take a set and helps keep the tire tread on the road surface. There are 3 ways to get more camber in a ep3/dc5.
1) Camber plates, these angle in the top of the strut and as a result angle the tire.
2) Crash bolts, these mount where the strut and the bearing carrier connect. This allows you to angle in the bearing carrier and allows you to angle in the tire inward.
3) Type-r LCA, these are wider than stock and as a result angle the tire inward. WARNING! If you decide to use these, you should not use your stock axles and you will need type-r front sways because of the extra width of the LCA.
What is the best camber setting for the front suspension? It depends on what you are doing and what tires you are using. As a general rule I would say -1 to -1.5 degrees for dd and about -3 for the autoX guys.
Cliff notes: Negative camber good for cornering in the front suspension.

Now look at the lower pic, the first thing I want to to look at is the front bushing on the LCA. That bushing is there to change toe settings as the cornering loads increase. It adds toe in as the gee forces go up, this = increasing under steer! Anyone that is trying to get our cars to handle needs to replace this bushing asap. Both Mugen and Energy Suspension make kits for this.
Cliff notes: The front bushing in the LCA needs to be replaced to make our cars handle.

Now I want to address the Caster angle of our suspension in the front. If you look at bottom pic you will notice the strut is almost strait up and down. The stock caster angle is around 1.5 degrees.....this sucks for handling and strait line tracking. If Honda screwed up anything with our cars suspension, this is the biggest thing. It is also the hardest to fix but it can be fixed. K-Mac makes a Camber/Caster plate for this. The strut towner's can also be re-drilled to angle the strut back. For road racing there are bushings for the LCA that shift the LCA forward to angle the strut back.
Cliff notes Caster good but hard to get.

Now the rear suspension layout





OK, you should notice a couple of things with this layout.
1) It is a unequal length duel control arm design. This means that as the suspension goes through its travel the shorter UCA pulls the hub carrier inward and increases negative camber. Negative camber is good for cornering and tires stay in contact with the ground.
2) It has a big toe effecting bushing on the front of the LCA. This bushing will add toe out as the cornering forces increase aid in turn in but it changes as the cornering loads change so the car needs more correction as it goes through the turn. For a more stable car, these bushings should be replaced with stiffer ones from Energy Suspension or Mugen.
3) The damper/spring combo are really short and placed away from the wheel. This means the motion ration between wheel movement and the damper movement is a lot different than the front ( .588 vs .90). This means you need a lot stiffer spring and higher damped shock in the rear than the front even though the rear has less weight over it. Any time you are looking at spring rates on coil overs, these rates should show this.
4) This suspension design is also really effected by ride hight. Lower it to much and side loads from cornering will force the suspension through it travel. The trick is to keep the LCA flat or angled down a little for the suspension to work right.

Overall Summery
In stock form, the car is designed to have a lot of under steer. With these toe effecting bushings, you get more toe-in in the front and more toe out in the rear so the rear will grip better than the front under load. You also get more negative camber in the rear than the front as the suspension loads. This is all to protect the novice driver and Honda of America. There is a old rule....car goes off the road front first, its the drivers falt. Car goes off the road tail first, its the car makers falt.

jagumbel

so why does Eibach say its Sportline kit (1.5,1.8in drop) handles more agressive and stiffer then its Pro kit(1,1.5in drop)?

I understand the lower sportline kit should be stiffer, but from what you say, the higher ride height pro kit should be more agressive because once you pass 1 inch you kill your handling?

DaveSi677

Because it has more to do then just how low you go! Sportline kit has a stiffer spring rate then the Prokit! If the Prokit hand the same spring rate as the Sportline, the Prokit would make the car a million times better the the Sportline.

Its a big misconception to think that the lower you are the better it is. A lowered car does have a better center of gravity but even that has it's limits. When you lower a car you have to take into consideration suspension travel. If the suspension can't travel you creating a car that can't handle properly period.

Anyways I don't want to steal the light from our own lil suspension GURU!

Thanks Mustclime, if you want to add more please do and I will sticky it!

mustclime

Well, on the topic of lowering springs. Mcpherson strut suspensions work very well in their "sweat spot". If you lower the car out of its sweat spot, you are forced to run huge spring rates and swaybars to control body roll induced by coring load acting on poor suspension angles. With our suspension design, any front springs that are progessive are just plain dumb....remember, you do not want your ft lca's angling up from the center of the car going into a trun, a progressive spring will allow this to happen with its lower rate in the first inch of travel. So why you ask do these tuning compenys make them? Because people that do not know any better buy them.
Spring makers are also limited in what spring rates they can use. If you lower a car 2 inches that only has 5.0 inchs of upward suspension travel, you should increase the spring rates by close to 100% to keep the car off its bumpstops. If you do this to a spring that is going to have the stock damper try to control its rebound. Do not expect that damper to last long. If you do not beleive me, ask some people that have some junk2 coilover sleeves. Junk2 sold people their kit that had a 570lb rate spring for the front when the stock ep3 had stock progressive spring rates of around 250lb and the dc5 had 280lb ish....I know people than had their almost new dampers blown in less than a month. What can you learn from this.....stay away from lowering springs. If you really want to TUNE your suspension remember this.....

1) the grip of the tires set the spring rates.
2) the rates of the springs set the dampers
3) the balance of the car sets the swaybar size
4) bushing and braces have their place in all of this but it is less than you think. Braces are pretty much the last thing you should get.

SkoundrelUSA

Stupid question: How come your car looks lower than 1"? lol

josh's ep3

Beefy tires and 17" rims will help in wheel well gap...

mustclime

225/45-17 tires fill the wheel wheels and that pic was taken on mt washington when I had about 300lb of vaca stuff in the back.....

hawaiiancb74

how bout this, how can someone take a not so great coilover set like a megan racing street kit and improve their suspension.

DrZFiNeSt

iTrader: (1)

Nice write up.Has a lot of important info that I found out

jagumbel

so say I lower my car 1.5 inches... When i go through a turn and pass the angle of no return as i go through my suspension travel, is it just going to understeer way more?

mustclime

Set the car to 6.5 inches at the jacking points, get a zero toe alinment(f&r), set the front camber plates to max neg camber and get a type-r rear sway.....I think you will be suprized.


Cornering loads act as a force multplyer and over power you outside front spring, the car body leans over the tire and you camber goes positve. Congrats you have a understeering pig. My advice is to buy a gray wig and wear it when driving around, that way the kids will not lol at you when you have to slow way down for turns.

hawaiiancb74

hmm well i have a progress adj in the back, and i have the em2 in the front which i think is 24.5mm ive been debating on trying to find something smaller to go up front.

mustclime

Next topic.....swaybars suck.

Have you ever though about how a swaybar( anti-roll bar) works? What are they good for? Have you ever thought "since the factory put a 25mm hollow bar on the front of my car, wouldn't my car handle better with a 27mm solid bar"?

Well, for the longest time I thought of swaybars(SB) as spring helpers. I thought that when you went into a turn, the swaybar(SB) being attached to the lca and the body helped hold up the car through the turn....WRONG!!!!

Think about what happens when you go through a turn......
1) the driver turns the wheel, the tires turn and bite, the car starts tochange direction...
2) As the car starts to change direction, weight shifts to the outside tires, the outside springs are overloaded and start to compress.
3) as the springs compresm the lower control arm starts to angle up.....the (SB) being attached to both lca's and the body is forced up on the outside side......
this is the important part!!!!
what happens on the inside suspension of the car???
4) the (SB) being nothing more than a "U" shaped rod/tube pulls up the inside lca because it "wants" to be flat not twisted.
think about that for a second.
.
.
.
.

Now, if down force increases grip( like having huge wings on a F1 car), what does up force do to grip???? Well, It decreases grip.....
This is why some people think of (SB)'s as grip reducers. Why would car makers ever put such a stupid thing on a car, why not control body roll with spring rates......simple, who wants to dd a car that can run over an ant and have the driver feel every bone in its body crush.....OK, what should you do with this knowage? IMO, understand that big sways on the drive wheels are really dumb, Understand that you should use the non drive wheels to control body roll because they are doing the least work in a turn. These are the reasons you wait till you have your tires, springs and dampers before you mess with the sways. (SB)s are for fine tuning the suspension not setting it up.

josh's ep3

Great info once again...

SkoundrelUSA

So you're only really referring to front sway bars right?

mustclime

Sways make your cars suspension less independant. Independant suspension is good for grip. I have had people on this forum tell me that sways do ont effect a cars ride, that BS if you are using big sways. If you were biulding a prepared autoX car that would not be driven on the street much, your goal would be to pick springs that would allow you to run no sways at all....with high grip street tires, something like 450-550lb ft and 1100-1300lb rear would do it depending on how much weight you tear out of the car....you would be forced to get some custom rear shocks for that and you are right on the limit of the koni insets for the front....but if you are going to run your car as a dd, yea, you want to run sways. You still want to run as little front sway as you can get away with.

hawaiiancb74

last time we went to midohio we removed the front sways on both rsx's , ive been looking for somekinda front sway that i can use on a daily, thats fairly small, but because i have a buddy club header my luck has been shitty

mustclime

03 em2 coupe.....thats the 15mm hollow ft bar....the barand the bushings is 60 bucks

or go to jdmland and get the edm ep3 type-r ft bar(25.4mm hollow)...its supose to be a very tunnel hugging bar.

hawaiiancb74

yeah i just looked that up 15.9 in the parts cat, now i just kinda wonder if that would cause too much over steer, i can deal with it with track tires on and open space to spin the car but on the daily road with no where to go and conti extreme dws's on idk.

mustclime

If you are worried about the car being to tail happy, add a little toe out in the rear.

lunpd

ok jst a question bout my suspension..... after i lowered my car i have a loud ticking noise coming from the driver side strut when i turn the wheel at low speeds to no speed..... i have a 02 civic si wit skunk 2 pro s coilovers...... thanks

mustclime

sounds like the binding strut top bearing....hard to tell with out seeing the car. How did that little blue plastic ring look when you swapped it over? If I remember correctly, junk2 coilover just give you a upper purch on the front that is supose to sit on the stock strut top bearing / upper strut top.

DecepticonDc5

wow.... this changes my plans for sure.... i was just planning on slamming it on BC N+'s

k so based on this ^^^

could i get suggestions on what route to take for my 03 DC5 please?
this is my DD...

alright, i got some sticky bridgestones on my stock 16's
1 what spring set up should i be looking at for a DD? [i don't mind bad street manners very much but there is always a limit....]
2. if you recommend just changing springs.... would koni yellows hold up to the spring rates recommended in in #1?
3. I am gonna get an EM2 sway in front to clear header and a Progress adjustable in the rear [24mm]
4 ebay for the braces cause a piece of metal is a piece of metal. and bushings if i get serious will probly be the Energy kit.

[already got camber kits lined up]


look forward to hearing from you mustclime!

mustclime

Ok, what stickie b-stones? If they are not re11's, the are just summer tires.....For dd, I would keep the stock springs....or go to the a-spec kit. If you keep the stock springs, I do sugest the koni's to tie them down....A set og hotchkis camber plates will help get you some neg camber in the front...aside from bushings, thats all I would sugest for dd.