06+ Civic Si 2/4dr Spring Rates and Drop Guide

[rwc]

according to honda.com

coupe: 2886 lbs, 61/39
sedan: 2945 lbs, 60/40

[cracker099]

Originally Posted by Cookstar

I added the stock '06 Si coupe springs to the list. I got the rates from here:

Watch the video:
http://www.vtec.net/articles/view-ar...icle_id=442426

WOW! If that is true, the spring rates on the Pro-Kits (progressive) are really low. That raises the issue of bottoming out and traction. Any thoughts?

[Cookstar]

Originally Posted by cracker099

WOW! If that is true, the spring rates on the Pro-Kits (progressive) are really low. That raises the issue of bottoming out and traction. Any thoughts?

The whole reason for progressive rate springs is to give you acceptable ride quality during ordinary driving, but become firmer while cornering. I'm sure the increase in rate also prevents bottoming out.

On a side note, I have emailed Progress to find out if their springs are indeed linear as stated in the initial post. I'm not sure they are:

(Edit) I just looked on their website and they are progressive:
http://progressauto.com/store/produc...roducts_id=267

[cracker099]

Haha, I find the stock ride acceptable so maybe that's why I question the really low spring rates.

[padded]

These numbers won't be accurately comparible.

Different suspension manufacturers (H&R/Bilstein/Vogtand/Eibach/Tein/etc.) use different methods to develop their lb/in figures. While at least two of those manufacturers use [Lh2 (load rate at loaded height minus 10mm) minus Lh1 (Load rate at loaded height)] divided by the diffence between the two heights (10mm) ; I know not all of them use that formula.

Therefore, any comparisons must take into account the different methods used to gather the data.

[MJ23FE]

Originally Posted by padded

These numbers won't be accurately comparible.

Different suspension manufacturers (H&R/Bilstein/Vogtand/Eibach/Tein/etc.) use different methods to develop their lb/in figures. While at least two of those manufacturers use [Lh2 (load rate at loaded height minus 10mm) minus Lh1 (Load rate at loaded height)] divided by the diffence between the two heights (10mm) ; I know not all of them use that formula.

Therefore, any comparisons must take into account the different methods used to gather the data.

Point taken. Isn't that kinda retarded on the part of the manufacturers to use something different than everyone else? Why not everyone use a universal method to keep it consistent? Weird to me, that's all.

What kind of discrepancy is there between the different methods? How much different are the rates when calculated differently?

-Jalal

[mO 64 StAnG 06]

Originally Posted by rwc

according to honda.com

coupe: 2886 lbs, 61/39

Not sure what model that coupe is but going by that I came out with this.

Spring
Front - 673.9 lb
Rear - 430.9 lbs

Damping
(Bumb/Rebound)
Front - 4.9 / 9.7
Rear - 3.1 / 6.2

Now this is just a formula I actually picked up off a Forza Motorsports tuning forum. Yeah, I know it's a game but this is a formula based off the Ferrari 360 Modena.

Anyone want to give this a try and share the results?

[aki]

I made a file of the different shocks' spring rate and dampening, might as well share ones not already on here:

LX/EX Sedan: 140/145 lbs/in

LX/EX Coupe: 170/200 lbs/in

Si Coupe: 200/230 lbs/in (3.6/4.1 kgf/mm)

Mugen:
Spring Rates F/R (kgf/mm) : 3.1/2.9

Shock Valving @ .3m/s
Front 152/200
Rear 152/88

Mugen CTR:
Spring rate F/R (kgf/mm): 5.3 (4.8) / 6.9 (6.5)

Shock Valving @ .3m/s
122/90
84/88

[mO 64 StAnG 06]

Looks like my calculation is way too high... But I dont know the difference between lbs and lbs/in.

[si_turbo]

you forgot to put in the sprint springs

[Cookstar]

I just received a reply from my email to Progress. It said their springs are indeed linear so I changed it in the first post. (It was right the first time until I changed it.)

[padded]

Lbs/in (pounds per inch) means that the spring requires a certain amount of pounds to compress the spring by 1 inch.

Lbs (pounds) is often the abbreviated form.

Originally Posted by Jalal

Point taken. Isn't that kinda retarded on the part of the manufacturers to use something different than everyone else? Why not everyone use a universal method to keep it consistent? Weird to me, that's all.

What kind of discrepancy is there between the different methods? How much different are the rates when calculated differently?

Yes, it's very retarded. But as I said, I only KNOW that two of the companies use that formula. That's because I worked for a time at one of said companies and that company private labeled for one of the others. No, I will not tell you which one.

I do not know what formula the other companies use. I only know the accuracy of that formula seems the best.

When comparing spring rates, the second and third issues arise when 2) dealing with progressive rate springs and 3) bump stop engagement, respectively.

Explanation: 2) If the spring is progressive in design, you will need to find out from the manufacturer at what point the loaded height is within the progression curve. If the progression begins at a +1" extension from loaded height and completes at loaded height, then this is a progression that you will never truly feel during normal daily driving and seldom even on track days. If the progression begins AT loaded height and completes somewhere during compression, this would be the superior design.

Explanation: 3) Bump stop engagement is a tricky thing. Most folks believe that when you lower a car you need to trim the bump stops because they will stop the car from bumping. This is entirely false. The bump stop in itself is a very small supplemental spring. This is why A) they are tapered, B) they are dense foam and C) (as it relates to the 06+ civics anyway) they are also progressive in design. One company may tell you that you are required to trim the bumpstop to accommodate their spring design. Another may not.

SO, in summary, comparing the rate of the steel spring by itself will not give you all necessary information required to make your spring decision, if this is the method you choose to use.

HOWEVER, if someone were to obtain each of these springs and test them ALL in the same manner and provide the progression chart from full extension to max compression, with indication of where the loaded height was during the progression; THEN, a more accurate decision could be made.

But this will never happen, because manufacturers don't like supporting these tests. I know, I was one.

[02SilverSiHB]

Originally Posted by aki

I made a file of the different shocks' spring rate and dampening, might as well share ones not already on here:

LX/EX Sedan: 140/145 lbs/in

LX/EX Coupe: 170/200 lbs/in

Si Coupe: 200/230 lbs/in (3.6/4.1 kgf/mm)

Mugen:
Spring Rates F/R (kgf/mm) : 3.1/2.9

Shock Valving @ .3m/s
Front 152/200
Rear 152/88

Mugen CTR:
Spring rate F/R (kgf/mm): 5.3 (4.8) / 6.9 (6.5)

Shock Valving @ .3m/s
122/90
84/88

so the mugen has a lower spring rate than stock FG2/FA5 springs???

[Cookstar]

How's your thread different from this thread already stickied?
06+ Civic Si 2/4dr Spring Rates and Drop Guide

[02SilverSiHB]

Originally Posted by Cookstar

How's your thread different from this thread already stickied?
06+ Civic Si 2/4dr Spring Rates and Drop Guide

lol..holy crap, how'd we miss that...think it was the title...made me think it was about the drop and not the rate also.

[Cookstar]

Threads merged and title changed for clarification.

[02SilverSiHB]

Originally Posted by Cookstar

Threads merged and title changed for clarification.

groovy, thanks man!

[ReddemonSI]

i got one question, i really hate to sound like a huge noob , but what spring would you recommend for my 07 SI sedan, that wont mess with the factory shock to much, yet still give a good enough drop

[Jardiniboy]

Originally Posted by ReddemonSI

i got one question, i really hate to sound like a huge noob , but what spring would you recommend for my 07 SI sedan, that wont mess with the factory shock to much, yet still give a good enough drop

I'd go with the eibach prokit. If an inch is not low enough then my second vote would be the Tein S-tech.

[yoshi23070]

whats a good set of springs for a EVEN drop si sedan about 1.5 inch - 2 inches i dont want the front to be higher than the back, any recommendations would be wonderfull!!!! Was thinking of the tien s tech or sportlines but wanted to know from the people that have them already in there sedans if the front was higher than the back or is it a even drop or not thnx in advance ;p