Spring rate calculation

[RedRyder]

I've been looking into buying a set of Ground Control coil sleeves, and found some useful info. Just thought some people might like an easy way to calculate and convert spring rates, if you don't know already. There are other standards which rates are calculated, but kg/mm and lb/in are the most commonly used.


1 kg/mm = ~56 lb/in

To convert kg/mm to lb/in, multiply your kg/mm value by 56

To convert lb/in to kg/mm, multiply your lb/in value by .0179


So I wanted 10k front (10 kg/mm):

10 x 56 = 560. So 10 kg/mm = 560 lb/in.
Or, 560 x .0179 = 10.024. So 560 lb/in = 10 kg/mm.


Or ask Google.

 

[Mikey]

What's a good rate? Or how do figure out what rate is good for us?

 

[RedRyder]

What's a good rate? Or how do figure out what rate is good for us?


Largely depends on what you’re trying to do. If you like the way your current porogressive springs ride, find out what those rates are. Then find out what a comparable rate would be for a linear spring. Though with a progressive and linear spring with the same or comparable rates, the linear will be firmer. You basically need to do two things...1) decide how much firmer you want to go comfort-wise, 2) determine if you need significantly stiffer rates or not to not rub on the wheels, which depends on the ride height.

Where I started was….I liked the ride of the Sportlines, and I wanted a linear spring that rode only slightly firmer. But then I got the wheels and decided to go lower than I originally thought to make them look better, so I needed even firmer rates since I would not have as much clearance. I needed rates that with only ½” of wheelgap, will disallow my tires from contacting the fender during everyday driving. I just looked at the rates for various full coilover systems (for example FF’s are 12 and 8, and people slam their cars on those things and do the whole fitment thing. I talked to Steven a lot, he was a huge aide in helping me discover how firm I needed to go (he was on 12 and 8). So was Kevin (Sleeper Cell), and his setup is crazy, plus he said he wanted to to 14 and 8 once and since my setup isn't as crazy I knew I didn't need to go that firm. The other thing I did was look at the rates of the Sportlines and the rates I was considering, on a scale like this...http://hondaswap.com/reference-materials/spring-rate-conversion-chart-30786/

So 10 and 8 seemed somewhere in the middle, and appropriate for my ride height. I mean it's still a bit of a guessing game but I feel confident these rates will work for my needs. If you read the discussion thread, you can kind of see my thought process evolve.

Here's my final conclusion, of sorts:
http://www.6thgenaccord.com/forums/showthread.php?t=40665&page=16

 

[SykVSyx]

Chris, thanks for the info, in this thread and the other.

Similarly, I could go with 10 up front, but with the audio in the back, I am more than certain 8 would not be enough., so, it would have to be 10 as well.

I have never heard of the same spring rates for front and rear, and whether or not my engine is heavier or lighter is debatable, but I think 12/10 would be the right setup. Will probably have to adjust the Yellows in any event.

Looking forward to your feedback once you have the setup.

 

[20-CG5-01]

Chris, thanks for the info, in this thread and the other.

Similarly, I could go with 10 up front, but with the audio in the back, I am more than certain 8 would not be enough., so, it would have to be 10 as well.

I have never heard of the same spring rates for front and rear, and whether or not my engine is heavier or lighter is debatable, but I think 12/10 would be the right setup. Will probably have to adjust the Yellows in any event.

Looking forward to your feedback once you have the setup.

What kind of audio equipments are you running Derek?

I had the mdf trunk (roughly 40lbs) along with 100+ lbs of sub + box and the 8kg handled it fine.

12/10 would be perfect for your needs. But remember wity higher rates, 8" springs won't put you as low as how I was when I had 8/6.

But if you don't plan on going lower than 24" I'm sure 12/10 would put you to 24" lowest all around with 8" springs.

 

[LowerMyCG5]

17 and 10 here i come

 

[SykVSyx]

What kind of audio equipments are you running Derek?

I had the mdf trunk (roughly 40lbs) along with 100+ lbs of sub + box and the 8kg handled it fine.

12/10 would be perfect for your needs. But remember wity higher rates, 8" springs won't put you as low as how I was when I had 8/6.

But if you don't plan on going lower than 24" I'm sure 12/10 would put you to 24" lowest all around with 8" springs.

Well, since you asked,

1. 2 x S15L7's
2. 2 x 6" coax's
3. Optima Yellow Top
4. 2 x KX1000
5. KX200
6. KX350
7. KX450
8. MDF probably about the same amount as you
9. 2 x Capacitors

So, what is your suggestion with the springs?

 

[RedRyder]

…But remember wity higher rates, 8" springs won't put you as low as how I was when I had 8/6.

But if you don't plan on going lower than 24" I'm sure 12/10 would put you to 24" lowest all around with 8" springs.

I’ll be able to get to 23.5 or 23.75 with 10/8, right?

I thought GC’s lowered you 3” regardless?

17 and 10 here i come

Why even have springs at that point, could just be solid bars of metal.

 

[SykVSyx]

I’ll be able to get to 23.5 or 23.75 with 10/8, right?

I thought GC’s lowered you 3” regardless?



Why even have springs at that point, could just be solid bars of metal.

I thought so as well, that GC's would get us a pretty aggressive drop. Chris, you are getting the 8" springs?

haha...for real.

 

[20-CG5-01]

Well, since you asked,

1. 2 x S15L7's
2. 2 x 6" coax's
3. Optima Yellow Top
4. 2 x KX1000
5. KX200
6. KX350
7. KX450
8. MDF probably about the same amount as you
9. 2 x Capacitors

So, what is your suggestion with the springs?

Pretty heavyyyy stuff! 10kg would be perfect for the rears. When I had my setup 6kg rears were a little soft for my audio.

I’ll be able to get to 23.5 or 23.75 with 10/8, right?

I thought GC’s lowered you 3” regardless?

Yes you shohld be able to acheive that height with 10/8. I said that necausr when I threw the 8kg to the rears at the same settinf, the rears were a good 3/4 higher than how it was with the 6kg. The 8kg 8" lengrh was at 23.5" lowest and 12kg 7" was at 23.25" lowest. You see what I'm getting here? Gotta balance out spring length also with kg.

Why even have springs at that point, could just be solid bars of metal.