Many coilover and springs manufacturers are using kg/mm instead of lb/in.
Here's a conversion chart.




Just to gove you an idea, Stock CRX Spring rates are around 130 lb/in front and 100 lb/in rear, if Im not mistaken.

 

You can also simply multiply by 56.

 

Cool post. Nice to have a quick reference chart to look at if you don't have a calculator available.

 

cool, thanks for the quick reference chart. now i know what my 16K, 14K springs convert to without searching google or using a calculator...lol!

 

That's pretty stiff, what vehicle are you running those on?

 

Thats crazy stiff .... I had 10k, 12k coilovers (buddy club) and my back has never been the same !

 

Im running 12k front and 14k rear on the street in my light crx... this is stifffffff !!!

 

You know there is such a thing as too stiff.

When your springs are too stiff for the weight of your vehicle (which is the case with 12k and 14k springs on a CRX) your vehicle will basically bounce over any bumps or dips, reducing mechanical grip and making the car handle poorly and become unstable.

You should really consider changing those springs for softer ones. And I bet you're running sway bars too right? Because everyone says "bigger sways = better handling" - which is not always true. In your case (crx with 12 and 14k springs) the sways will make your car handle even worse.

I wouldn't want to drive your car on the track or street, it would be extremely rough and unpredictable over bumps and dips.

Not trying to bash your car, I love crx's too. And I'm sure it handles very well on perfectly flat, smooth pavement. But ppl need to understand it's not as simple as throwing some stiffer springs in. There is such a thing as too stiff.

 

It was very scary at first, but you get used to it... The car is extremly tight and stiff for the street, and probably a lil too stiff for the track as well..
The PIC coilovers I bought were basically a try out. I wasnt sure exactly what rates to get at the time (4+ years ago) so I went with PIC's stiffest available rates for the Crx.
If I had to do it again, Id get 10k front and 8k rear for the street.

 

May I suggest...

For a crx, (assuming it weighs around 2200lbs and a 60/40 weight distribution) front ~ 6.5k and rear ~ 9-9.5k and throw away the sway bars (yes, remove them entirely...they are not necessary). If you did that I would put money on it the car would handle fantastic over any surface.

Typically, most fwd front engine cars with weight distribution more towards the front of the vehicle will need a higher spring rate in the front and lower in the rear. Doing the opposite would cause a lot of understeer.

 

You are correct
Going with higher rates in the rear for a Crx is good for autocrossing, makes the car
turn faster.
For daily driving on the road, it;s best to have higher rates in the front (most weight) and slightly lower in the rear, but it will cause some understeer.

Setting up a proper suspension is all about what, where and how you drive the car.
My cars never see track time, but I do like the feeling of a tight, highly sprung car.

 

Ok I just googled a crx si. Weight is closer to 2000lbs and weight distribution is 62/38.

In that case:

Front ~ 300in/lbs or 5.5k
Rear ~ 500in/lbs or 9k

(NO SWAY BARS)

That should give you a good place to start from.

Depending on your preference in handling characteristics...(some ppl like more understeer, some like more oversteer) you can tweak and change the rates to suit your preference. For example if you like more understeer, you should go with a softer rear spring. Or if you want more oversteer (I love lift-off oversteer in fwd cars) you should go with a stiffer rear spring.

 

Ahh, the truth comes out...lol. I was thinking all along your car was tracked...Still.

The calculations still prove true for the street as well. You can see the spring rates I calculated for a pure track setup would still be softer than what you have selected for street driving. And I'm willing to bet it would be a smoother ride too. 5.5K in the front instead of 10k. And 1k more in the rear wouldn't be that much stiffer, especially if you're used to 14k...yikes. Plus, if you're still running sway bars, then as soon as you enter a corner, the outside spring rates have now changed and become stiffer thanks to the sway bars taking away stiffness from the inside springs and adding it to the outside ones (this reduces mechanical grip). So basically the outside springs which were 12 and 14k, are now even stiffer! The 10 and 8K rates of the springs you suggested would become more than that on the outside during a corner because of the sway bar, yet the 5.5 and 9k spring rates with no sway, will always be 5.5 and 9k. The rates will never change, thus predictability on any surface will ensue.

Understand what I'm saying?

It's ultimately up to you, the owner. I'm just trying to help you or anybody else find the right setup. I believe this formula is the key, vs guessing without a true understanding of what is really going on.

Also I swear by getting rid of sway bars when looking for the perfect, stable and balanced street/track suspension system. They are only used on factory cars so that they can run really soft springs for straight line driving smoothness and they increase the outside spring rates in corners to give the ability to handle decently (say a 4k spring would become a 5k+ spring in a corner) and to combat too much body roll. The only reason race cars do have sway bars is to achieve a very specific spring rate for a specific vehicle roll rate. For example, say you need a 534in/lb spring rate for the absolute optimal setup. They would use say a 500in/lb spring with a sway bar who's rate when added to the spring would equal 534in/lbs. That's also why race car sway bars are usually quite small. They are mainly used for fine-tuning the vehicle roll rates.

Hope this helps and I'm not boring anyone. I can go on about this stuff for hours...lol.

 

Huh?

Are you talking wheel rates? There is no way I'd run 300lb front springs at a track.

Of course there is such a thing as being oversprung, but 12K on a CRX is not it, given a regular race track. If you are finding 12K skips too much, it will be your valving, not the spring choice.

90% of the time when I encounter oversprung setups its the rear end in a FWD.

I usually find 14K fronts to be the minimum for a track prepped car, where as 12K is probably about maxing out what I would run in the rear of a CRX.

 

Im pretty sure he's talking about a good street setup rate for decent handling, yet tolerable on the kidneys. :P

 

I guess this threw me off: "I was thinking all along your car was tracked"

 

Nah, but I do tend to "track it" @ onramps/offramps. LOL

 

Guys, I'm talking about spring rates for pure track setup.

The only reason I mentioned for the street was because Robb said he was going to run 10k front springs and 8k rears, which is too stiff (in the front) by my calculations for track setup, therefore, he could have a track setup that would be smoother than the street setup he originally suggested.

Aside from that, these calculations are a way to help you get close what would be an ideal setup for any car with any engine/drivetrain layout. These calculation are more geared for an autocross setup, but they still apply for a road course setup. You still need to tweak and adjust for a road course just the same as you would for autocrossing to get the right setup.

I'm not saying to go with what ever rates that come straight from the calculations, only that they will get you close to where the ideal setup would be. There is more to these calculations than I mentioned. I didn't think ppl would be interested in discussing this so deeply.

You also have to keep in mind the dynamics of the type of vehicle you're setting up, for example, if the vehicle has a straight solid rear axle, like that of an AE86 corolla, then you will need to significantly decrease the rear spring rate, because these type of rear axles...guess what... they act like giant sway bars! For an ae86 you may find you calculated for a rear spring rate of say 550in/lbs. and you had to drop it down to almost 400in/lbs. due to severe oversteer on mid corner and corner exit, which is exactly what happened to a friend of mine's ae86. He used this formula, got the base numbers, worked from there making adjustments (pretty much all he did was dropped the rear spring rates to combat the oversteer) and now it sticks unbelievably over any surface... in autocross and on the roadcourse. I believe he runs 350in/lb in the front and 400 in the rear (car only weighs about 1800lbs or less).

With a very light weight car like a crx, I'm sorry, but no matter how well damped the springs are, if it's as stiff as 14k, it ain't following the dips and bumps at speed, it's just skipping over them, which means you're loosing grip.

If you want to read more about these calculations and what I've been trying to explain... read this thread:

http://www.torontocivics.com/tccv5forums/t148112/

Start at post #14 and go from there. Though I think some of you have already read it.


Even though that guy gears it towards autocross setup, I've seen the theory work just as well for road track setups. The process of how to tweak for the perfect setup after you calculate your base numbers is just a bit different.

I'm not saying you're wrong, and I'm not saying I'm wrong. I'm just saying don't knock the theory, because I know it works.


Happy suspensioning everyone

I'm goin to bed....zzzzzzz. dream about springs....lol

 

You know, i thought it would be too stiff as well, but it's actually not as bad as i expected as i feel the damper is very well matched for the springs.

i have no rear sway bar at the moment and only the stock front sway bar. i have it set it up for a track day coming up at at the end of the month.

btw, suspension is Spoon N1.

 

What vehicle?