I think it would be cool if we could get one post with the spring rates of every spring/coilover available for the TSX. Since the TSX is a sport-luxury car rather than a true sports car, many of us prefer to maintain a modicum of luxury, so the rates of aftermarket springs become important when trying to determine ride comfort. Other factors such as tire sizing and construction will also come into play, of course, but comparing the compression rates of different springs provides a very easy way to quantitatively determine how much harsher a ride you will get from a more aggressive spring, as opposed to subjective assessments from others about how "it rides slightly harsher than X".

Here is what I've been able to collect thus far, from softest to stiffest:

Stock - 280F/175R
A-SPEC - 308F/193R
Comptech 110-155 - 315F/170R
Eibach Pro-kit - (1)308F/131R (2)371F/217R
Neuspeed Sport Spring - (1)?F/?R (2)365F/200R
Tein H. Tech - 320F/190R
Tanabe Sustec - 447F/224R
TEIN Basic and SS - 559F/336R
TEIN FLEX (JDM) - 559F/336R
Buddy Club - 672F/448R
TEIN FLEX (USDM) - 783F/448R


*Denotes progressive spring

All numbers are in pounds per inch of compression. The Neuspeed Sports are progressive springs like the Pro-kit, but I can't find the rate of their softer coil. I know there are lots of others, Eibach Sportline, Neuspeed Racing, H&R, Tanabe Sustec, etc. If you can add anything to this list, copy and repost with the new addition. Hopefully we can build something decent.

Mod Edit: Updated list...

 

My Tanabes are 8k/4k anyone wanna conver that? Otherwise I'll just check the documentation when I get home...

 

You may want list this as the U.S. specs. I don't know if anyone can get the JDM specs anymore, but it's got different spring rates.

JDM specs TEIN FLEX - 559F/336R

 

That would be 447F/224R.

 

thanks man

 

Stock - 280F/175R
Comptech 110-155 - 315F/170R
Eibach Pro-kit - (1)308F/131R (2)371F/217R*
Neuspeed Sport Spring - (1)?F/?R (2)365F/200R*
Tanabe Sustec - 447F/224R
TEIN Basic/SS - 559F/336R
TEIN FLEX (JDM) - 559F/336R
TEIN FLEX (USDM) - 783F/448R


*Progressive rate spring

 

First of all, let me say that I think this thread is a good idea; it will be handy for people to reference spring rates all in one spot. And it is good to know your spring rates.


The interaction between the strut and the spring in determining both handling and ride quality cannot be overstated. It is very important to have a strut that is valved properly with any spring, be it stock or all out race.

The US Spec Tein FLEX, which tops the chart in terms of spring rate, still provides an amazingly compliant ride, with no harshness at all. I have also been in a TSX with stock struts and Eibach ProKit springs, which are near the bottom in terms of rate. That ride in that car was awful; and judging by the number of people who have switched over to Koni's I know I'm not alone in that assessment.

The A-Spec springs for the 6MT are a 10% increase over stock; and you could also mention that the 110-160 Comptech spring is the Eibach ProKit spring......

 

I would think if springs lower the ride, they would stiffen up the springs too. how come the rear springs of the eibach and comptech softer in the rear?

 

That's true; you need more rate to keep the strut from bottoming.

The Eibach ProKit (and the Comptech 110-160, which is the same spring) is a progressive design. Progressive designs are hard to measure because they differ in spring rate throughout their range. With a linear design, a rate of 280lb/in means that if you apply 280 lbs to it, it will compress 1" and 560 lbs will compress it 2". With a progressive design, applying 280 lbs may compress it 1", but applying 560 will likely compress it less than that, because the tighter coils are now doing more of the work, and are much harder to compress. So maybe you'd need 650 lbs to compress it 2".

So the question becomes, how do you accurately rate them? If you cut the 650 in half, you could say that it's 325lb/in, but that does not convey how soft they feel initially. Most companies will give a high and low value.

 

ok, makes sense.
but what about the rear? the eibach prokit has 131lb/in. that just kind of stood out. sure the only way the rear will really bottom out is during hard acceration or on a hill/slope. Is there a specific reason to the low spring rate in the rear?

 

The true compression rate of a progressive spring is a logarithmic function of both coil rates. To accurately calculate the rate at which it would stiffen you would need to take the root of the average rate and multiply it by the coefficient of the highest rate.

Actually that wouldn't be it. Any degree'd ME's out there want to take this one?

Good point about the struts btw. I was hoping you and/or AZ would have something to add here.
Most of the car's mass resides over the front axle so you need proportionally less of a spring rate in the rear. Add to this that a higher front rate will reduce dive during braking and understeer in cornering, and a certain amount of suspension bias favoring the front wheels is a good thing.

 

Whats the a-spec listed at?

 

The spring rate (k) for a progressive spring is some function of its compression (x), so k=f(x). If you want to find out how much it compresses when exposed to a given force, just integrate k(x)dx from the initial to the final compression. In this manner, you could find the 'effective' spring rate for any force or compression.

 

Another interesting thing about progressive springs is that some springs that are marketed as progressive are not really progressive at all. I have seen springs that are wound progressively; that is, they have one set of coils spaced x" apart and then another set spaced closer together. But, when you install them on the car, the coils close upon themselves, at which point they do nothing. They are built this way to keep the springs in the perches when on a lift, nothing more. They function like any other linear spring, but they could (and have) been marketed as progressive. Now, if you were to look at the numbers for this spring, the initial number would be very low. So a manufacturer could claim a very low initial rate. But if the spring fully compresses under the static weight of the car, then that number means nothing. Only the rate of the remain open coils would tell you anything significant.

I'm not sure if the ProKit falls into this category or not, but with that low an initial rate, it's possible. Somebody with a ProKit needs to crawl under their car and snap a shot of the spring under load ......

 

Yeah, that's why when Comptech rates the 110-155, they list both a load and a length and show the resulting rate.

 

Stock - 280F/175R
A-SPEC - 308F/193R
Comptech 110-155 - 315F/170R
Eibach Pro-kit - (1)308F/131R (2)371F/217R
Neuspeed Sport Spring - (1)?F/?R (2)365F/200R
Tanabe Sustec - 447F/224R
TEIN Basic and SS - 559F/336R
TEIN FLEX (JDM) - 559F/336R
TEIN FLEX (USDM) - 783F/448R


Regarding the JDM FLEX coilover, is there a reason why it is so much lighter than the USDM version? Compared to where I live here in the US, the roads in Japan where I've gone are of far superior quality. I have always loved the FLEX due to the fact that I am a huge nerd and love to be able to control everything, but the high spring rates scared me away since I don't want to need $3000 in dental work after driving my car on the New England roads. Unless the ride on the USDM FLEX is really not that harsh, I'd love to get my hands on a JDM set.

 

All the Tein coilovers used to have the same rate springs (559F/336R). Tein indicated some people complained 559/336 was too soft. So they increased the Flex to 783/448.

High spring rate does not necessarily equate to poor ride quality. The higher the rate, the less likely your car will bottom out. I have found that bottoming out and lack of damping is the main cause of poor ride quality. This is why those w/ Eibach springs on stock shocks complain of poor ride quality after a while. As the shocks wear out, the damping decreases so the car tends to oscillate more.

If a car is lowered and the spring rates are not increased enough to prevent bottoming out, this leads to poor ride quality too. When the car bottoms out, the spring rate is essentially infinity (no give at all). This is is why a very stiffly sprung, aggressively lowered car has better ride quality over larger bumps. The suspension will obviously feel firmer over small bumps, but it is much more tolerable than driving a car w/ a suspension that bottoms out all the time.

It's about finding the right balance. For example, you can increase tire pressure to 44 psi and the car will feel much stiffer and give better turn-in response. But, the ride will be noticeably firmer. You can go the other direction and drop tire pressure to 20 psi and the ride quality will feel much softer until you go over a sharp bump that completely compresses the tire sidewall so that the rim is hitting the bump, the ride quality will feel like ass (not to mention you will dent your rim). Same goes for suspension. You need to select the proper spring rate so that your suspension does not bottom out in most driving situations.

 

My Tein H. Tech's - 320F / 190R

 

Buddy Club's

F12K/R8K

convert that

 

= 672 F / 448 R.............

 

I hate calculus. My head --->

 

Excellent thread! Adding to FAQ...

 

Cool, think you could edit my initial post to include what has been accumulated?


Stock - 280F/175R
A-SPEC - 308F/193R
Comptech 110-155 - 315F/170R
Eibach Pro-kit - (1)308F/131R (2)371F/217R
Neuspeed Sport Spring - (1)?F/?R (2)365F/200R
Tein H. Tech - 320F/190R
Tanabe Sustec - 447F/224R
TEIN Basic and SS - 559F/336R
TEIN FLEX (JDM) - 559F/336R
Buddy Club - 672F/448R
TEIN FLEX (USDM) - 783F/448R

 

Done deal!

 

Just wondering - are Tein H-Tech and S-Tech springs considred linear or progressive? I looked on their site... the H Techs appear to be a progressive design, but the S Techs appear to be more linear. Their spring rates are somewhat similar to the A-Spec and Comptech designs.

 

I have pro kit with koni shocks turned one full turn and find the ride to be comfortable as long as the road is in good condition, sometimes when I hit a pot hold or a decent sized bump in the road my car feels like it is getting rocked. any suggestions for this?

 

:gheylaugh:

Primary reason why I didn't get a set of TEIN FLEXes. Although LannyM's input is making me reconsider.

Also, why haven't I seen you at a meet yet dude?

 

I have ridden in a ProKit Koni car; my feeling is that the Koni strut performs better with linear or close to linear type springs like the Comptech 110-155 than it does with a progressive spring.

But while I surprisingly find my FLEX car a slightly better ride compromise, on a really bad road it is not a luxury ride. It's not bad enough that I feel the need to avoid such roads, but on roads like that you will know that you have an aftermarket suspension. I don't think there is any way around that. But it's still an amazing accomplishment considering the rates.

 

You know, there are a few different ways of measuing spring rates.....each manufacturer may be measuring differently.

You guys have to take these numbers with the persepctive that they are only going to be what they are relative to eachother....not necessarily a rock-solid number.


That Said, D2 RS coilovers are 13/9 I believe. See my sig for details on these.

Marcus

 

wow, I really learn a sh*tload of info about suspension on this. So comparing the Tanabe Sustec and Tein Basics, which one should give better ride quality (less bumpy/less harsh) and by how much?

-KC

 

Based on spring rate alone, the Tanabe looks to be the softest coilover. But, how the strut is matched/tuned to the spring has a lot to do with it too.

I will say one thing though, TSX.Fury has the Tanabes and with a moderate drop (no more than many Tein owners) he is experiencing a little rub in the rear with a 43 offset rim-even with a 225/40/18, which is smaller than stock. My feeling is that the softer spring rates are allowing more compression than you would see in the Teins.

More compression generally means softer ride, so they probably are more compliant than any other coilover out there. But if you're gonna drop very low, it looks like you'll need to keep the offset in the 50 range to keep from rubbing.

 

totally agree... I knew this in advance but thought I might be able to pull it off. the tanabes are a great ride (I got to ride in a TSX with Tein Basics the other day and was suprised at the ride difference) but if you get aftermarket wheels make sure to keep them at at least +48 or above (a friend and I did the calc and that's probably what I would need to not rub) granted there are other ways of not rubbing... like raising the coilovers but I didnt want to do that.

 

I thought he has rubbing the the rear because he put the 225/45/18 in the back.

 

The set of rims he bought had 2 225/40/18s and 2 225/45/18s. He originally had the 225/45s in the rear and had rubbing. I know we've seen someone else with 225/45/18 have clearance issues with ProKit springs, so that would be the obvious culprit, but when he swapped the 225/40s onto the rear, it still rubbed.

 

I'm running 225/40/18 +45mm offset, having Buddy Club coilovers installed this weekend, hopefully nothing will rub as I drop more than 2"

-KC

 

I ran a 225/40 +45 and no rubbing with buddyclubs.

 

Sometimes it also depends on the brand of the tires. I've experienced tire rubbing on my other car when I switched to a different brand of tires with the exact same size, and mounted on the same wheels. Pay close attention to tire specs, not just tire sizes.

 

thanks guys... also, are BC Coilovers able to be rebuilt or revalved?

 

Yup. Certain tires have a more square edge while others have a more rounded edge. Also, certain brands' 225 are wider than other brands' 225s.

For instance, according to the specs on Tirerack's site, a 225-40-18 BFGoodrich g-Force T/A KD has a tread width of 7.3" whereas the same sized Bridgestone RE050A has a tread width of 8.1". This .8" difference in width will definitely make a difference in whether a tire will or won't rub the fender/wheelwell.

 

Zeal Function B6 (Street) F=12K, R=8K ~ F=670, R=447