What to look for and WHY: Coilovers
 

So I'm sure many of the veteran forum fiends are sick and tired of these coilover threads from noobs (such as myself) that simply ask: "WHICH ONE IS BETTER!?"

Every coilover brand has their own PR documents stating what a great suspension system they have and how revolutionary their technology is. Furthermore everyone on the forum has their own favorite brand of coilovers and opinion on which one feels the best. I have yet to hear someone buy a set of $1500 coilovers and say that it was worse than stock.

Which brings me to my point. I don't just want to know about people's recommendation. A quick search will yield a ridiculous amount of threads with dozens of different answers. I want to know WHAT TO LOOK FOR. What MAKES a coilover system better than the other. Why is Tien better for one application and Apexi better for another?

I think it would be really helpful for everyone if we could educate noobs (once again, such as myself) on the merits of a proper coilover system and also what makes one more expensive than another.

Now I know that suspension setup is different based on application so lets get views on them all:

DRIFT
TIME ATTACK
AUTO-X
STREET (your average road warrior)

Are all coilovers within a price range acceptable and it simply depends on how you tune it? Is the price difference simply because of adjustability?


Now I'm aware of another thread with a lot of technical information on coilover construction and it had a lot to say regarding street vs. track coilovers regarding mono-tube vs. the other kind (can't remember off the top of my head). Though the technical aspects of the contruction of a coilover was exhaustive and interesting, it's been difficult for me to apply that knowledge toward an educated purchase when actually choosing a coilover brand.

I apologize in advance for the broken thought process, I'm just typing all of this out as I go. I will come back and edit when appropriate.

I'm of the opinion that any of the top-tier brands of coilovers will give you pretty much the same results. There's going to be differences in damping and adjustibility, but for the non-track user it's almost an academic difference. In my opinion, for someone who doesn't want to track their car, a good set of springs and struts will be more in line with what you need. If that won't lower the car enough, then I'd argue that you want to lower it too much and throw the suspension geometry all out of whack.

Budget coilovers are a different story. These all seem to be made in China or Taiwan, with little or no quality control. Material quality is suspect to say the least. I've seen shock dynos of cheapo coilovers and none of them matched each other, not to mention that each "click" of adjustment was not consistant between units. This is going to cause issues when one corner of the car reacts differently to inputs than another.

My recommendation for coilovers is to buy ones that use damper brands you've heard of. Many of the JDM coilovers use brands like KYB, Bilstein, etc. Make sure that you can easily have them rebuilt without shipping them halfway around the world and waiting on them for months. I'm not too crazy about the coilover setups that relocate the rear spring, but others have had no issues with it. I'd expect a set of known good coilovers to start at $2000 on up. If you want to go really crazy, go see if Moton or Penske makes a set of coilovers for a Z.

There is always a ton of talk on car forums about mono-tube vs twin-tube and coil-over vs spring-shock and I figured I would go ahead and post my thoughts on the subject given what I have learned over years of both street tuning and racing.

I was going to post a long thread about this but I think Tein does a better job then I ever could do but I want to add a few additions on the subject.

However, I would like to add a few important things for you to keep in mind before you read the article from Tein. After reading this article my respect for Tein has jumped about 100 fold since they seem to be the only company that tries to really inform customers.

The first thing is this article really keeps in mind the best possible scenario for mono-tube shocks. I want to add that not all mono-tubes are built the same because they have different goals to achieve. However, what it doesn't tell you is that mono-tubes have some serious downsides for the street that I think should be addressed. The first is that cheap mono-tube solutions Bilstein/KYB shocks or cheap coil-overs is that they are built for the street.

This means they need work over a long period of time compared to a racing shock. The average racing shock gets re-pressured at the very least before every racing weekend so they might need to work at optimal levels for a few days. The street mono-tube must work at optimal levels for years meaning that gas pressure has to be retained inside the floating piston. To do this they have to run significant amount of sealing on the floating piston so they shock will be durable to street use. The downside to this is that a floating piston with high sealing surface friction or stiction significantly reduces the shocks ability to deal with small amplitude and high frequency response and this is the real reason they ride so rough. The cheap mono-tube also runs high pressure. I have read that bilstein runs around 360lbs of pressure in there shocks. In a racing shock from AST or Moton on the track I run usually between 100-200lbs of pressure so you can see its almost double a racing shock. This means that resistance inside the oil is going to be higher and we see this on some racing shocks (Penske) but keep in mind they are valved for it. Bilstein does it so the shock will last longer and to keep the shock working relatively decently over the large pressure change the shocks will see during there lifetime they use divergent valving. This amazingly is the real reason for divergent valving and its a damn impressive solution but its not the advertising they would like you to believe. The mono-tube life span even with all the extra seal friction and pressure is about three years and given all the drawbacks that these shocks and coil-overs deal with I always suggest a different solution for street cars. Also, since these shocks usually don't work as good as a twin-tube even on the track I usually suggest going with a twin-tube setup unless you have the budget to spring for a higher end coilover with nitrogen port so you can enjoy them for a very long time.

Anyways for the following all credit goes to Tein and here is the link.

TEIN, INC. | SPECIAL | Why TEIN is "Mono-Tube / Twin-Tube Construction"

The structural differences between Mono-tube and Twin-tube.

These are the Mono-tube and Twin-tube shock absorbers you often find in magazines etc.
For those of you who have ever thought to yourself, “I think I know the differences in the structure, but what exactly is the difference?” Here is the explanation.
http://www.tein.co.jp/e/special/ni_t.../img_tigai.gif

The main difference between Mono-tube and Twin-tube systems, as shown above, is the number of tubes used for the shock absorber.

♦ Mono-tube: the shell case itself works as a cylinder and oil, gas, piston valve, etc are all set in a single tube.
♦ Twin-tube: there is a separate cylinder set inside the shell case and the piston valve moves up and down within the inner cylinder.

Other differences in construction.
Mono-tube uses a free piston that completely separates the oil chamber from the gas chamber. While for the Twin-tube, nothing separates the oil and gas chambers within the shell case.
The differences between Mono-tube and Twin-tube shock absorbers, is not simply the number of tubes but also the inner mechanism as well.


Let’s have a look at the merits and demerits of the mono-tube shock absorber.

http://www.tein.co.jp/e/special/ni_t...mg/img_tan.jpg

Merits
*Stable damping force can be generated, because of the larger oil capacity and improved heat dissipation.
*The larger sized piston valve creates a wider area to receive pressure, and even subtle damping force can be achieved.
*The structure allows no restrictions in installation angles.
*Oil radiates heat easier as the temperature increases.
*Aeration doesn’t occur because oil and gas are completely separated.

Demerits
*Maintaining sufficient stroke is difficult because the oil and gas chambers are positioned serially.
*Due to the high-pressure gas injection structure, there is a tendency for a stiffer ride.
*Due to high-pressure gas injection, high stress is put on seals and friction increases.
*Compared with the upright type, the inverted type tends to have more friction, because it has more moving parts with one stroke.
*If the shell case is damaged, the inner cylinder is directly affected.


Let’s have a look at the merits and demerits of the twin-tube shock absorber.

http://www.tein.co.jp/e/special/ni_t...g/img_fuku.jpg

Merits
*It is easier to secure sufficient stroke, because the oil and gas chambers are separated and not positioned serially.
*The base valve enables to keep gas pressure low, allowing for a more comfortable ride.
*Low gas pressure avoids stress on seals and keeps friction levels low.
*Compared to the inverted type, friction can be suppressed.
*Even if the shell case is slightly damaged, the function of the shock absorber remains unaffected.
*Superior manufacturing processes allow to keep production costs low.

Demerits
*Oil capacity is not as large as the mono-tube.
*Size of the piston valve is not as large as the mono-tube.
*The structure restricts installation angles.
*The oil and gas chambers are not separated, so there is a possibility for aeration to occur.

Did you understand the merits and demerits of the mono and twin-tubes?
Now, let’s directly compare the mono and twin-tubes.

http://www.tein.co.jp/e/special/ni_t.../img_vs_01.gif

1. Ride quality of street shock absorber.
Some manufacturers say the mono-tube is superior to the rest, but is it really true?
Let’s take a look back at the demerits of the mono-tube.

*Maintaining sufficient stroke is difficult because the oil and gas chambers are positioned serially.
* Due to the high-pressure gas injection structure, there is a tendency for a stiffer ride.
*Due to high-pressure gas injection, high stress is put on seals and friction increases.
*Compared with the upright type, the inverted type tends to have more friction, because it has more moving parts with one stroke.
*If the shell case is damaged, the inner cylinder is directly affected.

In recent years, the importance of ride quality has become essential for street shock absorbers.
To ensure optimal ride quality with street shock absorbers, it is vital to have the correct settings, but also sufficient stroke.
Within the mono-tube, oil and gas chambers are divided and distributed serially, and when comparing it with the same length twin-tube, it can not ensure sufficient stroke.



If you have a race shock absorber, designed for flat surfaced circuits, you don’t require as much stroke length as a street shock absorber, which has to deal with uneven surfaces and other conditions.
There is a direct link in experiencing deteriorated ride, such as sudden jolts etc, for street shock absorbers and not securing sufficient stroke.

2. What is the high-pressure gas ?

Similar to the insufficient stroke problem, the high-pressure gas injection creates a stiffer ride, enlarges friction etc. and is the main reason for deteriorating ride quality.
Some manufacturers have the base valve positioned above the free piston to lower the high-pressure gas injected. But this results in even further sacrifice in stroke space and a tendency to reverse the effect.

http://www.tein.co.jp/e/special/ni_t.../img_vs_02.gif

【Reference】 Why the mono-tube requires high pressure gas injection.

The twin-tube shares and creates the expanding/ contracting damping force with the piston and base valves, so there is no need for high-pressure gas injection.
However, the mono-tube creates the expanding/ contracting damping force with just the piston valve.
The mono-tube stroke action occurs when the free piston moves in the space created by the contracting piston rod. During this action, if there isn’t enough pressure on the free piston, it will easily move, over contracting and accurate contracting damping force will not be achieved.
For this reason, there needs to be enough high-pressure gas injected into the gas chamber to control the free piston.
When you inject high-pressure gas into the gas chamber, according to Pascal’s law, there will be an equal amount of gas pressure supplied to the amount of shock sustained. When this happens there will be high pressure applied on the oil seal, and the restraining force on the seal will increase therefore also increasing friction.

http://www.tein.co.jp/e/special/ni_t.../img_vs_03.gif


When there is low gas pressure.

http://www.tein.co.jp/e/special/ni_t...an_anime02.gif

When there is appropriate gas pressure

http://www.tein.co.jp/e/special/ni_t...an_anime01.gif


3. Which is better suited for the street ?

http://www.tein.co.jp/e/special/ni_t...ku_anime01.gif

You never know what is lying on the surface of a regular road.
If something strikes the shock absorber and damages the shell case, the mono-tube, which is constructed of only one inner cylinder, will not be able to perform its stroke action.

If you think about it, can you really say the mono-tube design is optimal for the street?
I'm afraid the answer is "NO".
Let's take a look back at the merits of the twin-tube.

*It is easier to secure sufficient stroke, because the oil and gas chambers are separated and not positioned serially.
*The base valve enables to keep gas pressure low, allowing for a more comfortable ride.
*Low gas pressure avoids stress on seals and keeps friction levels low.
*Compared to the inverted type, friction can be suppressed.
*Even if the shell case is slightly damaged, the function of the shock absorber remains unaffected.

The twin-tube design can answer all the street shock absorber problems. Furthermore, if you compare it with the mono-tube, it has lower costs due to superior manufacturing processes.
Other extremely important factors are high quality and reasonable price.
In other words, the optimal design for the street is the twin-tube.

4. Mono-tube for the Circuit.
Next let’s compare them for the circuit. For the street, the mono-tube’s demerits stand out, but on the circuit, its full potential is exhibited.
Let’s take a look back at the merits of the mono-tube.

http://www.tein.co.jp/e/special/ni_t...an_anime01.gif

*Stable damping force can be generated, because of the larger oil capacity and improved heat dissipation.
*The larger sized piston valve creates a wider area to receive pressure, and even microscopic damping force can be achieved.
*The structure allows no restrictions in installation angles.
*Oil radiates heat easier as the temperature increases.
*Aeration doesn’t occur because oil and gas are completely separated.


For the shock absorber, racing on a circuit is an extremely rigorous environment.
When racing continuously for long hours, the shock absorber, itself will generate a lot of heat. The nearby brake gives off even more, generating heat close to 1000 degrees. The shock absorber feels the full effects of this heat.
For this reason, even when driven hard for long hours, it is vital for circuit shock absorbers to perform consistently. So it’s the mono-tube’s merits that are naturally suited for hard driven circuits.
The stroke problem is not really a concern at the circuit because the flat surfaces and high spring rates don’t require as much stroke action as on the street.
This is why the mono-tube design is better suited for the circuit.


The twin-tube design....

*Structurally, the oil capacity is lower than the mono-tube.
*Structurally, the piston valve cannot be larger than that of the mono-tube.
*Structurally, the shell case cannot be inverted for strut type suspension.
*Aeration may occur because the oil and gas chambers are not separated.

Unfortunately we cannot say that it is suited for the hard circuit conditions because of these demerits.
But when we say the twin-tube is not suited for circuits, it is only based on direct comparisons with the mono-tube.

You can overcome the low fluid capacity issue of the twin tubes by finding one that has external reservoirs. Of course, those seem to be among the more expensive options.

^^^ THat was the article that I was thinking of. I saw the same thing in another thread. Like I said, very informative but hard to apply real world when comparing say, monotube-monotube. Like you mention in the very beginning, not all monotubes are constructed the same and this is a very general article on which performs better in certain situations.

But if you get into specifics between different monotube solutions there seems to be no readily available way to tell which one is better other than the brand name and cost. One would assume the higher cost yields you a finer result and more robust product, however, many of us know that is simply not always the case. Is there a way to determine quality between coilovers of different brands but similar design (mono, twin, etc).

To figure that out you have to do back to back testing/dynos/teardowns. No one is going to do that so you basically have to look at user reviews. However, you can't overcome physics the more seal friction you have the longer a mono-tube will last however as you up seal friction for durability you lose alot of ride comfort and response. That is why I say if your going monotube do it with a set of external resevoirs so you can re-charge the shock from time to time. That way you don't have that sacrafice of durability vs ride comfort/performance.

For someone like me who really can't tell the difference between coils other than what I know from the Tein article, Stance does a really great job of getting my attention:

Pro Comp

What's really compelling to someone like me is that little star graph they have on the left side of the page telling you what these coils are good for, (drift, time attack, etc). I really want them because of the graph but there are two problems:
1. no point of reference to qualify the graph
2. more importantly they don't make their competition coils for the 370z. LOL

I know stance has cheapy coils for the 370z but it's not of the same build quality, I assume, as their competition models.

Yeah. The only problem with user reviews is that there are only a few of people that have tried many different brands. UNfortunately there doesn't seem to be a quantifiable way to determine which coils are better for which application.

Like someone mentioned above, as far as I can tell any high end coil will do what you want it to do as long as it's adjusted properly for the application.

In the end perhaps I'm asking the wrong question. Perhaps it's more a question of what are the best settings to use on the track; but that's a whole different can of trolls, erp, worms. :tup:

The short answer is:

If you want them for the track, and fully adjustable, you will probably have to go high end (e.g., Bilstein, Ohlins), otherwise you tend to find mismatched valving, random spring rates, adjustability controls that either do little or even have the opposite effect desired.

If you are serious about it, get high end ones, and then get them adjusted on a shock dyno. Off the rack wil be a mystery without data for that specific set of shocks and springs.

Or... if you just want something reliable and suitable for day-to-day driving, I recommend not bothering with coil overs and just something basic like Koni yellows and, say, swift springs. Why get adjustable coilovers if you intend to set it and forget it and just drive on the street?

So is there a huge difference between different high end coils? Is there something that KW has the Bilstein or BC does not and vice versa? Or does it all come down to price in the end? At the high end stage does application even matter (going back to the assumption that high end coils can do it all and are dependant on settings more so than the product itself).

I do plan on putting this car on track duty for the long term but I will be driving it on the street as well. Personally I'm not terribly concerned with how comfortable it is but I will have to drive it two or three hours on the road every time I take it to the track.

So THATS what the little cylinders are on some coils. How do the external reservoirs benefit the twin tube?

usually speaking if you are going high end (external reservoirs, 3+ way adjustable, etc), chances are you have more than a rough understanding of what you need.

For most people a street application coilover is more than enough. I'd say look for a brand with a good reputation and go from there depending on your needs and if you have a preference in brand and such.

Hey Denny. If you are still in the market or researching, give Charles Park from powertrix a call. Just talk to the guy and see what he says. The advantage is he is local and can service your car's suspension if you need it.

Supporting a forum sponsor too.

Great thread guys. We've been road racing and in the car enthusiasts scene since the late 90s. It pains us to see kid buying all the BC/Fortune/Etc cheap knockoffs. The shock dynos on any of the $1000 coilovers is so inconsistent and awful it is actually worse than driving on your OEM setup. Lower your car too much and you actually make handling worse because you lose upward travel.

Our breakdown over the years has come down to this:
Street/Show- Springs and Struts or BC/Fortune/Knockoff-o-rama
Entry level HPDE- KWs or Bilsteins
Top Level HPDE/Entry Level Race- AST
Club Racing- Moton
Beyond that- Penske

-Mike Paisan

http://www.pbase.com/paisan/image/91072632.jpg http://www.pbase.com/paisan/image/14...8/original.jpg http://www.pbase.com/paisan/image/133406601.jpg http://www.whiteline.com.au/images/logos/perf1.jpg
Maintaining, Modifying and Educating TriState Enthusiasts since 2001.
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"Race Tested, Enthusiast Approved!"

I agree with this - to a point. I think for most normal drivers who desire to modify their car to a certain degree, lower-end coilovers are sufficient. Would you argue that the driver has more effect on the car than the coilover?

Agree for the most part as well, that's why we have "Street/Show- Springs and Struts or BC/Fortune/Knockoff-o-rama"

If you are going for "stance" then the knockoffs work fine because you aren't going for performance. The problem with them is their dampening is actually worse than the OEM ones in terms of consistency from coil to coil even in the same set. A good friend Angelo from ANZE suspensions gave a great talk at one of our track events to our racers and DE folks about how on these low end and even some of the entry level stuff 2 front dampers will be completely different on the shock dyno from each other. This leads to instability etc. etc.

As for driver skill, we always feel that the first mod on any car should be fixing the nut behind the wheel through education and practice at the track even if it is a stock car doing DE sessions. This "mod" is easily moved from one vehicle to the next as well.

As for driver skills overcoming poor coils, yes it's possible but given how inconsistent some of these coils are, why put yourself at a disadvantage if performance driving is your goal? :)

-mike

2 cents please
 

What are your thoughts or 2 cents about Tein Mono flex. Seems like no one talking about these on here. Want to hear.

FLEX is for cars that want to "Flex" like negative camber type stuff.

Have to bump this. So even fortune now with dyno sheets when bought are still a cheapo coil like the 510's? Whiteline endlinks just snap on this car so I wouldn't prompt them either if I was you.

We've never had WL end links snap on the 1000s we've installed on subies. Can't say for the 370z. There is also a difference between end links that may have had a bad batch and something like a coilover.

As for the dyno sheets, I'd have to test them and verify them to speak to them, but that is definitely a move in the right direction for the fortune auto ones. But at their prices, if they are doing a proper shock dyno/matched setup the price will begin to creep up as their labor costs also increase.

-Mike Paisan

http://www.pbase.com/paisan/image/153798190.jpg
Maintaining, Modifying and Educating TriState Enthusiasts since 2001.
Like us on Facebook! | E-mail: sales@azpinstalls.com | 725 Fairfield Ave | Kenilworth, NJ 07033 | 908.248.AZP1 (2971) |AIM: AZP Installs
"Race Tested, Enthusiast Approved!"

The Whitelines for the Z suck. I've got a busted set in my garage right now.

This isn't a subi forum yo! And Z bars are like double the girth.

Check it out then, I'll buy from a vender that's a third party tester to confirm. And their 510 is like $1700, I wouldn't think that's that cheap.

I would contact Whiteline, as they have a very good customer service department, they will replace them for you for free.

-Mike Paisan

http://www.pbase.com/paisan/image/153798190.jpg
Maintaining, Modifying and Educating TriState Enthusiasts since 2001.
Like us on Facebook! | E-mail: sales@azpinstalls.com | 725 Fairfield Ave | Kenilworth, NJ 07033 | 908.248.AZP1 (2971) |AIM: AZP Installs
"Race Tested, Enthusiast Approved!"

There you go...

$1700 is still very inexpensive for coilovers. It also depends on what your goals are with your car. If it's for looks/stance/ride height, then any coilovers will do. If you want repeatability on the race track that doesn't depend on the springs stiffness and has actually wheel travel you will start looking at the more expensive coils. We had a client/fellow racer who had very expensive Motons on his Caymen S racecar. The car would constantly would go into limp mode after hitting curbing on the track. They brought in all kinds of experts to try to get the ECU to stop going into limp mode. Eventually we suggested they raise the car up. As soon as they did that, the car stopped going into limp mode because the suspension travel had been restored and the wheels were actually staying on the ground.

-Mike Paisan

http://www.pbase.com/paisan/image/153798190.jpg
Maintaining, Modifying and Educating TriState Enthusiasts since 2001.
Like us on Facebook! | E-mail: sales@azpinstalls.com | 725 Fairfield Ave | Kenilworth, NJ 07033 | 908.248.AZP1 (2971) |AIM: AZP Installs
"Race Tested, Enthusiast Approved!"

I'd rather pay for a set of SPLs than buy another set of Whitelines. They aren't a good part on this platform. They make good parts in general. These are just a rare misstep.

Well free is free, but I understand, they do have rare mis-steps like that. Next time our rep calls us up I will make sure to have a discussion about these parts specifically and see what their take on the issue is.

-Mike Paisan

http://www.pbase.com/paisan/image/153798190.jpg
Maintaining, Modifying and Educating TriState Enthusiasts since 2001.
Like us on Facebook! | E-mail: sales@azpinstalls.com | 725 Fairfield Ave | Kenilworth, NJ 07033 | 908.248.AZP1 (2971) |AIM: AZP Installs
"Race Tested, Enthusiast Approved!"

They need to look at their balljoint supplier. I can't see them making their own. The threaded portion of the end link needs to be a harder metal as well.

Brother price doesn't represent quality. You really think jrz's are worth 10-15-18 grand? Jesus come on! That's a joke. In the end it all comes down to CNC, gaskets and design. I think many are capable of making very good systems or even carbon copies of someone else and having them work great.

I'm a total believer though! I will total be taught by you if you show me stuff. Not just dyno's but insides, metallurgy of components, oils used, gasket types etc etc. I thought my OEM calipers were great. Then I saw a stop tech or someone's inside and they are not the same. The OEM will basically melt seals and stuff if it goes beyond a 20min track session. I see why stop tech can do 24hr endurance races. I'm not saying I don't believe you but I must see proof first. Manufacture dyno's are the last thing I'll ever believe! But if you have independent ones its one step closer.

I need rears at the moment only. I need a way to adjust preload because in a 3 wheel situation my swift racing 10k springs can pop out of the spl mid link bucket. I have two options, buy a shock that's adjustable height wise so I get preload or sell the spl and swift spring and buy a true type from someone. Biggest issue though is FA told me they valve for +-2k of what you should use. In the end I'll probably have a much stronger spring so buying one now valved for 10k just means I need to pay more for a revalve later if I use greater than 12k down the road. What say you?

Sounds like a few tie rod ends used for camber kits. Kinetix and ams use cast while spl uses forged. Big different in a safety component if it snaps.

Necromancy warning
 

Bump for a couple of reasons. Read the far north racing site's Autocross to Win series. It will help you decide what you want from your damper and supports Mike's opinion.
Autocross to Win (DGs Autocross Secrets) - ATW Home Page

Also, Broadway Static now customizes Fortune Auto coil-overs. Digressive damping curve matched to your requested spring rates.
http://farnorthracing.com/autocross_secrets.html

Finally, MyG37.com board hosts the RWD Sedan Coil-over list in the suspension forum. All the companies listed have a Z34 option. I'm stunned at how long the list is!

Woah!
 

The amount of vague information here is pretty surprising. Springs in relations to ride quality and ride height is barely mentioned here, yet so much is blamed on the dampers and price. Yet no one is questioning how the spring comes into play here....:confused::eek:

9 times out of 10 what makes or breaks a suspension system is the capacity and quality of the springs and its implementation of supporting the weight of the vehicle. At the end of the day it is the spring"COILover" that facilitates the working motion of a suspension system. All other items and factors are secondary to this.

Most kits that have bad road feel, improper wheel travel and bump problems comes from a improperly matched spring for the ride height set by the user and overall compression capacity for the weight and and subsequent load during harder driving situations. The damper is not suppose to support the weight of the vehicle, its job is to absorb road imperfections and harmonic imbalances the SPRING creates. Having shocks with valve rates set stiffer to mitigate spring binding and bump is a poorly formulated solution for bad wheel rates. In most cases the damper should be as free flowing as possible without limiting spring travel.

There is a reason springs are usually the only object in the suspension system that has the [force per travel (ex. KG/mm)] information listed in the details of the product. You'll probably never see the shocks value of measurement because its extremely variable based on several factors.

It was mentioned earlier in this thread, but even though the defining factor of the kit is the spring rate (and overall load rating), the overall cost for a kit is defined by the quality and features available on the shock. Where as springs generally have a fixed price, the design of a shock is dependent on its tune-ability and build quality, most of which are unnecessary additives for road cars once you get passed the basic ability to change ride height and compression and rebound.

Way too much emphasis are put on the design of the shock here and its function. The tube design does play a role in overall cost and implementation, little of its capabilities are a defining feature. On average, a normal road car such as the 370z will only get up to about 5 inches and compression and rebound from static ride height. Any version of monotube or twintube damper can support this wheel travel. But in almost every case, a twintube shock is the cheaper option. This alone is the primary reason behind it being used more in OEM and lower priced shocks. In either case, neither design should have to bare the load of the vehicle and the bending forces of the wheel.

I can elaborate further for those who care. With regards with some problematic information -

This is so vaguely uninformative. For one - If you are going for the "stance" setup, its even MORE important to have the correct setup. With a lower suspension than advised, you are dealing with decreased wheel travel. Secondly - Saying the dampening is WORSE is horribly vague. What defines worse here? Way too stiff? Way too soft?

Well if its too stiff then that would actually make sense, as you have reduced travel and in turn reduced time for absorption. Instability can come from a plethora of factors in this instance. Bottoming out, not enough travel before bumpstops, Improper corner rates, and overloading the tires from any of these reasons.

Saying the dyno figures are off from "coil to coil" doesn't exactly mean anything either. Was the preload values the same? Was the temperatures the same? Was it tested with or without a spring? Saying this gives zero emphasis one what the ACTUAL problem could be. A company simply having horrible consistency between products doesn't truly argue bad quality but incompetency of the technicians of assembling the products.

Really???? You are going to come to a stickied thread and provide no useful information. Just self imposed chest pounding on how smart you think you are.

This post needs to be deleted.

Please elaborate on what wasn't useful? Or was everything i said completely obvious? Given the previous discussions, no one bothered to go over anything i said in great detail.

The topic is called "what to look for and why" Most of what was previously stated was about the quality of dampers, the price and which company. In the original question of type of driving, i'm not sure that was covered fully either.

Very few people, if at all, discussed how the springs come into play, how they effect the overall suspension dynamics and geometry.

I'm not trying to be a smarta$$. I just want people to be sure on what they are buying instead of marketing BS that has plagued the aftermarket industry for years. I'm coming from the BMW and VW scene and the information and vagueness i found in those forums were equally non-informative.

Why wouldn't this information be important on a stick'ied thread appose to some random question? I realize this is several years old, but these cars are still being sold and people are still heavily modifying them.

In order to appease Spoolers disgust of my rant. I'm linking this thread that was going around the same time this thread was started. With the intentions of figuring out the spring rate and overall car balance. Given the fact it was discussed in the "track,Ax..." topic. The information revolves around maximum grip settings and balance.

http://www.the370z.com/track-autocro...e-help-10.html

I hope people will continue sharing proper information and there views on the matter.

I think you missed the point. This thread was about basic coilovers and why cheap ones were actually a downgrade from the stock suspension. The track thread is a much better guide for a track setup and will give you great tips for a quality street setup. I remember reading that one a few years ago.

The OP poised several questions, with the global discussion clearly stated on "what and why" makes a coilover setup good. None of the questions were focused directly on cost per quality compared to the OEM specifications. However it was asked, why and what made high quality kits worth the price. Throughout the previous answers and advisories, spring rates matched to the potential balance wasn't really discussed with any detail. As i stated before, most of the "blame" for what was bad or improper revolved around the dampers.

But in any case i don't see why buying a cheaper kit would warrant an argument of why its bad. That can easily be solved by the age old answer "you get what you pay for". The bigger question would be why a expensive coilover may perform poorly, and their are several cases like this. Who is to blame here? The user or the manufacture?

If we were to even make a basic calculation on even a reasonably spec'd coilover kit we would be over 1000 dollars at the very least.

Here is my breakdown.

Swift, Hyperco, Eibach have competitively priced linear springs at about $60-80. With an average cost of $70 per spring we already have a total of $280 for springs alone (basic spring kits are closely priced to this figure on average). Lets throw in a set of tender springs for good measure so that we can tune preload in fine detail. Tender/helper springs in most cases cost more than their linear spring counter parts because of relatively complex rates and design (flat coil, thinner wall). A average cost for a set will go for about 360 dollars ($90/per).

We are already at 640 dollars. This is typically half the cost for a basic coilover set, buying a coilover kit for anywhere around the price of the quoted springs alone means somewhere along the line parts, engineering or technician wages were significantly under funded. In any of these cases i hope cheap parts was the cause. An improperly trained technician assembling a product or a poorly engineered design of vital safety components for a car can be significantly more catastrophic of a failure than cheaper pieces IMO.

DAMPERS -
Given the increased complexity of any basic damper unit (considerably more parts/consumables per unit- oil, shims, piston(s), piston rod, bolts, seals,etc) We can already guesstimate a single damper would be more expensive than a spring. Internals alone for a basic monotube damper can be as much as 65 dollars (from actual price figures of a Bilstein monotube shock). This doesn't even include adjustable parts for a simple 1-way tunable damper like adjustable bypass valves, compression adjustment springs and so forth. in total a single 1-way damper can cost up to 120 dollars a piece, and if both front and rear dampers are of the same design, a set is about $480 alone.

Linear springs - 280
helper/tender springs - 360
Damper set (monotube 1-way) - 480
Total - 1120

This would be for dampers and springs alone. We haven't factored in assembly cost, accessory pieces and any potential R&D.

So in this case i would 100% agree that a cheap system COULD be worse than OEM.

On a completely different corner of this table i have a complete breakdown on the cost of a single Ohlins ILX 2-way damper and how it cost 940 dollars (no spring or external pieces). Without the discussion of springs based on the cars weight and potential load, this same damper system would ride equally horrible to a 666 dollar kit if not setup properly. So how or why exactly is the cost of the damper system a good bases of ride quality? Without springs they are just fancy umbrella's, and that was my point about how emphasis of dampers was the wrong primary priority.

Instead of bad mouthing companies and putting all the blame on them how about we figure out a bases for complaints? In reality, almost no one in history who took the time to write a piss poor review also took the time to measure the shocks performance in relation to spring setup, preload and other external factors.

In a notable case a few years ago, a clubracer bought one of the most expensive Moton kits on the market for a M3 e36. Without any practical testing and setup analysis the customer went on to completely slam Moton by saying it was absolutely horrible to drive. After having it sent out to a professional to have it "fixed", the technician found out the damper was set to FULL stiff (oil bypass completely closed) and a gas pressure over 150psi (not untypical or the source of problem for Moton's, but high). How long it was like this is unknown, but the customer gave zero notice to anyone before making these complaints. Was this the absolute fault of the damper? In almost all cases having a damper set to full stiff means you are compensating for a separate issue outside of the dampers control.

In a recent situation, a time attack team with a BMW 135i had a custom Nitron 2-way kit. A full review was made about the car setup (some may have read about this). Within this article the driver/mechanic lodged a small complaint that the kit was not working to their standards and was considering tossing it for something "better". Also within this review, pictures showed clear details of both the front and rear spring perches adjusted with well over 1 inch of spring droop when unloaded. There was NO PRELOAD on these springs, even with both F/R having helper springs on the setup. From this, we can discern the car would've been practically riding on bumpstops if this was truly how the car was setup in normal conditions. I have yet to here back from them for whatever reason after trying to ask about the issue.

Examples like this show where misleading statements can manifest improper analysis for anyone else looking to potentially work with companies.

Sorry for writing so much (not really :roflpuke2:) rant over....

This is a much better response than your first one.

The biggest obstacle (other than price) is getting interpretable data.

Probably the easiest way around this is to find someone who is a good auto-x er in your make and model, with a nearly equivalent set up, and then buy what they have and set it about where they have it set. Same goes for tires, etc.

You might dial things in ever so less "aggressively" if it's street only, but its not as if folks in sports cars don't drive a wee bit more spiritedly day to day than the average driver (tho' hopefully in a safe and responsible manner...).

Failing that, the best OEM option on the table is as likely as not to be a superior (if over priced) set up that has actually undergone some real testing.

Just throwing down a bag of money on an aftermarket set up that has many options and configurations is useless if you aren't able to take advantage of it, and may even be counterproductive if you don't know what you are doing and/or the effect of a given adjustment cannot be validated (i.e., shock dynos, track day data, etc.).

Sounds like copying, not interpreting. Also cost here is open for interpretation as well. What if this hypothetical Ax driver has a 8k$ 4-way damper system ,sway bars, chassis bracing, etc, intended to support up to 2g's of lateral force at 80-120mph?

Opposing to this, what if a similar car in said field had a much simpler and cheaper coilover system with arguably worse tires, but comparable lap times? Do we just settle for the cheaper option because it's good enough?

How are we suppose to easily copy this setup? What if both drivers have no idea what the suspension system is actually doing and are just going off of what they bought and how some technician said it should work best at. And BLAM, it's fast, they're fast, and no reasonable amount of data was logged to truly understand what made said car and driver fast in those particular situations.

OR in another case (most cases), both drivers have lots of data logged and understanding of their systems, but given the fact competition...is competition. They don't want to share any of their knowledge and setup with you or anyone else. How do we go about copying it then? Break in to their race shop like Brian O'connor :excited::stirthepot: lol.

To be fair on the last point. There are several race shops and tuners that would charge upwards of $200/hr to setup your car and teach you how to tune a car and what to look for in a suspension setup. On top of the cost you already will have to spend for parts, this may or may not be sound investments if you have no intentions to recoup this cost through competitive racing/promotion. I for sure wouldn't turn around and just mouth out that knowledge to some guy looking to just flat out copy my setup.

Proprietary information aside any vendor on here that also competes with the same platform would probably supply you with a reasonable amount of setup information once you explain what you're after.

949 racing did with my Miata. Why buy without support?