Coilovers - What are they and are they always better?

[Racecomp Engineering]

This is intended to a basic guide to a few suspension terms that may be common knowledge to some, may answer questions some have been afraid to ask, or may correct some misconceptions. I won't mention brands here because it isn't really important. Lets please not turn this into a thread where we argue about which brand name we like best.

Some phrases I see a lot on car message boards:

"Don't waste your time with springs, just get coilovers."
"Gotta go with full coilovers bro."
"Lowering springs are a waste since you'll just upgrade to coilovers later."
"What the heck is an oilcover and do I need them?"
"I don't know what that means."
"You're an idiot man"




Introduction

First of all, lets talk about what a coilover really is. A coilover is simply a shock/strut with the spring (coil) mounted on (over) the damper. That's it. So, if you've ever looked at your BRZ or FR-S suspension you may have noticed that you already have coilovers. Congratulations!

Okay...so that's the nerdy technical definition that no one cares about anymore. Our dampers are a strut up front and a shock in the rear with perches for the springs that are fixed in place on the damper body. Few people will call that a coilover even though it technically is one.

In the sport compact world the term coilover now basically comes down to the spring + damper system being height adjustable. That term has for better or worse stuck and is how most refer to height adjustable set-ups. Non-height adjustable set-ups are sometimes called fixed perch struts or shocks.

So why are coilovers usually considered "better" than a conventional fixed perch strut or shock? What makes them so special?


Coilover Advantages

1. Height adjustability. Set the ride height wherever you want. Within reason. The body of the coilover is threaded and you can raise or lower the spring perch to wherever you want. Sometimes the lower mount of the coilover is threaded as well, and you can raise or lower with that method. There are advantages and disadvantages to both methods.

Most of the time you can't raise the car to stock or higher unless it's a specially designed rally coilover or you'll risk "topping out" the shock and doing some damage. You can usually go very low, but keep in mind that even coilovers have limits and the car may not necessarily handle better if you lower too far without looking at the full system.

Height adjustability is valuable for a variety of reasons. Obviously aesthetics is one of them...get that ride height that looks just perfect for your tastes. It also can be essential for a racecar to lower the center of gravity, adjust the rake (nose up/down) and attitude of the car, and corner balance the chassis (which can be covered some other time).

2. Suspension travel at lowered ride heights. Coilovers usually, but not always, have more bump travel at lowered ride heights. Stock and any other fixed perch strut/shock for the BRZ and FR-S are seriously limited in how much you can lower with a lowering spring and still expect a good ride and handling. My personal recommendation is that if you must go lower than 1.2 inches, start thinking about coilovers. There just isn't that much travel to spare and you will be using the bumpstops early and often. At stock height, the stock suspension will have more travel than many coilovers but this changes when you lower the car.

Coilovers use shock bodies that are (usually) designed to sit lower, and therefore give you a starting point of more bump travel when you're already down low. Bump travel is necessary to soak up bumps on the street and track. You need travel for the suspension to "work."

Sometimes coilovers do not actually have that much suspension travel. This is sometimes due to poor/lazy design, and sometimes simply because they're designed for stiff springs for a smooth racetrack. Be advised.

3. Standardized coilover springs. This is a pretty big one. The ability to use standard coilover springs means that you can choose any spring rate and length you want. It opens up almost infinite options for dialing in the car just right. Awesome for track people that want a specific spring rate or need to go with firm rates to control body roll with sticky tires.

With a conventional fixed perch strut, you need a spring that is specially designed for the BRZ and FR-S. These are almost always designed to match only the stock dampers, which means they can't be too firm or they'll overwork the standard valving. There's also a physical limitation in that you are limited in how stiff a spring can be and actually fit on the stock dampers before you start running into coil bind issues.

So if you need stiff spring rates, you need coilovers. Gotta make sure your coilovers are valved appropriately, though.

Whether you need stiff spring rates or not is another topic.


Other stuff

Adjustable damping. Both coilovers and fixed perch dampers can be, but are not always, adjustable for damping. Damping characteristics can be looked at in a general sense in terms of compression (sometimes called bump) and rebound. Most of the time you have 1 knob to turn and it adjusts bump and rebound together. Sometimes bump is fixed and the knob only adjusts rebound. Sometimes you have 2, 3 or 4 knobs to play with. You may have seen 2 way or 3 way shocks mentioned...this refers to the number of damping adjustment methods available (i.e. if bump and rebound are adjustable separately or further if separate low and high piston speed adjustments are possible).

Sometimes you'll see an advertisement for a 32 way adjustable coilover and that means that coilover simply has 32 clicks of adjustment, which is meaningless and whoever wrote that advertisement or marketing crap should feel bad.

In another write-up I'll look at what bump and rebound control and how 2, 3, and 4 way shocks change the game.

Ride quality. In general, coilovers are assumed to ride more harshly than OEM or a shock + spring combo. This is usually, but not always, true. In my opinion, the lower end coilovers sacrifice quality of valving (and thus ride quality) for features like camber plates and adjustability.

Maintenance. In general, coilovers are assumed to require more maintenance and may not last as long as a regular shock + spring combo. This is usually true. There are more points of failure, but different brands of coilovers do better than others.


Should I get coilovers?

It's often assumed that any coilover will be "better" than any stock or lowering spring on a conventional fixed perch strut/shock.

Is this always true?

No. There are advantages to coilovers but one of the most important parts of the system is the damper itself. The quality of the valving can simply make or break the system. Whether it's height adjustable or not takes a backseat to the actual valving of the damper. It can suck in a coilover and it can suck for a fixed perch strut. If you have a crappy height adjustable shock, you still have a crappy shock, you just get to set the ride height low and look pretty. There are some really awful springs out there and there are some really awful coilovers out there, too. Both can be worse than stock in ride and handling terms.

Coilovers have gotten a reputation for riding rough in some part because more people buy cheaper (usually poorly damped) coilovers than more expensive coilovers that have excellent valving. A coilover with proper valving can be ride well even with stiff springs.

Stock is an okay option for many people depending on their goals...AS LONG AS they're in good condition. There are other options now that are valved better than a few coilovers. You don't get the advantages listed above, but again, the damper itself is a huge part of the equation and it doesn't care if it's in a height adjustable coilover body or not.


Conclusion

Height adjustablity, more travel at lowered ride heights (generally), and the ability to run standard coilover springs with stiff rates are pretty strong advantages to running a coilover. These advantages can be accompanied by a poorly valved damper that causes reduced handling and ride quality. Or they can be enhanced by a properly valved damper that does well on the street and the track.

This doesn't mean that coilovers are necessarily better or worse for you. It's important to consider your budget, goals, and intended usage of your vehicle. If stiff springs aren't really needed, you have a limited budget, and a mild drop suits you fine, then perhaps a lowering spring will work great for you. If you hit the track often, use sticky tires, and can afford a quality set-up, a coilover should work well for you OR you might be happy with good springs and some toppings. If you really want to lower the car a lot, a coilover should be considered.

Like most things in life if you spend more money you get something better. However, you can still do pretty well on a reduced budget if you spend the time to investigate options thoroughly and do your homework.

[Racecomp Engineering]

Happy to answer any questions or take requests for another write-up.

Hope this was helpful to someone.

- Andy

[dem00n]

Sticky requested.

[CSG Mike]

Funny, I was gonna PM you seeing if you wanted to collaborate on a suspension Q&A thread just now...

Originally Posted by Racecomp Engineering

No. There are advantages to coilovers but one of the most important parts of the system is the damper itself. The quality of the valving can simply make or break the system. Whether it's height adjustable or not takes a backseat to the actual valving of the damper. It can suck in a coilover and it can suck for a fixed perch strut. If you have a crappy height adjustable shock, you still have a crappy shock, you just get to set the ride height low and look pretty. There are some really awful springs out there and there are some really awful coilovers out there, too. Both can be worse than stock in ride and handling terms.

Coilovers have gotten a reputation for riding rough in some part because more people buy cheaper (usually poorly damped) coilovers than more expensive coilovers that have excellent valving. A coilover with proper valving can be ride well even with stiff springs.

[Racecomp Engineering]

Originally Posted by CSG Mike

Funny, I was gonna PM you seeing if you wanted to collaborate on a suspension Q&A thread just now...

I like that idea...what topic next? Or pm me?

- Andy

[iketeru]

thanks for this article! great for a noob like me. interested in learning more, maybe how to tune suspension for street vs track, what solutions are out there for each, etc.

[ZDan]

I had been agonizing over ordering new coilovers for my FD. I just ordered the Ohlins DFV setup for it literally a couple of hours ago. I guess I'm asking if I've made a good choice.

Background:
I DD the car, and track it ~4 events per year (hoping to hit Watkins Glen in a week and a half).

The 9k/7k Tein SS's its on now just SUCK. It's like they have zero low-speed damping and infinite high-speed damping. You can bounce a corner of the car and easily get more movement than on my wife's stock '05 Mazda3 with new stock-replacement struts/shocks (which are doing an AMAZING job on that car)!

The PO installed the Teins, and he was running them at 6-8 clicks from all the way OUT. I think he must have misunderstood Tein's recommendation to ONLY run them within the first 16 clicks from all the way IN (32 clicks from all the way in to all the way out).
I reset them to 8 clicks out from all the way in after I discovered this. He had put ~10k miles on them that way, and I put another ~2k on them before changing settings, another ~12k miles since then.

In any case, as they are now they suck at the track and they suck on the street. Last track outing I went to 4 clicks out, and it didn't seem to help control under braking/cornering at all, but it sure made impacts a lot harsher!

I had thought about getting the Teins rebuilt/revalved, but I don't want the down-time, and as far as I know they might be performing as well as they ever will now (i.e., maybe they just suck)!

Anyway, after talking to some trusted track guys (one of the fastest guys in my time trial club is running them on his NC Miata, albeit revalved for much stiffer springs), I pushed the button on these for the FD.

I know DFV's are not considered "real" Ohlins, as they're made in Japan, and they're not "serious" racing coilovers, but for me, I like that they're specifically (I trust?) setup for the FD, from what I've read they should literally just bolt in without any fiddling with settings. And the 11k/11k spring rates that look good to me for my dual usage (I shouldn't have to get them revalved for different springs).
11k/11k springs should be ~6.7k/7.7k at the wheels, if I have the motion ratios right...
I don't think I *need* dual-adjustability, that's not a biggie to me as long as they're ballpark as-delivered.

What I *do* need is a shit-ton MORE low-speed damping and WAY THE FOOK LESS high-speed damping. Supposedly the DFVs are very digressive.

Anyway, just throwing this out there to see if I missed a better option for the price range.

They're not shipping out until tomorrow, so if I'm totally screwing up here, lemme know!

[Racecomp Engineering]

Originally Posted by ZDan

I had been agonizing over ordering new coilovers for my FD. I just ordered the Ohlins DFV setup for it literally a couple of hours ago. I guess I'm asking if I've made a good choice.

Background:
I DD the car, and track it ~4 events per year (hoping to hit Watkins Glen in a week and a half).

The 9k/7k Tein SS's its on now just SUCK. It's like they have zero low-speed damping and infinite high-speed damping. You can bounce a corner of the car and easily get more movement than on my wife's stock '05 Mazda3 with new stock-replacement struts/shocks (which are doing an AMAZING job on that car)!

The PO installed the Teins, and he was running them at 6-8 clicks from all the way OUT. I think he must have misunderstood Tein's recommendation to ONLY run them within the first 16 clicks from all the way IN (32 clicks from all the way in to all the way out).
I reset them to 8 clicks out from all the way in after I discovered this. He had put ~10k miles on them that way, and I put another ~2k on them before changing settings, another ~12k miles since then.

In any case, as they are now they suck at the track and they suck on the street. Last track outing I went to 4 clicks out, and it didn't seem to help control under braking/cornering at all, but it sure made impacts a lot harsher!

I had thought about getting the Teins rebuilt/revalved, but I don't want the down-time, and as far as I know they might be performing as well as they ever will now (i.e., maybe they just suck)!

Anyway, after talking to some trusted track guys (one of the fastest guys in my time trial club is running them on his NC Miata, albeit revalved for much stiffer springs), I pushed the button on these for the FD.

I know DFV's are not considered "real" Ohlins, as they're made in Japan, and they're not "serious" racing coilovers, but for me, I like that they're specifically (I trust?) setup for the FD, from what I've read they should literally just bolt in without any fiddling with settings. And the 11k/11k spring rates that look good to me for my dual usage (I shouldn't have to get them revalved for different springs).
11k/11k springs should be ~6.7k/7.7k at the wheels, if I have the motion ratios right...
I don't think I *need* dual-adjustability, that's not a biggie to me as long as they're ballpark as-delivered.

What I *do* need is a shit-ton MORE low-speed damping and WAY THE FOOK LESS high-speed damping. Supposedly the DFVs are very digressive.

Anyway, just throwing this out there to see if I missed a better option for the price range.

They're not shipping out until tomorrow, so if I'm totally screwing up here, lemme know!

Me and CSG seem to disagree on Ohlins R&T, but I'm generally a fan. They are usually not valved to be too hardcore but IMO a great Road and Track shock as the name implies.

The current crop of Ohlins R&T are a lot different than the mid/late 2000's stuff. A lot more "swedish" influence and Ohlins USA supports them better. Better valving and durability then before for sure.

The latest Ohlins R&Ts we've tested (EVO and Impreza) have been digressive and valved very well. I've heard one of the US based engineers of a Dutch competitor say very good things about their internals. It's a good shock, just set-up with a street emphasis.

If anything you'll want stiffer springs, and they can usually support a few more kg/mm out of the box without a revalve. The adjuster is mostly rebound, not too much crosstalk.

If you do want to fiddle with things and get really hardcore, there may be other options that will work better in that price range rather than going nuts on revalves and respringing everything.

IMO they are a good "easy button" set-up that can do everything pretty well with minimal headache. But not cheap.

EDIT: trying to keep brand type questions out of this thread and keep it more general tech stuff......

- Andy

[aiur55]

Thanks for the article. I am interested in learning more.

How would I go about choosing the correct spring rate and damping I want? Are there certain characteristics of the car I should be looking out for?

I would be pretty hard and expensive to test out many set ups. How would I know approximately what kind of setup to go with?

[Dimman]

Do the shim stacks fatigue and stop working over time/use?

ZDan's complaint sounds like a text book example of orifice damping as used on older motorcycle front forks. It's like a squared curve, er... Math squared or exponential or something. Starts horizontal-ish and quickly moves to vertical-ish.

Shims are what modify that curve, right? So they have an oversized orifice that they 'choke back' at low speed with shims that deflect and 'blow open' at high speed, which gets you (a very simplified) digressive curve.

So are shim stacks a part of r and r for an overhaul revalve?

[ModBargains.com]

Darn good post. Great info, thanks for posting that up

[Captain Snooze]

Originally Posted by aiur55

How would I know approximately what kind of setup to go with?

I am suggesting that the very first thing to do is establish a budget. Knowing how much you are willing to spend determines what choices you can make.

[CSG Mike]

Originally Posted by ZDan

I had been agonizing over ordering new coilovers for my FD. I just ordered the Ohlins DFV setup for it literally a couple of hours ago. I guess I'm asking if I've made a good choice.

Background:
I DD the car, and track it ~4 events per year (hoping to hit Watkins Glen in a week and a half).

The 9k/7k Tein SS's its on now just SUCK. It's like they have zero low-speed damping and infinite high-speed damping. You can bounce a corner of the car and easily get more movement than on my wife's stock '05 Mazda3 with new stock-replacement struts/shocks (which are doing an AMAZING job on that car)!

The PO installed the Teins, and he was running them at 6-8 clicks from all the way OUT. I think he must have misunderstood Tein's recommendation to ONLY run them within the first 16 clicks from all the way IN (32 clicks from all the way in to all the way out).
I reset them to 8 clicks out from all the way in after I discovered this. He had put ~10k miles on them that way, and I put another ~2k on them before changing settings, another ~12k miles since then.

In any case, as they are now they suck at the track and they suck on the street. Last track outing I went to 4 clicks out, and it didn't seem to help control under braking/cornering at all, but it sure made impacts a lot harsher!

I had thought about getting the Teins rebuilt/revalved, but I don't want the down-time, and as far as I know they might be performing as well as they ever will now (i.e., maybe they just suck)!

Anyway, after talking to some trusted track guys (one of the fastest guys in my time trial club is running them on his NC Miata, albeit revalved for much stiffer springs), I pushed the button on these for the FD.

I know DFV's are not considered "real" Ohlins, as they're made in Japan, and they're not "serious" racing coilovers, but for me, I like that they're specifically (I trust?) setup for the FD, from what I've read they should literally just bolt in without any fiddling with settings. And the 11k/11k spring rates that look good to me for my dual usage (I shouldn't have to get them revalved for different springs).
11k/11k springs should be ~6.7k/7.7k at the wheels, if I have the motion ratios right...
I don't think I *need* dual-adjustability, that's not a biggie to me as long as they're ballpark as-delivered.

What I *do* need is a shit-ton MORE low-speed damping and WAY THE FOOK LESS high-speed damping. Supposedly the DFVs are very digressive.

Anyway, just throwing this out there to see if I missed a better option for the price range.

They're not shipping out until tomorrow, so if I'm totally screwing up here, lemme know!

I'd disagree that the R&T can be used with higher spring rates.

The construction IS great, and there's minimal crosstalk on the rebound adjustment. However, that exact reason is why they cannot effectively be used with higher spring rates. The static compression damping is made for one spring rate, and any deviation means that under compression, the system is either overdamping (softer spring) or underdamping (stiffer spring). Of the two, underdamping compression is a lesser performance loss on this car, IMO. Increasing rebound damping will marginally increase compression damping, which helps partially offset this.

If you're going to use 11k/11k spring rates, why not go with an option that is designed for that kind of spring rate to begin with? To me, it's like purchasing a C63 AMG, and then using 87 gas.

For the price of the Ohlins R&T, you're awefully close to proven Tein and JRZ options.

[Racecomp Engineering]

I started a new thread for questions on any suspension topic here:
http://www.ft86club.com/forums/showt...32#post1177232

I answered a few that were asked here.



- Andy