Coil-overs vs upgraded struts/springs?

There are some solid setups from the "bargain" companies, but it's not easy or cheap. A friend just bought a BC racing setup but the internals were swapped to single adjustable Bilstein and the springs to Swift. This was getting into the half the cost of the car range however. Sorting through suspension is hard. Making good choices based on what's out there is harder. It's often easier to start with a budget and see what's the best you can do for that. Also, don't be afraid to experiment. Maybe you just need better shocks and once you have that sorted you'll find that you're happy with the springs. 

Blaise said:

Trackmouse said:

In reply to Blaise :

Because when you lower it, the threaded body goes up, and that, eventually, takes up room where the shock shaft operates. 9 out of 10 times it occurs when some kid wants that slammed look, and then nails pot holes and complains that his dumped Miata broke down at Walmart. 

You're referring to just moving your static height to have no bump travel left.

I'm asking why the total travel would be reduced.

Because of packaging. An adjustable body shock consists of a generic shock cartridge with an adapter screwed on the end. The adapter takes up space, so the shock cartridge is limited to how long it can be. On a non-adjusable shock with a one-piece body, the entire length of the body can be used to package the shock shaft.

If you're running at minimum ride height, the difference is minor. If you're running above that, the difference becomes more and more dramatic.

Note that shaft travel does not change depending on how you adjust a two-piece shock, unlike what Travelmouse said. The screwed-on adapter is not changing the actual internal volume of the shock cartridge, it's simply stuck on the end.

Pictures! Here's a cross section of an adjustable body shock and a single piece shock at a given minimum height. You can see there's a bit of a difference in the amount of room available to package a shaft.

And if we run at longer than minimum (say, because the minimum length causes the suspension to bind up), it gets more dramatic. Look at how much longer the shaft can be in a fixed body shock.

An intelligently designed single-piece shock will always allow for as much bump travel as the suspension can legitimately offer, and maximum shaft travel given that constraint - or as much shaft travel as the suspension can offer in droop. A two-piece shock will be (hopefully) be designed to allow for maximum bump, which makes it only a little bit worse than a single piece shock - it's just heavier with a bit less travel available. If the two-piece setup is designed for a minimum length that is shorter than the car can actually handle, it will really suffer.

Again, this is only an issue in situations where you're travel limited. Some applications have loads of room for the shock shaft - for example, there's 2.5" of unused potential shaft travel in the front shocks of an NC. But in the rear of almost every Miata, you need as much shaft as you can package in the shock. For example, the rear of the ND comes with over 7" of shaft travel from the factory. I've seen aftermarket two-piece coilover setups from major companies that use springs that are only 5" long - that's not the range of motion of the spring, that's the free length. Obviously they're only using half the travel the factory ever did, which has a massive effect on handling and ride.

You'll notice that neither Flyin' Miata nor 949 Racing offer two-piece shocks at any price point. Both of those companies take suspension very seriously.

This is a really poorly understood thing, and there are some suspension manufacturers who aggressively market bad information. Next time, we'll talk about how preload is not a thing outside of edge cases 

Judging the cost of suspension versus the cost of the car is a race to the bottom. Think of it this way, if you only spent $1k on the car you have a lot more available to spend on the suspension   The value of the car has no effect on what it costs to install a good suspension.

Another option if the car is mostly a DD with only occasional autocross use, and you don't plan to maximize preparation at this time, is to go with the stock springs, really good shocks like Konis or Bilsteins, and a set of aftermarket swaybars, plus good tires.  This should make a big difference without compromising suspension travel. For many years, the SCCA stock categories only allowed shock changes, front swaybar change and alignment, and those worked well.  To get started, these changes are relatively cheap and simple.

In reply to Keith Tanner :

OK, so we are talking single-piece vs two piece. I guess I missed that, I thought it was a blanket statement for adjustable perches meaning less travel.

Thanks for the info as always :)

More fun tech stuff: What's with helper springs? I understand technically what it does for force vs shock displacement but not in practical terms. KW coilovers and Xidas both have em, so I'm intrigued for my DD.

Keith Tanner said:

Judging the cost of suspension versus the cost of the car is a race to the bottom. Think of it this way, if you only spent $1k on the car you have a lot more available to spend on the suspension   The value of the car has no effect on what it costs to install a good suspension.

I agree 100%, but I also live in a world where I have to justify expenses. My wife understands that track weekends cost roughly the same no matter what I drive, but she gets bristly when I suggest spending $2k on the car that I just bought to "save money". Incidentally, this is also why I always look up the most expensive high zoot options when parts shopping. That way I can say "you know, I think I can get 95% of the performance while spending 1/3 of what the best stuff costs" Makes me look smart. 

While we can talk in generalities about 'coilovers' vs springs, looking at your actual options for the P5 is pretty dismal.  You simply have the wrong car for doing this the right way. 

No matter which way you go, you'll want some good high performance tires.  Preferably a dedicated summer tire, and for a daily driver maybe something like a BFG Sport Comp 2.

While they may allow you to adjust the ride height, quality coilovers are generally expensive and stiff.  If this is in your budget, great.  It sounds like the KW might be as good as it gets for the P5 without going to a cu$tom setup.

Otherwise, a quick search of parts suppliers and a dedicated Mazda/Protoge forum shows that there does not appear to be any decent off-the-shelf performance shocks for the P5.  As such, I'd skip whatever 'affordable' lowering springs are available and just use the stock springs with a set of reasonable stock replacement shocks like the KYB GR2 along with a rear sway bar like the one from Progress.  Supposedly their sway bar end links have a tendency to wear out and loosen up, so replacing them may be a good idea as well.  Apparently the 2002 Escape replacements from Moog fit, are more robust, and might even be cheaper.

Slightly off topic but relevant, I am adding coilovers to a fox chassis mustang.   There are countless well documented options.  Switching to coil overs on a fox moves the spring location, and if you switch to a SN95 chassis shock you get your bump and droop back on a lowered car.  This all greatly influences the ride and handling characteristics.

In my case it makes a world of difference, on a car that that already has coil over shock and strut setup stock go for the best shocks that you can afford and spring to match.  

Blaise said:

In reply to Keith Tanner :

OK, so we are talking single-piece vs two piece. I guess I missed that, I thought it was a blanket statement for adjustable perches meaning less travel.

Thanks for the info as always :)

More fun tech stuff: What's with helper springs? I understand technically what it does for force vs shock displacement but not in practical terms. KW coilovers and Xidas both have em, so I'm intrigued for my DD.

That's why I specified adjustable body shocks/struts. You're right, adjusting perch height doesn't have any real effect on travel unless you get the spring into coil bind. That's bad in just about every way unless you're setting up a NASCAR.

There are two types of secondary springs. One is called helper, one is called tender and I have seen each type defined as each name 

Light ones (5-15 lbs) are there to keep everything from falling apart when you fully extend the main spring. That's all they do, just keep everything from falling out of alignment when you've got the car up on jackstands. At this point, you really have more droop travel than you can use.

Non-trivial rate ones (100 lb+) will continue to extend the shock after the main spring is fully extended. They provide some functional benefit because of this by effectively allowing you to use all your travel. Downsides are that they tend to open and close on small bumps so you get clacking noises from the suspension. These also tend to be more expensive.

In both cases, they should be fully compressed when the car is at rest. Otherwise you get a step change in your spring rate that is impossible to damp properly. One damping rate for small wheel movements, one for larger ones. I tried this on the road and the track a few years ago - works great under certain conditions but doesn't work at all in others. If you see a car with live secondary springs at rest, it either has bypass shocks (offroad vehicles) or the springs are locked out at rest (AFCO sells the parts for this, I never got around to implementing them).

Right, bc with a stiff enough spring, you'd have essentially no sag, thus the tender/helper would help extend the suspension to full droop when needed, right?

I'm trying to understand the benefit of running a full-body coilover like  KW with a tender/helper vs a traditional Bilstein B8 with lowering springs. (Current DD is an 86 with stock shocks and eibachs - all I care about is very good damping for street use, not racing).

Yeah, very little spring compression on a stiff spring.

The benefit of the KW would be the spring rates, ride height and damping quality. Or maybe that's the benefit of the Bilstein setup. It all depends on how each of them was engineered - not every manufacturer gets it right every time. Heck, factory Miata Bilsteins were only a good option for 3 years of production despite the fact that they've been available as an option since 1993. The damping was wrong for the other 21 years.

Keith Tanner said:

Yeah, very little spring compression on a stiff spring.

The benefit of the KW would be the spring rates, ride height and damping quality. Or maybe that's the benefit of the Bilstein setup. It all depends on how each of them was engineered - not every manufacturer gets it right every time. Heck, factory Miata Bilsteins were only a good option for 3 years of production despite the fact that they've been available as an option since 1993. The damping was wrong for the other 21 years.

KWs are typically soft, and almost always a progressive spring to try to get some ride quality back on the street/not crash the bumpstops under big load. 

In a particular use car, ie: track use, the owner is generally upside down in the vehicle.  On a DD, I would tend to lean towards bang for the buck.  If it is new stock springs and the best cartridges you can afford, go for it.  If i is coil overs, so be it.  It all depends on the type of use the vehicle is daily driven.   Not to mention, how fat your wallet is.

WOW! Interesting, maybe someone did bring it up, but what about Fortune Auto? They've basically taken Taiwanese components and stepped them up big time!  They've great customer service, already have a model for you (@$1300) , can re-valve their lowest end model for your specific needs .

https://fortune-auto.com/coilovers/500series/ 

Not only can they re-valve them to your needs, but they can upgrade to a 2-way canister set-up as your skills and bank account mature. Give them a shout!

2GRX7 said:

WOW! Interesting, maybe someone did bring it up, but what about Fortune Auto? They've basically taken Taiwanese components and stepped them up big time!  They've great customer service, already have a model for you (@$1300) , can re-valve their lowest end model for your specific needs .

https://fortune-auto.com/coilovers/500series/ 

Not only can they re-valve them to your needs, but they can upgrade to a 2-way canister set-up as your skills and bank account mature. Give them a shout!/

Do they have any motorsport pedigree that isn't figure skating, like the boys at FEAL do?

In reply to z31maniac :

They've done well in Pirelli World Challenge and Time Attack. Not sure how much "pedigree" is needed for you....

2GRX7 said:

In reply to z31maniac :

They've done well in Pirelli World Challenge and Time Attack. Not sure how much "pedigree" is needed for you....

Yes, I'm sure they used the off the shelf dampers like FEAL has to trophy at Nationals..........but keep with the apples-to-oranges.

Let me guess, you own a set of FAs?

In reply to 2GRX7 :

I was just doing a bit of reading about these and I'm intrigued. Do they send shock dyno plots with the stuff they revalve? Has anyone independently thrown them on a shock dyno? 

I've known a few sets of inexpensive Bilsteins that perform like $$$$$ shocks due to custom valving, so if people are opening up this part of the market, it's very interesting. 

In reply to z31maniac :

Uh, no I don't. I have HKS on my RX7, and Bilstein on my 7-Series. I'm going on my time working at Pirelli World Challenge and seeing a car podium several times with their products.  

In reply to mazdeuce - Seth :

I was intrigued as well, so I did a bit more digging.  To be honest, I really like what their doing over there. I believe they do provide dyno graphs with their products, verifying their custom valving. Their website has some info, but it was more insightful speaking with their engineers, directly.

I would call Lee at Koni 

I have a set of the latest Fortune 500 series coilovers in my E28. I did not get dyno plots with mine which I was a little disappointed about as it seemed like others have gotten them in the past. I will say I have been impressed with their customer support though, the original lower mounts for the rears had the back of the car very low, they had another option in stock that they sent to me no charge so I could put my car back up where I wanted it. To Keith's point the shock travel is limited which isn't the greatest but these style of coilovers are very easily adapted to many different cars which is great if you want to turn a 30 year old family sedan into a track car like I did. I'm happy with my purchase, they do ride well with the adjusters backed off and perform on the track. I don't think I'd want these on a daily driver though as the limited suspension travel is more of downside there, my daily is a Legacy on Bilstiens that just eats up the crappy winter roads here. Had I known about the BC racing coilovers with the Bilstien pistons like Mazdeuce has mentioned I would've been very tempted by those at the time.

Adam