Fox Coilovers

I see that Fox and Flyin’ Miata teamed up to make coilovers. Does Fox make coilovers for other cars? Do they custom make them for other cars?

Fox teams up with Ridetech so yes they make a ton of coilovers just not all under the Fox brand.

There are a lot of Fox options for the off road scene for Jeep and Nissan products as well.

I'm pretty sure there's a lot of information on the Flyin Miata website.

Fox stuff is popular with the desert racing crowd, I believe. Google is your friend.

I was more wondering about performance car applications outside of Miata. 

I've wondered before if any of the Fox dampers could be adapted to run in a strut application. Subarus, specifically. Do the shocks have the necessary build and stiffness to tolerate the side loadings that struts have to endure?

Keith Tanner....

That's the problem with Fox for the performance market, they don't have a strut application.  I'm sure they could do it, but they're seeing exponential growth in the powersports (read UTV) field that's tied up all their R&D heavily. They've got the performance car chops - one of our contacts there was the head of Bilstein Competition for over a decade and knows his stuff. I don't know if they're really set up to do one-offs efficiently. There are two factories, the Scott Valley one is probably more likely to do custom applications based on what I've seen.

The shocks in our size range don't have the strength for strut side loads, either in the tube wall or in dealing with stiction. I don't know if they have small diameter shocks that are burly enough to use for struts - and these guys consider anything that goes on a passenger car to be "small".

They've been really good to deal with. We get support from them like nobody else, even though we have to be pretty small potatoes. We've been selling their parts for a few years and I don't think we've had one fail in service yet. Plus it just really works. That Fox setup that's on Atomic Betty is fantastic, and the Fox I run on my big Dodge pickup and my XJ have made big differences to the cars. Now my wife wants a set for her WJ daily driver...

This is what the SEMA show is good for. If you're in the industry, you can go to the Fox booth and talk about a custom application and see what they say. Their booth is staffed by the real hardcore engineers, not booth babes.

I see ridetech has a custom coilovers option. Are these just relabeled fox shocks? I can’t seem to find any info confirming this. Seems that ridetech focuses on the domestic market, but I wonder if you could spec the custom units to fit other applications. 

Also any general info on what makes a good set of coilovers? I can read specs for different units but don’t know how that really translates to quality and durability. 

Ridetech doesn't make as big a deal about their Fox relationship as we do, but it's there if you look. For example: https://www.ridetech.com/info/new-q-series-monotube-shocks/

Ridetech's custom coilovers allows you to pick from a couple of different upper mount designs and the stroke length. That's probably not going to be enough to get you a Subaru setup, as they're all still shocks and not struts and your car may not have the same sort of mounts. I was able to use a set of custom coilovers like this on my MG build because I could spec the dimensions I wanted, but you couldn't build a set of Miata shocks this way.

The sort of thing you need to know for quality and durability doesn't usually show up on a spec sheet. For example, the design of the seals and the difference between stamped and ground shims are going to be a big factor but you'll never see that. Usually the spec sheets concentrate on things like the number of clicks, which is a useless number. More useful info is things like does the manufacturer make shocks for an OE (such as the shocks on the Raptor)? The durability testing is in a different league in that case. Are the springs from a name brand or are they sold by the same company under the same name? Getting spring metallurgy right is a very different thing than getting shock valving right, and I don't think anyone can do both well. Can they be rebuilt? Do they use high wear spherical bearings or long-lived bushings? Can they provide a dyno chart? Even if you can't read one, the fact that dyno charts are something that can be discussed will set some companies apart from their competitors.

In reply to Keith Tanner :

Is price a good indication of quality when it comes to coilovers/shocks/ struts? Also what obvious specs does one look for in a daily/hpde/ autocross setup? The more adjustment the better? Twin tube or single? Bigger pistons better? 

Sorry for all the questions but all the options kind of muddy the waters for me. 

What car are you looking at struts for?  From what I understand, Ground Control are pretty good to work with for custom applications that may not be common or listed on their website.  You'll probably need to call them.

Price is an indicator of what you'll pay, but not necessarily much else unfortunately.

The big thing to look for in design is travel. If the shock has "adjustable travel" or "adjustable preload" then it's a generic cartridge with an adapter screwed on the end. This will limit your overall travel, so a fixed length shock is always preferable. Those marketers that don't understand suspension (there's a prolific one in the Miata world) will sputter and complain, but a bit of time with paper and pencil will show this to be the case. Autocross is less reliant on travel than daily driving or hpde, but any time you run out of travel you've hit an edge case in your suspension and something undesirable is about to happen to your ride and your handling. I've seen high end Ohlins that are basically maxed out on travel at their normal ride height, which has all sorts of bad consequences.

If all the manufacturer talks about is drop, then you're probably looking at a set of coilovers designed mostly for the low cost/low performance stance market. Also, if you are planning on running the car lower than stock then you will need a significant increase in spring rate. 15% more is basically nothing. We double or triple it, because that allows the car to stay off the bumpstops and use the available travel better. Because of this, a high spring rate often ends up being more comfortable than a soft one. 

Twin vs mono tube is a big marketing feature. They have different characteristics which are basically low pressure vs big piston. Koni uses twin tubes, Bilsten uses monotubes - and if you've experienced both of those, you've probably felt the behavior of each. It's a big obvious design choice that manufacturers love to use to try to differentiate their products, but it is not as important as a properly selected damping curve. 

Adjustment is only good if you know how to use it. Rebound is the one that's going to make the biggest difference and the first one that's always available. Separate compression is good for fine-tuning transient behavior, but people are far more likely to just leave it alone.

Ground Control specializes in converting off-the-shelf shocks to coilovers. They tend to use good shocks like Konis or Bilsteins as the base. Because of this, they usually offer full travel (good) but the conversion parts may or may not work well with the shock (boo). For example, their early Miata Koni conversion is really well done but their early Miata Tokico conversion is not, simply due to the way those shocks are designed. 

Does it sound as if there isn't a single spec sheet item you can't look at to determine the best coilover? That's right. Shocks are one of the most complex pieces of equipment on the car with a lot of compromises and interrelated factors, and most of them are ones that don't show up on a spec sheet. The best thing you can do is drive a bunch of options and do your best to isolate the effects of the shocks from the owner's chosen ride height/wheel package/etc. If you're in the Subaru world, talk to guys who do rally because rally is very hard for shocks, and a surprising number of really good shock guys have roots in that world.

And yes, definitely tell us about your particular application.

In reply to Ian F :

Nothing in particular really, I just have a habit of liking oddball cars and not knowing too much about coilovers/shocks/struts. I’ll check out ground control. 

In reply to 80sFast :

Too low of a price is a good indicator that many of the items Keith identified are missing. The exceptional design, build quality and testing to back it up all cost something. Some or all of those elements will be missing from less than $100 aftermarket shocks/struts. In these custom/racing applications you are paying for consistency, adjustability, and low weight. 

There are many complex elements to strut applications, and lots of ways to get it wrong. As far as I can tell Fox only makes monotube shocks, but most struts except Bilstein are twin tube designs. Bilstein makes monotube struts by basically flipping a small diameter shock upside down in a strut, so the shock body becomes the strut rod. This requires a new seal to the shock body/strut rod. So Fox needs to create som e new stuff for strut applications. 

Flipping a shock upside down shouldn’t require a new seal. The internal pressures are higher than you’d see from gravity. 60-100 psi at full extension. 

Twin tubes are different structurally, I wonder if that’s a factor? 

And yes, sub-$100 coilovers are likely to be stancebro trash. I was thinking of the difference between, say, $200-500 per corner. 

This picture shows a diagram of the Bilstein monotube strut.

https://m.imgur.com/qIOaPz8?r

It is also explained in a post here by series8217.

https://grassrootsmotorsports.com/forum/grm/learn-me-roll-your-own-coilovers/98453/page1/

series8217 said:

In reply to cmcgregor:

The Fiat uses struts, not shocks, so the Miata information does not apply. Bilstein shocks cannot carry strut side loads.

In order to make a strut from a Bilstein, you have to:

1) hard chrome plate the shock body so it's like a linear bearing guide rod

2) weld a strut mount plate stud to the bottom of the shock body

3) fabricate a strut housing with a couple dry-slide bearings that match the chrome-plated shock body, mounting ears for your knuckle, and a hole on the bottom cap that fits your shock shaft end. you'll also need a spring perch on it, so add a c-clip groove or weld on a perch.

4) the shock, shaft end first, into strut housing with a bit of grease, and tighten a nut to the end of the shock shaft to fasten it

6) install your spring and bolt your strut plate to the top of the strut (which is actually the bottom of the modified shock body).

EDIT (2015-02-11):

Here are some illustrations I made to show how Bilstein shocks and struts go together:

And they have it listed as a”strut bearing” but it also requires a seal if it will be used on the street .

So what is the difference between a strut and coilover application? A Miata typically has struts but FM created a Fox coilover kit. Couldn’t the same be done for other platforms? 

I keep using fox as an example but if the conversation moves past that it would be awesome. Just general information on shocks/struts/coilovers would be appreciated. When should you use what? How can you tell quality when purchasing? Is the more adjustable the better?

Maybe I should start a new “Learn Me” thread for this topic. 

In reply to 80sFast :

Basically the difference between a strut and a coilover shock is the suspension design.  A strut functions as a suspension locating link (so it's exposed to side loads, etc.) while a coilover shock that isn't a strut looks similar, but doesn't help locate the suspension, so it primarily sees vertical loading (like a separate spring and shock would). 

So what happens to those loads when people switch struts for coilovers? Are the coilovers designed to replace struts built different than those to replace shocks/springs?

In reply to 80sFast :

The damper configuration (shock, strut or coil over) is dictated by vehicle application and therefore suspension design. Most trucks in the rear axle use a shock (with a separate leak or coil spring).

Struts are used on the front of most cars today with a coil spring inline with the damper.  The strut supports side load and defines camber and caster.

Coilovers are just an assembly of a spring inline with a shock damper and normally they have an adjustable spring seat height, but sometimes that term is used for any spring over shock assembly. These are used in double A-arm/SLA or multi link suspensions.

There are lots of explanations of suspension types if you search GRM and a bunch of books to explain the details of suspension design.  

80sFast said:

So what is the difference between a strut and coilover application? A Miata typically has struts but FM created a Fox coilover kit. Couldn’t the same be done for other platforms? 

A Miata does not have struts.

A "damper" is a device that damps suspension movement.  Both shocks and struts are dampers.

Technically, a "coilover" is a setup where the spring goes around the damper, this is really just a packaging thing.  It is commonly used (arguably incorrectly) as a shorter term for "adjustable height coilover", where the spring perch is threaded onto the damper body, thus allowing the ride height to be adjusted.

A "shock" is just a damper, it doesn't do anything else.  A "strut" is a damper that also acts like a control arm in that it constrains the arc in which the upright can move.  To do this, a strut needs to have a lot more strength than just a shock.  Generally speaking, shock setups have one or more upper control arms, whereas strut ones don't.

I know a lot of early 90s cars used "strut inserts", where the strength was provided by a steel tube, and the damping was provided by a thin shock that went inside that tube.  Sometimes the inserts were intended to be replaceable, other time you had to cut them open.  Is that still the case?  If so then that might be one option for trying to retrofit parts like this.

So are some coilovers actually struts with adjustable spring seats and others shocks with adjustable spring seats? 

80sFast said:

So are some coilovers actually struts with adjustable spring seats and others shocks with adjustable spring seats? 

 

Yes.  Spring packaging and use of the damper for providing location are independent features.

That said, almost all struts are coilovers, and many (not sure what percent) shock applications are not (think the back end of a live axle pickup, for example).  The Miata is somewhat unusual.

In reply to codrus :

Okay, things are becoming clearer. The main advantage to coilover packaging then is the ability to adjust ride height without changing springs and their packaging size?

In reply to 80sFast :

Not entirely. The big benefit of coilovers for a performance car is being able to more accurately corner-weight a car so it's evenly balanced.  Effective ride height is generally dictated by the geometry of the suspension. Sometimes lower is better. Sometimes it's not.  

In reply to Ian F :

Meaning it’s easier to change out springs to address corner weights?