replaceable coilover shock/damper bodies?

Just curious.
I noticed a lot of coilovers have a similar damper style.
It's basically a big black cylinder with the piston sticking out. and the whole body is just threads.

Is this an industry standard? 
Are the threads (the pitch/size) going to be the same on any coilover?  How about diameter?

I'm just wondering because if they are at least somewhat common, then wouldn't it be possible to get a second hand set of ebay coilovers then 
simply swap out the damper catridge for something high end!?

Seems like an easy way to get some high end track coilovers for much much cheaper.

Not standard and you may be starting with a fundamentally flawed design.

And the "cartridge" is the bit that's going to be expensive.

Obviously, and it depends on the brand.
but the "packaging" around the cartridge is prettymuch good no matter what brand you get.

That's why ebay coilovers are so popular nowadays. they look like thousand dollar coilovers. but the dampers inside are crap.

Also I live in california. so things like corrosion, or threads getting jammed are not something I have to worry about.

But the packaging is not pretty much good. Watch the video for examples of why. That set of coilovers in my hand were limited in travel to the point where you couldn't even run a stock ride height. There's a reason none of the good coilovers for a Miata have adjustable length bodies. Oh, and if even if you solved that problem you'd be stuck with whatever spring rate they used because it was a weird diameter.

If you took that orange set of coilovers and threw away the upper mounts and the shock cartridge, you'd end up with a coilover that was limited in travel but not tragically so. Then if you managed to find a supply of quality springs in the weird diameter and the rate you wanted, you'd have potentially a decent setup. How much do you end up saving?

eBay coilovers are popular because they're cheap and people buying them think they've unlocked some secret. But in reality they're learning the hard way that sometimes you get what you pay for, and sometimes what you're paying for is very basic engineering from someone with some understanding of the platform they're designing for.

The only time I've seen something like a universal cartridge being used for different cars is when people build their own rally coilovers. There's at least two people who have done that in their build threads here but they're doing a decent amount of fab work for it to work. Basically they end up building their own struts using some stock bits and some high end bits. I think it's because they can't get purpose built rally parts for their cars, or because they want more suspension travel than the stock pieces supply. 

Edit:

These are the two threads:

Volvo 240 Rally Build 

BRZ Rally Car... Eventually

Keith Tanner said:

That set of coilovers in my hand were limited in travel to the point where you couldn't even run a stock ride height. There's a reason none of the good coilovers for a Miata have adjustable length bodies. Oh, and if even if you solved that problem you'd be stuck with whatever spring rate they used because it was a weird diameter.

Why is that important? The overwhelming majority of adjustable height coilover systems for all cars aren't going to get you up to stock ride height and it's not really a good indicator of quality by itself.

They can't get DOWN to stock ride height. Which is fine if you're setting up for rallycross and a problem in just about every other aspect. Even for rallycross, you'd find yourself running out of travel much earlier than you would with stock shocks.

There's a video.

Keith Tanner said:

They can't get DOWN to stock ride height. Which is fine if you're setting up for rallycross.

Ah yes, ok.

Tadope said:

I'm just wondering because if they are at least somewhat common, then wouldn't it be possible to get a second hand set of ebay coilovers then 
simply swap out the damper catridge for something high end!?

Seems like an easy way to get some high end track coilovers for much much cheaper.

I mean technically yes you could potentially do that. But the cartridge is the expensive part. A properly tuned "universal" damper cartrige with cheap outer housing would probably be 80-90% of the cost of just buying the complete nice damper. And would still potentially suffer from the packaging issues that Keith is talking about. And you'd have to do the math/research/experimentation to make sure you got the right damper insert which could potentially take a few iterations to get right, and there goes your cost savings and then some if you odn't get it right on the first try.

thatsnowinnebago (Forum Supporter) said:

The only time I've seen something like a universal cartridge being used for different cars is when people build their own rally coilovers. There's at least two people who have done that in their build threads here but they're doing a decent amount of fab work for it to work. Basically they end up building their own struts using some stock bits and some high end bits. I think it's because they can't get purpose built rally parts for their cars, or because they want more suspension travel than the stock pieces supply. 

Edit:

These are the two threads:

Volvo 240 Rally Build 

BRZ Rally Car... Eventually

 

 

 

Pretty sure irish44j also made up a set of new struts for his E30 from a set of tubes and off-the-shelf Bilsteins.

It's really not all that much fabrication.  Get tubes, add ears, zip zap done.  Chris's Frisbee is a fabrication fun job because he wanted to ensure that he didn't run out of travel at the wrong times, so he went with longer strut tubes/shocks and raised the chassis mounting points a bunch.

Even a hack like me can do it... did a set of Subaru struts, with another set of ears to get the right bolt spacing, so I could run WRX Koni inserts in an RX-7.

You can revalve the bc coilovers.  My understanding is the shafts are the same size as something else that isn't as janky and you can swap out the interal bits with quality parts.

Revalved BC coilovers for motorsport use

Back in the early 2000's I built a set of coilovers for my b13 SE-R with koni 8611 inserts and ground control collars and camber plates.  They certainly were not inexpensive though.  I had around $2,000 in the components to build them.

Ok, that video is not a good example because they just happen to use the "one bad egg".
There are literally thousands of reviews of cheapo ebay coilovers that lower plenty more than anyone would need.
Sometimes they don't go as low as people want. Sometimes they drop you to the ground. 
I have heard more horror stories about miata  ebay coilovers for some reason.  Perhaps the miata chassis just has bad luck with ebay coils?

Personally I'm running an audi tt MK1 .
And this chassis unfortunately has very few brands selling coils for it. The problem is that the TT comes in FWD as well as 4WD. So most coilover brands just build a FWD kit.  

Anwyays. I'm still learning the car, so I want a cheap setup to start off with. That way I can feel out what springrates work, and how the dampers feel.  Then after I do all that, I can then upgrade to a proper track ready setup at around $1k 

Ebay coils are getting very good at listing the springrates that they come with. And you can see videos/reviews of other people that installed them already. That way you'll know exactly those coilovers are going to do. What kind of drop you'll get, what kind of suspension travel, spring rate, and even how firm the shocks are.

I am simply hoping that I can take the cheap coil setup, and then swap in a high end damper cartridge later on. 
I'll also be trying many different springrates eventually.

Let's run through an example. I'm going to use YCW for the sole purpose of that's what I know from having just custom spec'd (body lengths, shaft travels, and spring rates) a setup from them, and their options pricing is readily available on their website. 

List price, as optioned up with spherical (NSK bearing standard) camber plates,  industry standard 65mm ID Swift springs, and fully assembled, the list price on them is $1650.  If you stick with stock style rubber mounts, it would be $1550.

Assuming that their threaded body is the same diameter (52mm) and pitch (1.5mm) happen to be some type of 'industry standard', to spec out the same 'cartridges' would run you $320 per front and $300 rear (or $1240 total) at list price.

Now you've still got to source all of the mounts and springs for $410 with sphericals, or $310 with rubber. Is it possible? Sure. But where is the value? What exactly are you gaining at that point? You'll be spending very nearly as much, having to put the time and effort into sourcing, disassembling, and reassembling them into the desired configuration, and then still ending ups with hardware and springs of unknown (dubious) quality.

So the Ebay coilovers tell you springs rates. Neat. Do they also tell you damper body length, shaft travel, and spring travel?  Without that, you'll be just as likely to run into problems with coil bind and/or bottoming the suspension at your chosen spring rate and ride height. Running crap dampers and crap springs also doesn't necessarily correlate directly to what you would end up wanting to run for your later quality dampers and springs. They may just as likely end up feeling totally different to each other.

Tadope

Keith is the one who made the video.  He designs suspension components for a living.  I would trust him when he says there is no free lunch so to speak.  His video does a good job of explaining why.

I think the point folks are trying to make is instead of buying cheap components and later upgrading them, just save up until you can get something quality.  You will be better off in the long run.

If you don't have the money at the moment for a quality set of coilovers.  A set of bilsteins or konis and some lowering springs will serve you much better than a set of chinesium coilovers.

Tadope said:

I have heard more horror stories about miata  ebay coilovers for some reason.  Perhaps the miata chassis just has bad luck with ebay coils?

...or perhaps Miata owners have higher standards. It's a handling platform and there have been a number of very skilled people working on optimizing that handling for over three decades. Other platforms may be more focused on other attributes.

The video illustrates a point - by starting with those cheap coilovers, you are immediately handed some constraints. They may be constraints that hamper you until you replace every single part of them. Or they may not. Simply assuming that quality coilovers and minimum viability coilovers share a lot of attributes can get you in trouble. 

I've had platforms with little or no aftermarket support before. I modified a set of Protege5 struts to make my 323GTX work, for example. If you're lucky enough to find a quality shock insert that fits something else, awesome. But you're going to have to go looking for actual specifications and measurements, and I suspect that you'll have better luck adapting a quality setup for a different car than trying to make a set of crap coilovers into something that's not crap. 

Your TT shares a platform with a LOT of performance cars. I suspect the bulk of quality parts will come out of Europe. You've also got a lot of factory upgrade options you could play with. I'd concentrate on that instead.

Keith Tanner said:

Tadope said:

I have heard more horror stories about miata  ebay coilovers for some reason.  Perhaps the miata chassis just has bad luck with ebay coils?

...or perhaps Miata owners have higher standards. It's a handling platform and there have been a number of very skilled people working on optimizing that handling for over three decades. Other platforms may be more focused on other attributes.

The video illustrates a point - by starting with those cheap coilovers, you are immediately handed some constraints. They may be constraints that hamper you until you replace every single part of them. Or they may not. Simply assuming that quality coilovers and minimum viability coilovers share a lot of attributes can get you in trouble. 

I've had platforms with little or no aftermarket support before. I modified a set of Protege5 struts to make my 323GTX work, for example. If you're lucky enough to find a quality shock insert that fits something else, awesome. But you're going to have to go looking for actual specifications and measurements, and I suspect that you'll have better luck adapting a quality setup for a different car than trying to make a set of crap coilovers into something that's not crap. 

Your TT shares a platform with a LOT of performance cars. I suspect the bulk of quality parts will come out of Europe. You've also got a lot of factory upgrade options you could play with. I'd concentrate on that instead.

Higher standards for miata drivers? Miatas are like THE #1 hooptie track car builders out there! Not that i'm hating though (plenty of impressive hooptie miatas) but i'm just saying, the most common miata you'll see out there will be lacking any polish and be a bit "slapped together".

Also the problem shown in the video was that the kit provided zero lowering at its lowest setting. That is a very specific issue, and has nothing to do with "quality".
It's an obvious case of a company that makes a ton of different applications, and does not bother to make sure that every single application fits properly.
Expensive brands probably have a 99% perfect fitment rate. Ebay coils are probably 80%.   Which is pretty bad. But can be avoided easilly by simply looking up your product before purchasing.

If you think Miatas are hooptie track cars, try to beat one in the Thunderhill 25.

The video showed a large number of problems and not a single redeeming value of the parts, but you're not going to believe them. You're here to be told how clever you are, not to learn. Good luck with your build. 

Tadope said:Higher standards for miata drivers? Miatas are like THE #1 hooptie track car builders out there!

There are a lot of Miatas out there.  Some of them are driven by the same sort of folks who prefer the 5th generation Golf because you can get the negative camber in the rear just right, handling doesn't matter as long as it looks a certain way.  Some of them are driven by old farts to and from the golf course on sunny days, handling doesn't matter as long as it is pleasant on the road.

A LOT of them, however, are used very seriously on track, both in noncompetitve and competitive form, and they have been a force to be reckoned with at autocross since 1990, and very serious people have approached their handling in a very serious manner.  Handling matters because there are twenty-five other people in your class with the same exact trim as yours and the margin of victory is measured in hundredths of a second. 

There is a very good reason why the Miata is the Answer.

There's plenty of cars that aren't geometry limited and a short stroke damper isn't really an issue....but there's also plenty of cars that are. And when you're bringing lowering into the equation, you don't really know if it's an issue or not until you find out the hard way it doesn't work. But as we've already established, the method you propose is, in a lot of cases, an okay way to get 90% of the performance for 80% of the price and 1000% more effort. So if that's what you want to do, by all means please go for it and report back on the results.

In reply to dps214 :

Some of my friends won a 24 Hrs/lemons race with a Celica Supra with the springs cut so short that the bumpstops were the suspension.

Any suspension geometry works if you don't let it.

Now, that's not to say it handled the greatest, of course, but for the money, it worked okay.

Meanwhile, if you want something that is forgiving of driver inputs and track undulations and crests and dips and curbs and stuff, you need suspension travel, and with travel comes need for good geometry and damping.

Good point. From what i know, F1 actually incorporates bumpstops heavily into the suspension tuning of their cars.
And i've actually gotten deep into virtual car tuning via sims like assetto corsa, and rfactor2.
Cars absolutely handle better with some bump interaction at the end of the suspension stroke.

I found that giving the car enough travel to never touch the bumpstops was far worse actually.

In an attempt to answer a specific part of the original question- yes, there are some semi-universal thread dimensions.  If, for example, you can find something that matches threaded Bilsteins, you could potentially interchange parts.  Same with (differently) threaded AFCOs or Fox or similar.  That said, by the time you figure out what has a copy of which higher end damper's thread pitch/diameter, you've effectively just bought different perches/ends/ears and it's debatable whether you've gained anything vs just going with the complete Bilstein/AFCO/whoever coilover in the first place and making adapter-y bits to fit it on your car.

If somebody with MaxPeeDingRods wants to measure the thread pitch/diameter I can tell you if it matches the fine thread Bilstein stuff that looks sort of similar.

Also, since I figure that the Audi TT might be a more popular platform elsewhere and you're having trouble finding off the shelf options, I looked on Demon-Tweeks in the UK and see at least 5 brands selling coilovers for that platform pretty reasonably.

Thanks thats what i was wondering about