I believe the latest iteration of the MX-5 uses the same shocks and struts as the RX-8. Anybody know for sure which year models are interchangeable?

 

The dampers aren't interchangeable. The NC Miata uses a shorter version of the RX-8 dampers. Though the attachment points are the same design, the lengths are not. If you were to use standard RX-8 springs or lower springs, they would not fit. However, they are a good option if you want to put coilover sleeves over the dampers and run coilover springs (essentially build your own coilover).

 

Thanks for the update. I was considering geting a set of threaded shocks from an ex-MX-5 cup car. What year did the NC body style start?

 

Started 2006

 

Soooooooooo, if I bought a set of threaded body shocks from an ex MX-5 cup car would these work on my 8?

 

Glad to see someone use the proper terminology.

The shock absorbers (shocks) are actually the springs.

The McPherson struts, which many folks misnomer the shocks, damper the oscillations, and thereby the more proper term damper.

"Coilovers" are integral springs (coils) and struts (dampers).

 

If you have high enough of a rate on your springs to soak up the decrease in droop travel then they can conceivably work, and I don't think that's too hard. My worry is that the change in body length of the dampers might necessitate a spring rate combination that throws off the balance of the car to get it to a proper ride height. However that can be remedied by the application of tender springs on one or both axle sets.

I would get the damper dyno'd to figure out what spread of springs they can take. You don't want to end up with a system that is too underdamped or overdamped. The NC Miata units are very suitable for building your own RX-8 coilovers in so far as since they're shorter, you don't need massive tender springs to get a good ride-height out of them while you increase the springrate, an issue I've run into while building my own RX-8 Bilstein based coilovers. However, top hat applications will still need to be figured out. See my Bilstein build thread for details.

And yes, the terminology has always bothered me as well.

 

neither the MX-5 nor the RX-8 uses struts, macpherson (a specific type of strut design) or otherwise. shock absorbers and struts are both dampers, and are wholly different in form and purpose from springs. shocks are not springs.

springs support the weight of the car; dampers damp the motion of the springs.

shocks and struts both provide suspension damping, but in different designs. in a strut design, the damper unit serves as both a moving and structural part of the suspension. struts generally support side loads; shocks generally do not. shocks, OTOH, generally do not serve any structural purpose, although in a coil-over design, they serve to support the spring.

some people argue (accurately) that all dampers are "shocks", and struts are simply shocks contained inside a load-bearing housing.

"coil-over" is a term that describes and spring/damper design in which the damper is located along the center axis of the srping coils. that design can use either shocks (e.g., rx-8 or miata) or struts (e.g., mazda3).

http://en.wikipedia.org/wiki/MacPherson_strut

http://en.wikipedia.org/wiki/Coilover

http://en.wikipedia.org/wiki/Shock_absorber

 

I think we're basically saying the same thing dmitrik4, although you may have better articulated.

Springs do support the weight of the vehicle and hence the term "sprung weight." They are also the 'first line of defense' when it comes to shock absorption. Consider the very ol' days when all there was were springs (leaf and then later coil).

Struts/dampers came later and serve to fine tune oscillation absorption or dampening (damper).

btw: the tower strut brace does indeed better facilitate side load rigidity.

btw2: sorry to take this thread on a further tangent, but I think the MX-5 vs. RX-8 question was already well answered.

 

shocks are not springs.

shocks=dampers

 

perhaps. not sure what you mean by "shock absorption." there are two components of suspension movement: distance and speed. springs control distance (i.e., how far the suspension deflects for a given input); dampers (shocks or struts) control speed (i.e., how quickly the suspension deflects for a given input).

springs by themselves do virtually nothing to damp oscillations. without a damper of some type, a spring will continue to oscillate until the energy it stores and releases is dissipated through friction in the spring itself. the damper functions by absorbing the "excess" energy stored in the spring, preventing that excess energy from being used to expand the spring beyond its resting state (which would otherwise then be re-absorbed as the spring compresses, etc). it essentially creates more friction in the system.

i don't know whether tower bars do anything to help; i suppose a properly-designed one might in certain applications. that's been debated ad naseum on every car forum i've seen. i was referring to the strut itself seeing loads that a shock does not.

one thing we can all agree on: if your dampers are "dampening," it might be time for a rebuild or replacement.

 

Shocks were springs long before dampers were invented.

All a matter of perspective. You say tomato and I (and Dan Quail) say tomatoe.

====================================

I see we totally agree on damping of oscillations via dampers.

 

actually, it was "potato."

i think the disconnect is in the use of the term "shock" or "shock absorber." you seem to be redefining it to refer to anything in a suspension that absorbs impact (which would/could include springs, dampers, bushings, tires, etc, or the entire suspension itself)...but everyone else seems to understand it as a term of art that refers to a specific type of damper. you might as well say "springs are apples."

 

thanks for hashing out the scemantics. if the ORIGINAL question had been answered already (will MX-5 shocks work and what mods are needed) then would someone kindly point me to that thread? my crappy search turned up nothing.

 

By the way, these "dampers" will be used on a track build so I'm not concerned about "road" manners only whether or not I can achieve a decent ride hieght with them. I've got to go down to the parts store now and ask the 12 year old behind the counter if he has any "dampers" for my tow vehicle, I'm sure he'll know what I'm talking about.

 

Just having a bit of fun. As an engineer, who also [atypically] has a pretty fair command of our ever-evolving English (American?) language, I occasionally get hung up on semantics in colloquial application as opposed to precise definition. Anyway, we all know what we're talking about here, and you better simply ask the 12 year old for "shocks."

 

dieselsdad-



from what i understand, the applications are very similar, some geometry issues notwithstanding. you might contact Shaikh at FatCatMotorsports, who has done a ton of work with suspensions on all generations of Miatas, including custom-valved Bilsteins for the NC. I think he's been looking into RX-8 applications as well; he's extremely knowledgeable, and if he doesn't have the info i'd bet he can point you in the right direction.

 

Thanks, I appreciate ALL of the comments, even the "colloquial engineer language".

I'll see if I can hit them up at FatCat. I purchased the shocks. If nothing else, I'll let everyone else know how it goes.

 

Here you go: https://www.rx8club.com/series-i-wheels-tires-brakes-suspension-55/custom-bilstein-build-up-thread-148914/

I'm working with Shaikh to hash out the RX-8 application. Provided I can find another source of 70mm tender springs by this weekend, I should have everything on the car and ready to do a little (very little) testing on the latest iteration right before I leave for Boston. Feel free to ask if you have any questions.

 

Please bring some Pasadena Sun with you to Boston!!

 

I have a 2008 NC MX-5 and I've been asking myself how much of an RX-8's suspension I could swap into my Miata as an inexpensive way to beef up the suspension, breaks and other parts. This is partially because I'm not a light person and I have a tendency to carry a lot of heavy stuff in my daily life. I'd actually be okay with a slightly higher ride if I could better soak up bumps before hitting the bump stops.

 

you’d be better off going here for your answers

https://forum.miata.net/vb/

some parts are and some aren’t, but for shocks/springs you’re better off buying aftermarket MX5 parts imo. The rear RX8 shock mount in particular is a lot taller than the MX5 with a longer shock to match. It’s not a direct bolt in.
.