Hi all, this is possibly a completely stupid question but have been looking at renewing my shocks and springs and whilst looking on mx5parts website they offer KYB AGX adjustable shock absorbers and a Gaz classic coilovers kit…
Do both these products do the same thing?
As my dear old dad used to say “There’s no such thing as a stupid question, Nobody knows everything”.
The term “Coilover” refers to a spring that coils around the damper (Shock absorber). Cars used to have them mounted separately, But these days most cars use a design that combines all the suspension and steering into one unit (A McPherson strut).
The MX5 uses a (Better but more expensive to make) double wishbone design with a combined damper and spring unit on each corner.
OK, Now we’ve done the basics, Back to your questions.
The main differences between a damper and a Coilover (With reference to an MX5) is that the Coilover is the whole of the suspension unit with the spring included and the shock absorber doesn’t.
The adjustable bit adds another little twist though.
There’s 2 main types of adjustment that a Coilover can come with (Everyone, Please don’t start overly complicating this by saying I should be treating bump and rebound separately, Who here has a kit that can change them independently anyway…? Thought not. 
)… Anyway, First adjustment is “Damper rate”. This refers to how easy or hard it is to move the dampers piston up and down. Some dampers are fixed at one rate, But some give you the ability to adjust them, This means (In a very basic fashion) that if you predominantly drive on pot hole filled lanes you could set them to have less damping force for a gentler ride. On the other hand, If your going to drive on a perfectly smooth race track you can make them harder to help with the handling. One is usually at the detriment of the other though, It’s rare to drive a car with great handling AND a comfortable ride.
The second adjustment is for “Ride hight”. If the Coilover has a threaded section that holds the bottom spring mount you can adjust the length of the Coilover to make the car sit higher or lower. On the MX5 most people lower it for the style benefit as the handling’s pretty good as standard but there are other pluses (I’m not getting into CoG and roll centres here, This is already turning into a bloody long post).
After doing any Major suspension work, Always remember to have a geometry check done.
Thats basically all you need to know about MX5 suspention…So I’m off to bed now. Night night.
Scotty B.
The AGX dampers are adjustable for damping but are not supplied with springs. The GAZ Classic kit comes with adjustable dampers which also have adjustable spring platforms (to allow adjustment of the trim/ride height) and is supplied with a set of springs. The GAZ items have more/finer damping settings.
Good, clear and informative post which I’m sure many people will find very helpful.
Thanks Scotty B, that was a lot more info than I expected to get, thanks for going into so much detail, and keeping it fairly straightforward for me to follow.
After digesting the info, I think I will settle on the Gaz classic coilovers, as they seem to be more adjustable and I can play around with them to suit my comfort settings…
Thanks for the other posts… now just to decide whether to do the dirty work myself or get the coilovers and visit my local friendly mechanic…??
Oh, what is a geometry check and is this something a local mechanic can do or is this a specialist job?
Thanks Scott
One of the best things about the MX5 is that pretty much everything too do with how the wheels sit on the ground can be adjusted… BUT, That also means that the possibility of getting everything setup wrong is infinitely higher.
Rather than going though all the aspects of what a cars “Geometry” actually refers to, I’ve found a website that explains it quite well… Click here (No point rewriting something thats already been written a hundred times on the Internet 
).
This isn’t something that your local Quickfit can do, It’s about an hours work using some bloody expensive equipment so most places charge around £100 to do it, But the difference it makes means that it’s the best £100 people can spend on their MX5.
Scotty B.
Hi
You can do a full alignment yourself, but only if you know what you are doing and have a few simple bits of home made gear to help. It takes me a day to do including thinking time and setting up my raised level working area. I’m retired so I have the time, also I do not have the cash to pay somebody else. Also there is the satisfaction of completing a well done job oneself. Incidentally my home made bits include lasers, so I could claim to have done a “laser alignment”. Don’t worry, I do know the difference between that and a full geometric alignment. Most normal people will pay somebody else to do it.
Alan
Completely agree.
Some owners claim to be able to do it themselves, but even if you accept that, it requires a lot of knowledge, care and skill. If you’re not even sure what “geometry” (no discourtesy intended), then take it to a competent specialist workshop. Even a Mazda main dealer will not necessarily have both the necessary equipment and operator skill, so you need to find a specialist.
And indeed, it is £100 well spent.
Thanks for that guys, I’m going to spend some time seeking out a specialist here in Northern Ireland, but I’ll not hold my breathe at finding one, thanks again for the advice, really can’t wait to make the changes to my mx and get the new coilovers on…
Scott
Good plan! If you don’t have any luck in finding one through this forum, try asking here:
http://www.mx-5.com/Forum/Room/?roomId=11
I believe there was a poster on there from NI who eventually did manage to find a suitable alignment specialist. Otherwise, try contacting Tony at Wheels-in-Motion - a very helpful guy who is amazingly willing to advise people who live too far away to visit his workshop in Chesham.