I am using a set of EBAY coilovers with 450/250 lb/in springs on SD revalved Bilsteins and FCM bump stops. Currently I have no spring isolators installed under the NA top hat to locate the spring. I have read some threads about this being acceptable. The fronts are fine but it sounds/feels like the rear springs do move around when I back out of my steep driveway and hit the curb or drive over a speedbump at an angle. At any speed above 10mph it seems to do just fine with no noises or movement. I need to do some simulated autocross slaloms to test this though. Higher speed interstate on ramps and exits are fine as well as transitions. I can get the springs to stay in place but this requires some preloading on the springs which results in 15"++ ride heights.
My question is, do I have to have spring isolator installed like the one FCM sells(or even energy suspension) to keep the spring centered or will it center itself?
I am 90% sure I will go ahead and get the whole FCM mount and 2.5" coilover spring isolator, but it might take a while to get here and I have a trck day coming up. Will I hurt anything running without these isolators?

 

They only time you should ever "hear" them, is if they have dropped down...which means you need to be at some substainal amount of droop.


you really dont need them. but it sounds like your rear springs are just entirely too short?

 

I am running 7" front and rear. Doesn't sound/feel like it is bottoming out though.

 

think about what happens when you put the car down on the springs, they compress. so they springs should always be under compression and stay "seated".

they only time they could potentially fall/rattle is at full droop, where there isn't enough preload on the spring perch to keep them fully seated.

So what I'm saying is, the only time you should ever be hearing them is if at droop they are too short and do fall off the top mount.

easy test would be to jack the entire rear up and see if you can move your rear springs around. if htey are still under some compression, that's not the noise you are hearing.

 

Brain, I understand what you are saying, I am thinking it might be more of a coil rubbing on sleeve issue then. I will get the car up on jackstands this weekend and see for any rubbing evidence. The funny thing is that I hear it in the rear and the rear springs are slightly compressed at full droop where the fronts springs are off of the top hats at full droop. I have not noticed any issues on the front though.
Let me ask you this. Do you run some kind of top spring isolator/locator?

 

I don't have them on my daily and there are no noises or whacked out springs...and one spring is bent from an old shock failure.

 

You dont need them or the FCM stuff, try ICS top hats for the rear ansd facory nb hats for the front.

 

I am leaning more and more towards just running straight NB mounts since I am trying to stay close to factory ride height. Now I am just trying to find just 4 of the toughnuts needed to fit the Bilsteins. I might just get 10 nuts for $38 and sell the rest of them. If I run an insulator I will more than likely just run the ES universal 2.5 insulator. I could not see a justification for the FCM $100. I am also not getting any luck communicating with FCM since I am trying to find out if I can get these mounts shipped in 2 weeks. I have panicmotorsports just down the road from me, so I might just swing by there and get a ?NB set this weekend.

 

I think your confused about what the parts do. The nb/ics/fc top hats are for travel which you need. Forget about the spring isolater 1000 spec miatas across the country don't have them.

 

U have sleeves. Ride height should not be an issue since it can always be adjusted.

 

Well I figuired since I am shooting for close to stock ride height and am using the 36mm FCM bump stops I should be ok for shock travel concerns. I realize more is better.
I want an insulator not for the insulating part but more to locate the spring and keep them from rubbing on the sleeves. I have been screwing around with a ring or blocks that I am planning on welding to a spare set of tophats that wil keep a spring in place around the OD instead of the ID, this way I do not have to glue am isolator in place and I am not adding any kind of spacing in between the shock and top hat.

 

I want to revisit this before I button up my ebay coilover/QA1 spring setup. A set of isolators from FCM is $52 shipped. I bought a used set of sleeves that seem to show the common wear pattern at the top of the sleeves. I as well am concerned about the spring remaining centered on the top perch.

Any new opinion/consensus on need/not need spring isolators???

 

I have never seen them on an IT car. That says enough for me.

 

Thanks for keeping money in my pocket.

 

Yup its not needed and an added expense that could be spent on bumpstops or hats for travel. The key to Bilsteins on a 90-05 Miata is travel. You need to minimize the amount of material under the hat(washers/bushings), run a shorter/cut/proggressive bumpstop, and add travel through hats. 99 front hat/ICS rear on 700/350 is a plush ride compared top NA hats with factory bumpstops and 450/350. Watch out how much crap you add under the hat, everything you add on the shaft under the hat takes that much travel away. I normally run a thick fender washer and a small rubber washer under the hat then used the rest of the leftover washers and big rubber isolaters on the top. I need to make a youtube video of how to setup a Miata Bilstein.