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I disagree that the FM Springs are weak. Their spring rates are 318/233 which matches the damping of the bilstein's perfectly. You just can't run them too low as the shocks are too long for ride heights below 5.25 in.
After copious reading on both this thread and others I'm about ready to firm up my buy list. My use is a '95 base model doing 100% street driving with canyon carving when the opportunity presents itself - my unique call out is I have a bad back.
So I need it firm, fun, compliant and safe but NOT bone jarring. Here's my list, stuff I already have on the shelves I italicized:
NB Top Hats (because I had them and they need to be used)
Allstar Sleeves & Rings
QA1 Torrington Bearings
Energy Susp 9.6103 Isolators
FCM 36/46 bumpstops
FM Adjustable end links
IL Bushings all around & MazdaComp Eng/Diff Bushings
Mazda RSpec Tie Rod ends
FM 1" front SB (keeping the OE rear)
Bilstein NB B8's
QA1 400/300 7" springs
Other data points are the area I live has horrible roads in all the low speed residential zones but the main roads are fine. Also considering unsprung weight as I've added NB Sport Brakes and am prolly going with 225/45/15's on 8" +35 wheels.
Yes, the FM springs are weak and will allow contact more easily. Extended tophats may get you the travel you need to not contact as often but they still might under aggressive cornering on uneven pavement.
That sounds like it will give me what I am after. They are on the soft side and they are a compromise, but for where I live and the sort of driving I do with the car as a daily, it's a compromise that is perfect 90% of the time. 10% of the time it's too soft, but I've made the mistake of setting cars up for the 10% before and have ended up hatting having to live with them.
I am tempted to get another set of used shocks to set up stiffer for track days and just swap them in and out as I need them.
Originally Posted by emilio700
I disagree that the FM Springs are weak. Their spring rates are 318/233 which matches the damping of the bilstein's perfectly. You just can't run them too low as the shocks are too long for ride heights below 5.25 in.
It was your references to the valving matching the FM springs that led me down this path.
Interestingly, there is a post on the Australian mx5cartalk forum from someone who claims to be a former employee of Mazda. In the post he claims that after Mazda and Bilstein had developed the suspension together, Mazda changed the spring rate without consulting Bilstein and that is why Miata Bilsteins are over damped. In the post he claims that the original spring rate agreed on by Mazda and Bilstein was pretty close to FM spring rates. What is also interesting is I'm pretty sure this post is from before FM released their springs. Unfortunately, the post is so old I can't find it anymore.
Now, I have no idea if the post is true. But it is interesting that you and FM seem to have come to the conclusion that this is the spring rate these shocks are valved for. Could it be that the story is true and people such as yourself also found out somehow? Or is it just folks who know suspension knowing how to work these things out?
Originally Posted by HarryB
How's your ride height with these? Any chance that you also have free-length data?
To be fair the Bilsteins are not perfectly valved for that spring rate. A bit too much low speed compression damping for street use and not enough high speed rebound damping for track use. The Bilstein uses the same basic valving front and rear but a Miata needs different valving front and rear.
So while not precisely ideal, the spring rates of the FM and Tein springs are closer than OEM or what's used in Spec Miata. After all is said and done though, they still have better damping than most <$1,000 aftermarket coilovers, which is why this thread exists
I'm in the middle of moving house now, but I'll get some pics as soon as I can.
Also, noob here, what is free length?
*edit*
You mean free length of the spring? I didn't measure them, but on the front without extended top hats, I didn't have to use a spring compressor. The spring was just slightly compressed by hand to get the top hat on so the spring is captive, but only just.
On the back, they needed spring compressors to get them on with the extended top hats. Once on the car, the compression is taken up by the lower rate at the top of the spring though.
Not to hijack the current conversation, but does anyone have a source for extended top hats?
I am just now getting around to assembling my bilsteins (we moved and that took over life for a while) and can't find extended top hats in stock anywhere.
Not to hijack the current conversation, but does anyone have a source for extended top hats?
I am just now getting around to assembling my bilsteins (we moved and that took over life for a while) and can't find extended top hats in stock anywhere.
Not to hijack the current conversation, but does anyone have a source for extended top hats?
I am just now getting around to assembling my bilsteins (we moved and that took over life for a while) and can't find extended top hats in stock anywhere.
But also, they say "ONLY FITS Ground Control coil-over kits.". I have no clue why that would be true, but $250 is a lot to find out.
Thats doesnt make any sense to me. Their "coilover kits" are just a spring and sleeve deal. It works with an OEM top hat so idk why it wouldnt with their extended top hat.
Know anybody with a lathe and a MIG? It would be a pretty easy DIY job.
On an aside, I like the FCM spring isolators from 5XRacing over the EnergySuspension ones.
EDIT: Yes, that Japanese link works.
Thank you! Email sent. If I end up getting them from Maruha I will go ahead and get a few sets in case some people here want some.
Originally Posted by Full_Tilt_Boogie
Thats doesnt make any sense to me. Their "coilover kits" are just a spring and sleeve deal. It works with an OEM top hat so idk why it wouldnt with their extended top hat.
Know anybody with a lathe and a MIG? It would be a pretty easy DIY job.
I am with you, I do not see why it would matter. I would just be afraid to spend $250 just to find out that it doesn't work for some dumb reason. Unfortunately I do not know anyone with a lathe. I do know someone with a MIG though. But I think it would be tough to get the cuts centered right without the lathe.
Do you have a 3d printer? Print a bush that sits in the center of the top hat and use it as a guide for a 2.5" hole saw. Might want to swap the pilot bit for a dowel if you use plastic, either that or sleeve your bushing.
Got my coilovers assembled and installed. The start of the track day season was a great motivator. Prior to buying the ISC extended tophats, I was looking at my total and thinking "I probably should have just bought Xidas" and then once I added the tophats, I was thinking "wow I really should have just bought Xidas". But, you live and you learn. These did great at my first track day last weekend, but it was also hard to get a feel for their performance since it was pouring rain the whole weekend. Hopefully I can run them with Hoosiers at the next one and give a real report on their performance.
Brofab E30 hubs installed at the same time, these should be able to handle the Hoosiers!
I am getting some rubbing that is a little concerning. Both coilovers on the passenger side (it is a CCW track) had this rubbing on the coilover sleeve. Should I be worried?
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