Evening all.
My 92 Eunos has standard shocks and springs which I’m more than happy with, however I also have a set of NA MX5 Bilstein shocks. Can I run my standard springs on these? What am I likely to gain/lose? 10mm lower ride height and slightly firmer ride?
The car is only used for normal road use.
Thanks in advance.
Hi Matt
My advice is to fit the Bilstein shocks by all means but with the Bilstein springs they were designed to work with.
Given the state of roads nowadays Bilsteins give a rough ride. Down here in Devon our Eunos came back from an MOT test with 2 of the Bilstein shocks(one front and one rear) pouring oil. Obviously the car had been dropped down off the ramp way too quick. I had to make a quick decision and replaced with MK2.5 standard suspension which raised the car to UK spec height or thereabouts. Best move ever as car rides stiffer than MK1 standard shocks but no bottoming.
Trying to fit a standard spring into a shorter bistein shock is not something I have done or heard of being done. In my opinion it will not work well as you would be increasing the preload on the springs and departing from their characteristic action when in use.
Suspension is about the springs - the shocks are just a damper. If you depart from standard setup on these you could be lucky but are more likely to compromise the ride and road holding.
I would sell the Bilstein shocks and stick with the MK1 standard that you are happy with.       Â
On Bilstein cars, the front spring is identical to standard; different part number for the rears. Given that the S-Specials don’t sit nose up, the length of the rear spring is the same as standard, just stiffer (110lbs not usual 97lbs). The Bilstein has a much higher rebound rate than standard Showas, but the compression rate is lower. MX5 suspension guru Shaikh provides an excellent explanation why the Bilstein ride is what it is:
https://www.youtube.com/watch?v=ahkmJ6earo8
The Bilsteins hit the bumpstops a lot; jacking down. Mazda fitted shorter bumpstops on these cars, but you can’t get replacements. Attention to the bumpstops is why some users have reported improvements fitting Audi A3 bumpstops.
The confusion arises because most S-Special Roadsters have had aftermarket lowering springs fitted. Bilsteins aren’t shorter; they have a spring perch 10mm lower than standard. You should be aware that Mazda fitted modified trackrod ends to reduce bumpsteer.
Excellent video showing the factory Bilsteins on a Miata LE; a S-Limited in all but name
https://www.youtube.com/watch?v=PUyLtPk8JT4
Hint; changing the springs isn’t issue.
Hi Matt
A good post above which unfortunately highlights glaring errors in my contribution. I am not going to edit my post but please ignore the parts that are obviously incorrect.  Â
Hopefully there is someone out there who has fitted standard springs on Bilstein shocks to their NAÂ and can report back from personal experience.
The many MX5/Eunos cars I have seen with Bilstein shocks all sit considerably(more than 10mm) lower than standard. It would be interesting to know the ride height with a standard Bilstein shock/spring setup. Interestingly MX5Parts sell Bilstein shocks and most everything else but not Bilstein springs.
A lot of the ride quality issue with Bilstein is hitting the bumpstop which is explained above. Has anyone successfully modified the standard bumpstops to prevent/limit this?     Â
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Hi Matt,
When I got my eunos, it had had its bilsteins replaced with standard shocks. In an effort to
go back to original, I sourced bilsteins and fitted standard springs, including bump stops from mx5parts.
The car sat around 10mm lower and after a wheel alignment, they were just fine.
The bilsteins give a much firmer ride than the standard and for me it’s too harsh, especially on the roads I tend to drive on.
So I sacrificed the 10mm and went back to standard and have been very happy with them.
Hope this helps,
Steve
Â
Couldn’t wait to get them OFF my VR. Made driving VERY unpleasant on the roads around here (Derbyshire) so the car simply stood, unused, for days on end.Â
Maybe they’d be fine if you do nothing but drive on Motorways and run the occasional track day though?
Since replacing them it’s really nice to jump in, go for a good drive and know you’re going to come back with all your fillings in tactÂ
Back in the day, people used to trim the standard bumpstop. Then Fat Cat Motorsport came along, and made that a lot more scientific. The problem with looking at ride heights on cars 20+ years old is that the springs sag. If you look at the original press shots (not the staged studio photos) on the Mk1, even for early cars, its surprising how high they ride. And they quickly settled, enough to convince people later Mk1 springs were somehow different; they weren’t. Even Mazda’s specs for ride height has a wide range of tolerance.
Early UK car, when brand new. Anyone actually remember a 1990 car sitting this high?
The only springs that were “Bilstein springs” (they weren’t made by Krupps Bilstein) were the rear springs, which were a little stiffer.
No Mk1 MX5 came with Bilsteins from the factory; only Miatas and Eunos Roadsters. I think the uprated orange KYBs were available in the UK, or they appeared in the early Finishline catalogues.
Many years ago, I tried a stock S-Special straight off the boat; it had a normal ride height, and the ride, while firm, was actually fine. Given it had pretty much the same springs as standard, I suppose thats close to your request.
There is a whole industry in the US that is based on modifying the original Bilstein. It can be made into a very good shock.
Perfect, thanks everyone for all the help & advice. I’m all about getting the car back to original spec, with the exception of one or two of the period Mazda shop options (hence these Billies), oh, and the missing V-Spec boot w/spoiler & beige mohair hood… but the correct items are safely stored in my parts stash though.Â
I may just finish the Bilstein cosmetic refurb and move them on. My car has 1 Y.O standard springs and sits pretty much where the press pic from saz9967 sits I think:
That clearance looks very similar to my 1997 car Matt -Â an extra couple of inches higher to allow people like me to get out without twisting something:-)
Car looks great!
What did you replace them with?
Koni Sport Kit, MX5 Mk1 (mx5parts.co.uk)
Prices have rocketed though. I’m sure they were in the region of £425 when I bought them! (But that was about six or seven years ago.)
To be honest I preferred the KYB AGX’s I had on my earlier Mk1 but the Koni’s adjust from the top mounts whereas the KYB’s required contortions to reach the adjusters on the body of the shocks, inside the wheelwells. If I was still young and agile I’d have gone for them again though.
