Not sure on 1.6 or 1.8 stock springs measured at top ..US source so I suspect 1.6 cars as they are the most heavily tuned/explored.

They will be different no doubt .. Eunos are different colour codes to Miatas at the least .. anyway the whole subject is a little dangerous anyway as no one gives out real numbers for fear that you will copy them .. and the stockists mostly do not know.

A '94 1.8 Miata has the following characteristics from which I could guess the spring rate with some large assumptions
Front; White mark, 11mm wire, 83mm Inner diameter, 293mm free length, 6.32 coils
Rear; Yellow mark, 10.1mm wire, 83mm Inner diameter, 348mm FL, 7.68 coils .

(12/99)

Changing the shock/springs is a VERY easy job. You will need a couple of spring compressors (about 20) and a good socket set and preferably a torque wrench but that's all. You can do it by yourself (I have done all 4 in about 4 hours), but for a first time a second pair of hands/feet are a big help for pushing and pulling at things to help you remove the shock/spring assembly.

For a total of 70 I would say that it would perhaps be worth giving it ago to see how it turns out, if it turns out bad you can put it all back the way it was for free and when you buy more shocks you'll save money by fitting them yourself (''cause by then you'll be an expert;-). Have a play with the Bilstiens before buying, visually check them for wear etc. The rod should be able to be pushed in by hand by a steady force and should return slowly when pressure is released. By no means a proper test of the shocks 'goodness' but it will at least pick out a really dead one. I know nothing about the Bilstiens ride quality or their life expectancy though. I'm pretty sure the shocks from 1.8 to 1.6s are the same as far as fitting specs go, but can't be sure. (1/01)

Is 35mm too much?

I would say thats about as much as you'd want to go. You could go to 60mm, but you're going to hit speed bumps etc all the time. I think the Eibach springs are fairly stiff.

Is there a better lowering kit out there?

Lots of spring kits out there. I think most 30mm lowering kits will work ok with standard shock absorbers, if these are in good condition.

I suppose any lowering will in theory improve handling, just because you're lowering the centre of gravity. But compressing standard shocks too much will quickly knacker them, and then you find back roads are a pain; often the car will feel its lsing control somewhat on roads with an adverse camber.

If you're doing the springs, and the car has more than, say, 30k on it, change the shocks while you're at it. Note, most direct replacement shocks will go the same way as stock shocks on madly lowered springs, unless you invest in an adjustible lower perch kit (the bit on the shock what the spring sits on). But then by the time you've figured these in, you're well on the way to something like a Koni kit or imported KYB AGX kit. Bilstein do a pricey shock/Eibach spring combo, but Spax do a good value complete kit (they're a lot better than in the past) (7/01)

My main motivation for fitting them is to reduce body roll and eliminate the choppy ride when pressed hard.

Although stiffer springs will reduce body-roll due to their shorter travel, they won't improve the ride. The cheapest way to keep the car more level in corners is to uprate the roll bars. The choppy ride can also be improved by a change of dampers. Tests in the States suggest that the handling suffers when excessively lowered, and the optimum geometry is achieved when the axis of the lower arm inner and outer pivot points are parallel with the ground. Lower than this and the roll centre actually rises, increasing roll. The general consensus is that standard springs, together with height and rebound adjustable dampers is the way to go, both for ride and grip. Ultra low cars might look quick round corners but they ain't ;-) (7/01)