Better / cheaper to use coil overs?

Hi all,

I’m looking to lower the stance of my mx5, it by a crazy amount, and there’s some fairly cheap sets which may be the trick considering how little I’ll actually be driving the car (eg, not a daily driver).

The alternative is the old fashioned lowering springs.

My question therefore is what is better / cheaper. Springs are lower price than coil overs but I imagine the labour cost is greater in comparison.

It’s not a race car, it’s just a nice little summer car to come out on nice days.

  1. My model of MX-5 is: mk2.5
  2. I’m based near: Durham
  3. I’m looking for technical help or recommendations on: lowering

All I did on my 2.5 sport was fit the shorter eibach springs, with original shocks, it’s been like it a long while now, and never a problem, a bit lower so the chance of grounding out is greater but still a rare event. Worth it for the improved look I think.

Eibach lowering springs are the way to go, they will give the car a nice stance.
If by cheap coilovers you mean the ebay sets for under £300, don’t waste your money they are out and out dangerous.

With other users on Eibach, maybe try to score a nice set of factory-optional Bilsteins for firmer damping, which suits the springs a bit better.

Labour to fit either will be the same. If fitting springs, fit good quality ones.

Another well regarded brand to consider is California’s Racing Beat. Racing Beat are basically the people behind Mazdaspeed products since about 2004, and naturally have a close relationship with Mazda

Interesting that their NB1 springs are a bit different from NB2.

Also Tein

https://uk.tein.com/srch/uk_search.php?maker=MAZDA&carmodel=MX-5&modelyear=1999-2005&item=default&genuine=0&tuvchk=0

What’s important to thnk about is the rear spring bias (spring rate ratio); how stiff the rear springs are in comparison to the fronts.

Different springs were fitted to various NBs.

Front/Rear:
Stock NB: 162/118 lb per inch
Tein S Tech: 235 / 173
Eibach Pro Kit: 228/137
Racing Beat: 195/145

So, you will notice a very different ration with the German Eibach compared to the Japanese Tein. Tein keeps closer to the factory split.

Someone with a great deal more knowledge than me on MX5 suspension said:

“Grip varies inversely with roll stiffness. Thus, if you stiffen one end’s springs or swaybar, it will lose grip and slide at lower loads than previously. E.g., stiffen the front to get more understeer (or less oversteer)”

So softening the rear spring decreases oversteer(more grip at the rear) but increases understeer. The Japanese like a looser rear end for more “sporty handling” in gymkhanas.

Spring rate can be misleading. It depends on the shock. A good shock can have apparently very stiff springs, but the ride quality can be fantastic (eg. P5 Puredrives). Standard shocks might be overpowered by stiff springs, and the ride can end up choppy.

If you are not fitting yourself, I would seriously consider at the same time also replacing the shocks, or at least renewing things like the bumpstops. The lower featured “name brand” shock-springs sets (Gaz, Koni, Tein) will be better than the Chinese (PRC or Taiwanese) sets, which are generally built around a generic tube (this is why they have gone for these “extandable shock bodies”; its a way to use the same shock on many different models, with easy changes). At the really cheap end you have the Raceland/Rokker coilovers (adjustable for height, fixed shock body). The shock body, when cut open, turned out to be containing a shock insert stuffed in a threaded tube, probably for something like a Micra. I’m not sure i fthis is basically what the Vmaxx shocks are.

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Adding, changing the shocks is actually a pretty straightforward DIY job. After changing a clutch slave cylinder 25 years ago, in a MX5, this was the second DIY job I tackled (and I had never tried car DIY before in my life; the major factor was being an underpaid University Research Fellow at the time, when mortgage rates were ~8%…). At the tme, Miata.net gave me enough information to fit Racing Beat springs and some used Bilsteins.

Garages will charge ~3-4 hours labour, which these days, can translate into £150-400.

That’s a big chunk of change towards renewing some of the other suspension parts at the same time. There are different views of when shocks are “done”. Some will only feel inclined to change a shock absorber when its leaking, or sometime after thant (ie. when they really have to). It was Norman Garrett, who was a senior chassis engineer on the original MX5 project, who observed that there are significant fall off in performance of standard shocks from about 60k miles (conversely, Krupps-Bilstein were bullish in their observations to me that the Bilstein will still be at 90% of original performance at 200k kms, unless the shock has suffered external damage…A Roadster I got with factory billies and shredded boots, had rear shocks that were done at 70k miles…)… At the very least, renew the rubbery bits; the gaiter, the bumpstops. Even the last NBs are, now, old cars.

If you can DIY, you are closer to fitting new shocks, something like the KYB AGX (£120 each, Excel Gs are cheaper), where its simple to adjust the shock to match the stiffer lowering spring.

I recommend anyone giving it a go. I did mine on my own, with 3/8" drive sockets (though, now, I would use half inch drive), some axle stands,acheap torque wrench and £20 coil compressors. Took me a weekend, but I was taking my time. You don’t need to touch the alignment bolts, nor split ball joints, and the car is fine to drive afterwards.

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