- My model of MX-5 is: __NC PRHT 2014 Sport Venture
- I’m based near: __Rugby
- I’m looking for technical help or recommendations on: __Bilstein dampers
Hi all - a quick query if I may! This is my 3rd MX-5 but the first one to have Bilstein dampers and there is a noticeable difference from the last two cars. Against all expectations, the ride is significantly BETTER than standard shocks; softer damping, longer travel, less crashy and much better on a long journey.
Is this correct, or are my dampers starting to go squidgy at 56,000 miles?
Hiya and welcome to the club,
I found and preferred the ride on the 1.8 compared to the more sporty 2.0 setup. Especially on badly maintained road surfaces.
In all honesty, it’s very individual how one feels about any car and if you are happy, that’s great 
Shocks or dampers? Shock absorbers are the springs, they absorb the shock of an impact by compressing or extending allowing the chassis to remain unmoved in the main, the spring then oscillates and turns the ‘shock event’ into heat. It takes a very long time for these oscillations to return to zero because a coil spring is not good at changing movement (flexion) into heat. So you employ a damper unit, the job of the damper is to dampen the oscillations from the shock absorbing spring. The damper is a very high efficiency energy exchanger, it turns oscillations into heat very quickly and the heat is mostly radiated from the damper into its surroundings. Remember energy MUST be conserved, so the kinetic energy from an impact on a wheel must be changed into another form, it can’t simply disappear. Heat is almost always the easiest way to go.
A damper fights against the shock absorber, so in fact it reduced its ability to do its main job of smoothing out the ride, but without a damper the oscillations mean the energy stored in the springs results in wild and uncontrollable wheel movement, the tyre will literally leave the road and bounce like a tennis ball on a hard surface. I’m sure we have all seen a car on the motorway with a wheel doing exactly this, and the driver will be all confused about the odd high frequency vibration in the cabin. So both components are highly important and only work when they are both healthy and matched to each other.
Your ‘improved’ ride quality is entirely to your personal preference. The spring is absorbing shocks, the damper is keeping the shocker in check and maintaining as high a mechanical load as possible between tire and road for as much time as possible. You have no grip when the tire leaves the road surface after all
I think if you are happy with them, leave well alone.
Do check the condition though, springs or any leaks (oil misting) a certain small amount could be expected for aged units.
My experience with Bilsteins… I had the springs changed because I wanted the car lower. Everything fine but over a couple of year and around 60k miles the rear end used to bottom out occasionally over undulating roads when I was cracking on a little. Been on tours with a fully loaded boot and it’s been fine, just those times over certain roads I would have to be careful.
Now all changed to MeisterR’s a firmer ride but that is adjustable, so is the height and far happier with how the car rides.
Like I say leave well alone if they are doing their job and you are happy.
OK, thanks guys - next question:
Are Bilsteins rebuildable? If so, any recommendations as to who could do it?
I called Bilstein UK to ask about rebuild but they themselves don’t do it. Not sure if a third party rebuild option exists.
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I’m sure Gaz rebuild bilstein units.
I don’t belive the Mazda supplied Bilstiens are economically rebuildable (everything is rebuildable if you throw a skilled craftsman at the problem).
I believe they are compression sealed, not screwed together so will need cutting open, internals replaced, welded together and the compression fitting replaced with threads. All this on a unit that costs about £80 new - OK you will pay a lot more than that as there are a lot of fat middle men, but a genuine B6 or B8 Bilstein, that is in a higher league quality wise, is rebuildable and can be bought with a set of Eibach springs for under £600 - making even them uneconomic to rebuild.
So you may get a quick repair where a hole is drilled, compressed gas and oil injected and the hole sealed that makes the dampers ‘feel like new’, but the reality is they are old and worn, and merely re-gassed which might be OK for a while. The original ones leaked and lost pressure for a reason, and that reason has not been addressed, so the re-gassed ones will go the same way fairly quickly. With the cost/effort of removing and refitting it probably makes more sense to get a new set unless a quick ‘get it through an mot’ bodge is what is called for.
Gaz stock rebuild components and can rebuild any sort of damper. Ok some times they will advise you buy new for economy but they will supply parts cheaper than main stealer. They can advise on upgrades to dampening and all the rest too. Very long standing company well respected in the track, road and rally world.
I may pop and ask about M140 dampers soon too 
. Got mine Thursday and it’s a great car but a little soft on the handling.