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Soft Top & RF Roof Care

The ND MX-5 ships in two roof variants and they age in completely different ways. The standard car has a manual cloth top with a heated glass rear window. The RF (Retractable Fastback), added for 2017, replaces it with a power hardtop that tucks its rear glass and three body panels into a well behind the seats while leaving the rear buttresses fixed. The cloth top wears out from sun, dirt, and the fabric itself; the RF wears out from motors, switches, and connectors. Care advice for one is mostly useless for the other.

The cloth top

Section titled “The cloth top”

The ND soft top is a single-piece cloth top with a single center latch at the windshield header. Pull the latch, throw the top back over your shoulder, and the Z-fold stows itself flush behind the seats — it never eats trunk space, and you can do the whole thing one-handed from the driver’s seat at a light. The rear window is heated glass, bonded into the fabric, so it folds with the top instead of unzipping. That glass is the single biggest functional upgrade over the vinyl/plastic windows on older Miatas: it doesn’t yellow, fog, or scratch, and the defroster works.

Cleaning the fabric

Section titled “Cleaning the fabric”

The fabric is a woven acrylic-type cloth, not vinyl. Treat it like outdoor furniture canvas, not like paint.

  • Work in the shade. Cleaning a hot top in direct sun dries the soap before you can rinse it and leaves rings.
  • Rinse loose grit off first, then work in a mild soap with a soft brush. A brush lifts dirt out of the weave; a sponge just pushes it around. Skip chamois and microfiber on the cloth — they shed lint that catches in the fabric.
  • Don’t spot-clean. Doing one stain leaves a clean patch that stands out against the rest. Wash the whole panel.
  • Rinse thoroughly and let it dry fully before lowering the top. Folding a damp top traps moisture against the rear glass seal and the headliner.

For stubborn dirt or bird droppings, dedicated convertible-top cleaners (303, RaggTopp, Renovo) are gentler than household degreasers, which can strip the factory water repellency.

Protecting it

Section titled “Protecting it”

Factory water repellency wears off over a few years; you’ll notice when water soaks in and darkens the fabric instead of beading. Re-treat with a fabric (not vinyl) protectant — RaggTopp and 303 Fabric Guard are the two most-named in the ND community. Vinyl/rubber dressings are the wrong product here: they leave a sheen on cloth and can clog the weave. Spray-on, let it cure, and keep it off the glass and paint.

The heated glass rear window

Section titled “The heated glass rear window”

Because the ND uses glass, the plastic-window routine from older Miatas (Plexus, Renovo polish, never wiping in circles) does not apply. Clean the ND’s rear glass like any other auto glass, just gently, since it lives in a fabric pocket. The defroster is a printed grid like a hardtop’s; if a line stops working it’s the same failure mode (a broken trace), repairable with conductive defogger paint.

Common cloth-top issues

Section titled “Common cloth-top issues”
  • Water in the footwells or behind the seats is almost always drains, not the top. The ND has drain channels and tubes that route water from the top’s gutters down and out behind the rear wheels. They clog with leaves and pollen. Clear them before you suspect a leaking seal.
  • Header seal wear shows up as wind noise or a drip at the top corners of the windshield. The header weatherstrip is replaceable.
  • Fabric shrinkage and a hard-to-latch top after a top has sat down in the heat is normal; it usually pulls closed with a firm tug and relaxes back over a few minutes up.

The RF

Section titled “The RF”

The RF roof is a powered assembly: the hard panels and rear glass fold rearward into a well behind the seats while the rear buttresses and the section above them stay fixed, giving the targa look. The cycle takes about 13 seconds. Crucially, it will operate on the move at up to 10 km/h (about 6 mph) — you can drop it pulling out of a parking spot. Above that speed the cycle stops midstream and waits.

The roof will only run when the ignition is on, the shifter is out of reverse, the trunk lid is closed, and the car is sitting at no more than about a 15-degree tilt. If it refuses to move, run that checklist first — a roof that won’t operate on a steep driveway or with the boot ajar is behaving exactly as designed.

RF mechanism care

Section titled “RF mechanism care”

The RF has far more to go wrong than a cloth top, and almost all of it is mechanical or electrical rather than fabric:

  • Keep the well and channels clear. Leaves and grit collect in the panel well and around the moving seals. Debris in the wrong spot can foul a position sensor or jam a panel against a stop.
  • Don’t fight a stalled cycle. If it stops partway, don’t keep stabbing the button. Let it settle, check the obvious blockers (speed, reverse, trunk, slope), and let it complete a full cycle.
  • Seals want the same treatment as any rubber weatherstrip — a rubber-safe conditioner keeps them from drying and squeaking. This is the one place a vinyl/rubber dressing is correct, unlike on the cloth top.

Common RF faults

Section titled “Common RF faults”

The headline symptom is a “Retractable Roof System Malfunction” message, usually with the roof dead or stuck partway. Owners and shops have traced this to a handful of recurring causes:

  • Roof position / limit switches (the rear roof-link limit switch and deck position sensor) reading wrong because they’re dirty, misaligned, or failing. These tell the controller where each panel is; if one lies, the controller aborts.
  • Connector corrosion on the harness blocks and at the roof switch. Reseating connectors has fixed a number of cases outright.
  • A short to ground in the harness or a fault inside the hardtop control module, which is the harder, dealer-level end of the range.

A widely reported first step before anything invasive: disconnect the battery for about five minutes, reconnect, and re-cycle the roof. That clears a latched fault and resets the controller, and for a surprising share of “malfunction” messages it’s the whole fix. If the message comes back immediately, you’re into switch and connector diagnosis.

There’s an aftermarket angle worth knowing about: smartTOP-style roof controllers (Mods4cars and similar) add one-touch operation and, notably, raise the speed at which the RF will cycle, so you don’t have to crawl under 6 mph. They tap the existing roof control module rather than replacing it.

Which top, if you’re choosing

Section titled “Which top, if you’re choosing”

That’s a different question than care, and it’s covered separately — see /nd-miata/rf-vs-soft-top/. The short version for maintenance planning: the cloth top is cheaper to live with and trivial to service, the RF is quieter and more secure but has the failure modes above. Both are honest choices.

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