The Hot Seat

Installing a seat heater in your roadster

Story & Photos by Jim Youngs

A lot of replica owners claim to appreciate not having modern creature comforts and convenience items in their specialty cars. They consider this sort of omission to be part of the rugged, individualist charm of a particular vehicle. They may even brag about owning a car without heaters, weather gear, cruise control, tilt steering, reclining seatbacks and air conditioning. Taken to extremes, you’ll even see roadsters with those virtually useless, manually operated windshield wipers — and by manual, we don’t mean one with a switch that has to be activated. The wiper is actually clamped to the top of the windshield and has to be cranked by hand. They sure looked interesting and minimalist, but practical? No way.

But surely some of these convenience items might be worth considering if they help extend your driving season, right? Not only that, but many of us enjoy bringing along our significant other in the name of family harmony, so some of these comfort items are necessary (read: demanded). That’s probably the case with the bundled-up passenger shown in the lead photo.

Colder temperatures can make for unhappy passengers in open-cockpit roadsters. Take the edge off for frigid passengers with an easy-to-install universal seat heater kit.

For the sake of brevity, we’re only showing
the process on the seat bottom cushion, but the pads shown here for the seatback install the same. Note the electrical leads that clip into the supplied wiring harness. Position the pads where you want them, and try to keep them smooth without folding or touching any metal or plastic pieces.

The first step for installing the seat heaters was to remove the leather upholstery to expose the foam seat cushions. It would be even easier to install warmers before the upholstery was completed, of course. In this case, the seat base cover was stapled to particleboard as a separate, removable cushion.

Once the pads are positioned where you want them, and trimmed if necessary, the adhesive along each side can be exposed to hold them in place on the foam. Rostra Precision Controls cautions not to trim the cushions vertically, as that might cause dead spots in the pads and could cause overheating.

Regardless, those of us who live in parts of the country that experience actual seasons know that a cockpit heater might be a good investment, but there’s something else that’s ideal for less-than-ideal weather — seat heaters. One of these products, the ComfortHeat universal kit from Rostra Precision Controls, provides an easy answer to extending your cruising season.

At the heart of the ComfortHeat kit (part No. 250-1870) are the PTC heating elements that are tear- and puncture-resistant. Basically, you secure one of these carbon fiber mesh pads, measuring 19.5 by 10.5 inches, on the seat’s bottom cushion and one on the lower back of the seat, and then wire them to the car’s ignition. The pads can be trimmed to fit virtually any seat shape if necessary. Once installed, they provide even, adjustable heat controlled by a three-way switch.

We drilled a hole in the seat base through which to feed the seat heater wires, and then plugged the leads into the supplied wiring harness.

Once the pads are in place and the wiring
is routed, we reinstalled the upholstery
and restapled the upholstery pieces.

The kits come with two pads for a dual-zone heating system — for the back and seat — and have a built-in thermostat and temperature sensor. The pads are connected to an included wiring harness, complete with a high/low switch, and a fused power connection. Not shown here but also offered is a universal kit (part No. 250-1872) that has a five-position heat controller for fine-tuning your comfort level.

Installing these seat warmers will likely be one of the easiest procedures you will ever accomplish on your project car. And your backside will thank you, as you and your favorite passenger will be a little more comfortable on those less-than-comfortable cruising days.