On a kart track in rural Japan, a homemade replica Tyrrell 6-wheeler proved to a handful of spectators that anything is possible.

That is of course, if you happen to be Yuji Watahiki of Watahiki Custom Build & Restoration.

Having followed Watahiki-san’s unique build since I first saw it under construction a year and a half ago, the talented automotive engineer finally messaged me to say that he was taking it to a local kart track for a shakedown. You don’t see a handmade F1-inspired car every day, let alone a six-wheeler, so naturally I jumped at the opportunity to go and check it out.

I arrived a little late, but I couldn’t resist snapping a few shots of the cars parked up around the facility as I made my way in. Of particular interest were a couple of old school single-seat race cars powered by Subaru FJ1600 engines from the Leone. I didn’t want to risk tempting my tetanus immunisation, so I let them be and headed for the single-seater I had come to see.

I found the Tyrrell was only just being wheeled out onto the circuit for its first run. Watahiki-san told me they had spent the first hour repairing a damaged driveline component which had presented itself upon arrival. That appeased my feeling of guilt for being late.

The shell was separated from the body of the machine, exposing the hand-crafted, well… pretty much everything. Everything except for the wheels, the suspension units and the engine have been fabricated by Watahiki-san in his workshop.

It’s not the first time Watahiki-san has formed beauty from plain old sheet aluminium either. The first time I visited his workshop, I showed you the Ferrari Dino replica he was working on, and also talked about a Miura Jota replica so amazing that Lamborghini themselves asked for it to be displayed at the Feruccio Lamborghini Museum in Italy, and also at the Turin National Automobile Museum.

With the welding repairs complete, Watahiki-san and his team of helpers (all fellow enthusiasts) pushed the six-wheeler into pit lane and prepared to shake it down for the very first time.

Watahiki-san had jokingly said, “the car is ready, so let’s dress up in Ronnie Peterson cosplay.” The driving suit may be nothing but a bit of fun, but the excitement was very real.

Back in the mid-1970s, Tyrrell developed their P34 six-wheeler as a way to improve aerodynamics both in drag and clean airflow over the rear wing. The smaller wheels meant they could sit behind the front wing, and doubling them up meant a greater contact patch could be achieved with the four tiny wheels.

The design, to the astonishment of the general public, actually worked rather well and the six-wheeler took first and second at the Swedish Grand Prix the same year it was unveiled. Jodie Sheckter was behind the wheel for the win, but despite his victory left the team soon after. The following season saw Ronnie Peterson take the wheel in a revised design of the P34, which is the iteration that Watahiki-san has based his homage on.

Let’s have a look at how Watahiki-san has put this together, using components from a truly diverse parts bin.

The iconic four front wheels, 10-inches in diameter just like the originals, are actually meant for a three-wheel sand buggy. The rear wheels are 13×15-inch SSRs from a F3000, while the tyres are Avons from England measuring 8.5/16.0-10 up front and 15.0/26.0-13 at the rear.

The brakes and hubs are taken from a classic Mini, but as the rear required a little more stopping power, Watahiki-san runs Porsche 911 front brake callipers out back.

Here’s where things get interesting…

In order to keep weight down, Tyrrell designed a steering mechanism which used one rack to drive both pairs of front wheels. Basically, one set was a slave to the other. Luckily, Watahiki-san had a plan handy and was able to fabricate an almost exact replica of the original design. The front suspension units came from a Honda Grom bike and are fully adjustable, while the rear units are Suzuki GSX-S1000 fare.

Mounted longitudinally is a 2008 Suzuki GSX-R1300 Hayabusa engine, which makes 175PS. When it sits in the bike it’s in a transverse position, so running a drivetrain to the real wheel is no problem. In the Tyrrell, however, Watahiki-san has had to fabricate a chain drive system to link the engine with a mechanical-LSD-equipped diff from a Suzuki Cappuccino. Integrated into that system is a rear driveshaft and hub from a Lancia Delta Integrale.

I told you this was an international melting pot of parts. It’s also enough to forgive Watahiki-san for the technical difficulties which set him back a few hours in the morning, don’t you think?

The frame of the single-seater is fabricated from square steel and the body cowl is of course punched out of aluminium. The front and rear wings, side skirts and tub were handmade by Watahiki-san himself.

After the first run, the chain drive system was still knocking somewhere along the driveline. The volunteer pit team attempted to make adjustments, but it seemed like it may have needed to be re-welded somewhere to give clearance to the troublesome contact point. It was an annoying niggle, but one I’m sure will be sorted soon.

Racing around the track, acceleration looked gut-wrenchingly quick, and on such a tight course the steering rack and pinion from a Porsche 911 really came into its own. Those little uprated Mini brakes performed beautifully too.

I don’t know about you, but I’m patiently waiting for Watahiki-san to build a couple more of these mini F1 cars so he can hold a mini Grand Prix. Who knows, maybe he’ll let me have a go in one.

I’ve never been to an F1 event, but after this, I sure do have an itch. I’ll always remember hearing F1 cars screaming up the hill at the Goodwood Festival of Speed and being blown away by the immense volume they made as they passed under the footbridge below me.

It just goes to show, anything is possible if you have a vision, a little (or a lot) of skill, a sense of humour and a spare Hayabusa engine laying around. I think Watahiki-san is an absolute legend, just like this Tyrrell P34 six-wheeler homage that he fabricated by hand in his workshop.

Toby Thyer
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