2018 was a good year for the Yamaha team, with Carl Reuterman, Bob Uttridge and Joel Giddy dominating the NZ Off Road Racing scene.
For 2019 Ruiterman and Giddy are in identical new mounts, built together with a third for Brian Rutgers by E&H Motors in Pukekohe, and starting to show results, straight out of the garage door.
We talked to Ruiterman at E&H and followed the Yamaha YXZ Racer build transformation from brand new factory recreational buggy to turbo-charged S-class pocket rocket.
Yamaha YXZ Racer Build
Once the cars are received from Yamaha Whangarei, the first thing in the process is stripping everything off — down to the chassis and running gear. Plastics, seats, undertrays etc are removed, and the factory cage lugs and other brackets are cut off.
One of the chassis is then 3D scanned by Alex at Devise and the new cage designed on solid works. All pipe bending and notching is carried out by CNC.
Both sides of the cage are mirrored, then the chassis is squared up before welding. Extra gussets and braces are designed and installed, many of them responses to previous experiences, as the compact racers get pushed harder and harder.
With the cages on, the chassis is then sent to Onehunga Panel and Paint for final finishing, and all the plastics etc are notched and refitted.
Then the E&H speciality parts are installed, Chromoly steering arms, window nets, mirror, kill switch, horn and helmet pump wiring, and bucket seat.
Off-the-shelf shocks are tuned in-house, E&H changing the shim stacks, and springs, along with fitting a heavier aftermarket swaybar to complete the suspension rebuild. All three buggies are using the same suspension settings.
The buggies run stock tyres, but on wider offset bead locked rims, which makes them 40mm wider per side.
Engines run stock internals, which Ruiterman reckons is a testament to just how strong the 998cc 3 cylinder motor is. For the U-Class entrants, a performance exhaust is fitted, and the computer is reflashed by Ruiterman at E&H using their Dyna Pack Hub Dyno.
For the S-Class Rigs, E&H has built a Turbo Kit from scratch. Again the motor is scanned, then assembly stencils 3D printed around available pipe bends and flanges. The segments are cut and welded in jigs, and fitted, for the intercooler and cowlings, and inlet and exhaust manifolds.
Boost is limited to a conservative 7psi for race conditions, and the computers are tuned by Ruiterman. The engines are tuned for Gull’s 98 Octane Force 10 fuel. Reuterman is also adamant about the quality of this bio-ethanol boosted fuel. The team organises for supplies to be sent to the South Island rounds, where it is not available.
Motul Synthetic oils are used in the engine, gearbox, and both differentials, as well as Motul’s MoCool in the radiator, which takes a further 10 deg out of the coolant temperature compared to the traditional water\ antifreeze mix when the engines are being pushed hard.
Ruiterman has lost count of the trophies won. He is philosophical about the number of competitors he is putting into those very fast racers, “the number of drivers doing well pushes us to do even better,” he reckons. “In the last four years speeds have really been increasing. The side by sides are being developed at a very fast rate, and the drivers are learning to push them harder.”
Coming in at just over 700kg they have a top speed of around 150kph. “While we don’t have the top speeds a lot of other classes have, a UTV’s ability to accelerate fast, brake late and corner quickly makes them very competitive even against the 800hp class 1 vehicles.
Ride height, and shock settings are altered to suit each track, and even during events for the changing conditions during the day. “We got the shock valving package close on around the second or third try” says Reuterman. “They’ve been apart about another 10 times trying to better it, but we keep coming back to the same combination.”
Each brand of UTV can be built into a class winning car. “Each one has its own strengths. While the Yamaha has an edge on the smooth fast tracks, the Polaris and Can-Ams perform well in the rough.”
“Spending time on suspension bridges this gap, but it is really cool to see each brand is capable of winning a championship. We are very excited to see what the new Honda and Kawasaki models bring to the sport as well.”
Data capture and analysis are the focus of the 2019/20 season. Emtron computors and AIM dashes are being tested to help drivers protect their engines, and also use data for suspension testing, rather than driver feedback alone, to perfect shock settings.
Obviously, this level of development has taken serious input from a number of associates, and Ruiterman asked us to acknowledge the input from E&H Motors, Gull NZ, Motul and Onehunga Panel & Paint who have supported the team since their drift car days. Yamaha NZ, Jamie and the team at Yamaha Whangarei, Devise, Concrete Treatments, JG Civil, and Core Steel.
“Special thanks go to the crew at E&H Motors, particularly Theresa who dedicates her weekends helping with preparation in looking after the team of cars at the track, Jamie, Scott, Mike, Kane, Neil, Emy, and everyone else that helps us to do what we love.”
See the full build in the gallery above. Story photos by Bob Uttridge. Main image by Mark Baker.