Sinister kid

Sinister kid

Jeep Sinister Kid

Saying that Sylvain is a real offroad enthusiast is an under-statement. In fact, he must have been fed with motor oil as a child, his first child book must have been a moped FSM, and his first holidays must have been spent wrenching in a garage.




Lets study a bit the profile of our friend :

 at 7 he tore down and rebuilt a Caddy moped

 at 14 he started offroad wheeling with a Dodge WC51 and bought a “junky” Jeep Willys in order to rebuild it with the help of his father. The project lasted for 3 years.

 at 18, once he got his driving license, he bought a Range Rover V8

 then he built an AMC 360ci powered Jeep CJ8 which was super reliable, he never had any problem with it

 in parallel, he followed mechanical studies and graduated several degrees in engine tuning, electrical and injection systems, etc…

 in 2012 he built the Sinister Kid (the name comes from a song performed by The Black Keys band)

Levers from Left to Right : Atlas Shifters, Transmission Shifter, Front and Rear Left/Right Cutting Brakes

A dual cooler for steering and transmission

So Sylvain acquired a strong practical and theoretical knowledge, both in the familial circle and at school. You can feel his passion and even some kind of fascination when he starts talking about his work. Another important thing to note is the fact that, besides having an impeccable vehicle, his main interest is the process and the gameplan that comes with such a project.


LY5 5.3L Aluminum Vortec from a Chevy Avalanche

The project of the build of this buggy came as an idea after several participations to the “Chambon sur Jeep” meeting. It’s a big Jeep meeting where the first American rockcrawling buggy has been revealed in Europe (the Currie Fire Ant project).
His good friend Fabien already having a Juggy, and Sylvain having helped him to build it, this idea makes even more sense.

HomeMade Exhaust

PSC full hydraulic steering

This project is also like a challenge, a defy he swore to tackle. This will also be, at 36 y.o. some kind of evaluation of his know-how and competences. And, as you will see, he managed to pass it high-hand.

K&N Filtrer

You can recognize a good craftsman at its tools

Before starting actual work on his buggy, Sylvain wanted to have a proper shop to build in the best possible conditions. He proceeded at the work with a specific idea in mind :

 a welding/grinding

 a bench zone in order to assemble parts

 a central zone to hold two cars and still having ample space to move around.





This shop is a mechanic dream !

The LY5 Vortec was chosen for his good power/torque ratio. Cheap performance parts are a plus too.

He spent about 18 months building it, while making it work with his budget and family schedule. Like he said, he took time and didn’t rush this part.


At first the idea was to make a copy of his buddy Juggy, but more he thought about it, more the idea of starting a tubular chassis from scratch appealed to him. The challenge would become more interesting and at that time, in France, a full tubular chassis was really innovative.

The ATLAS transfer case allows the buggy to run with front, rear or both drivelines under power

Autometer Gages : Tach, Water Temp, Transmission Temp, Oil Pressure, Voltmeter

Winch controls

First step : Spend hours thinking, looking at and analyzing what was going on the other side of the Atlantic ocean.

He finally felt in love with the « Geodynamic » chassis from twisted Customs (, build by Jason PAULE (a famous american RockCrawling champion) and his crew. Sylvain e-mailed him to ask his permission in order to copy the chassis and have some advice. Jason agreed to the idea and, while not sending plans, he helped Sylvain with pictures and dimensions. « He has been fabulous with me ! » said Sylvain. Now, as the build is done, Jason doesn’t hesitate to make suggestions and advices on the Facebook wall of our Frenchy.


Next comes up the design phase, with drawings and listing the parts. Sylvain wanted to have all the parts before starting to build. He chose to let Nicolas from 4Krawl Products handle this task.

And soon, some goods showed up in the shop :

 Twisted Customs Jeep TJ front clip

 Spidertrax axles

 LY5 Chevrolet Vortec Engine (5.3l and 300hp).

Finally, in September 2012, he starts to bend the first tube. His wife had been very supportive, allowing him a complete autonomy, the only condition being that the whole build doesn’t exceed a reasonable time limit. Sylvain choose to build the buggy in 9 months, no more, no less. He planned and followed a regular schedule : from 8pm to 1am from Monday to Thursday and from 8 pm to 4am every Friday and Saturday. That’s a real commitment, but as you noticed, Sylvain is a man of challenge.

Goodyear MTR Kevlar 40/13.5/17

He started by setting up the powerplan combo in order to build the bottom half of the chassis. It supports the front clip, radiator and seats. Then the upper tubes are put together in order to have the searched look. His buddy Fabien has been a great help in this step.

Then, as the axles are shipped unfinished, he cut, assembled and welded them. Each step was carefully planned and he didn’t have to tinker and improvise here.

Here you can see the Atlas transfer case. A rockcrawling reference

The rear TMAX winch has the duty to limit the suspension travel

Aluminum control arms. Stronger and a lot more flex resistant

Rear end : The finish work is spotless !

The big SPAL fan is here to cool down the aluminum dual pass radiator

Jaz 12 Gallon fuel tank

Walker Evans Racing Wheels

1000 hours later the buggy was done and on display at the 2012 Pirate4x4 annual meeting.

The Ohlins choice

For suspensions, he chose the same setup his buddy Fabien has been using on his Juggy. He chose to stay with trail-proven parts, meaning 4 Ohlins coilovers, with 14” of travel and integrated bumpstops. As he planned some high speed use (with an upcoming participation in the next European Ultra4 series), airshocks were completely out of the question.

The Ohlins Company is located really close to Sylvain’s place, at Aurillac. They brought their vast competition experience and knowledge in order to build the best shocks for this car. They engineered and calculated the spring rate and tuning of the shocks after the car sprung and unsprung weights. The found compromise is awesome, you just have to look at this buggy running to be amazed by the quality of the suspensions on it.

Ohlins coilover

3 coils : A progressive one, a standard one and a tender spring

The Currie Antirock SwayBar is here to keep the chassis level in any situation.

Spidertrax drilled rotors / Willwood 4 pistons calipers



Build Year 2012
Name Sinister Kid
Builder Sylvain
Build lenght 9 months
Chassis inspired from Twisted Customs JASON PAULE’s Geodynamic chassis
Type Fully Tubular with 51“ width
Tube material TU37B
Lenght 360 cm
Ext Cage Width 130cm
Height 183cm
Wheelbase 107“
Track 198cm
Weight 1464kg
Others fully TIGed chassis
engine maker CHEVROLET
displacement 325 cubic inch 5.3 L VORTEC LY5 found on a Chevrolet Avalanche
Power / Torque 300 HP – 454 Nm at 4000 rpm
Battery Red OPTIMA
Radiator Griffin aluminum radiator with 1 SPAL fan / PS and transmission Derale twin radiator
Air filtration K&N Filter
Exhaust Home made
Transmission TH400
Adaptater Advance adapter
Shifter Winters Sidewinder
Transfer Case Atlas II 4.3 to 1
Fuel cell 12 Gal
Body & Interior
Body Lexan
Skids aluminum
Front clip Jeep TJ Twisted Custom
Panels Aluminum
Gauges Autometer : Tach, Water temp, Transmission temp, Oil pressure, Voltmeter
Direction Full hydraulic with PSC pump and ram
Brakes Willwood pedal with 2 master cylinders
Harnesses – seats Mastercraft – CROW
Electronics Turn key engine ECU and wire harness
Lights Hella
Security 1 fire extinguisher
Winches front and rear Used for suspension suck-down : Warn 9.0 RC and Tmax ATW4500
Front Suspension/ type / materials 4 Aluminum links with uniball heat treated joints
Front shocks Ohlins Coilovers with integrated bumpstops and 14” of travel
Front axle Spidertrax 9”
Diff / Locker Currie 9” + Detroit Locker
R&P 4.88 Ratio
Axleshafts 300M 35 splines
Joints CTM U-Joints
Drive flanges / Hubs Spidertrax
Front brakes Slotted rotor and Wilwood 4 pistons caliper
Front and Rear Driveshafts Dumas et Colinot
Others Front pillow block
Rear Suspension / type / material 4 Aluminum links with uniball heat treated joints – Currie antirock sway bar with aluminum arms
Rear shocks Ohlins Coilovers with integrated bumpstops and 14” of travel
Rear axle Spidertrax 9”
Diff / Locker Currie 9” + Detroit Locker
R&P 4.88 Ratio
Axleshafts 300M 35 splines
Drive flanges / Hubs Spidertrax
Rear brakes Slotted rotor and Wilwood 4 pistons caliper
Cutting brakes CNC
Wheels and Tires
Tires Goodyear MTR Kevlar 40/13.5/17
Wheels 17 x 8 Walker Evans Racing Beadlocks













Translated by Bebop

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    Sinister kid

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