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Spitfire IFS Ultra4 by Off Road Armoury

Those who are familiar with the European Ultra4 championship know that name : Rob Butler. He is the owner of OffRoad Armoury, a competition vehicle builder. On top of his personal rig, Rob built Ultra4 buggies for people like Levi Shirley (USA), Filipe Guimarães (PT) ou Jorge Araujo (PT) (who just finished second in the King of France 2017) and vehicles running in other series. Those first gen vehicles, dubbed the Eurofighters did amazing, and Rob even finished the 2016 King of the Hammers driving one of them. It was the first time a european vehicle actually made through this famous race.

Text and pictures Nicolas Stévenin / translation Enzo

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The first European IFS Ultra4 ! Made by Rob Butler of Off Road Armoury

But in the secret of his workshop in Uckfield in the East Sussex region of UK, Rob worked during about 8 months to complete his new project.

And what of a project ! It’s a European first : a Ultra4 buggy with IFS (Independant Front Suspension) ! So far we only saw such vehicles in the USA in the hands of people like Shannon Campbell (3 KOH wins), Nick Nelson, Ben Napier, Levi Shirley, Jason Scherer (erererererer), etc…

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This 4x4 full of surprises is the subject of this EXCLUSIVE article. This is a worldwide first as, to my knowledge, no-one ever wrote a paper about it !

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SPITFIRE IFS ULTRA4 by Off Road Armoury : a surface to surface weapon !

Rob has become the master in the art of creating chassis, he is part of this little european community of people building building small series of Ultra4, just like Nicolas Montador from Team WSR (cock-a-doodle-doo !).

Choosing to drive with an IFS is a bet who revealed to be a winning one a few times (see the titles of Shannon Campbell who was one of the first people to compete with a buggy with such a front end). The particularity, as you probably noticed by looking at the first pictures, is this front end with suspension triangles that replaces a conventional solid axle. While it carries a reputation of being weaker, this technology is currently booming in the US, and, as it gets more and more recognized, it gets better and better with new parts improving the concept everyday. One of the major downfalls is the price of such a front end, around $60000.

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IFS means Independent Front Suspension but unlike a standard SUV, the travel here is waaaaaaaaaaay longer !

The Spitfire from Off Road Armoury is a full tube single seater, made from 4130 Chromoly and DOM steel. The weight is about 4400lbs, around 700lbs heavier than the new buggy from Nicolas Montador, but lighter than most of Ultra4 buggies which weight around 5000lbs. The width seems huge, being 90’’ (field average is 88’’ and might be a little less depending if wheels with a big backspacing are used). Wheelbase is 114’’, pretty standard. Body panels are aluminum and the skid plates are doubled with 1/2’’ HDPE.

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The suspension triangles are laser cut, TIG welded and reinforced from the inside.

Its line is very agressive line and the fact it is so low gives a very dynamic look to the vehicle. No doubt the center of gravity is placed as close as possible to the ground. This vehicle has a very nicely flowing and way less massive look than its predecessors, the Eurofighters. Even if this is not a concourse of elegance, staring at a nice buggy is always pleasant.

Engine and transmission of the Spitfire

In order to help this Ultra4 take off, Rob used a rear mounted 525hp Chevy LS3 engine (6.2L) with a GM Performance ECU. Cooling is handled by a giant custom radiator by Allisport with twin 18’’ fans. A competition Alders 4L80e transmission is matted to the block, and a 2600rpm stall Coan Full Race converter is used in between the two. Setrab radiators cool this beast. The transfer case is a Trail Worthy Fab Hero 2 speed with a 2.0 to 1 gearset. The 8 into 2 with X-Pipe exhaust is home made. The 30 gallon reservoir is US made (Pyrotect). Only the best of the performance parts are being used here !

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The engine is really tucked in but you can see the full custom exhaust here.


The front axle is a marvel of fabrication. Every single part has been CAD designed, laser cut, TIG welded and turned into a magnificent assembly. Despite the complexity of creating an independent front suspension, the outcome proved at its first race (King of France 2017) that it was ready to win ! This IFS kit comes from Jimmy’s 4x4 (USA) and the traction it gives is formidable as the front tires are planted on the ground way better than with a rigid front axle. Away with the tires lifting during flex ! The front wheels, being independent, now perfectly follow the shape of the terrain. Rocks feel like nothing, but it’s really in the fast portions that this new Spitfire shines. Some obstacles completely disappear, and as you see drivers of solid front axle cars lift, Rob, on the contrary, is flat out ! CV joints are 30 series size, sourced from RCV and they compliment nicely the ARB RD99CE locker you find in the front diff, tucked inside a Gearworks 10’’ third-member.

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Off Road Armoury is distributing this Jimmy’s 4x4 IFS kit
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The rear end stays more traditional, with a solid axle and a 4 links suspension. Uppers are classic tube style, but the 2 lowers are what’s called trailing arms, housing the shock mounts and thus giving a mechanical advantage over a standard shock setup. It gives the car huge travel ! Spidertrax, well… no need to present this american company that specializes in high end custom fabricated housings ; it has become a reference in the competition field, particularly the Ultra4 scene. This car uses a 4’’ Pro-Series housing, with all Pro-Series outers. Gear works 10’’ third-members with a spool feed power to the Spidertrax 40 spline shafts. Nothings is breaking here. Last detail, a PAC Racing sway-bar.

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In order to stop this racing beast, Rob equipped it with D&D 6 piston calipers front and rear. This car stops hard and quickly, but at this level of competition, it is a must.

Next step, suspension ! It has to live to the potential of this buggy, so like everything else, only high-end parts are found here. King Shocks (USA) shocks are used everywhere, with a 2,5’’ coil-carrier and a 3’’ bypass shock at every corner. Obviously they are linked to large and finned reservoirs in order to provide optimal cooling during the races. King Shocks bump stops are also present at each corner, to damp the hard hits like jumps and various situations this vehicle might encounter.

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Sway-bar and bump stops

Last but not least, the steering is a full hydraulic rack, coming directly from the trophy truck world.

The interior is business only, with the driver on the left side and the right side houses the transmission. A quick disconnect steering wheel, racing harnesses and a Racepack IQ3 dashboard complete the cockpit. This little unit monitors and displays all the vehicle parameters (like ground speed, oil pressure, water temp, …) but also allows for dataloging and custom alerts to be programmed.

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Just sprinkle some parts on top of this, like a Gigglepin GP100 winch, Lazer R16 and ST8 LED lights and the tour is finished ! OH ! I almost forgot the Trail Gear CreeperLock beadlock wheels with their 8 piece sectional ring and the 40’’ Maxxis Trepador wheels that are attached to them.

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The King of France 2017 was the maiden voyage of the Spitfire and Rob discovered what it felt to drive it. It was literally finished hours before the start of the first round and some new car blues was experienced during the race, like losing a wheel at some point. That said, when everything worked as it should, Rob posted the fastest time of the track ! This Spitfire handles like nobody’s business, with unmatched jumping and cornering abilities, turning this vehicle and driver into a very fast package we will have to follow closely during the next races. No doubt there is a new player in town and Rob is going to make some damage to the competition !

Keep following the journaldu4x4 for all the Ultra4 Europe news, we will be present at all the races of the championship to feed you the latest infos !

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Voir tous les reportages sur la marque Ultra 4

Voir tous les articles de cette rubrique : 4WD ARTICLES IN ENGLISH

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Textes et photos

Nicolas Mailfait Stèvenin

Participent au magazine :

- Raphaël Hétier (photo)
- Christophe Imholz
- Eric Rieuf

- mais aussi quelques lecteurs fans !

- 3, grande rue
- 02160 MOULINS


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