It looks mild, but this G63 AMG packs some se­ri­ous off-road en­gi­neer­ing to help it scale bru­tal heights!

4 x 4 Australia - - Contents -

We all love hard­core off-road, trail-smash­ing brutes, but they can be a pain to drive on reg­u­lar streets, the fam­ily nor­mally hates them and they’re as prac­ti­cal as a fly­screen on a space shut­tle. Lux­ury mod­els from Europe are nice, but they don’t seem to have the same abil­ity off-road. Are we des­tined to cruel com­pro­mise?

Not if Ger­man com­pany Letech has any­thing to do with it. The shin­ing white G-class on th­ese pages is one of the demo ve­hi­cles out of the now-de­funct Letech USA, an out­fit run out of the Bill Rader Mo­tor­sports work­shop.

Letech de­sign and man­u­fac­ture the por­tal hub con­ver­sions used on AMG’S own beastly 6x6 G-class, but now it has de­signed a kit that can be used on reg­u­lar G-wa­gens. You’d do this con­ver­sion if you wanted to keep the on-road man­ners of a stock G-se­ries, but with an ex­tra 457mm of ground clearance.

A por­tal con­ver­sion es­sen­tially moves the drive­shaft to the top of the hub where it drives a re­duc­tion gear. It lifts the drive axle away from the cen­tre-line of the wheel and gifts a healthy in­crease in ground clearance. This saves hav­ing a diff or axles hang­ing low un­der the car, keeps the orig­i­nal sus­pen­sion ge­om­e­try and re­duces strain on hubs thanks to the re­duc­tion gear.

Por­tal-driven hubs aren’t new – they’ve been used on mil­i­tary

Letech’s Bill Rader is the per­fect guy to build the ul­ti­mate dune-hop­ping, rock-crawl­ing brute that can then back up and be com­fort­able on a free­way com­mute

ve­hi­cles and some Volk­swa­gens dat­ing back to the 1940s – but they’re se­ri­ous af­ter­mar­ket up­grades and the en­gi­neer­ing doesn’t come cheap. Un­i­mog por­tal axle con­ver­sions have been pop­u­lar on com­pe­ti­tion off-road ve­hi­cles for many years, while Marks 4WD in Mel­bourne uses Aussie know-how and skill to pro­duce its own por­tals for Pa­trols and Land­cruis­ers.

Thank­fully for Letech, Bill Rader is no Johnny-come-lately to the sport of en­gi­neer­ing. Bill has spent years work­ing on trans­mis­sions for Porsches and cus­tom-built race cars that com­pete – and win – in heavy duty events like the Day­tona 24 Hour, as well as SCCA, Grand Am, Amer­i­can Le Mans Se­ries and World Chal­lenge.

He knows pre­ci­sion en­gi­neer­ing and how to make gear-driven parts sur­vive un­der high-stress en­vi­ron­ments. So he’s the per­fect guy to build the ul­ti­mate dune-hop­ping, rock-crawl­ing brute that can then back up and be com­fort­able on a free­way com­mute or dawdling through the sub­urbs.

“The axles used in this con­ver­sion are the same ex­act brand Por­tal axles used by the Mercedes-benz fac­tory in the G63 6x6,” Rader says. “We have taken the ul­tra-lux­u­ri­ous, powerful and very off-road ca­pa­ble G63 and given it al­most 18 inches of ground clearance – mak­ing it one of the best off-road ve­hi­cles avail­able, while also giv­ing it a men­ac­ing pres­ence on the street.”

As part of the kit, ex­tended wheel arches are in­cluded, with

The twin-turbo 5.5-litre AMG V8 has been spruced up from 544hp to a mon­strous 700hp, thanks to a suite of Brabus up­grades

a choice of car­bon-fi­bre or fi­bre­glass for their con­struc­tion and, while the Letech USA white knight rocks stan­dard G63 bars, the Ger­man com­pany has up­grade front and bumpers which in­clude a winch op­tion, as well as a range of side steps and a roof rack with a lad­der, too. Not fit­ted to the G63 were the up­graded bash­plates or on-board tyre­in­flat­ing sys­tem.

The bead-locked wheels span 18x8.5-inches and have been wrapped in Falken Wild­peak All-ter­rain rub­ber that mea­sure 37x13.5x18in. Letech spent time en­sur­ing the G63 would still drive like the well-en­gi­neered ma­chine it left the fac­tory as, a fact com­pli­cated with the huge suite of elec­tronic safety tech­nolo­gies on board.

“Us­ing the por­tal axles and the tyres to gain all the lift means the sus­pen­sion ge­om­e­try is not changed at all,” Rader ex­plains. “This trans­lates into no change in on-road han­dling other than the feel of the larger tyres, while the gear ra­tio in­side each of the por­tals is the ex­act ra­tio to com­pen­sate for the 37-inch tyres. So all sys­tems work as nor­mal, in­clud­ing the speedome­ter, ABS, ESP and so on.”

The twin-turbo 5.5-litre AMG V8 en­gine has been spruced up from the stan­dard 544hp to a mon­strous 700hp, thanks to a suite of Brabus up­grades. If AMG is Mercedes’ HSV, then Brabus may as well be the Holden Rac­ing Team.

For decades it has spe­cialised in adding hun­dreds of horse­power to un­sus­pect­ing Merc mod­els with its al­most-

“The G63 is ready to take on any ter­rain you could throw at it; from malls to moun­tains this thing will go any­where, in style”

silly tur­bocharged V12 and V8 en­gines. Its twin-turbo 800hp V12 Rocket model is based on the hum­ble CLS, but it has been the fastest four-door car on the planet for 10 years, with the cur­rent model ex­ceed­ing 370km/h!

While plus-200mph Au­to­bahn bombers are its forte, even the G-se­ries can’t es­cape its at­ten­tion, with a full range of per­for­mance up­grades avail­able for the leg­endary off-roader. The magic of tur­bos means most of this comes down to air and fuel man­age­ment, and a healthy in­crease in boost.

The stock seven-speeder re­mains un­der the Letech G63, as do many of the elec­tron­i­cally con­trolled sus­pen­sion com­po­nents. Stock-stan­dard AMG equipped the G63 with huge six-pis­ton front brakes, and they have re­mained on the Letech model.

It’s a bom­bas­tic ve­hi­cle, but it’s not Bill’s first at­tempt at build­ing a se­ri­ous off-road G-wa­gen. Letech USA’S other test ve­hi­cle was a fully kit­ted­out G500 that sported all the bars and rock-ready up­grades. Bill even took it up trails in the Las Ve­gas area with his lo­cal Jeep club, best­ing many of the kit­ted-out Chryslers!

But the G63 re­mains a spe­cial beast, even if it is cur­rently for sale. “This is cur­rently the very first and one and only Letech por­tal axle G63 in the USA,” Rader says. “A 2014 model, it has un­der 6000 miles on it, is in per­fect con­di­tion and is ready to take on any ter­rain you could throw at it; from malls to moun­tains this thing will go any­where, in style.”

The only catch is the price, with Rader re­quir­ing US$250,000 (AU$330K ap­prox.) be­fore he signs over the ti­tle to the new owner. We might have to com­pro­mise a lit­tle longer with rough dailies!

This spe­cific V8 AMG en­gine is hand­crated

by Marc Ditze. Ger­man com­pany Brabus turned the al­ready bonkers V8 into some­thing of a Franken­stein.

Por­tal con­ver­sion gives the 4x4 a lift and keeps the diff and axles safe.

18.5-inch bead-locked wheels are wrapped in Falken Wild­peak A/TS.

Check the clearance thanks to the por­tals

G63’s twin ex­haust sys­tem takes things to the next level.

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