The Turtle V – Update #4 – Drivetrain, Suspension & Fuel – 2019

June 7, 2019


Traffic was light in Azerbaijan.

Traffic was light in Azerbaijan.

Not the least important part of any vehicle, the drivetrain of The Turtle V has been carefully selected and designed to do a job, reliably.

The front differential of the F550 is a heavy duty Dana 60. We added an ARB Air Locker and protected it with the Dynatrac Pro Series off-road differential cover. The function of the ARB is simple. It is air actuated from our 5 gallon AccuAir air tank which is constantly kept full, (120 psi), by our twin ExtremeAire Magnum 12 Volt Compressors by Extreme Outback Products. If we start to lose traction it’s simply a matter of pushing a button on the dash and the ARB locks the front axles together like a spool, giving maximum traction to both wheels at the same time. Otherwise the front differential remains totally open for comfortable normal driving. ARB Air Locker has proven its reliability in both The Turtle III & IV.

The rear axle holds a massive Detroit S135 fitted with a Detroit Truetrac (by Eaton) limited slip. The Truetrac operates as a standard or open differential under normal driving conditions, allowing one wheel to spin faster or slower as necessary. When a wheel encounters a loss of traction or the terrain changes, the gear separation forces take effect and transfer torque to the high-traction wheel. The helical-shaped gears mesh with increasing force until wheel spin is slowed or completely stopped. When the vehicle exits the low traction situation, the differential resumes normal operation. We tried the Detroit Locker but it proved to be much too aggressive on hairpin gravel roads and even on pavement. ARB does not make one for the Detroit S135.

(See Turtle V Blog Part II for information on the Dynatrac Free-Spin bearing replacement.)

South Bend Clutch

Ford’s factory clutch exploded after only 60,000 miles. We replaced it with a HD South Bend Clutch, pressure plate and throw-out bearing. There had been an annoying tendency for the clutch to grab. We replaced the factory clutch slave cylinder and its hard plastic line with the South Bend unit that features a flexible stainless steel line. The problem instantly disappeared.

The ZF six-speed manual transmission and two-speed transfer case are not as smooth as our old four speed in The Turtle III or the five speed in The Turtle IV, but now, with a hard 200,000 miles on it, we should not complain. We never used the PTO option. A periodic oil analysis of all the gearboxes has shown that there is no unusual wear in the transmission.

K&N Breathers

Thanks to highly mounted K&N breathers on The Turtle II, we had no problems crossing this flooded two-track where beavers had decided to dam a creek in the Upper Peninsula Michigan.

Thanks to highly mounted K&N breathers on The Turtle II, we had no problems crossing this flooded two-track where beavers had decided to dam a creek in the Upper Peninsula Michigan.

Where possible remote K&N breathers on gear boxes and differentials were added to keep water out during river crossings or beaver ponds.

Deaver Springs, Rancho and Hellwig

Custom suspension has been designed by Deaver Suspension to carry our anticipated fully loaded weight of 14,000 pounds, all the time. No overload springs. All our Deaver Spring packs feature a full “military wrap” and have Teflon pads between leaves for smooth flexing. Dual adjustable Rancho RS9000XL shock absorbers in front set on #3 and single adjustable RS9000XLs set on #6 at the rear have shown to be reliable under the harshest conditions. Adding Hellwig Air Assist bags at the rear softens the ride and Hellwig HD sway bars front and rear improve stability and cornering.

The Turtle V carries 94 gallons of Diesel thanks to Transfer Flow’s two tanks

Our factory fuel tank was replaced with a custom Transfer Flow tank with a 46 gallon capacity and an emergency drain plug if we should get a bad tank. Transfer Flow also installed their 38 gallon auxiliary tank and designed a special switch-over valve so we can choose which tank to run from. Those two tanks along with our two 5-gallon jerry cans give us a total of 94 gallons of diesel, or an easy 1,000-mile range. If there is a road anywhere in the world 1,000 miles long, there will be diesel somewhere, or it wouldn’t be a road.

Racor and Airtex

An auxiliary Racor fuel filter/water separator/fuel pre-heater with a clear bowl allows inspection for dirt or water in the fuel before it even reaches the Airtex fuel pump.


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