Unimog U 1700 L

The most capable 4×4 variant in the Series 435 family. Full spare parts coverage for the OM 352A piston-cooled turbocharged powertrain, heavy-duty portal axle system, and the complete mechanical architecture of the Unimog U 1700 L — the platform chosen by defence forces demanding maximum capability within the Series 435 chassis.

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Unimog U 1700 L — Maximum Capability Within the Series 435 Platform

To understand the U 1700 L correctly, you must first understand what it is not. It is not simply a U 1300 L with a more powerful engine. The two vehicles share the Series 435 chassis and the same iconic angular cab — internally designated 425.820 — and on the surface they appear near-identical. But underneath, the U 1700 L is a fundamentally different vehicle built around a substantially heavier axle rating, a more sophisticated turbocharged engine with piston-level cooling provisions, and a drivetrain calibrated for sustained operation at higher gross vehicle weights.

The defining engineering distinction is the axle. The U 1300 L uses what the Unimog community accurately refers to as "light axles" — a design closely related to the axle architecture of the earlier Series 416, sharing many brake, portal, and differential centre components with that platform. The U 1700 L, by contrast, is equipped from the factory with genuinely heavy-duty axles rated to approximately 7 tonnes per axle — a completely different component family, with larger-diameter axle tubes, heavier portal housings, more robust hub bearing assemblies, and greater brake caliper sizing. This is not a marginal upgrade; it is a categorical step up in structural capacity.

The engine difference is equally significant in maintenance terms. The U 1700 L's OM 352A was not simply the OM 352 with a turbocharger bolted on. Mercedes-Benz engineered specific internal modifications into the OM 352A from the outset: additional oil passages for piston cooling, a lower compression ratio of 16:1 compared to 17:1 for the naturally aspirated OM 352, and a strengthened bottom end to manage the additional thermal and mechanical load of forced induction. These differences mean that internal engine components are not freely interchangeable between OM 352 and OM 352A variants despite identical external dimensions, and sourcing errors at this level carry serious consequences.

Produced under the internal Mercedes-Benz designation Series 435.111, the U 1700 L was adopted by military forces well beyond Germany. The Australian Defence Force deployed the U 1700 L as its primary medium tactical truck from 1982, eventually operating nearly 2,000 Unimogs across Army and Air Force variants — making the Australian fleet one of the largest single-nation U 1700 L concentrations outside Europe. New Zealand, Portugal, Switzerland, and various Middle Eastern and African defence forces also operated the platform in significant numbers. AB Defence maintains dedicated inventory and sourcing networks for all major operator configurations.

Technical Specifications — Unimog U 1700 L (Series 435.111)

Series Designation:

Unimog 435 / 435.111

Production Run:

1975 — 1993 (Australian production from 1982)

Engine (Standard):

Mercedes-Benz OM 352A · 5,675 cc · Inline-6 · Turbocharged Engine (Late Production / Replacement): OM 366A · Inline-6 Turbocharged · 168 hp

Power Output:

170 hp (124 kW) @ 2,800 rpm (OM 352A)

Compression Ratio:

16:1 (OM 352A turbocharged, vs 17:1 NA)

Piston Cooling:

Yes — dedicated oil passage system (OM 352A specific)

Gearbox:

8-Speed Fully Synchronised Manual (8 Forward / 8 Reverse)

Transfer Case:

Integrated · 2-Speed with optional auxiliary reduction stages

Crawl Ratio (with auxiliary gearing):

Up to 490:1 (5.76:1 reduction) or 4,500:1+ (55.87:1 super-low)

Drive System:

4×4 Selectable Part-Time AWD Differentials: Front and Rear — both lockable; drivetrain pressurised under diff-lock engagement

Axle Rating:

Heavy-duty · Approximately 7 tonnes per axle

Wheelbase (Standard):

3,250 mm (128 in)

Wheelbase (Long — U1700L/38):

3,850 mm (152 in)

GVM:

10,600 kg

Dead Weight (Cab-Chassis):

Approximately 5,650 kg

Payload Capacity:

Up to 4,950 kg (road conditions)

Max Towing:

Up to 8,500 kg (braked trailer)

Length:

5,210 mm (standard body)

Width:

2,340 mm Height: 2,650 mm (cab, unloaded) Track Width: 2,350 mm

Ground Clearance:

500 mm (portal axle advantage)

Braking:

Air-Activated Dual-Hydraulic Circuit Disc Brakes (all four wheels)

Steering:

Hydraulic Power-Assisted (recirculating ball)

The Heavy Axle Distinction — Why It Changes Everything for Spare Parts Sourcing

The single most important technical fact that any procurement officer or fleet manager must understand about the U 1700 L is this: its axle components are not interchangeable with U 1300 L axle components, despite the two vehicles appearing externally near-identical and sharing the same Series 435 chassis family.

The U 1300 L's "light axles" share significant parts commonality with the older Series 416 — the brake components, portal housings, and differential centres are closely related, and many components cross between the two platforms. This actually makes U 1300 L axle parts relatively straightforward to source. The U 1700 L's heavy axles are a different matter entirely. They are a dedicated heavy-duty design with larger axle tube diameters, substantially more robust portal gear housings, heavier hub bearing assemblies, and larger brake assemblies. Used parts exist in Europe where military surpluses have been disposed of, but new old-stock and aftermarket components require a supplier with genuine U 1700 L axle expertise.

AB Defence maintains completely separate inventory and sourcing records for U 1300 L light axles and U 1700 L heavy axles. When a customer submits a parts request referencing the Series 435, our first action is always to confirm axle specification — because issuing a light-axle component onto a heavy-axle vehicle, or vice versa, is not simply a fitment problem. It is a structural safety failure waiting to occur under load.

OM 352A Engine

The OM 352A fitted to every U 1700 L from the start of production represents the most highly developed state of the venerable OM 352 engine family. Its engineering differs from the naturally aspirated OM 352 in ways that matter deeply at the component level: dedicated oil squirters that direct pressurised oil to the underside of each piston crown for thermal management, a reduced compression ratio to accommodate boost pressure safely, and a reinforced bottom end to handle the additional combustion loads of forced induction.

These differences mean that pistons, piston rings, cylinder liners, and connecting rod big-end bearings specified for the naturally aspirated OM 352 are not correct for the OM 352A — even where dimensions appear similar. The piston cooling passages in the OM 352A block also require that any oil system overhaul correctly addresses the feed galleries and squirter nozzle condition, something that is irrelevant when working on a naturally aspirated variant. AB Defence's engine parts inventory is catalogued separately for OM 352 and OM 352A applications, eliminating this source of error at the point of order.

Complete Engine Overhaul Kits — OM 352A Specific Full gasket and seal sets specific to the turbocharged OM 352A configuration, including head gasket, rocker cover, and all core plug assemblies. Cylinder liner sleeves, piston assemblies (with piston cooling oil squirter bosses), piston ring sets, and circlip kits. Main bearing shell sets and big-end connecting rod bearing shells, with undersized options for reground crankshafts. Camshaft and timing gear assemblies, timing cover seals and front crankshaft seal sets. Rocker shaft assemblies, push rod sets, and valve train components. Cylinder head bolt sets with replacement torque specification documentation. Complete piston cooling oil squirter nozzle assemblies and feed gallery hardware.

Turbocharger System — KKK/BorgWarner Application Complete turbocharger cartridge assemblies (CHRA) for OM 352A applications as originally fitted. Compressor and turbine wheel inspection criteria and replacement sets. Turbocharger oil feed banjo bolt and copper washer seal kits. Oil scavenge return line hardware, including return elbow fittings, sealing rings, and check valve assemblies. Boost inlet hose and clamp assembly from air cleaner to compressor inlet. Exhaust manifold to turbine inlet gasket and mounting stud sets. Wastegate actuator assemblies and boost calibration hardware.

Bosch Fuel Injection System — OM 352A Calibration Bosch in-line injection pump barrel and plunger assemblies calibrated to OM 352A turbocharged specification. These are not interchangeable with naturally aspirated OM 352 pump elements despite sharing the same Bosch PE pump family architecture. High-pressure injection delivery valve assemblies and valve spring kits. Injector nozzle and needle valve assemblies (turbocharged calibration). Injection pump governor spring and tensioner sets. Complete 6-cylinder high-pressure fuel line sets. Primary and secondary fuel filter elements and housing seal kits. Fuel lift pump assemblies and diaphragm repair kits.

Cooling and Thermal Management Heavy-capacity radiator cores and complete assemblies sized for the sustained thermal output of the OM 352A under full military GVW in high-ambient-temperature environments. The U 1700 L's higher GVM compared to the U 1300 L places greater sustained demand on the cooling system, making correct radiator specification critical for operators in hot-climate theatres. Thermostat and housing assemblies. Water pump complete assemblies and mechanical seal sets. Viscous fan coupling assemblies. Complete coolant hose sets by chassis and superstructure variant. Coolant pressure cap assemblies and system test hardware.

Lubrication System — Including Piston Cooling Circuit Oil pump assemblies, pressure relief valves, and pressure regulator components. Piston cooling oil squirter feed circuit hardware — a maintenance item unique to the OM 352A that must not be overlooked during any bottom-end overhaul. Oil cooler matrix elements and housing seal kits. Front and rear crankshaft main seals and sump gasket sets. Military oil filter elements and complete filter housing assemblies. Engine breather and crankcase ventilation components.

Air Induction System Military-grade two-stage dry-type air cleaner assemblies. Primary and safety filter elements with pre-cleaner cyclonic separator units. Air restriction indicator service valves. Turbocharger inlet pipe and hose assemblies. Intake manifold gaskets and associated fastener hardware.

8-Speed Fully Synchronised Gearbox & Drivetrain

The Series 435's straight 8-speed fully synchronised gearbox is one of its defining advantages over older Unimog transmission architectures. Unlike the 2×4 split gearbox layout of the Series 406/416, the 435 uses a dedicated 8-speed box — 8 forward and 8 reverse — where every speed is fully synchronised, eliminating the need for double-declutching even during reverse gear engagement. This is a significant operational advantage in military use where drivers may not be highly trained on heavy manual transmissions.

Optional auxiliary reduction gearboxes extend the 435's low-speed capability dramatically. A 3.19:1 auxiliary reduction extends effective crawl ratio to approximately 271:1. The 5.76:1 reduction delivers approximately 490:1. The most extreme 55.87:1 super-low option, when combined with the base gearbox ratios, produces crawl ratios exceeding 4,500:1 — making the U 1700 L capable of controlled movement at speeds measured in metres per minute, critical for winching, crane operation, and obstacle negotiation.

An optional gear-splitter, increasing any gear ratio by approximately 22%, provides an additional layer of ratio finesse across all gears, both forward and reverse.

Gearbox — Series 435 8-Speed Straight Transmission Synchroniser ring and hub assemblies for all 8 gear positions, forward and reverse — noting that the 435 straight gearbox components are not interchangeable with the 2×4 splitter gearbox of the Series 416. Input, output, and layshaft bearing sets with shaft seals. Gear selector fork assemblies, shift rail interlock mechanisms, and detent spring sets. Gearbox housing gasket and o-ring seal kits for in-field overhaul. Reverse selector mechanism assemblies. Gear lever mounting hardware, rubber isolator mounts, and pivot bush kits. Complete exchange gearbox units remanufactured to OEM specification.

Auxiliary Reduction Gearboxes (Working Gears) Auxiliary underdrive housing gasket and seal kits for 3.19:1, 5.76:1, and 55.87:1 reduction units. Reduction gear engagement mechanism assemblies and selector fork hardware. Auxiliary gearbox input and output shaft bearing sets and shaft seals. PTO drive output shaft seal and bearing assemblies (where auxiliary working group is fitted).

Gear-Splitter Components Gear-splitter internal gear sets and synchronising components. Splitter engagement actuator assemblies (air or mechanical operated types). Splitter housing gasket and seal kits.

Transfer Case Transfer case input and output shaft bearing and seal kits. Front axle engagement dog-clutch and fork assemblies. Transfer case differential lock mechanism hardware. Low-range engagement components and selector hardware. Transfer case housing gasket and cover seal kits. Breather valve and magnetic drain plug assemblies. Hardy-Spicer universal joint assemblies for front, centre, and rear propshaft sections.

Differential Assemblies — Heavy-Axle Specification Front and rear differential carrier bearing sets and shim packs — heavy-axle dimensions, not interchangeable with U 1300 L light-axle differentials. Crown wheel and pinion matched gear sets. Differential lock pneumatic actuator components and solenoid valves — noting that the U 1700 L's drivetrain is pressurised with air when diff-locks are engaged, sealing all drivetrain elements from water ingress during fording. Planet and sun gear sets with spider cross assemblies. Axle shaft seals and hub gasket kits for heavy-axle positions. Diff-lock engagement indicator switch assemblies.

Clutch Assembly Clutch disc and pressure plate assemblies matched to the OM 352A's turbocharged torque output. Release bearing assemblies. Clutch hydraulic master and slave cylinder overhaul kits. Flywheel ring gear assemblies. Clutch fork pivot pins, return springs, and dust cover assemblies.

Heavy-Duty Portal Axle System — U 1700 L Specific Components

The U 1700 L's heavy-duty portal axles deliver the same fundamental design benefit as all Unimog portal systems — approximately 220 mm of additional ground clearance gained by mounting the wheel hub below the axle shaft centreline through a portal reduction gear — but the components themselves are a separate family from the U 1300 L's light-axle portals. Ground clearance of 500 mm is among the highest of any wheeled military tactical truck, and it is achieved without any sacrifice in payload capacity or drivetrain robustness.

The U 1700 L/38 long-wheelbase variant (3,850 mm vs 3,250 mm standard) sees the same heavy-axle system deployed on an extended chassis, demanding additional attention to propshaft length and universal joint specification when sourcing drivetrain components. AB Defence catalogues the standard U 1700 L (435.111) and the long-wheelbase U 1700 L/38 (435.113) as distinct configurations.

Portal Hub Reduction Gears — Heavy-Axle Specification Heavy-axle portal gear sets — sun, planet carrier, and ring gear assemblies to U 1700 L specification, dimensionally distinct from light-axle U 1300 L portals. Portal housing bearing sets (inner and outer). Portal cover gaskets and o-ring seal kits. Backlash setting shim packs. Complete portal hub overhaul kits. Magnetic drain plug assemblies and oil level inspection plugs. Portal gear oil specification documentation.

Wheel Hub & Bearing Assemblies — Heavy-Duty Outer and inner wheel hub bearing cone and cup sets to heavy-axle dimensional specification. Military-grade hub oil seal assemblies. Hub lock ring and adjustment hardware. Wheel stud and nut sets — noting the U 1700 L typically uses a 10-stud wheel pattern, distinct from lighter-duty Unimog variants. Hub cap assemblies with level inspection plugs.

Coil Spring & Suspension Linkage Front and rear coil spring sets rated for the U 1700 L's higher GVM compared to the U 1300 L. Torque tube pivot bush and mounting assemblies — a known wear item under sustained heavy-load cross-country operation, where torque reaction through the tube system places high cyclic loads on the bush material. Transverse link (Panhard rod) end bush and bolt assemblies. Heavy-duty hydraulic shock absorber units matched to U 1700 L GVM loading. Bump stop assemblies and mounting hardware. Anti-roll bar bush sets (where fitted).

Axle Shaft Sets — Heavy-Axle Dimension Heavy-axle solid axle shaft sets — inner and outer sections — to heavy-axle dimensional specification. Half-shaft flange seals and o-ring kits. Axle shaft circlips and retaining ring sets. Reconditioned axle shafts with magnetic particle inspection certification available for high-criticality fleet applications.

Steering System Hydraulic power steering pump overhaul kits and complete exchange assemblies. Steering box (recirculating ball) repair kits and complete exchange units. Drag link and track rod end assemblies — heavy-axle geometry specification. Power steering cylinder seals and piston kits. Hydraulic reservoir filter elements. Steering column universal joint assemblies.

Air-Hydraulic Brake System Air compressor overhaul kits and unloading valve assemblies. Dual-circuit air-hydraulic brake booster assemblies and diaphragm kits. Brake disc rotors and caliper overhaul seal kits — heavy-axle brake size, not interchangeable with U 1300 L components. Air dryer cartridges, purge valves, and pressure protection valves. Brake chamber diaphragm kits — service and spring brake types. Trailer brake coupling head assemblies. Parking brake mechanism components. Brake pipe and union sets for field repair.

U 1700 L/38 — Long-Wheelbase Variant: Sourcing Implications

The U 1700 L/38 designation identifies vehicles built on the extended 3,850 mm wheelbase chassis (internal designation 435.113), compared to the standard 3,250 mm wheelbase of the 435.111. The extended wheelbase was applied primarily to cargo carriers and shelter-body platforms where rear body length was operationally critical. The mechanical differences between the /38 and standard U 1700 L are concentrated in the drivetrain: the rear propshaft is lengthened and uses a support bearing and centre carrier bracket, the chassis cross-members are repositioned, and body mounting sub-frame geometry changes accordingly. AB Defence catalogues the U 1700 L and U 1700 L/38 as distinct variants and requests wheelbase confirmation before issuing any propshaft, chassis-related, or body mounting component.

Extended rear propshaft assemblies with centre support bearing and carrier bracket hardware. Centre propshaft support bearing and rubber mounting assemblies. Extended chassis cross-member fastener hardware. Rear body mounting sub-frame hardware to extended wheelbase geometry.

Deep Fording Kit Components

The military specification U 1700 L was frequently issued with or retrofitted to a deep fording kit, extending unprepared fording depth beyond the standard 1,200 mm by sealing all drivetrain breather points and routing breathers to cab-height locations. The pressurised drivetrain system — whereby engaging the differential locks pressurises all drivetrain cases with air, preventing water ingress — already provides a substantial natural fording advantage, but dedicated fording kits extend this further. New Zealand Army U 1700 Ls were noted for having factory deep fording kits fitted, allowing fording to approximately 1,200 mm with pressurised headlights.

AB Defence stocks the key consumable components of the deep fording system: extended axle breather pipe and fitting assemblies, drivetrain housing breather relocation kits, cab penetration breather grommet and sealing sets, pressurisation system check valve assemblies, and deep-fording headlight seal and pressurisation hardware where fitted.

Cab, Body, and Crew Environment

The Series 435 cab — shared across the U 1300 L and U 1700 L — is a robust, angular steel unit that has proven highly durable across decades of military service on every continent. Its known long-service wear points are consistent and predictable: door perimeter seals deteriorate progressively, cab-to-chassis rubber isolator mounts compress and crack, and windscreen lower channels accumulate moisture leading to seal failure and structural corrosion at the frame. Australian fleet operators add cab air conditioning as a common modification, requiring additional penetration seals and evaporator mounting hardware that AB Defence can source alongside the standard cab component range.

Cab Mounting and Structure Cab-to-chassis rubber isolator mount sets. Cab tipping pivot bracket hardware, locking pins, and safety stay assemblies. Engine tunnel gaskets and heat shield assemblies. Cab floor seal plates and drainage hardware. Windscreen frame seal profiles and retaining beads.

Door Hardware and Glazing Door hinge pin and bronze bush kits. Door check strap assemblies and anchor hardware. Door lock striker and latch assemblies. Full-perimeter door seal rubber profiles — military specification. Side window glass assemblies with military rubber glazing surrounds. Ventilation flap hinge and actuator linkage components.

Heating and Ventilation Cab heater matrix cores. Heater blower motor assemblies. Heater control cable sets and water valve hardware. Fresh-air flap seals and actuator linkages. Windscreen demister nozzle and duct assemblies. Auxiliary air conditioning evaporator mounting and penetration seal hardware (for ADF and other modified configurations).

Wheels, Tyres, and Spare Carrier Heavy-axle wheel rim assemblies — typically 10-stud pattern, compatible with 365/85 R20 or 14.00 R20 military cross-country tyres. Valve core and extension assemblies for portal hub fitment. Spare wheel carrier frame hardware and securing assemblies. Tyre pressure indicator hardware.

Why AB Defence for Your Unimog U 1700 L Fleet

The U 1700 L is the most demanding Unimog platform to source parts for correctly. Its heavy-axle system shares nothing with the U 1300 L's light axles. Its OM 352A has internal provisions — piston oil squirters, reinforced bottom end, turbocharged injection calibration — that differentiate it at the component level from the OM 352 in ways that are invisible to a non-specialist. Its variant diversity across European, Australian, New Zealand, and Middle Eastern military operators means that cab configuration, electrical specification, and body mounting geometry all require operator-level identification before any component can be correctly issued.

AB Defence has built a Unimog supply programme that begins with platform identity, not with a parts catalogue. Every U 1700 L inquiry is processed against series designation (435.111 or 435.113), engine generation (OM 352A or OM 366A), wheelbase variant, axle specification, and operator configuration. We cross-reference against NATO Stock Numbers where available. We maintain separate inventory for heavy-axle and light-axle Series 435 components. We source to the military specification — not the commercial catalogue — where these diverge.

For U 1700 L and U 1700 L/38 spare parts quotations, submit your chassis number, series designation, engine variant, and NATO Stock Number reference where available. Our Unimog technical team will confirm specification and respond with availability and lead-time within 24 hours.

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Below is a representative selection of NATO-codified (NSN) and OEM spare parts stocked by AB Defence for this platform. View the full category catalog or click any component for complete cross-reference specifications:

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