Doosan D20S-5, D25S-5, D30S-5, D33S-5, D35C-5 2008 Service Manual

If you’re tearing into a Doosan forklift mast or steering knuckle without the factory book, you’re gambling with time and parts. I’ve seen experienced mechanics guess torque on a kingpin nut and end up buying a new axle. The Doosan D20S-5, D25S-5, D30S-5, D33S-5, D35C-5 2008 Service Manual gives you the exact sequence and numbers straight from Doosan’s engineering floor. No aftermarket guesswork, no reprints of reprints. This is the original 92-page PDF that the dealer techs use. Every time I open this manual, I find a spec I would have guessed wrong – like the tilt cylinder rod gland torque, which differs between the standard and secondary cylinders. That kind of detail saves comebacks. If you’re serious about doing the job once, you need this book.

This manual covers the hydraulic control valves, mast disassembly for FFT and quad masts, steering cylinder rebuild, and every fastener torque you need. I’ll walk you through what’s on each page and why it matters on the bench.

What’s Inside the Doosan D20S-5 to D35C-5 2008 Service Manual

You get the full Vehicle System section starting on page 5. That’s where the Hydraulic Control Valves live. From there the Disassembly & Assembly section runs from page 9 through page 84. It covers hood removal with seat, overhead guard, forks, backrest, carriage assembly, mast assembly for both FFT and quad masts, all three lift cylinders (standard, secondary, primary), and the tilt cylinder. Then the steering section from page 60 to 84 includes the steering wheel, steering unit, master cylinder (listed twice – page 70 and 71 – check both for different models), steer wheel and bearing, tie rod, steering knuckle with kingpin and bearing, steer axle, steering cylinder, universal joint, and counterweight. That’s every major component you’d service in a shop.

Hydraulic Control Valves: Disassembly and Assembly Sequence

Page 5 kicks off the hydraulic control valve section. If you’ve ever had a valve stick or bypass, you need the factory disassembly order to avoid scoring bores. The manual shows exploded views and step order. You’ll see the spool, relief valve, and seal locations. Don’t rely on a parts diagram from an online parts house; they often skip the assembly torque for the valve body bolts. The manual lists those torques – and they vary by model. Use the Doosan spec, not a generic bolt torque chart.

Mast Rebuild: FFT and Quad Mast Procedures

Page 26 gives the full assemble procedure for the FFT mast. Page 34 does the same for the quad mast. These are not just pictures – each step tells you which fastener to torque and in what pattern. I’ve rebuilt a mast using this manual and the chain adjustment specs alone saved me from a bent carriage. The manual also covers the standard lift cylinder (page 42), secondary lift cylinder (page 44), and primary lift cylinder (page 47). If you’re replacing seals on any of those, you need the rod gland torque.

Steering System Overhaul: From Master Cylinder to Kingpin

Steering problems on these forklifts often trace back to the master cylinder or kingpin bearings. The manual covers master cylinder disassembly on page 70 and again on page 71 – difference likely depends on cab configuration. Then the steering knuckle and kingpin bearing section on page 78. That’s where the torque spec for the kingpin nut is critical. Over-torque it and you bind the bearing; under-torque and you get play that eats the steering cylinder seals. The manual gives the number. You also get the steer axle disassembly (page 80), steering cylinder rebuild (page 81), and universal joint inspection (page 84). Don’t skip the tie rod section (page 78) – it’s easy to misalign the toe-in without the factory procedure.

Torque matters.

Safety Warnings You Cannot Afford to Skip

The first few pages of this manual contain the Important Safety Information. Page 3 has the standard Doosan warning about reading all safety precautions before operation or repair. But the manual also places specific warnings throughout the procedures – for example, when disassembling the mast, there are warnings about supporting the carriage to prevent dropping. You’ll see them in bold. If you’re working alone in a home garage, pay attention. Forklift components are heavy. A falling mast section can crush you. The manual doesn’t sugarcoat it.

Why OEM Factory Specs Beat Aftermarket Reprints

I’ve seen aftermarket manuals that claim “covers all models” but they reuse generic torque values. The Doosan factory manual lists specific torques for each bolt based on the 2008 model year. If you use a generic chart, you might over-torque the M10 bolts on the steering cylinder and strip the cast iron. The difference is 15 to 20 ft-lb. The factory manual also includes the safety warning labels and the exact part callouts. Aftermarket copies often skip the warning pages. That’s a liability. Stick with the original. This manual is a direct scan of the Doosan publication SB4256E01 from January 2008. No reprint, no third-party editing.

If you need other Doosan forklift manuals, check the Doosan Forklift 2008 Service Manual for related models. Also see Doosan Forklift D-Series Service Manual 2008 and Doosan D20S-5 D25S-5 D30S-5 D33S-5 D35C-5 2008 Service Manual for additional coverage. For general reference on manual transmissions used in some equipment, you can read about Manual Transmission basics, and if you work on other vehicles with Manual Transmission, you’ll appreciate having the same level of detail.

Frequently Asked Questions

What years does this manual cover?

2008.

Does this cover the D35C-5 model?

Yes, the manual covers the D35C-5 model. It also includes the D20S-5, D25S-5, D30S-5, D33S-5, plus the G20E-5, G25E-5, G30E-5, GC20E-5, GC25E-5, GC30E-5, GC33E-5, G20P-5, G25P-5, G30P-5, G33P-5, G35C-5, GC20P-5, GC25P-5, GC30P-5, GC33P-5. This manual is applicable to all those models as per the 2008 publication. Verify your serial number range from the front matter.

Is this a genuine OEM manual?

Yes, this is a direct PDF scan of the original Doosan publication SB4256E01 from January 2008.

What tools are needed for the mast rebuild?

The manual lists required tools in each section. For the FFT mast assembly (page 26), you’ll need a press, torque wrench capable of the specified values, and standard mechanic tools. No special tools required unless noted.

Ready to work with real factory data instead of guessing? Download the Factory Manual from AutoRepairManuals. You’ll get the 92-page PDF with every torque, every assembly step, and the safety warnings that keep you alive.