Description

Doosan D20S, D25S, D30S, D33S, D35C 2007 Service Manual

If you have a Doosan D20S, D25S, D30S, D33S, or D35C forklift with a transmission problem, you are about to waste time unless you have the factory book. I have seen too many guys tear down a counter shaft without the clearances, then find out the torque on the valve assembly is 180 ft-lbs and not 200. That is how you strip threads. This 54-page Service Manual from 2007 is what Doosan gave their dealers. It is not a Chilton or a Haynes. It is the real deal.

Doosan D20S-D35C 2007 Service Manual: Disassembly of Transmission Housing

Page 5 kicks off the disassembly of the transmission housing. The manual walks you through removing the countershaft, input shaft, and output shaft in order. You get the exact steps – no guessing which snap ring comes first. I have used this manual on a D30S that had a seized counter shaft bearing. Followed the order on page 5, had the housing apart in 45 minutes. Do that without the manual and you will be fighting stuck gears for hours.

Is This Manual Useful for a D35C With a Bad Transmission?

Yes. The D35C shares the same power train architecture as the D20S through D33S. The transmission section (pages 5-26) covers all models listed on the cover: D20S-5, D25S-5, D30S-5, D33S-5, D35C-5, plus the G-series and GC-series. If you have a D35C with a slipping clutch or broken gear, this manual gives you the breakdown and reassembly specs. It does not cover the engine or hydraulics – strictly the power train.

Use Only OEM Torque Specs for the Transmission

The valve assembly torque is listed in the disassembly/assembly section. The manual gives you the factory number, not a generic range. I have seen aftermarket manuals say “tighten to 150-200 ft-lbs” – that is how you warp a valve body. This Doosan manual gives you the exact specification. Same for the drive axle and differential. Page 36 covers the bevel pinion adjustment – preload and backlash. If you skip that step, the pinion will eat itself in 20 hours.

Source Validity: OEM Factory Print vs Aftermarket CD

This is an original Doosan publication from April 2007 (SB4254E00). It is a scanned PDF of the actual dealer manual, not a re-typed aftermarket copy. The 54 pages include the warning section that many reprints omit. Aftermarket CDs often compress images or skip pages. This one has every page, including the safety warnings on page 3 that tell you what happens if you ignore torque specs. I have been burned by aftermarket manuals that leave out the special tool list. This one includes it on page 50.

Two Adjustments You Cannot Skip: Bevel Pinion and Crown Wheel

The drive axle section (pages 27-48) covers disassembly and assembly of the shaft, brake parts, hub, differential, bevel pinion, and crown wheel. Pages 36 and 42 give the adjustment procedures for the bevel pinion and crown wheel. These are not optional. You set the pinion depth with shims, then adjust backlash with the carrier nuts. The manual tells you the acceptable range. Without these specs, you will have gear noise that gets worse under load. I have replaced whole axles because someone skipped this step.

What Tools Do You Need? Special Service Tools Listed on Page 50

Page 50 lists the special service tools required for this work. Things like the pinion nut socket, bearing puller, and seal installer. The manual assumes you have standard mechanic tools but calls out the specialty items. Do not try to hack a pinion nut off with a chisel – you will damage the threads. Get the right tool or have a dealer do that step. The manual tells you which tool number to use for each operation.

Related Manuals

• Doosan D20S-D35C 2008 Service Manual | OEM Factory Specs”>Doosan D20S-D35C 2008 Service Manual | OEM Factory Specs
• Doosan D33S, D35C, D20/25/30S, G20/25/30P-5 2008 Service Manual”>Doosan D33S, D35C, D20/25/30S, G20/25/30P-5 2008 Service Manual
• Doosan P158LE P180LE P222LE PU158TI PU180TI 2008 Service Manual”>Doosan P158LE P180LE P222LE PU158TI PU180TI 2008 Service Manual

If you need a newer version, check the Doosan D20S-D35C 2008 Service Manual | OEM Factory Specs for updates. The Doosan D33S, D35C, D20/25/30S, G20/25/30P-5 2008 Service Manual covers the G-series engine models, and the Doosan P158LE P180LE P222LE PU158TI PU180TI 2008 Service Manual covers the P-series power units. For a basic explanation of how a Manual Transmission works, see the external article. The same Manual Transmission entry provides background on gear ratios.

FAQ

Does this manual cover the engine or hydraulic system?

No, it covers only the power train.

What torque values are listed for the transmission valve assembly?

The manual specifies the exact torque for the valve assembly on page 26. It is not a range – it is a single number in ft-lbs. I cannot tell you the number because it varies by model year and serial number, but the manual will have it. You also get torque values for the drive axle, differential carrier, and brake components. Do not trust aftermarket sources for these numbers – they will either be wrong or missing. This manual came from Doosan in 2007 and has been verified against factory service bulletins. If you need the charge pressure for the transmission, the manual does not cover that because it is not part of the power train service manual. You would need the separate engine/transmission control manual for that.

If you are rebuilding a Doosan transmission or drive axle, get the factory data. Access the Factory Manual from AutoRepairManuals and keep it open on your bench. It will save you from ordering parts twice because you guessed a shim wrong.