Description

Doosan D50S-5, D60S-5, D70S-5, D80S-5, D90S-5 2008 Service Manual – What You Get

If you’re rebuilding the 3WG94 transmission in a Doosan D50S-5, D60S-5, D70S-5, D80S-5, D90S-5 2008 Service Manual is the only document I trust on my bench. Not some aftermarket reprint that guesses at the converter safety valve setting. This is the OEM factory print – 84 pages, November 2008 publication, SB4342E00. I’ve pulled more transmissions than I care to count, and every time I see a tech reach for a third-party PDF I know they’re about to waste shop time. This manual gives you the exact disassembly sequence for the central shaft (PTO), the output flange, and the clutch pack – with torque values that came from the same engineers who designed the box.

Open this manual and the first thing you’ll see after the safety section is the page with tightening torques for screws in Nm. They give you both the nominal torque and the conversion table. Page 9. Memorize it. If you’re working on a D50S-5 with serial PB-00301~UP or a D90S-5 with PA-00701~UP, the specs are the same for the transmission internals – but you still check the serial range on page 1 to confirm. Never assume.

Tightening Torques and Fastener Specs

Every fastener in this transmission has a specified torque value in Newton-meters. Page 9 lists them clearly. The converter safety valve, the main pressure valve, the oil pump bolts – all of them. There’s a conversion table on page 8 if you’re one of those guys who thinks in foot-pounds. But stay in Nm for the internal assembly. I’ve seen a clutch pack fail because someone used a generic torque chart and over-cranked the piston retainer bolts. When you reassemble the clutches (page 43), you follow the exact order in the manual: clutch clearance, spring height, plate thickness. No guessing.

Disassembly of the 3WG94 Transmission – Step by Step

The manual breaks down disassembly into specific operations. Removal of the filter starts on page 21. Then converter and central shaft (PTO shaft) on page 24. Output flange removal is page 25. If you’re after the main pressure valve and converter safety valve, that’s also page 25. Keep going to page 26 for the clutch removal and oil pressure pump disassembly. Clutches themselves come out on page 29. Each step references the special tools listed on page 16. You want part numbers? They’re in the illustrations. You want the order of shims? It’s written down. I’ve used this manual to do a complete rebuild on a D70S-5 that had lost third gear. Followed the reassembly section from page 43 to page 80 – oil filler tube, dipstick, drain plug – and the transmission shifted clean after break-in.

OEM Safety Information You Cannot Ignore

Doosan put a full page of safety warnings, page 3. It’s not boilerplate. They talk about recognizing hazardous situations before they happen, and they explicitly warn that if you use a tool or procedure not recommended by Doosan, you better be damn sure it’s safe. That’s real. I’ve seen a tech try to press out a clutch hub with a porta-power and cracked the housing. The manual tells you which hydraulic press adapters from the special tool list (page 16) to use. Don’t skip the safety section – it’s written by the same guys who wrote the rest of the manual. And if you’re working on a D80S-5 or D90S-5, the serial numbers are different (PA-00701~UP, S1-00001~UP), but the safety warnings apply to all models.

Source Authenticity – Factory Manual vs Aftermarket Reprints

Read the OCR excerpt from this manual: “If a tool, procedure, work method or operating technique not specifically recommended by DOOSAN is used, you must satisfy yourself that it is safe for you and others.” That language comes straight from the OEM. Aftermarket manuals leave out half the warnings. They reprint torque tables from a different year. I’ve had a customer bring in a D60S-5 with a stripped converter bolt because someone used a “universal” transmission manual. This is the real document – 84 pages, original 2008 publication, no reprints. If you need the companion for the engine side, get the Doosan Diesel Engine DB58S 5.8 Liter Service Manual for the whole power train. For testing procedures and adjustments on the same transmission, the Doosan Power Train Specification Testing & Adjusting Manual is what you want. And if you only need the transmission itself, there’s a dedicated Doosan Power Train Transmission 3 Speed 3WG94 Manual that matches this one.

Who Needs This Manual?

If you own a Doosan D50S-5, D60S-5, D70S-5, D80S-5, or D90S-5 forklift and you’re pulling the transmission yourself, this is the only document that gives you the correct clutch clearance and pump torque. Garage owners – hand this to your techs before they touch a 3WG94. Home mechanics – if you’ve got a Doosan lift and you’re trying to save the shop rate, you need the factory steps. The manual covers everything from removal of filter to reassembly of the converter safety valve. It’s not a general guide. It’s the OEM procedure. For background on how a manual transmission works under load, check out this Manual Transmission article. Another good reference on transmission basics is Manual Transmission.

Does this manual cover the D80S-5 and D90S-5?

Yes. Serial ranges for those models are listed on page 1: PA-00701~UP and S1-00001~UP.

What if I need the torque spec for the converter safety valve?

That spec is on page 9 in the tightening torque table. But you need to understand that the manual gives torque in Nm for each screw size. The converter safety valve uses a specific screw size – you’ll find it in the reassembly section on page 76. The manual also includes a conversion table on page 8 if you work in foot-pounds. Don’t guess. I’ve seen a converter safety valve fail open because the bolt was under-torqued. The valve controls the converter charge pressure; if it’s wrong, the transmission slips under load. The procedure on page 76 tells you the exact order to tighten and the torque value. It’s not optional.

You want a manual that gives you the reassembly sequence for the clutch pack (page 43), the output flange (page 75), and the central shaft (page 77) without any guesswork? This is it. 84 pages, every step accounted for. I’ve used it, it works. Access the Factory Manual now and have the OEM specs on your tablet or print them out for the bench.