Description

Clark-hurth GPX 35, GPX 40, GPX 50E Service Manual – OEM Factory Procedures

If you’ve ever been halfway into a transmission overhaul and realized the pressure specs you scribbled off some forum are wrong, you know the cost of guessing. This Clark-hurth GPX 35, GPX 40, GPX 50E Service Manual is the factory binder that came from Lexington, KY – not a scanned photocopy with faded torque values. 411 pages of OEM data. Page 2 alone tells you this manual includes the new GM Vortec V-6 overhaul information that the earlier SM593 didn’t cover. That’s the difference between walking into a job cold and having the sequence right before you pull the first bolt.

GPX 35/40/50E: What’s Inside the 411 Pages

Page 4 of the manual shows the full contents table. You get the complete Engine group (00) covering removal, replacement, and the full disassembly/assembly of the GM Vortec V-6. Transmission group (06) gives you the stall RPM checks, clutch pack pressures, converter pressure tests, and the neutral start switch test. Brake group (23) covers the inching system bleeding procedures – both manual and power bleed. Fuel system (02) walks you through the IMPCO LPG setup and carburetor overhaul. Every system has its own troubleshooting section, not just a generic “check this and that” table. That’s the kind of depth you need when a lift truck is down and the flat rate isn’t paying you to invent procedures.

OEM Factory Specs vs Aftermarket Reprints

Third-party manuals leave out the critical fastener torque checks, the voltage drop test sequences, and the exact pedal freeplay measurements. This one includes them because it was printed for Clark dealers. The “Critical Fastener Torque Checks” in the Planned Maintenance section are there. The wiring diagrams in group 14 are color-coded with factory wire colors, not generic abbreviations. Aftermarket reprints often take a low-resolution scan and lose the fine print on hydraulic filter restriction light testing – you get a blur instead of a spec. Don’t trust your safety or your reputation to a reprint.

Transmission Pressure Checks and Overhaul

Group 06 requires specific tools – the manual lists them. You need a pressure gauge set capable of reading inching pressure, clutch pack pressures, and converter pressure separately. The stall RPM check tells you if the converter or clutches are slipping before you even drop the pan. Transmission removal and overhaul steps are written in order: drain, disconnect, unbolt, remove. No shortcuts to trip you up. If you’re digging into a GPX 40 that’s losing forward drive, you need the clutch pack clearance specs – they’re in section 06-04. Understanding the overhaul is easier if you know basic Manual Transmission theory, but this manual gives you the real numbers.

Engine Removal and Vortec V-6 Overhaul

Section 00-02 is worth the price alone. The Vortec V-6 has specific crankshaft thrust bearing clearance checks and piston ring gap positions. Disassembly steps call out which fasteners to replace, not just “remove bolts.” The Delco distributor section (00-02A) shows the correct rotor alignment for the GM ignition system. When you reassemble, the torque sequence for the intake manifold is printed – not a generic pattern but the factory order. Check Manual Transmission for gear theory if you need, but stay focused on the engine group for the actual work.

Brake and Inching System: Factory Bleeding Procedure

Group 23 separates the service brake troubleshooting from the inching system troubleshooting. The manual bleeding procedure (23-02) tells you to start at the caliper farthest from the master cylinder – same as a car, but with the specific pedal pushrod adjustment for the inching valve. Power bleeding procedure requires a pressure bleeder set to 30 psi – the manual says that. Axle end removal is cross-referenced from group 20 because the caliper comes off with the axle assembly. That kind of cross-reference saves you from disassembling things out of order.

Fuel System: LPG and Carburetor Overhaul

GPX 35 and GPX 50E models often run on LPG. Section 02-02 covers the IMPCO vaporizing system – vaporizer removal, carburetor overhaul, velocity governor adjustment. Fuel pump pressure test (gas only) gives you the psi range and the flow volume test. Aftermarket manuals skip the governor overhaul steps because they require special tools to set the droop – this manual doesn’t skip them.

Pages 2 and 4 are the only page references I’m giving you because the rest you need to read when you’re holding the wrench. If your shop works on heavy-duty transmissions alongside these Clark lift trucks, the Spicer Clark-hurth HR Service Manual – Factory Specs for Heavy-Duty Transmission”>Spicer Clark-hurth HR Service Manual – Factory Specs for Heavy-Duty Transmission covers similar depth. For the older Clark 55A series, grab the Clark-hurth 55A SERIES II Service Manual – 136 Pages of Factory Specs”>Clark-hurth 55A SERIES II Service Manual – 136 Pages of Factory Specs. And if you’re into the newer TMX and EPX models, the Clark-hurth SM-715, TMX12-25, EPX16-20s 2007 Service Manual – 502 Page OEM Facto”>Clark-hurth SM-715, TMX12-25, EPX16-20s 2007 Service Manual is waiting.

That’s the kind of factory reference you need when the lift is down and the customer is watching. Access the Factory Manual – you’ll have the OEM specs in your hands, not a forum rumor.

Does this manual cover the GPX 50E model?

Yes. The cover and page 1 list GPX 35/40/50E. The 50E uses the same engine and transmission groups with specific brake and upright specifications.

What torque specifications are included?

Critical fastener torque checks are listed in the Planned Maintenance section. All major engine and transmission fasteners have torque values in their respective overhaul sections. Wheel lug nut torque is in group 22. I don’t have the numeric value in front of me, but it’s there.

Is this a genuine OEM manual or a reprint?

This is the original factory PDF from Clark Material Handling Company. The copyright page states “Intended for CLARK dealers only” and includes the SM606 part number. It contains the same content as the printed binder – not a third-party reconstruction. Aftermarket reprints often omit the wiring color codes and the voltage drop test procedures because they are difficult to scan clearly. This manual has them all.

Can I use this manual for a GPX 30?

No. The GPX 30 is a smaller capacity machine with a different transmission and axle setup. Use the Clark-hurth manual specific to the GPX 30 series. Using the wrong pressure specs could cause clutch pack failure or brake fade.