Description

GEHL 8435, 8500 Installation Manual – Factory Specs for Truck-Mounted Mixer Feeders

I have torqued enough PTO fasteners on mixer feeders to know that the difference between a running unit and a $6,000 transmission rebuild is a torque wrench and the right page. If you are fitting a GEHL 8435, 8500 Installation Manual onto a truck chassis, you do not want to guess. This 16-page OEM supplement is the only document that gives you factory numbers for cab-to-axle dimensions, weight distribution, and hydraulic routing. Skip it, and you will blow a driveline or overload a single rear axle. Period.

What This 16-Page Installation Manual Covers

This is a supplement for the MF8000 Series Mixer Feeder Operator’s Manual. It covers only the truck-mounting procedure for the MF8435 and MF8500 models. You get the mounting dimensions in inches and millimeters, the PTO torque requirement of 200 ft-lb (271 N·m), and the exact rotation direction for the PTO drive shaft. The manual also includes Table 1 and Table 2 for potential loaded weights and minimum cab-to-axle dimensions. For the MF8435, the empty feeder weight is 9,565 lb (4,339 kg), and the potential loaded weight hits 20,305 lb (9,230 kg). The MF8500 runs 10,288 lb empty and 22,588 lb loaded. If your truck cannot handle that, you are wasting time.

All safety warnings are printed in the operator’s manual, so you need that document open alongside this one.

PTO Requirements: Don’t Guess the Torque

Page 1 states the truck PTO assembly must transmit a minimum of 200 ft-lb of torque and rotate opposite to the engine crankshaft so the PTO drive shaft turns clockwise from the rear of the mixer feeder. If your truck has a Manual Transmission, you still need to verify the PTO output rotation. Many aftermarket instructions skip this, and the driveline binds first time you engage it. The manual makes you check rotation before bolting anything up.

3 Critical Tables You Need for Truck Selection

Table 1 gives the potential weight at 30 lb/ft³ feed density. Table 2 gives the minimum cab-to-axle dimension: 126 inches (3,200 mm) for the 8435 and 138 inches (3,505 mm) for the 8500. These are not suggestions. Mount a 8500 on a 126-inch wheelbase and you will have clearance issues with the drive line. The manual also warns against tandem rear axles because interference problems develop when connecting the drive line. Follow these numbers exactly, or the unit does not fit legally.

Aftermarket vs. Factory: The Safety Gap

Aftermarket installation sheets often say “tighten PTO bolts securely” but give no torque value. The factory procedure does not list a torque value for every fastener in this 16-page supplement? Actually, it defers to the operator’s manual for shutdown procedures and general torque charts. That is typical. The value of having the OEM supplement is the geometry and hydraulic routing you cannot get anywhere else. The manual specifies that the discharge conveyor is on the left side when standing behind the feeder facing forward. Get that backwards and the conveyor hits the truck cab.

Get the Orientation Right: Right vs Left

This manual defines “right” and “left” from a position standing behind the mixer feeder and facing forward. That is the standard, but I have seen techs flip it. The supplement includes a diagram (Fig. 1) with unit dimensions and mounting locations in inches and millimeters. Use it. If you are working with the 8500, the extra length requires a different mounting bracket location. The manual highlights it.

Common Installation Mistakes and How This Manual Prevents Them

Most mistakes come from ignoring the mandatory safety shutdown procedure described in the operator’s manual. The supplement tells you to exercise that procedure BEFORE any installation modification. Another common error is selecting a truck with inadequate GVWR. Table 1 makes it plain: the 8500 loaded weighs 22,588 lb. Add truck weight, and you need a 30,000+ lb GVWR single-axle truck. If you think you can mount an 8500 on a 26,000 lb chassis, you will crack frame rails. This manual stops that nonsense.

For replacement parts, you need the GEHL 8435 8500 Parts Manual. If you are working on other models, see the GEHL 7210 7285 7335 7435 7500 Installation Manual and the GEHL 7285 7335 7435 7500 Mixer Feeder Installation Manual.

For a broader reference on driveline components, check Manual Transmission basics. Understanding the PTO engagement sequence is critical for these units.

Does this manual include torque specs for every bolt on the mixer feeder?

No. It covers only the truck-mounting installation – PTO torque (200 ft-lb), weight tables, and cab-to-axle dimensions. For fastener torque values on the feeder itself, you need the separate operator’s manual for the MF8000 series. This 16-page supplement is specifically for matching the feeder to the truck chassis.

What is the exact page count?

16 pages, including the foldout diagram with unit dimensions in inches and millimeters.

If you are mounting an MF8435 or MF8500, do not waste time with photocopies or third-party reprints. Access the Factory Manual directly from AutoRepairManuals. The PDF is the same print you would get from a GEHL dealer – no missing pages, no blurred tables. Get it, read it, torque it, and move on to the next job.