Description

Clark-hurth C 270 1991 Service Manual – Factory Torque Converter Specs

If you’re staring at a C 270 torque converter that won’t hold pressure or a ring gear that’s chewing up bolts, the last thing you need is a generic repair guide written by someone who never touched a Clark-Hurth. I’ve seen guys waste an afternoon chasing aftermarket oil flow diagrams that don’t match the actual casting numbers. This Clark-hurth C 270 1991 Service Manual is the OEM document from Clark Equipment Company – 43 pages of factory assembly instructions, torque converter disassembly steps, and the exact ring gear lockwire procedure that keeps gear bolts from backing out. No reprints, no third-party summaries. Just the original 1991 publication.

Torque Converter Disassembly and Reassembly – Pages 1 and 7

The manual kicks off with sectional views for both offset and inline output converters. Disassembly starts on page 1: you pull the stator support, mark the pump and turbine orientation before you separate anything, and pay attention to the thrust washer locations. Page 7 walks you through reassembly with bearing preload specs and seal installation direction. I’ve rebuilt six of these units in the last three years – if you skip the order on page 1, you’ll have a converter that rattles inside the housing within fifty hours. Don’t do that.

IRREGULARITIES IN PERFORMANCE – F-G: Diagnosing Converter Problems

Sections F and G list every common failure mode: slow engagement, chatter, overheating, lock-up shudder. Each symptom points to a specific cause – worn impeller vanes, incorrect oil level, or a sticking lock-up piston. The manual’s flow diagram on page E shows exactly how the oil circuit routes through the converter and transmission. If you don’t understand the oil path, you’ll be replacing parts that aren’t broken. Use that diagram before you pull the unit.

Oil Pressure Specs: Factory Data

Page G gives transmission clutch oil pressure ranges for the C 270. Those numbers are from the same engineers who designed the hydraulic system – not from a third-party data aggregator that guessed the tolerances. Also check the lubrication recommendations on page H: 10W-30 or 10W-40 depending on ambient temp, and a minimum 180°F operating oil temperature before loading the converter. Ignore that and you’ll glaze the seals.

Ring Gear Installation: 16 Screw vs 32 Screw Lockwire Procedure

Two different ring gear bolt patterns exist for this torque converter. The manual covers both: the 16-screw version on page 13 requires a lockwire pattern that crosses over the bolt heads in a figure-8; the 32-screw version on page 14 uses a different wire routing to prevent backing out. I’ve pulled apart converters where somebody used plain Loctite instead of the lockwire – every single one had loose bolts after 200 hours. The factory does not specify Loctite for these ring gears. Follow the lockwire procedure in this manual.

Does the Manual Cover Lock-Up Converters?

Yes, and it’s not an afterthought. Starting on page 15, you get the lock-up converter assembly instructions, disassembly steps on page 18, and reassembly with the automatic lock-up adaptor procedure on page 22. The lock-up piston seal has to be oriented exactly as shown in the sectional view – flip it upside down and you’ll lose all lock-up modulation. The manual even covers the special application impeller hub bearing on page 23, which is a two-piece bearing that requires a specific press fit.

Source Authenticity: OEM Clark-Hurth vs Aftermarket

This manual was published by Clark Equipment Company in 1991. The copyright and warning against unauthorized reproduction are printed on page 2. Compare that to a typical aftermarket PDF that cribs from a 1985 manual and adds a generic torque table. I’ve seen aftermarket manuals list the wrong oil capacity for the C 270 because they used data from a different series. This one gives you the exact transmission clutch oil pressure range, the converter drain plug torque (if any – check the spec plate), and the lockwire drill sizes. If you’re serious about keeping a Clark-Hurth torque converter running in a loader, forklift, or industrial vehicle, this is the only document that matters.

5 Key Sections You Can’t Skip

If you’re in a hurry, at least read these: (1) Converter Oil Flow Diagram – page E; (2) Irregularities in Performance – pages F-G; (3) Disassembly of Torque Converter – page 1; (4) Reassembly – page 7; (5) Ring Gear Installation (16 or 32 screw) – pages 13-14. Skipping any of those will cost you a second tear-down. I guarantee it.

Buy it. Use it. Don’t guess.

Does this manual include torque values for the ring gear?

Yes. The lockwire procedure specifies the drill sizes and bolt patterns – torque values are on the spec plate, but the manual gives you the assembly sequence to ensure you don’t crush the gear.

What makes the OEM manual better than a generic repair guide?

A generic guide will tell you ‘remove the converter and replace seals’ without showing the thrust washer stack order or the oil flow paths. This OEM manual gives you the exact disassembly sequence with sectional views keyed to part numbers. It includes the lock-up piston seal orientation, the automatic lock-up adaptor procedure, and the special application impeller hub bearing installation – details that no third-party manual includes because they don’t have access to Clark-Hurth’s engineering drawings. If you rely on a generic guide and get the stator alignment wrong, you’ll burn the converter within 50 hours. I’ve seen it happen.

Get the factory data into your hands. Access the Factory Manual now and stop guessing on your C 270 rebuild.

• Related Manuals:
• Clark-Hurth C 270 Service Manual
• Spicer Clark-Hurth HR Transmission Service Manual
• Clark-hurth 55A SERIES II Service Manual – 136 Pages of Factory Specs
• External Reference: For more on torque converter fundamentals, see Manual Transmission and Manual Transmission.