Muncie 8405A and 8406A PTO parts

8405A / 8406A at a glance

Type

Air shift PTO, integral SAE 8-bolt mounting pad

Housing

Ductile iron

Speed ratios

Three codes: 07, 08 and 09

Top rating

230 lb ft intermittent at ratios 07 and 08

Approximate weight

35 lb (15.9 kg)

Main parts book

SP10-02 8405A/8406A Series Service Parts

What the 8405A and 8406A are

These are Muncie's economy 8-bolt PTOs. The housing is ductile iron with the 8-bolt mounting pad cast in, and the air shift is built into the housing. There is a drain port, and an inspection port for checking backlash. Muncie describes the rigid structure as a fit for high vibration work, and lists dump and tow and recovery as the target markets.

Output is either a 1 1/4 inch round keyed shaft or an SAE B or BB pump flange with a splined shaft. Everything is built in one assembly arrangement, with the shaft low on the left side.

Where it fits

Muncie sells the pair for the 8-bolt openings on Eaton, Meritor and Mack transmissions. The difference between them is the input gear. The 8405A uses the universal U68 gear (6P, 20 degree spur) and the 8406A uses the Mack M65 gear (6.48P, 17.5 degree spur). The B versions of each, 8405B and 8406B, ship with a metric stud kit. Muncie calls the three ratios equivalent to the same ratio codes on the TG Series TG8S-U68.

Reading an 8405A or 8406A model number

Muncie's example is 8405A-07-A-3 K-X. The tag reads: PTO type, speed ratio, shifter, assembly arrangement, output and special feature.

• PTO type: 8405A, 8405B (with metric stud kit), 8406A or 8406B (with metric stud kit).
• Speed ratio: 07, 08 or 09.
• Shifter: A is manual air at 12 volts, P is manual air without the activation kit.
• Arrangement: 3 only, left side shaft low.
• Output: K is SAE B pump mount, P is SAE BB pump mount, B is a 1 1/4 inch round shaft with a 5/16 inch key.
• Special feature: X, none.

Use the model number guide to compare with other series tags.

Parts that wear and what to order

• Gear and shaft set from Chart 1 of the parts list. Each model has its own input gear and output gear, and the output shaft changes with the K, P or B output.
• Spacer shims from Chart 2, in 0.20, 0.30 and 0.50 thick sizes. Muncie sets the gear end play at 0.002 to 0.005 inch with them.
• Gasket and seal kit (8405-GSK) and rebuild kit (8405-RBK) for the O-rings, seal, bearings and snap rings.
• Air shift parts, meaning the piston, spring, shift fork and covers, plus the standard air shift system.
• Installation kits and stud kits, including the metric stud kit for the B models, and the activation kits for the A and P shift options.

Questions we get about the 8405A and 8406A

Can I rebuild one myself?

Muncie publishes a disassembly and reassembly sheet. It says to have the rebuild kit on hand first, because pulling the seal out damages it. The sheet also warns that air to the activation port throws the cover and piston out with force, so catch them.

How do I choose between the 8405A and 8406A?

Look at the input gear on the tag or the parts list. U68 means 8405A and M65 means 8406A. The ratio code and output letter then pick the gear and shaft set.

Is there more than one assembly arrangement?

No. Muncie lists arrangement 3 only, with the shaft low on the left side.

8405A / 8406A parts breakdown

How the Muncie 8405A and 8406A PTO parts list is organised on our store. Each section opens the exploded view with every part number, the quantity used and an order button.

Muncie 8405 Series

The store also files this same book under Muncie 8406A Series.

8405A / 8406A torque and horsepower by speed ratio

Ratings as published by the manufacturer for the Muncie 8405A and 8406A PTO. Check the current Muncie application data for your transmission before you size a pump.

8405A / 8406A manuals

All 8405A / 8406A books: Muncie PTO parts manuals.

Need a complete rebuilt unit?

Our sister site rebuiltmunciepto.com covers rebuilt 8405A / 8406A units. This site is the parts and model reference side.