Muncie PTO adapters and adapter gears

Adapters at a glance

Type

Adapter gear assemblies that mount between the transmission and the PTO

Purpose

Reverse PTO shaft rotation and clear mounting obstructions

Standard offset

A standard adapter moves the PTO out about 3 inches

Rating effect

Adapters often reduce horsepower ratings and service life; some call for a 30% derate

Bearing endplay

0.002 to 0.006 inch on the single gear adapters

Main parts book

SP93-03 PTO Adapter Gear Assemblies Parts List and Service Manual

What a PTO adapter is

A PTO adapter gear assembly is a small gear case that bolts to the transmission opening, with the PTO bolted to it. The adapter gear is driven by the transmission gear and drives the PTO's input gear. That changes the direction of rotation, and the adapter body moves the PTO away from the case so it can clear a driveshaft, a frame member or a cab part. Muncie also uses adapters to fit standard SAE PTOs to non-standard transmissions and bolt patterns.

The tradeoff is power. Muncie says adapters often reduce horsepower ratings and service life, and its table marks many models with a 30 percent derate for the PTO application.

Where it fits

Adapters are chosen by transmission opening and by the clearance problem you are solving. Muncie's guide groups them by body: solid body single gear, flanged body single gear, vertical offset, angular offset and horizontal offset, plus specific bodies for Isuzu, Nissan and Mitsubishi, 8-bolt to 6-bolt and Mack openings. A standard adapter moves the PTO outward about three inches.

The DT12 adapter is the one built around a specific transmission. It is listed as 40TA6479 for Detroit DT12 types OC (OHE and OV) and 40TA6480 for type OD (OVX). Type DC (DHE and DV) has no adapter option. The PTO is sold separately and Muncie lists the TG8S-U68 and 828S-U68 for it.

Identifying an adapter

Adapter gear numbers start with 40T and do not decode digit by digit, so Muncie's dimension table is the key. Each row gives an application code, tooth count and dimensions. On offset types the row lists a code for each end, called X and Y, so the 40TF6668 shows F66 with 23 teeth at one end and U68 with 24 at the other. On several numbers the -1 and -2 versions swap which gear sits at X and which at Y.

Send us the number cast on the housing or the model of the transmission and PTO, and we will match the gear and kits.

Parts that wear and what to order

• Adapter gear and idler shaft with their tapered roller bearings, listed as a set in each adapter's parts list.
• Shims or spacers that set bearing endplay to 0.002 to 0.006 inch, in several thicknesses.
• Mounting stud kits and gasket packs such as 20MK0108 and 52MK1000, which hold the 0.010 and 0.020 inch gaskets.
• DT12 kits: installation kit 48TK6569, metric bolt kit 20TK6570 and gasket kit 52TK6571.
• Edge molded gasket 13T65089 between the adapter and the PTO or spacer on a DT12 setup.

Questions we get about adapters

Do I still have to set backlash with an adapter?

Yes, between the adapter and the transmission gear. On the DT12, Muncie gives 0.006 to 0.012 inch, adjusted with the second gasket. See mounting and backlash.

Do I set backlash between the PTO and the adapter too?

On the DT12 adapter, not for a TG or 82 series at ratios 05 to 13 when the edge molded gasket is used. It is required for the 82 series 15 and 19 ratios.

What is the 0.002 to 0.006 inch endplay?

It is the bearing endplay of the adapter gear, set at assembly by choosing the shim or spacer, with the set screw torqued to 10 ft lb. See the model number guide for the PTO's own tag.

Adapters manuals

All Adapters books: Muncie PTO parts manuals.

Need a complete rebuilt unit?

Our sister site rebuiltmunciepto.com covers rebuilt Adapters units. This site is the parts and model reference side.