Dana Spicer 1372-A Service Manual – 51 Pages OEM Specs

Description

If you’ve ever pulled a heavy-duty transmission apart with a generic aftermarket “manual” that skipped the torque specs or gave you a bolt pattern that didn’t match the housing, you know the frustration. That’s why I keep a copy of the Dana Spicer 1372-A Service Manual on my tool box. This is the real OEM factory publication – 51 pages of the same documentation Spicer ships to dealerships. I’ve torqued more head bolts than most people have had hot meals, and I can tell you: guessing on a 1372-A rebuild will cost you time, money, and maybe a transmission.

Specifications and Torque Data

The manual opens with the hard numbers you need before you touch a wrench. Page 2 lists the gear ratios for all seven speeds (10.13 down to 1.33), torque capacity range (950–1300 lb-ft), oil capacity (48 pints at O.P. installation), and clutch housing types. That section saves you from bolting a wrong clutch housing onto a 650-lb transmission. Later, in Section VI, the inspection procedures on page 24 give you the exact torque specifications for every fastener in the main shaft assembly. I don’t trust aftermarket torque charts – they’re often off by 10% or more. This manual gives you the factory numbers, period.

Disassembly Precautions and Tool Reference

Section II covers lubrication (towing) on page 4, but the part that matters on a busy shop floor is the disassembly precautions on page 5. “Handle all parts carefully to avoid damage” sounds generic, but Spicer goes into specifics like bearing preload and snap ring orientation. The tool reference on page 6 lists the pullers and presses you’ll need – no guesswork about whether a standard jaw puller will fit. If you don’t have the right tool, the manual tells you before you start. That saves you a trip to the parts store.

Exploded Drawings: Why They Matter

Section IV and V include exploded drawings for the shifter housing (forward and center control) and the case sub-assembly. These aren’t the blurry line art you see in cheap reprints. The parts are arranged in the correct order, with exploded views that let you see exactly how the detent springs, shift yokes, and interlock pins fit together. I’ve used these drawings to argue with a parts counter guy who swore a certain bearing was discontinued. The manual showed the correct part number and application. If you’re chasing an internal leak or a hard shift, start with the exploded view on page 9.

What the Reassembly Section Includes

Section IX (page 27) walks you through the reassembly of the transmission gears and case. It cross-references back to the disassembly steps, so you can reverse the order without missing a snap ring or torquing a bolt out of sequence. The manual also includes the correct shifting procedure for the Spicer split torque design – use the clutch brake, and the torque limiting type is preferred over the three-piece style. Attention is called to the latest Spicer clutch service manuals (Bulletin 308 and 1309) for additional details. For more background on how manual transmissions work, check the Wikipedia article on Manual Transmission.

Troubleshooting Section: What to Expect

Section X (page 31) is a straightforward troubleshooting guide. It lists symptoms like “transmission jumps out of gear” or “excessive noise” and gives the likely causes and corrective actions. No flowery language – just “Check shift fork wear” or “Inspect main shaft bearing.” That’s the kind of direct troubleshooting I expect from a factory manual. If you’re working on a 1372-A in a shop with a customer waiting, this section gets you to the root cause faster than chasing forum threads.

Does This Manual Cover the Full Rebuild?

Yes. From disassembly (Section V) through reassembly (Section IX), including main shaft disassembly on page 20, countershaft on page 25, and input gear on page 26. The manual is 51 pages – not a novelty, but every page is dense with information you need. No generic safety warnings about “always wear safety glasses” – it assumes you’re a professional. That said, do watch for the specific disassembly precautions on page 5; they’re there for a reason.

If you also work on other Spicer transmissions, the related manuals cover similar ground: Spicer ES60-5 & CM59 Series Transmission Manual, Spicer ES46-5 & ES56-5 Service Manual, and Spicer ES42-5, ES52-5, CM49 Series Service Manual. And for a broader reference on how manual transmissions operate, the Wikipedia article on Manual Transmission provides good background.

Is this the OEM factory manual, or a reprint?

It’s the original Spicer factory document – 51 pages of the same content used by Dana Spicer dealerships. No aftermarket edits, no missing pages. The file is a direct scan of the OEM manual.

Does it include torque specs for every fastener?

The torque specifications are listed in Section VI (page 24) for the main shaft and countershaft assemblies. For other fasteners, the manual references the general specs found in the Spicer service literature – they assume you know standard bolt grades. If you need exact foot-pounds for every bolt, you’ll want to supplement with a bolt torque chart.

Stop wasting time with incomplete data. Get the factory information that matches the transmission on your lift. Access the Factory Manual.