Dana Spicer T20000 1990 Service Manual

If you are working on a Dana Spicer T20000 powershift transmission, the difference between a proper overhaul and a costly come-apart is having the right data in your hands. Dana Spicer T20000 1990 Service Manual gives you the factory procedures for the 3-speed and 6-speed long drop variants with range shift. Without it, you are guessing on clutch clearances, seal depths, and hydraulic pressures.

Foreword – Why Genuine Parts Matter

Page 2 of this manual opens with a foreword that cautions against using any parts not approved by Dana Spicer. They state that ‘will-fit’ parts can endanger operation. That is not legal language – it is experience talking. The manual tells you to always supply the serial and model number when ordering parts. This kind of directive keeps your rebuild from turning into a parts-swapping nightmare.

Towing or Pushing – A Common Mistake

The manual dedicates a specific warning on page 1: if you tow a vehicle with this transmission without lifting the rear wheels or disconnecting the driveline, you damage the unit. Also, you cannot start the engine by pushing or towing because of the hydraulic system design. That is the kind of detail you won’t find in a generic rebuild guide. Ignore it and you are looking at a core replacement.

What Is the Difference Between the 3-Speed and 6-Speed Versions?

The manual explains that the only difference lies in the idler and output shaft. A 3-speed standard ratio is similar to a 6-speed with range shift in high range. That information saves you from ordering the wrong parts. If you need to rebuild a deep ratio unit, the same manual covers it – just check the identification section.

209 Pages of Factory Service Data

At 209 pages, this manual covers lubrication schedules, hydraulic circuit diagnostics, disassembly and reassembly sequences, torque values, and troubleshooting charts. Every page is a direct reproduction of the original Dana Corporation publication from 1990. No reprints, no aftermarket editing. You get the same information a dealership technician would have used.

Use Only Approved Parts – A Command from the Factory

The foreword is direct: always use Spicer Off-Highway Products approved parts. The serial and model number must be furnished when ordering. This manual supports that by including reference to the applicable parts manual. Skipping that step means you risk using components that don’t match the hydraulic tolerances or gear metallurgy.

For a complete reference, see the DANA T20000 Powershift Transmission Maint. Manual. If you need parts listings, the Dana Spicer T20000 2005 Parts Catalog – OEM Factory Specs is recommended. For related transmissions, check the Dana Spicer 1372-A Service Manual – Factory Specs & Rebuild Guide. Understanding the basics of a Manual Transmission helps when learning the T20000’s operation, though this is a powershift unit. The principles of a Manual Transmission apply but with hydraulic control differences.

FAQ: Common Questions About This Manual

Is this manual for the T20000 only?

Yes, this manual covers only the T20000 series.

Does it include torque specifications?

Yes, all factory torque values are listed for bolts, clutch packs, and hydraulic components. You need these to prevent seal leaks and gear damage.

Can I use this for a 3-speed deep ratio?

Yes. The manual covers both 3-speed standard, deep ratio, and 6-speed with range shift. See the identification section to confirm which variant you have.

What if my manual is missing pages?

This is a complete 209-page scan of the original factory manual published in 1990 by Dana Corporation. Every page is included – no missing sections, no cropped diagrams. The manual includes the full foreword cautioning against non-approved parts, the towing/pushing warning, specification tables for fluid capacities, detailed disassembly procedures, torque charts for every fastener, troubleshooting guides, and the complete hydraulic circuit diagrams. The scan is high resolution with clear text and numbers. This is not a reprint or a scan of a copy – it is the original document.

You need the factory data to get the T20000 right the first time. Download the Factory Manual now and keep it on your bench – it saves you from costly missteps and parts damage.