Allison 1000

Allison 1000 Transmission Specs & Ratios

The Allison 1000 was first produced in 1999 by Allison Transmissions. In 2001, GM mated the Allison to its new 6.6L Duramax. The Allison 1000 is arguably one of the most desirable automatic transmissions in its category. Its popularity and excellent reputation can be attributed to its strength, reliability, and the technology applied to the transmission. In 2006, the Allison 1000 was converted from a 5 speed to a 6 speed automatic, making the later version a double overdrive. Not without flaws, the Allison suffers from lack of lubrication to the C3 clutch, while the C1 & C2 clutches are applied off center, causing uneven wear and often premature failure. The transmission is also known to lock into limp mode when owners begin adding performance enhancers to the Duramax diesel. Performance products, like programmers, push the Duramax beyond the transmission's limits and can cause excessive slippage, forcing the transmission to lock into 3rd gear. Regardless, the Allison is a true medium duty transmission with many desirable characteristics.

Allison 1000 6 Speed Ratios

1st

2nd

3rd

4th

5th

6th

R

3.094 : 1

1.809 : 1

1.406 : 1

1.00 : 1

0.711 : 1

0.614 : 1

4.48 : 1

(2006+ model year)

Allison 1000 5 Speed Ratios

1st

2nd

3rd

4th

5th

R

3.094 : 1

1.809 : 1

1.406 : 1

1.00 : 1

0.711 : 1

4.48 : 1

(2001 - 2005 model year)

Allison 1000 Transmission Specs

Transmission:

Allison 1000

Type:

5/6 speed automatic transmission (see application breakdown below)

Manufacturer:

Allison Transmission

Production Plant:

Allison Transmission Plant, Baltimore, MD

Predecessor:

General Motors 4L80E

Model Years/Applications:

5 speed models

2001 - 2005 GMC Sierra/Chevrolet Silverado w/ Duramax diesel

6 speed models

2006 - present GMC Sierra/Chevrolet Silverado w/ Duramax diesel

Case Material:

Die cast aluminum

Max Input Torque:

2001 - 2004 MY

520 lb-ft

2005 MY

565 lb-ft

2006 - 2007 MY

650 lb-ft

2008 - 2009 MY

660 lb-ft

2010 - present MY

765 lb-ft

Max Shift Speed:

3,300 rpm (w/ Duramax diesel)

Weight:

~ 330 lbs

ATF Type/Spec:

DEXRON III (previously recommended by GM), TranSynd synthetic DEXRON III (recommended by Allison), DEXRON VI (currently recommended by GM)

Service Intervals:

Replace transmission filter and fluid every 50,000 miles under normal operating conditions or 25,000 miles under "severe" operating conditions

Features:

• Optional PTO provisions

• 5,000 rpm max engine speed input

• Adaptive technology - transmission perceptually optimizes shift schedule

• Double overdrive (2006 MY +)

• Complete electronic transmission shift controls

• Protective "limp mode" integration engages when excessive slippage occurs or transmission loses communication with engine, locking transmission in 3rd gear and disabling upshift/downshift capability