GM’s 2MT70 - Transmission Digest

GM’s 2MT70

In the June 2010 issue of Transmission Digest we left off looking at the 2MT70 with having gone as far as removing the valve body. Getting back to this unit to have a brief look at the inside of it, with the rear covered removed the drive motor/generator assembly unit B becomes immediately visible (Figure 1). Inside the cover are the fourth clutch and the generator-position sensor.

GM’s 2MT70

Technically Speaking

Subject: Internal components and operation
Unit: GM 2MT70
Vehicle Application: 2009 Saturn Vue 2.4-liter
Essential Reading: Rebuilder, Diagnostician
Author: Wayne Colonna, ATSG, Transmission Digest Technical Editor

Part 2

Technically Speaking

  • Subject: Internal components and operation
  • Unit: GM 2MT70
  • Vehicle Application: 2009 Saturn Vue 2.4-liter
  • Essential Reading: Rebuilder, Diagnostician
  • Author: Wayne Colonna, ATSG, Transmission Digest Technical Editor

Part 2

In the June 2010 issue of Transmission Digest we left off looking at the 2MT70 with having gone as far as removing the valve body. Getting back to this unit to have a brief look at the inside of it, with the rear covered removed the drive motor/generator assembly unit B becomes immediately visible (Figure 1). Inside the cover are the fourth clutch and the generator-position sensor.

Around the outside of both the drive-motor/generator assembly units A and B is a tube assembly used to cool these motor/generators as shown with generator assembly unit B in both figures 2 and 3.

A torque-damper assembly is used in this transmission instead of a conventional torque converter. This damper assembly contains both internal torsional springs and a clutch that acts as a spring coupling to smoothly transmit power from the engine to the transmission.

The clutch is applied only during engine starting and stopping events. Hydraulic pressure is used to control the application of the clutch via the damper-bypass clutch valve and pressure-control-solenoid 5 signal oil in the valve body. Pressure enters the assembly through the tip of the input shaft (Figure 4). The O-rings fitted to the input-shaft seal control exhaust pressure returning to the damper-bypass clutch valve where the application of the clutch is controlled.

When you split the case (Figure 5), many internal components come into view such as the drive-motor/generator assembly unit A, the auxiliary pump (used in EVT modes when engine is shut off), the 1-3 reverse-clutch assembly (figures 5 & 6) and the main fluid-pump-body assembly.

Since there are two pumps – the auxiliary pump and a gear crescent-style pump in the fluid-pump-body assembly (Figure 7) – there are also two internal filters (Figure 8).

Once the drive-motor/generator assembly unit A and the cooler-tube assembly are removed, the variable high and 2-3-4 clutch-drum assembly can be lifted out for service (Figure 9).

Inside the case you can see that the variable low & 1-2 reverse-clutch assembly needs to be unbolted so you can service it (Figure 10).

A simple special-tool package will prove to be quite helpful in disassembling a couple of these drum assemblies. It is part number DT 49098 from Kent-Moore, to be used for both the variable high and 2-3-4 clutch drum and 1-3 reverse clutch-drum assemblies. Without it, you could have a bit of a difficult time. The kit includes shim inserts and a two-piece snap-ring compressing device that clips onto the tips of a typical pair of pliers. The compressing device enables you to properly depress the snap ring. The shim inserts hold the snap ring in the compressed position, allowing you to easily remove the pressure-plate and clutch assembly from the drum.

You May Also Like

Sherlock Holmes Approach to an AB60 No-Move Situation

The effectiveness in diagnosing automatic transmission malfunctions is an art form. Although there are similarities among the wide varieties of transmissions on the road, each transmission has its own peculiarities. Aside from having mechanical, hydraulic, and electrical hardware systems to contend with, software/programming issues and various vehicle platforms make diagnostics much more difficult.  Using scopes provides

ab60

The effectiveness in diagnosing automatic transmission malfunctions is an art form. Although there are similarities among the wide varieties of transmissions on the road, each transmission has its own peculiarities. Aside from having mechanical, hydraulic, and electrical hardware systems to contend with, software/programming issues and various vehicle platforms make diagnostics much more difficult. 

GM 6T40 Pump Identification Guide

The 6T40 was introduced in 2008 for General Motors front-wheel-drive cars in the Chevrolet Malibu and has gone through several changes throughout its three generations, specifically in the pump area. The 6T40 is closely related to the more lightweight 6T30 and the heavier duty 6T45 and 6T50. Generation one started phasing out during the 2012

Seeing the Forest AND the Trees

They say that the proverbial phrase “I couldn’t see the forest for the trees” means that a person or organization cannot see the big picture because it focuses too much on the details. Related Articles – 4L60E Harsh 1-2 Shift – TASC Force Tips: Diagnosing 8L45 & 8L90 Shift Complaints – TASC Force Tips: Hydraulics

The Manifold Pipeway

The Honda six-speed transmission has been on the bench of many specialty shops for one reason or another (figure 1). But, for those of you who have yet to lay your hands on one, mounted on the upper side of the unit is one of the largest, if not the largest solenoid and pressure switch

8L90 Vacuum Testing

Below are the diagrams for vacuum testing GM 8L90 transmissions. Note: OE valves are shown in rest position and should be tested in rest position unless otherwise indicated. Test locations are pointed to with an arrow. Springs are not shown for visual clarity. A low vacuum reading indicates wear. For specific vacuum test information, refer

Other Posts

Sometimes, a diagnostic code is all you need

With ATSG having the opportunity to help shops solve problems, sometimes we get faced with some real doozies. A shop will call and give us a laundry list of DTCs, leaving us to think someone must have a bulkhead connector unplugged. We then go through the arduous task of deciding which codes prompted other codes

10L80 and 10R80 pump gear differences

You may have seen an article in the August 2023 issue of Transmission Digest called “GM 10L80: A new kind of pump noise,” which goes over how the front cover housing in the 10L80 is fitted with a converter drive gear and idler gear. The idler gear drives the pump’s driven gear, and is press

Spotting different 68RFE designs through the years to avoid issues

The Chrysler 68RFE has had several changes through the years. Its four-speed predecessor began with a noisy solenoid pack identified by a black colored pass-through case connector (seen in Figure 1).  Related Articles – Going the extra mile: Proving your transmission repair suspicions – Diagnosing Ford 10R60, 10R80 and 10R140 series speed sensor issues – Jatco JF613E

Sometimes, you should sweat the small stuff

It’s a common phrase: There may have been a time when you worried about something, and someone who knew what you are going through said, “Hey, don’t sweat the small stuff.” Sometimes, this may be good advice. But other times, it may be wise to handle the small stuff before it becomes bigger “stuff.”  Related