6T70 Archives - Transmission Digest
A 6T70 IMS Invalid Range Signal

There are four inputs to the TCM from the position switch assembly, that indicate which transmission gear range has been selected.

GM 6T70/75/80 (Gen. 1 & 2) Jig Plate

The new plate can be used with both Gen. 1 and Gen. 2 oversized actuator feed accumulator piston kits.

GM 6T70/75/80 (Gen. 2) Oversized Actuator Feed Accumulator Piston Kit

The new oversized actuator feed accumulator piston kit re-establishes correct clearance for revived shift control in all ranges.

GM Gen. 2 6T70, 6T75 and 6T80

Critical Wear Areas & Vacuum Test Locations

Friendly Rivalry Builds Success

Four years later, the results of the collaboration were two very similar (though slightly different), highly efficient, 6-speed transmissions. They boasted a 4% increase in efficiency over similar vehicles with automatic 4-speeds. Ford decided to name their models 6F50 and 6F55, while GM decided on 6T70/6T75/6T80. Ford has used their transmissions in the Edge, Taurus and Escape, to name a few; while GM has used them in the GMC Acadia and Terrain, and Chevy Impala and Traverse.

Valve body – GM Gen. 2 6T70, 6T75, 6T80 – Vacuum testing

Critical Wear Areas & Vacuum Test Locations
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 parameters,
refer to additional information available at www.sonnax.com.

Trading Places

Most builders swapping hard parts have learned that mismatching drive components in a transverse unit will result in a host of negative consequences. The wrong ratio sprocket(s) or carrier can result in TCC and ratio codes, along with converter and unit clutch slippage. Unfortunately, optional ratios aren’t exclusive to the final drive; they can exist in the valve body as well.

‘Yaw’ Making Us Chase Our Tails

The vehicle is a 2012 GMC Acadia with a 6T70 that has 85,000 miles on it. It comes to us from a dealer, and it belongs to a dealer employee’s relative. What difference does who owns it make? Bear with me, it all comes together to create a nightmare.

GM 6T30 Six-Speed Automatic – Junior Addition – Part 1

During development, the GM 6T70 and Ford 6F50 basically fell off the same sheet of paper resulting in a noticeable amount of interchangeability of various components. One key difference between the two models is that GM chose to go with a mechatronic (TEHCM) valve body design, whereas Ford stuck with the traditional external TCM (PCM). Another variable between the GM and Ford transmissions were the dreaded cushion springs that have been tweaked over the years. Both designs accommodate the larger vehicles equipped with higher output engines and both have received continuous changes and upgrades.

6T70/75 Converter-Pilot Issues

To date most of the converters seen at converter-remanufacturing facilities have had vibration and/or leak complaints. After taking a closer look at the attachment between the pilot and cover, it is easy to see why (Figure 2).