What does the Performance Automatic C6 shift kit change?

It replaces the pressure regulator spring to raise line pressure, swaps accumulator circuit springs for a firmer 1–2 shift, mods the accumulator circuit and band-apply servo, adds a spring under the cut-back circuit valve to prevent line pressure reductions over 10 mph, and enlarges a separator plate hole to firm up 2–3 shifts.

Is anything else recommended for high-horsepower builds?

Yes — for engines making 400+ hp, the article advises also installing PA's Super Servo kit, whose larger-surface-area piston increases force applied to the band on the rotating drum and works best with the shift kit's elevated line pressures.

What tools are needed to install the shift kit?

The usual assortment of handtools, a small pick, ideally a low-range torque wrench, and a large lipped cookie pan (or drain pan) — with small magnets on its underside — to keep valvebody springs and check balls from flying off.

What were the C6's main competitors in the muscle-car era?

GM's heavy-duty TH400 and Chrysler's A727 TorqueFlite.

Home/ Registry/ Ford/ Ranchero/ 1977-1979/ 1979 Ford Ranchero/ Photo supermotors.net/registry/media/1145920

Ford C6 Automatic Shift Kit Install - Hot Rod April 2019 'Quicker Shifter' Article

Hot Rod magazine Quicker Shifter article: Performance Automatics shift kit in Ford C6 automatic, page 1

‹ ›

Magazine how-to (Hot Rod) on installing a Performance Automatics shift-improvement kit in Ford's C6 three-speed automatic: explains valvebody modifications that raise line pressure and firm up shifts.

AI caption February 2019 · Photo 309 of 363

This is page 78 of the April 2019 issue of Hot Rod magazine (HOTROD.COM), a 'Wrenchin' @ Random' article titled 'Quicker Shifter: Install a Shift-Improvement Kit in Ford's C6 Automatic Trans' by Marlan Davis, with photos by Marlan Davis and Mark Sanchez/AEW. The article introduces the installation of a Performance Automatic (PA) shift-improvement kit in Ford's heavy-duty C6 three-speed automatic transmission, used in various applications from 1966 through the late 1990s (the photo caption cites 1966–2004). Working with Advanced Engineering West's Mark Sanchez, the article explains why smooth factory shifting can cause excessive clutch/band-apply times, heat, and eventual failure behind high-torque engines. It lists the kit's specific enhancements: a stiffer pressure regulator spring to raise line pressure, accumulator spring swaps for a firmer 1–2 shift, servo mods, a spring under the cut-back circuit valve to prevent line pressure drops over 10 mph, and an enlarged separator plate hole for firmer 2–3 shifts. It also recommends PA's Super Servo kit for 400+ hp builds and offers practical tips such as using a magnetized cookie pan to catch valvebody springs and check balls. A full-page photo shows a bare C6 transmission case.

Is this accurate? Sign in to help verify it.

Frequently asked questions

What years was the Ford C6 transmission used?: The article says the C6 three-speed automatic was used in various applications from 1966 through the late-1990s, and the photo caption cites 1966–2004.
What does the Performance Automatic C6 shift kit change?: It replaces the pressure regulator spring to raise line pressure, swaps accumulator circuit springs for a firmer 1–2 shift, mods the accumulator circuit and band-apply servo, adds a spring under the cut-back circuit valve to prevent line pressure reductions over 10 mph, and enlarges a separator plate hole to firm up 2–3 shifts.
Is anything else recommended for high-horsepower builds?: Yes — for engines making 400+ hp, the article advises also installing PA's Super Servo kit, whose larger-surface-area piston increases force applied to the band on the rotating drum and works best with the shift kit's elevated line pressures.
What tools are needed to install the shift kit?: The usual assortment of handtools, a small pick, ideally a low-range torque wrench, and a large lipped cookie pan (or drain pan) — with small magnets on its underside — to keep valvebody springs and check balls from flying off.
What were the C6's main competitors in the muscle-car era?: GM's heavy-duty TH400 and Chrysler's A727 TorqueFlite.