It is common to have poor 3-4 shifts, no 4th Gear or a burned 4th clutch in GM 4T65-E units. This can be caused by excess wear at the 3-4 accumulator piston pin bore, which allows 4th clutch oil to exhaust and can result in harsh 4th, no 4th Gear or a burned 4th clutch. Pin bore wear also reduces 3rd clutch pressure during 3-4 shift. The 4th shift quality depends on the condition of the piston and accumulator valves. If the 4th accumulator piston seizes, the 4th shift will be very hard. Sonnax 3-4 accumulator piston 84880M-01 restores accumulator pressure and eliminates cross leaks.

Piston is manufactured from high-grade billet aluminum to prevent wear
Tight tolerances and surface finish restore proper clearances
Piston accepts OE or standard replacement D-ring

More From This Category

TCI Vacuum Modulator, Adjustable, For Ford, Push-In, Green Stripe, Each

TCI Vacuum Modulator, Adjustable, For Ford, Push-In, Green Stripe, Each

$43.50

Sonnax Oil Pump Shaft, Ford, Axod/Ax4S/Ax4N/4F50N / Axod-E, Each

Sonnax Oil Pump Shaft, Ford, Axod/Ax4S/Ax4N/4F50N / Axod-E, Each

$97.79

Sonnax Yin. Shaped Valve Retainer, Chrysler, ZF6/8/9, 6R60/75/80, 6R100, Each

Sonnax Yin. Shaped Valve Retainer, Chrysler, ZF6/8/9, 6R60/75/80, 6R100, Each

$18.61