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

Sonnax 2-3 Accumulator Piston, GM, 4T80E (1994-Later), Each

Sonnax 2-3 Accumulator Piston, GM, 4T80E (1994-Later), Each

$21.89

TCI TH400 Forward Drum Nitrided Clutch Plate (.063 Thickness)

TCI TH400 Forward Drum Nitrided Clutch Plate (.063 Thickness)

$296.29

TCI TH400 Pressure Regulator Spring

TCI TH400 Pressure Regulator Spring

$29.41