4T65E

Symptoms:

• 3-4 Concerns
• 4th Clutch burned
• Soft 3rd
• No 4th

Cause:
Wear at the 3-4 accumulator piston pin or bore.

Correction:
Sonnax 3-4 accumulator piston is made from high grade billet aluminum to prevent wear and restores clearances at the pin.

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. The Sonnax 3-4 accumulator piston 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

SONNAX Installation Instructions