4T65E Tech Info

This page provides information about the GM THM-4T65E 4 speed Automatic fwd transmission/transaxle which is found in many 1997 and newer vehicles equipped with the 3800 engine and most 2000 and newer vehicles with the 3400 engine. This is a great trans and has been refined a bit over recent years and as many of you know has its shortcomings, especially when the mileage gets high or extra power is added. 

If you have a question about something that you do not see on this page feel free to contact us.

This transaxle is a fully automatic and electronically controlled. Shifts are all controlled by the pcm by two shift solenoids, line pressure is also fully electronic and controlled by a Pressure Control Solenoid, or EPC which is commanded by the pcm. This transaxle also employs the use of a Torque Converter Clutch, or TCC and is used to further enhance gas mileage and keep engine rpms lower. The TCC style in this trans is a PWM type, which stands for Pulse Width Modulation. This style PWM TCC system was developed to allow for a smooth engagement of lockup and allows constant slippage of the TCC and can apply in 2nd through 4th gears. The constant slippage is tolerable to the converter because of a special TCC lining developed especially for this purpose and is called a Woven lining. An ordinary TCC clutch would burn up and shudder violently if used in this type of system.

-Below are the gear ratios for each gear of the transmission

1st 2.92:1

2nd 1.56:1

3rd 1:1

4th (OD) 0.70:1

Reverse 2.38:1

There are numerous gear ratio combination options for the 4T65E transmission and below are ratio options that can be found

-Final drive-differential ratios

2.86:1 in standard differential only

3.05:1 in standard differential only

3.29:1 in standard differential and also the HD (Heavy Duty) and Volvo version differential

-Drive and Driven sprocket combinations and ratios

33 Drive / 37 Driven creates a 0.892:1 ratio

35 Drive / 35 Drive creates at 1.000:1 ratio

37 Drive / 33 Driven creates a 1.121:1 ratio

The Drive and Driven sprocket ratio will directly factor in to calculate the overall transmission ratio. For example most of the Supercharged 3800 powered vehicles come with a 3.29 HD differential but they have a 37/33 sprocket orientation and this will overdrive the transmission and create an overall ratio of 2.93:1

-Here are the resistance specs on the internal solenoids

Connect Pins  -  Solenoid Resistance at 68*F, 190*F 

A-E   -  1-2 Shift Solenoid 19-24, 24-31 

B-E  -   2-3 Shift Solenoid 19-24, 24-31 

T-E  -   TCC/PWM Solenoid 10-12, 13-15 

C-D  -   EPC Solenoid 3-5, 5-6 

S-V  -   Input Speed Sensor 893-1127, 1132-1428

M-L  -   TFT Sensor 3164-3867, 225-285

Output Speed Sensor  -  981-1864 

Below are the Torque Specs for the 4T65E:

Bottom Pan Bolts (mid 98+)  M6 X 1.0 X 17  106 lb/in

Side Cover Bolts  M8 X 1.25 X 25  18  lb/ft

Side Cover Bolts ( Torx head )  M8 X 1.25 X 21  18  lb/ft

Final Drive Housing Bolts  M10 X 1.5 X 35  26  lb/ft

Forward Servo Cover Bolts  M6 X 1.0 X 20    106 lb/in

Vehicle Speed Sensor Bolt  M8 X 1.25 X 12    106 lb/in

Drive Sprocket Support Bolts  M8 X 1.25 X 24  18  lb/ft

Manual Shaft Detent Lever Nut  M10 X 1.5  23  lb/ft

Line Pressure Test Plug  1/8 - 27 NPTF  12  lb/ft

Cooler Line Fitting into Case (97- early 99) 1/4-18 NPSF  28  lb/ft

Cooler Line Fitting into Case (mid 99- 03) Feed 3/8-18 NPSF  28  lb/ft

Return 1/4-18 NPSF    28 lb/ft

Cooler Line Fitting into Case ( 04+ )  9/16-18 UNF    18  lb/ft

Accumulator Cover Bolts  M6 X 1.0 X 28    106 lb/in

2-1 Manual Servo Cover Bolts  M8 X 1.25 X 25  17  lb/in

Oil Pump Cover Retaining Bolt (97-mid 02) - 1  M6 X 1.0 X 20    70  lb/in

Oil Pump Bolts - 9  M6 X 1.0 X 85    106 lb/in

Oil Pump Bolts - 2  M6 X 1.0 X 95    106 lb/in

Valve Body Bolts - 3  M6 X 1.0 X 65    106 lb/in

Valve Body Bolts - 3  M6 X 1.0 X 60    106 lb/in

Valve Body Bolts - 1  M6 X 1.0 X 30    106 lb/in

Valve Body Bolts - 2  M6 X 1.0 X 45    106 lb/in

Valve Body Bolts - 3  M6 X 1.0 X 55    106 lb/in

Valve Body Bolts - 1  M6 X 1.0 X 95    106 lb/in

Valve Body Bolts - 2  M6 X 1.0 X 20    106 lb/in

Valve Body Bolts - 1  M6 X 1.0 X 85    106 lb/in

Valve Body Bolts - 1  M8 X 1.25 X 90    18 lb/ft

Case Cover / Channel Plate Bolt - Torx - 1  M6 X 1.0 X 32    106 lb/in

Case Cover / Channel Plate Bolt - 3  M6 X 1.0 X 30    106 lb/in

Case Cover / Channel Plate Bolt - 3  M6 X 1.0 X 40    106 lb/in

Case Cover / Channel Plate Bolt - 3  M8 X 1.25 X 50    18 lb/ft

Detent Lever Spring Bolt  M6 X 1.0 X 16    106 lb/ft