4R75E Transmission Teardown Inspection Summary
"4R75E Transmission Teardown Inspection - Transmission Repair" (YouTube video)
I. Introduction and Initial Disassembly (0:00-2:50)
The video begins by identifying the 4R75E transmission from a 2005 Ford vehicle and differentiating it from the 4R70W model.
Initial steps involve removing external components like speed sensors and the transmission range sensor to prepare for a full teardown inspection.
The pump is removed, revealing the intermediate clutch piston and selective washers, and the pump assembly is further disassembled to examine the pump gears and sealing rings.
II. Pan Removal and Metal Debris (2:50-5:00)
The transmission pan is removed, showing a significant amount of metal debris, indicating internal damage.
The conductor strip, connecting external sensors to internal solenoids, is highlighted.
The valve body is removed, and the video notes that the gasket's adhesion to the case suggests overheating.
III. Accumulator and Servo Disassembly (5:00-8:20)
The third accumulator piston and spring are examined, emphasizing the common failure point of the inner spring in earlier models.
The one-two accumulator cover, springs, and piston are removed and explained.
The video demonstrates the careful removal of the snap ring from the overdrive servo, warning about the potential for it to fly off due to spring pressure.
IV. Input Shaft and Overdrive Band (8:20-11:20)
The transmission is flipped, and the input shaft with the anti-rattle spring is removed.
The intermediate clutches and steel plates are inspected for signs of wear and heat damage.
The video focuses on the overdrive band, showing signs of wear and discoloration, indicating slippage in fourth gear.
V. Reverse Input Drum and Forward Clutch Drum Damage (11:20-15:00)
The reverse input drum housing is removed and its functions as a multi-function drum (reverse input, overdrive, and intermediate) are described.
The input clutch housing (forward drum) is disassembled, revealing a burnt clutch pack, a key indicator of transmission failure.
The root cause of the burnt clutch pack is identified as a split in the forward drum where the snap ring sits, potentially due to material or high line pressure.
VI. Planetary Gear Assembly and Sun Gear Shell Wear (15:00-19:40)
The video examines the forward hub assembly, Sun Gear shell, and the bearing that commonly fails, leading to gear train damage.
The design changes to the Sun Gear shell in later models (to accommodate the added speed sensor) are explained.
Significant wear is noted on the Sun Gear shell, specifically on the castellations where the reverse input drum spines in, potentially leading to noise and drivability issues.
VII. Center Support, Low Reverse Servo, and Bands (19:40-23:55)
The center support and anti-clunk spring are removed, along with the planetary gear assembly.
The video revisits the intermediate sprag assembly (mechanical diode), contrasting it with the roller and cam design found in earlier models.
The low reverse band is inspected, highlighting wear at the apply point and anchor points, indicating the need for replacement.
VIII. Third Gear Drum and Output Shaft Differences (23:55-27:40)
The third gear drum is disassembled, showing good condition frictions.
The output shaft and ring gear assembly are removed, emphasizing the differences between early and later model ring gears (number of holes and parking gear extension) due to changes in output shaft speed frequency.
Using an incorrect ring gear can lead to significant drivability problems, particularly with overdrive engagement.
IX. Case Inspection and Conclusion (27:40-29:15)
The case is inspected for wear, focusing on the sealing rings and potential wear patterns caused by driveshaft issues in two-wheel drive models.
The video concludes by summarizing the key findings of the teardown inspection: burnt forward clutch hub, worn overdrive and low reverse bands, a cracked forward drum, and a worn Sun Gear shell.
The video emphasizes the importance of replacing these worn components and highlights the need for hard parts (not included in soft part overhaul quotes) to ensure a proper repair.
This is a common problem on '04 and up 4R75-e transmissions. On this video we can see the damage on the forward drum plus the normal ware that you expect to see in these units. This being a 4X4 unit, is more prone to ware and off road use.
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