model BMW 740 gearbox 6HP21, equipped models are: BMW x1, BMW 325i, the BMW 7 Series in 2008 before: 730, 740, 535 BMW 5 Series. Fault-prone period in the vehicle traveling 70,000 to 80,000 kilometers.
BMW 740, the Car speed when traveling a significant break subtraction Car phenomenon, since the early performance failure, the failure check code does not detect the fault, Is determined empirically or more maintenance staff phenomenon Is caused by a gearbox problem, we need to dIsassemble the gearbox for maintenance.
Incidentally detachable gearbox assembly make a large maintenance work, demolition Is a torque converter, there Will be pull jitter and abnormal sound weak acceleration phenomenon when it fails. The torque converter in the
Usually a torque converter failure, are needed to remove the gearbox maintenance and serious need to cut the torque converter for maintenance, if there Is no damage to the internal torque converter, the majority of the torque converter gap Is too large, the torque converter does not need to be cut maintenance.
Take thIs transmIssion repair abnormal sound due to converter case Is concerned it, with weakness particularly evident in how the fuel door, the speed Is not improved, when open to the store maintenance the torque converter gearbox found serious erosion phenomenon, cut the torque converter found inside lining erosion and wear have, fortunately, Is inside the torque converter turbine Is not damaged, if the damage occurs Is equivalent to a transmIssion needs to be replaced the new torque converter, after the failure to lift the damaged parts with the change.
Removal of the valve body and the gearbox computer:
for thIs transmIssion to PCHe said fault lights, lock files (not lifting gear to stay at a certain range), do not take the Car, frustrated, started punching. Relief solenoid valves and the like. These symptoms occurs in the valve body, the solenoid valve, the three sections computer board. Still need specific aftermarket equipment to be checked.
Computer scored and the valve body
Mechanical means for dIsassembly processes: control of each gear clutch Is coordinated to each group work . Mechanical parts to be dIsassembled and the input shaft of the oil pump Is:
on the input shaft and the pump dIsassembled
won the first pump
dIsassembled to check the oil pump, the oil pump given finding that both locking shaft have different degrees of wear, wear occurs once the stator shaft, the transmIssion Will cause internal pressure relief, so that the Car Is traveling shift impact, and break the Car phenomenon. Once thIs thing Is broken, you need to replace a whole new set of copper sleeve, in order to solve the above gearbox failure.
continue our removal process, view the following dIsassembly process if there are other parts appear damaged, if not, you can also clean and look great conservation gearbox,
Removal of each gear clutch: a gear, clutch and brakes A D; 2 block, the brake clutch A and C; 3 speed, the clutch and the clutch A B; 4 speed, the clutch and the clutch E A; speed. 5, the clutch and the clutch E B; 6 gears, clutches and brakes E C.
Maintenance case: a Car damage caused by a clutch gear punch, or break
After repair: fault lights, gearbox failure prompt, test maintenance staff checked and found the Car at the time of break-liter 4-speed Car phenomenon Is more obvious, the computer connected to the gearbox, the clutch E Is determined to detect the fault slip. Gearbox need to be removed for maintenance.
damages: In addition to the clutches E, other clutches are normal, the failure may be speculated that maintenance personnel about the drain. After sealing the oil passage adverse temperature rIse, the oil leak tension decreased, the clutch operating cylinder due to oil WillPressure Is too low and slipping the computer detects a fault, fault lights prompt a gearbox problem and make self-protection measures.
Solution: Remove the transmIssion check the clutch, the clutch input shaft sleeve aluminum found excessive wear of the dynamic seal ring serious leak oil passage. Replace aluminum cover sleeve and dynamic oil passages, seal tested again, leakage dIsappears. Again, we found that the problem should solve the problem Is the most sensible approach.
The following groups are dIsassembly clutches
The clutch plates dIsassembling
check whether the pIston Will vent pressure
found that wear imagined friction plate
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