AT clutch solenoid repair 0B5, DL501

The modern automatic transmission DL501 is developed by Audi AG for all-wheel drive vehicles with longitudinal arrangement of the power unit. The axle differential is located in the body of the mechanical part of the gearbox and allows the distribution of forces along the axes (front / rear) from 15/85 to 65/35. The DL501, also known as the S-tronic brand, is a seven-speed, two-shaft DSG family gearbox, first installed on the Audi Q5 in 2008, adding to the model name the addition of a "quattro" - permanent all-wheel drive. The mechanical part of the gearbox is designed for a system of two embedded primary shafts that are responsible for certain gear sets. The primary internal shaft is marked K1 - it is responsible for odd transmissions 1,3,5,7. The primary outer shaft is marked K2 - it is responsible for even transmissions 2,4, 6 and Revers. The torque to the primary shafts is transmitted through the means of a double differential clutch (Coupling K1 + Coupling K2).

The mechanical part of the box is controlled by an electrohydraulic Mechatronik module. Mechatronik consists of a hydraulic system control unit, an electronic control unit, a sensor system and a set of actuators.

The pressure regulating solenoids are responsible for the operation of the clutch mechanism- solenoid No. 436 (for shaft and clutch K1) and 440 (for shaft and clutch K2) of the electrohydraulic unit.

With the non-stable operation of these solenoids, the following problems are observed:
- bumps and thumps when starting at Park-Drive or Park-Reverse
- floating RPM in the steady state of the running transmission
- clutch slippage
Clutch slippage is diagnosed by 022FE. As a result of slippage, friction and clutch systems fail.

A diagnostic stand is used to determine the operability of solenoids.

Installing a solenoid for testing

For each solenoid, a plunger state graph is plotted over the entire range of the control signal

The graph of the failed solenoid. Unstable operation, the presence of flat horizontal sections indicates the jamming of the solenoid core.

Unstable operation of solenoids can be caused by a defect of the solenoid bushing. During operation, the solenoid bushings are worn out by the action of fine particles (metal shavings, oil oxidation products, etc.) which get into the oil inside the valve body housing. As a result of the wearout, the central bore of the bushing acquires an eccentricity (displacement of the hole center relatively to the normal one).When the center of the hole of the guide bushing is displaced from at least one side of the solenoid, the axis of the core movement can be skewed and, consequently, the core jam occurs during its movement inside the coil of the solenoid. Such jams are marked on the chart of the unstable solenoid by flat section.

Solution.
The failed solenoids are to be replaced or restored. The method of solenoid recovery was developed by the specialists of Maktrans companyon the basis of many years of experience in valve body servicing .

The essence of the methodology.
The design of the solenoid consists of a core, a lid with a bushing and fastenings with a plunger for mounting on a valve body plate. The housing includes a solenoid coil, control terminals and the guide sleeve.

To restore the work of the solenoid, the failed couplings are replaced with new ones.

Disassembly of the solenoid, replacement of the bushings for the new ones and assembly (closing) of the solenoid are carried out by a special tool developed by the specialists of Maktrans company. After assembly, the solenoid with a new set of bushes is tested for compliance with operating parameters.

In addition to testing the solenoids, to ensure the reliability of the clutch control system, a set of conductive loops transmitting the control signal to the solenoids is checked. During the test, an additional heating of the loop is performed to simulate the real temperature operating conditions.

After a fault is detected, the current conducting elements of the loop are repaired. At the end, the restored solenoids and a set of conductive loops are installed in the valve body. Further, the operation of the automatic transmission is tested on the go. Solenoids, restored by the technique of the specialists of the Maktrans company, respond to the operatonal parameters of solenoids for automatic transmissions 0B5, DL501. The service life of the solenoid after recovery corresponds to the life of the new solenoid, at a relatively lower cost

Cooling system repair DSG 0B5

The DSG 0B5, DL501 seven-speed robotised gearbox (according to the Audi- S tronic classification) is an in-house development of the Audi AG group together with BorgWarner Inc. This model of automatic transmission is installed on all-wheel drive Audi A4, A5, A6, A7, Q5 cars. Wet double clutch box allows you to transfer a large torque (up to 550 H * m) without breaking the power flow, with smooth and clear shifting.
Structurally, the automatic transmission consists of a mechanical part and an electrohydraulic control unit -Mechatronics. Each of the parts has its own oil circuit. And if the oil is used in the mechanical part to lubricate the interacting elements, then in the electromechanical block, oil is used to control the hydraulic shift system, control the friction clutch (closing and opening), and also for cooling the friction clutch. Although the friction clutch is part of the mechanical part of the box, it is cooled and lubricated by the oil circuit of the electromechanical unit. This circuit is also called the ATF contour. Returning to what was said before - the ATF circuit uses oil for both the gearshift and cooling of the friction clutch. Moreover, cooling control of the friction clutch is one of the tasks performed by the electromechanical control unit.

You can see the ATF lubrication system below

And this is how the ATF cooling system looks like

If there is a malfunction in the cooling system of the ATF circuit, the oil temperature rises above the permissible values, which adversely affects the operation of the electromechanical unit (especially electronic parts) and the differential clutch. Therefore, the value of ATF temperature is one of the main indicators of the automatic transmission.When a certain ATF temperature level is reached, the protection is activated, which is expressed in the reduction of the engine torque or the complete opening of the couplings (complete stop of the car) - no torque is transmitted to the box.

The ATF temperature is measured by a diagnostic tool. If the temperature is exceeded, an error P17D800 occurs, which means the limitation of the torque value due to the coupling temperature. At the same time, bumps when shifting from the 2nd to the 1st gear or bumps (jerks) of Park-Reverse and Park-Drive are possible.

The Mechatronik cooling control system includes:
Solenoid N471 and ATF cooling valve

The failure of one of these nodes leads to a violation of the proper operation of the cooling system. Among the most common faults are the wear of the solenoid bushing and the wear of the ATF cooling valve channel.

An example of a worn out bushing of a solenoid. Bushing central opening wear

Maktrans company offers the following solutions based on years of experience in repairing automatic transmission:
1. Manufacture and installation of the ATF cooling valve bushing into the worn channel. The valve bushing is made of high-strength aluminum.

2. Repair of the solenoid. The method of solenoid recovery was developed by the specialists of Maktrans company on the basis of many years of experience in servicing valve bodies.
To restore the work of the solenoid, the failed couplings are replaced with new ones. The new couplings are made by the specialists Maktrans company.

Disassembly of the solenoid, replacement of the bushings for the new ones and assembly (closing) of the solenoid are carried out by a special tool developed by the specialists of Maktrans company. After assembly, the solenoid with a new set of bushings is tested for compliance with operating parameters.
Stand for testing solenoids.

Solenoid setting for testing

Solenoid test results after regeneration.

After testing regenerated solenoid is installed in the valve body.
Further, the operation of the automatic transmission is tested on the go.
Solenoids and valves of the cooling system restored by the technique of the specialists of the Maktrans company, respond to the operatonal parameters of solenoids and valves of the coolong systemfor automatic transmissions 0B5, DL501. The service life of these parts after recovery corresponds to the life of the new ones, at a relatively lower price.