DSG7 MECHATRONICS REMOVAL (FWD)
1 For ease of photography, the gearbox has been removed from the car and the gearbox oil drained. Working within the engine bay, you may have to remove certain parts from the front of the gearbox, such as the air filter housing, starter motor, undertrays, battery tray, hoses or other ancillary components, to gain access. Note how the dry clutch pack is located on the gearbox side, rather than bolted to the engine flywheel. CM will feature DSG7 dry clutch replacement in another issue.
2 The Mechatronics unit on the DSG7 gearbox is identified by its black cover. This thin metal case is vulnerable to corrosion and impact damage, so check its condition – but NEVER unbolt it from the Mechatronics casting.
3 Remove the multi-plug that supplies power from the wiring harness to the gearbox. Check that the pins are present and in good order. Corrosion, or broken pins, could well be the source of your problem.
4 The DSG7 has its own separate oil supply. To prevent leaks, open the breather on the top of the gearbox using a suitable tool and insert a clean bung. Note that some breathers might break as you do this, so take care.
5 Carefully prise out the gearbox input speed sensor 3 (G182) with a screwdriver, as pictured. Corrosion and excessive force can cause the integral locating tab to snap off, necessitating a replacement sensor. Take your time.
6 A special tool (part no. T10407) is required to separate the gearbox’s clutch and gear selector levers away from the Mechatronics unit’s plungers. Otherwise, you will not be able to separate the Mechatronics unit from the gearbox.
7 The special tool c is inserted into the gearbox, between the plungers and the engaging levers. Push the tool into the face of the gearbox – but not too far.
8 When the strengthening ridge on the gearbox aligns with the slot on the tool, it is in its correct position; do not press the tool in further. Twist the lever 45° clockwise.
9 The tool will separate the two plungers (i.e. the clutch ‘slave’ cylinders) from the two mechatronics’ clutch levers and be locked into position. Note the final position of the handle. The tool should not be removed until the Mechatronics unit has been refitted.
10 Here is another picture of the tool in position, after the Mechatronics unit has been separated from the gearbox, showing how it moves the clutch operating lever from one side.
11 If you do not own the appropriate diagnostic equipment, or if the Mechatronics is unresponsive, selecting neutral might be impossible – but you can do it manually, by removing the gear-selector bracket and plastic cover plate.
12 Locate the selector within the gearbox, as pictured inset. Manipulate it as far as you can to the right. This ensures that no ratio is selected. If you do not do this, the replacement Mechatronics will not be aligned.
13 As you risk breaking the Mechatronics unit’s delicate sensors by tilting it as you withdraw it from the gearbox, you will need to purchase a pair of special guide pins, part number T10406.
14 As the Mechatronics unit contains oil that can be pressurised up to 60 bar, remove the T45 bolts only; there are four short and three longer bolts. Note their original positions. NEVER remove the bolts that hold the cover in place.
15 Start by removing the two long bolts that hold the Mechatronics to the gearbox. Using a flat-headed screwdriver, screw-in the guide pins (see step 13) that help to prevent the Mechatronics unit from dropping as it is withdrawn.
16 Loosen the remaining bolts but in a diagonal sequence, so the pressure is released evenly. Ensure that the T10407 special tool remains in position; if dislodged, the clutch adjustment will be affected.
17 Take out the remaining bolts, leaving one of the top bolts in-situ, until you are ready. Then, pull the Mechatronics unit from the gearbox without tilting it. Catch any spilled gearbox oil that comes out (which should have been drained beforehand).
18 The main reason for being so careful is that you risk snapping the pictured plastic sensors from the main body. Apart from ruining the Mechatronics, you might have to dismantle the gearbox to retrieve the broken parts.
25 The two clutch ‘slave’ plungers require priming in the same way. The top one is at the highest point of the system, so if it will not prime, the fluid might need topping-up. Do not forget to refit the filler plug.
26 Once the unit has been primed, ensure that all four gear selectors protrude by 25mm precisely and verify this with a set of measuring calipers.
27 Prior to offering the Mechatronics to the gearbox, check that the gear actuators’ collars (visible in step 26) will slot into their relevant selectors within the gearbox.
Every replacement 28 Mechatronics unit should be supplied with a new rubber gasket. Fit it into the groove, noting that the seal’s locating tabs align with those on the casting. The gearbox mating surface must also be clean to avoid gearbox oil leaks.
29 Remembering to locate the Mechatronics straight-on, refit the unit, using the guide pins to help you. Do not force the unit into position. Secure the unit with a top bolt. Reassemble the gearbox side cover, if you removed it (see steps 11 and 12).
30 Refit the remaining bolts but do not torque them up yet. Remove the two guide pins and replace them with the original bolts. Ensure that the rubber gasket does not become dislodged.
31 Manipulate the clutch plungers so that their balls locate into the dimples stamped in the operating arms. Failure to do this will damage the Mechatronics unit.
32 Tighten all retaining bolts diagonally to 10Nm. The special tool T10407 can now be twisted 45°, then lowered and withdrawn. Now, refit the speed sensor (see step 5) into the gearbox housing.
33 Remove any bungs, or replace the entire breather assembly if it is damaged. During the refitting procedure, make sure that no oil leaks emanate from the Mechatronics unit.
34 Reassemble the ancillary parts that you removed earlier but do not forget to refill the gearbox with the appropriate quantity of oil that meets the specifications stated by VAG, printed in the handbook.