Wet dual clutch housing repair PowerShift 7DCT300 (Renault EDC 7 PS251)

PowerShift 7DCT300 (Renault EDC 7 PS251) - 7-speed preselective robotic gearbox with a double wet clutch.Since 2015 Renault has been installing it on almost all of its modern front-wheel drive cars paired with engines up to 2 liters in volume .7DCT300 is capable of "digesting" torque up to -  320 Нм.

The 7DCT300 is based on the popular PowerShift 6DCT250, but Getrag replaced the dry double clutch with an oil bath multi-plate clutch. In general, in theory, a wet clutch has a number of advantages over a dry clutch, it withstands a large thermal load, is capable of transmitting more torque, the maximum permissible engine speed is also higher if it is paired with a wet clutch, however, in the case of the 7DCT300, the manufacturer made a constructive mistake and thereby made the wet clutch a weak point in the box.

We are talking about the clutch housing, which, due to loads, simply breaks, the housing breaks along the factory weld and thereby makes further transmission operation impossible.

                                                                                In the video below you can see a broken clutch housing 7DCT300

Let's take a closer look. The hub tears off exactly along the factory weld, but the gap between it and the body is too large and it will not work if we just  weld it with a semiautomatic device, there will be no necessary alignment.

Our task is to accurately center the torn off hub, for this we use a press and specially made mandrels, we expand the hub to the hole diameter, it is necessary to obtain such a result.

We weld it in 4 places

Welding. We use a laser welding machine. Unlike other types of welding, laser welding provides local sector heating of the metal, which is extremely important when welding precision structures, where any kind of run out and violation of the geometry of the parts to be welded are unacceptable.

Laser welding process

Result

Checking if the disk can be installed on the hub

We install the clutch housing into the lathe and clean the inner surface with fine-grained emery paper

The repair is over, the clutch can be assembled. This repair technology has already been tested in operation on many vehicles and has shown its reliability. The cost is only $ 100, while "Maktrans" gives 1 year warranty for repaired components and assemblies without mileage limitation.