Adventures in Motoring: Ms Skyline's Evil Clutches.. There can be no escape for the horses!

The rebuild continues apace at MGT and the engine is temptingly close to installation. Apparently there are minor small complications where my attention to detail is not the same as anyone else's. I couldn't possibly comment without probably upsetting the whole world.

Anyway. The clutch (always useful) is in. This is a Xtreme 230 mm organic sprung twin plate clutch, all the way from Australia (where huge chunks of Ms Skyline are from)

Clutch plates, The rest of the photo's show in order of installation. As a twin plate you get to see everything.. twice! But I have included all of the pictures as a fitting memorial to the new clutch that will (hopefully) not be seen again for a long time.

A twin disc works by effectly doubling the amount of frictional area used when connecting the engine to the drivetrain, which doubles the amount of grip from the engine to the transmission (Same theory applies when people choose to use wider tires and rims, they want a bigger "contact patch" with the road). There are many ways a clutch can be designed to increase grip from the engine to the transmission, increasing the frictional area is only one them. Multi disc clutch setups are favorable (despite their high price) because they offer more grip without neccessarily increasing the clamping load of the pressure plate (which is very bad for the crankshaft).

On a regular single disc setup, the friction disc rubs on the flywheel's face, and on the pressure plate's face (two fricitional surfaces). The frictional disc itself is connected to the transmission via the input shaft, and the flywheel and pressure plate are bolted together (they are connected to the engine via the crankshaft).

On a twin disc setup, there is a center plate which rotates with the flywheel (effectly this center plate is an extension of the flywheel). You can consider this plate to be a second flywheel. Sandwiched in between the two flywheels is the first friction disc. On the other side of of this center plate, there is the second friction disc. After the the second friction disc comes the face of the pressure plate. Here is the order:

flywheel -> friction disc 1 -> center plate -> friction disc 2 -> pressure plate

This makes for a total 4 frictional faces (flywheel, two sides for the center plate, and the pressure plate). This is DOUBLE the amount of frictional surface area than a single disc setup.

To visualize how this kind of setup works, you have to keep in mind what is attached to what. There are only two rotating bodies here (think to yourself "engine speed" & "drivetrain speed"). The first body is the a splined input shaft from the transmission that is connected to the two friction discs (the friction discs spin with the transmission). The two friction discs spin together because they are both connected to the transmission's input shaft. The second body is the flywheel, center plate, and pressure plate which are all bolted to each other and spin together in unison with the engine's crankshaft. Any difference in rotational speeds between these two rotating bodies happens when the clutch pedal is depressed down (when the clutch disengaged) or if the clutch is slipping under power.