Friction Discs or Diamond Washers – A New Era
Component downsizing and cost saving during manufacture has pushed vehicle manufactures to look for other ways of carrying out what used to be a simple undertaking. One example is moving away from keyways on high load components such as camshafts, crankshafts and injector pumps.
The main fastening bolts need to be firmly attached so that they can absorb the applied torque without slipping, and the manufacture will always specify a torque setting on these bolts, which can be as high as 240nm or higher on some applications (plus a degree setting if the bolt is TTY). With the keyways gone, the bolt itself is not always enough to transfer the load and prevent slipping. Usually if we want to transfer greater torque, we need larger and therefore heavier and costlier components.
However using a friction disc or washer in between the components locks them together firmly and allows for the transmission of four times the amount of torque. These friction discs or washers are coated on both sides with a nickel matrix. The nickel is embedded with a fixed amount of diamond particles that have a specified size. If the disc is mounted between two engine parts, the hard diamond particles are pressed into the mating surfaces and locks them together. To ensure the washer works reliably it is important to replace it whenever the connected components are removed or their positions disturbed.
Not all engines require friction disks so be sure to check with the manufacturer. We have many customers re-fit cylinder heads and balancers, only to have the crank or cam pulley slip and bend valves or cause other internal damage. If your unsure give Southside Cylinder Heads a call, were happy to help in any way
Warning – because these washers and shims are located behind pulleys or sprockets they can easily fall when the larger component is removed. They could end up in the sump or jammed into an awkward spot without being noticed.