After recently having upgraded to a Spec II+ Hybrid a few weeks ago (Extremely satisfied btw!!) I ran across this article regarding crank walk with high pressure plates.
A word about crankwalk:
It isn't so much the grippyness of the clutch that kills the thrust bearings or the power the motor is making, is the increased clamp loads on some pressure plates such as ACT and RPS that are used to get more friction and thus hold more power. With the factory clutch start switch, you must depress the clutch to start the car; when the motor is not running there is no oil between the thrust bearings and block/crankshaft, so it's essentially metal on metal which is not how the bearing is supposed to operate. At factory clamp loads this is not a huge issue unless you own a DSM, but increasing the clamp loads with a stiffer pressure plate puts more stress on the thrust bearing every time you start the car with the clutch pressed. The wear on the thrust bearing is also not the biggest issue, but the design of it where it will fall into the rotating assembly if it wears too much and do lots of bad things.
2 Solutions:0
- Disable clutch start switch (illegal on cars after 1990 or something like that even though most nissans in the 90s didn't have them). I've done this and I see no signs of crankwalk on my heavy pressure plated-2jz
-Get new thrust bearings and pull small tack welds to hold them to the block, so they can never fall down into the rotating assembly. This is a bit overkill IMO but if you have access to them, its a bit of added security for relatively cheap. Even just changing the thrust bearings periodically is sufficient I'd think, if you insist on leaving the clutch-start enabled
**
The clutch start doesn't necessarily have anything to do with lubrication, its the fact that without the engine running, there is no lubrication and you're applying direct thrust from the pressure plate to an otherwise un lubricated bearing. Pretty much the only time the crankshaft sees any signifant amount of thrust is during clutching, the power strokes are all acting radially aswell any tension from the drive belts and torsional resistance from the clutch/tranny/tires.
Wondering if this is something to be concerned about.??
A word about crankwalk:
It isn't so much the grippyness of the clutch that kills the thrust bearings or the power the motor is making, is the increased clamp loads on some pressure plates such as ACT and RPS that are used to get more friction and thus hold more power. With the factory clutch start switch, you must depress the clutch to start the car; when the motor is not running there is no oil between the thrust bearings and block/crankshaft, so it's essentially metal on metal which is not how the bearing is supposed to operate. At factory clamp loads this is not a huge issue unless you own a DSM, but increasing the clamp loads with a stiffer pressure plate puts more stress on the thrust bearing every time you start the car with the clutch pressed. The wear on the thrust bearing is also not the biggest issue, but the design of it where it will fall into the rotating assembly if it wears too much and do lots of bad things.
2 Solutions:0
- Disable clutch start switch (illegal on cars after 1990 or something like that even though most nissans in the 90s didn't have them). I've done this and I see no signs of crankwalk on my heavy pressure plated-2jz
-Get new thrust bearings and pull small tack welds to hold them to the block, so they can never fall down into the rotating assembly. This is a bit overkill IMO but if you have access to them, its a bit of added security for relatively cheap. Even just changing the thrust bearings periodically is sufficient I'd think, if you insist on leaving the clutch-start enabled
**
The clutch start doesn't necessarily have anything to do with lubrication, its the fact that without the engine running, there is no lubrication and you're applying direct thrust from the pressure plate to an otherwise un lubricated bearing. Pretty much the only time the crankshaft sees any signifant amount of thrust is during clutching, the power strokes are all acting radially aswell any tension from the drive belts and torsional resistance from the clutch/tranny/tires.
Wondering if this is something to be concerned about.??