Tuesday, August 07, 2012

Project R69S /2 Motor rebuild: Removing the crank

Today, I'm going to remove the crank from this /2 bottom end.  This is part of the R69S motor rebuild project. The Slash Two motor is a wonderful little engine. Slash Two engines are virtually indestructable and run very well, even on very little maintenance.  

The main problem with this motor is the oiling system. In addition to a small gear oil pump, the crank bearings are oiled by centrifugal action.  Oil slingers on the main crank shaft whirl the oil inside a centrifuge and it is then pumped through the crank shaft hollow center. 

The centrifugal action causes the particles in the oil to separate and eventually harden inside the slinger. Once the slinger has filled up with particles, the oil hole is blocked and the crank bearings will no longer receive oil, leading to catastrophic results.

It is recommended that you tear down your Slash Two engine every 20k-40k  miles to inspect and clean the slingers.  

This is the process: 

Lock the flywheel and use a 41mm socket to remove the crank nut.
Note position of the locking washer.  If it is all bent up, put this on your parts list to order a new one.
Remove the flywheel.  This is a Bunch tool.
On the oil seal side, note position of the washer, and remove.
Inspect condition of woodruff key. This one has been around a while but is still servicable.
Remove the nuts and bolts on the bearing / oil pump cage.
Use a puller to remove the cage.  This is a Bunch tool #216. I have a peice of aluminum between the center screw and the crank nose to protect the crank nose.
Case removed.  I will leave the tool attached until I'm ready to reinstall.
Inspect bearings and oil pump gears.

Here's one-a-tha buggers we came here for. The front slinger.

The slinger screws should be punched with a screwdriver or cold chisel when installed. Always use new screws when reassembling.

Full slingers look like this.  This slinger came out of a motor that had destroyed its crank  rod bearings.  The cost of dirty slingers is a crank rebuild. If the journal bearings disintegrate it could throw a rod through the block or destroy other parts inside the motor.  

Use a hook to remove the oil seal and spacer.
Heat the case to 180'F
Position the Crank web like this and pull the crank out of the case. If it sticks use more heat!
Once the crank is free of the rear bearing, tilt it downwards like this.
Now you can wiggle the crank out , like this.
IT'S A GIRL!!  (I have a weird sense of humor.)
The crank is removed!  In the next episode, we'll remove the rear bearing and rear slinger. 

1 comment:

  1. Great pics and comments Scottie......even if it is a girl ;))