INSTALLATION INSTRUCTIONS FOR THE SHRINK FIT PROP HUB
(NEW 2.5" SHRINK FIT HUB)
Make sure that the keyway has rounded corners to match the prop hub's milled keyway slot. If you are using a stepped key, make sure the step clears the step cut adjacent to the main keyway.
Make sure the keyway is not too tall and prevents the hub from going over the crankshaft.
Polish the crankshaft nose with the keyway removed using 600 or 800 grit. This will prevent the hub from grabbing the crankshaft.
The hub cannot be pressed on to the crankshaft or drawn down by the prop hub bolt. It must be heated up and placed over the crankshaft nose so it can "shrink" onto the crankshaft when it cools. The hub should seat against the oil slinger. The hub will not seat against the step inside the hub, when you measure from the washer seating surface in the prop hub to the nose of the crankshaft - it should be approximately .590" with the prop hub installed. The hub should be up against the oil slinger. The slinger's cup faces forward.
Size the bolt and cut to length after the hub is in place on the nose of the crankshaft, if needed. Make sure the bolt does not bottom out in the threads before it is tight on the hub. Torque 40 to 50 FT. LBS. with blue Loctite and install locking cotter pin. NOTE: The bolt is no longer drilled. Torque the hub up and use a 1/8" drill bit to mark the bolt through one of the index holes in the hub. Remove the bolt and drill with a 1/8" drill bit.
If the pin does not line up at torque value, grind several thousandths off the washer and re-check alignment until it fits correctly.
On pusher applications - the prop hub seal must be used (aircraft applications only). After installing the hub and waiting until it cools, cut the seal in half with a Dremel tool cut off blade. Using JB Weld, attach the seal to the nose of the case with the split line of the seal horizontal. The JB Weld can be formed with a wet finger. The case must be dry from any oil and paint removed from both the seal and the case.
If the prop hub does not literally "fall" onto the nose of the crankshaft, it is not hot enough. Many times the oven or burner you are using is not hot enough to heat the hub. A propane torch or gas torch may be used to heat the hub hot enough to shrink on the nose of the crankshaft. Apply heat to the I.D. of the prop hub, not the O.D. when using a torch. Airboat prop hubs with the built in pulley need to be heated with a torch to get the mass hot enough.
If your heat source is not directly next to hub (in the same area), chances are the hub will cool off prior to matting it to the crankshaft. (From the oven to the garage, is too long of a trip, the hub will cool off almost 75 to 100 F in the span of 25 to 30 seconds.)
To remove the hub, the crank should be removed from the engine with the hub attached and placed and supported in a hydraulic press where the crankshaft is pressed out of the hub.
When the hub is installed correctly you should measure between .580" and .600" from the washers seating surface to the nose of the crankshaft. Note: The prop hub does not bottom out against the step inside the hub, when installed correctly.
When the hub is installed correctly, photo below is the way the hub and crankshaft should look. The hub should be tight against the oil slinger.
Go back Shopping Cart Index
Go back to Instruction Index