jrice45516
Heliman
Location: SoCal
| watch out for metal fansA few flights after installing heliproz' metal fan, i noticed axial play in startshaft assembly. I split the sideframes. Startshaft bearing block areas in both sideframes melted, lower startshaft bearing ruined (plastic bonded to outer race, excessive inner/outer race slop, it was done). I then measured runout of metal fan at fan hub to be 6thou. Because the fan THREADS onto the crankshaft, no amount of playing with the tapered collets affects the runout, & you're stuck with what you get. I also measured crank runout on that & two other OS32SX-H's to be ~1/2thou...acceptable. Obviously, if the fan has runout, the clutch will too adding to any misalignment with the startshaft assemby.
I ALSO measured installed stock plastic fan runout at the aluminum hub to be ~1thou. Needless to say I went back to the stock fan. If you cannot get the runout of your metal fan down to that of the crankshaft, I would suggest not using it. Let us know how it goes.
By the way, I have over 900flights on the R30 using the stock fan & no shroud extension of any kind. Be assured it puts out plenty of air. Put your hand under the bird while it's idling & you can feel the airflow. If your engine is overheating, don't blame the fan.
Another consideration. Metal fans are alot more massive than plastic & therefore do not crash well. So, if you do run a metal fan, recheck your runout after any incident. If the runout at the fan hub is bad after a crash then your crankshaft may be bent also.
Don't buy the ronlund metal fan. It has a collet which either has to be machined before it fits into the fan or has to be forced in. It also screws onto the crank. ;-(
Dances With Woofs |
