Conversion and Installation Instructions
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I. Completely Remove Existing Head
First, determine if LEFT or RIGHT THREADS are used on the arbor. Either view string head with engine running or observe location of cutoff knife (if single) to determine the type of thread.

Other Helpful Ways to Help you Determine Left or Right Thread Recall the direction (right or left) IF you have removed the head's knob: If it turned to the left to remove, it's a right thread. If it turned to the right to remove, it's a left thread. If you are having difficulty loosening the fastener, the thread may be the opposite direction.

II. Arbor Type

III. Short Arbor

1. Lock Shaft
   Use lock pin or wrench to hold shaft from turning while you unscrew the head.
   
   
   
2. Entire Head Slides Off
   Unscrew entirehead from threaded arbor. To determine thread directions, refer to Section I (Right threads - turn head off to left. Left threads - turn head off to right.) It will take a strong initial force to release; then unscrew the head.
   
   
   
3. Install Aero-Flex^® Short Arbor Head
   When you remove the ENTIRE head, you will see the threaded arbor (will be male or female). Now you're ready to select and install the AERO-FLEX^® SHORT ARBOR head (with internal fastener cavity).
   
   

IV. Long Arbor

1. Remove retainer knob & line spool
   After removing knob and any possible retainers, long arbors are identified by a long 3/8" arbor shaft that extends from the head's base. There are 3 primary types of Long Arbor Heads. See below:
   
   
   
2. Remove the entire head
   TYPE 1 - Head cup simply slides off. Found on most Homelite, yellow shaft Ryobi, Toro, John Deere, curved shafts, Stihl, and IDC models.
   
   
   TYPE 2 - Retainer washer holds head. Attempt to tap off the head with hammer. If head remains in place, cut retaining washer with a thin sharp chisel and hammer. Found on MTD and older silver shaft Ryobi, Bolens, and Yardman models.
   
   
   TYPE 3 - You will need snap ring pliers, and a small chisel. This involves a yellow Speed Spool head made by MTD. The difficulty will be simplified if you follow these directions very closely.
   
   Follow these steps:
   
   
   
3. Install Aero-Flex^® Long Arbor Head
   When you remove the ENTIRE head, you will se the long 3/8" arbor. Now you're ready to select and install the AERO-FLEX^® LONG ARBOR head (with internal fastener cavity).
   
   

V. Install Line Blades & Cap

Now you're ready to install the Aero-Flex^® Line Blades and the snap-on cap. (See line blade selection chart in the Operation Instructions). All remaining unused parts are no longer needed. They can be discarded.