Trimmer Line Replacement:

How to Install String Trimmer Line in a Traditional Bump Head

Learn how to do a trimmer line replacement to prepare for a season of lawn care and maintenance.  String trimmer line should be replaced at the start of each season as old line can be brittle and lead to easy breaks.  Line may wear down faster if you're cutting thick weeds or against hard surfaces.

The traditional bump head has a round, black cutting head with a spring loaded knob in the center.  Installing line in a traditional bump head requires you to disassemble the cutting head.



Step 1: Prepare the new string trimmer line

Begin installation by cutting 10 feet of replacement trimmer line.  You can either use twin-strand split line or cut two pieces of 0.95" trimmer line to 10 feet each.

Step 2: Disassemble the cutting head

To take apart the cutting head, unscrew the bump knob and remove the inner wheel and spring.

Step 3: Insert the string trimmer line

Find the two holes on the top of the inner reel and insert both ends of the line into one of the holes.  Pull the line through until 2 to 3 inches remain.

Step 4: Loop the ends and close the loop

Loop the short ends of the string trimmer line through the other hole and pull the long ends to close the loop.

Step 5: Wind the line around the wheel

Wind the line around the wheel in the direction of the arrow on top.  Apply some pressure to wind it evenly.  When you have about 6 inches left, push each string into the holding slots marked 0.95". 

Step 6: Replace the spring

Place the spring back on the shaft.

Step 7: Feed the string trimmer line through the eyelets

Find the eyelets on the spring head and feed the strings through.

Step 8: Tighten the bump knob

Place the reel back on the shaft and align the holding slots on the reel with the eyelets on the head.  Holding the reel down to compress the spring, tighten the bump knob back onto the trimmer head.

Step 9: Release the line

Gently pull the lines to make sure they were released from the holding slots and you're ready to go!


Keep your bump head trimmer in prime working condition with string trimmer replacement line and other trimmer parts from MTD.  A well maintained string trimmer will help you trim and edge your lawn, creating a well-manicured landscape each season.  Show now to stock up on any replacement trimmer parts you'll need throughout the summer.