DIY – Mercury Tiller Wobble Fix Tutorial

If you own an older Mercury two stroke (A 15HP was used during this DIY) like me from the early 2000’s or before, you probably have a loose or wobbly tiller extension. The 8, 9.9, and 15HP 2-stroke motors from this era may all experience this problem at one time or another. This is due to the bushings and washers wearing down from years of use in the connection joint where the tiller arms meets the swivel bracket on your outboard. Since I use a tiller extension, this issue is amplified because the now longer tiller handle is able to wobble and show each loose joint much more than the stock rubber grip. Have no fear, there is a fix at hand. Well maybe have a little fear, this DIY is pretty meticulous and time consuming. I consider myself to be an above average mechanic that can figure almost anything out, but getting into this would test my patience and frustration levels.

Time and Difficulty

Approximately 3 hours. Moderately difficult, time consuming.

Tools Needed

  • Box wrenches in various sizes
  • Small and medium ratcheting wrenches
  • Long-nose pliers
  • Flat-head screw driver
  • Phillips-head screw driver
  • Dieelectric grease
  • Marine grade lubricant grease
  • Other miscellaneous tools you may need when something is stubborn

Replacement Parts Needed

  • 12-8239172 : SS BY – 12-889734 – HOUSING-SWITCH
  • 12-823939 : BUSHING
  • 12-824918 : CLIP
  • 12-826792 : WASHER-WAVE
  • 12-9600910 : INSULATOR
  • 12-822145 : WASHER
  • 12-822146 : WASHER


To start, remove your starter (if your outboard has the electric start option) and begin disassembling the tiller handle assembly. You will also need to disassemble the throttle cable female connector that resides inside the elbow of the tiller handle. I did not take photos of this part of the process, but you can reverse-engineer the photos below to accomplish it.

1. Stare at empty swivel bracket
We will start here, after disassembling the tiller extension and removing all parts and cables, this is what we should be looking at: an empty swivel bracket tiller-extension-connector ring.
2. Insert plastic bushings into swivel bracket
Grab the two new black plastic bushings and push them into the tiller-extension-connector ring. There should be a notch in the ring which allows the plastic bushing to be properly indexed.
 3. Place the new washer set over the throttle cables
Here is the washer sequence from inside to out: Flat metal washer > wave washer > flat metal washer > plastic ring washer with extrusion notch.
4. Grease and replace tiller extension arm
Put a small dab of marine lubricant grease on the tiller extension arm’s end which will be slid into the plastic bushings inside the tiller-extension-connector ring. Slide the tiller extension arm into the washers you just loosely placed over the throttle cables, and be sure to index the plastic ring washer with the extrusion to the under-side of the tiller extension arm so it lines up as show to the left. Then push the tiller arm extension into it’s place inside the connector ring. It should slide right in, but be careful not to push out one of the bushings inside the connector ring while doing this.
5. Put female throttle cable fitting back together and push into tiller extension elbow
Put your throttle cables back into their circular fitting and place back into the throttle cable casing, screw it back together. You can take the tiller handle tube and place it into this female fitting now and turn it to make sure your throttle is responding properly and in the correct direction.
6. Screw interior metal end-plate back on with two hex bolts
Replace the metal end-plate on the inside of the tiller connector ring and screw in the two hex bolts which hold it on/hold the whole assembly together.
7. Assemble your throttle handle/kill switch
Feed the kill switch wiring through the metal handle extension tube and slide the throttle handle up from the bottom.
8. Slide throttle handle extension into female throttle casing hole
Slide the black male plastic piece into the female hole of the throttle casing. There are two alignment ledges on the male piece, one is larger than the other. This is so you dont reverse your throttle polarity for forward and reverse. If you assembled your throttle casing wrong you will know it here because the handle will be backwards.
9. Reinstall electric start (if you have one) button and casing
Clip your electric start casing back onto the throttle handle extension tube, it should snap right on.
10. Reinstall the starter and connect all wiring
Screw your starter back in and connect all of your wiring from the starter and kill switch wiring harnesses. It should be one ground wire, two bullet connectors, and one ring terminal to your solenoid.

Ta-da! You’re all done! Was it worth it? If you’re OCD like me then yes, if not, then it’s debatable.


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