Yamaha ST12 Inner shaft seal replacement

Dennis was kind enough to drop off his 2012 that needs work.

First up is the inner Shaft Seals. This is the second time I’ve done this repair. Naturally this makes me an expert on the matter 🙂

Tools needed:

  • Yamaha manual
  • Rubber mallet
  • Various spanners and what have you
  • Yamaha seals
    Number #21 93211-54698-00 Inner O ring
    Number #25 93102-70004-00 Inner Seal.
  • Parts page: http://www.yamahapartspro.com/oemparts/a/yam/5004d842f87002275461de7b/drive-shaft

The inner seals pretty much leak all over.  Easy enough to tell.  The inner shaft will leak out through the drain hole at the end of the shaft.  Luckily for Dennis, this wasn’t the case.

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  • Remove the rear tire.
  • Drain the drive oil
  • Clean off the bolts and any grime that might be in them. Previously, I removed the pumpkin from the shaft, but this time, it made more sense to leave the whole thing on.
  • Remove the bolts.  The Pumpkin has two pry locations (one towards the back, one towards the front).  I used a large flat screwdriver that was taped up with electrical tape, not to score or mark up the face of the cover.  Cover will pop off easily.
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Cover off, and on the bench. Seal sits flat just towards the tapered metal. Letter on Seal are facing out. Remove the gear by tapping it out with the rubber mallet

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    Close up of seal

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Parts needed.

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I took my rubber mallet, and tapped around the seal from the outside in (tap on the lettered side.) Grease the new seal, and install it by using the old seal, and mallet as cushion. Tap around the seal evenly so it seats properly. TOP TIP: Watch your washers. Both the one on the drive, and the large one shown in this picture. Don’t forget them! The outside rubber ring doesn’t leak, but might as well replace it while you’re here.

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Notice the seal sitting flat with the surface. Grease the inside of the seal. Grease the gear, and tap it in as far as it’s willing to go. You do not need to push it all the way in.

Slap the whole thing back on the pumpkin.  Push it on so each bolt starts with about two to three threads.  Don’t forget the washers.

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Go around the pumpkin and tighten the bolts bit by bit. Make sure the cover sits evenly. It will slowly push the gear through the new seal. Torque to spec.

Fill the drive with oil.  Check for leaks.  The work should take roughly 1.5 hours from wheel off, to wheel on.

Next up….Swing arm grease rev 01.

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2 thoughts on “Yamaha ST12 Inner shaft seal replacement

  1. Do you have a photo of the back side of photo 4? I am trying to figure out when I pull out the cover, what else comes out with it? Also what did you sue to clean out the grime?

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