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Hy dash final drive timing

Daytodaze · 2025-01-23 03:28

Hi all First time post *I purchased a complete undercarriage kobelco sk120 unsure of the year. *The sun gears have been removed and lost by the previous owner. *When i removed the covers for the final drives to test replacement sun gears it appears theres some marks on the 3 star gear set. *At this stage i havnt done anything further than test the fitment of new sun gears. After considerable reading it appears the sun gears need timing with the 3 star gear set, does anyone know the procedure? What is the process to fully reset the timing as i didnt remove the sun gears initially so the timing marks dont mean much to me? Are the sun gears i have too small, i have read these are meant to be a loose fit but it doesnt seem quite right to me. Photos will follow. Thanks

Replies15
  1. #1Daytodaze2025-01-23 03:49
  2. #2Daytodaze2025-01-23 03:50
  3. #3Daytodaze2025-01-23 03:51

    Left hand side

  4. #4Kobe Steel2025-01-23 06:10

    hopefully this should help. See attached. The sun gear in your pic looks to be too small in its profile. There are different Travel motor versions between the SK-III and SK-V, I believe these were either GM17 or GM18 units. The sun gears in your pic maybe missing a ball bearing that sits in the center cavity of the sun gear. The end cover would usually have a corresponding ball mark in the center where the ball bearing would thrust against. Kind regards

  5. #5Daytodaze2025-01-23 06:37

    Thankyou alot for this attachment. *I will include the photo of the model plate it is in fact a gm18vl *To date i have tried 2 different sun gears 41mm outer and 43mm outer (43mm is pictured). The supplier is saying thats the only 2 available. I am still researching this.

  6. #6Daytodaze2025-01-23 06:41
  7. #7Daytodaze2025-01-23 06:45

    Also noted about the ball bearing you are correct and i do infact have that

  8. #8Tones2025-01-23 17:17

    When installing that ball bearing make sure it stuck to the cover or sun gear well. It's a barstard and expensive when they unknowingly fall out after rebuilding the hub.

  9. #9Welder Dave2025-01-24 03:10

    Sun gear is not only too small but the tooth profile is different from the other gears. Also doesn't appear centered. Looks like the teeth would get sheared off by the spur gears. Could the sun gear be aftermarket or something? It's just wrong.

  10. #10Daytodaze2025-01-24 06:43

    Understand thankyou for your reply

  11. #11Daytodaze2025-01-24 06:49

    Hi there Thats correct i purchased the whole undercarriage without the sun gears they have been lost. Although these are the sun gears listed for the gm18vl 38t spur gear set something else is not quite right. After more discussion with supplier it looks like when teijin seiki merged with nabtesco in 2003 they made other changes including the spacing of the 3 spur gear case. I will update as this develops Kind regards all.

  12. #12Lagwagon2025-01-24 17:40

    The sk120-5 had a hy-dash motor, attached is the model details. Does it look like this? they could be compatible . when you put the sun gear in did the small splined end slot into a coupler?

  13. #13Lagwagon2025-01-24 18:06

    I’ve just looked back at your original pic and they are different, the -5 looks bigger and has 12 x cover bolts as opposed to yours with 10

  14. #14Daytodaze2025-01-24 21:04

    Hey there Thanks for your reply Im pretty sure that type of track motor is the early plantetary gear set type (manual saying gm17 there). The later model ones are a cylodial walker pin design where they only have the gears out the front, the rest is cams, plates and pins. Kind regards

  15. #15ShaneV 32025-09-15 14:04

    I need the timing for the final in this picture