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Thread: Alpha 1 U-Joint service

  1. #1
    Join Date
    Dec 2011
    Posts
    2

    Default Alpha 1 U-Joint service

    Good day everyone,
    I am fairly new to this boating world. I grew up around fishing boats with small outboard motors. I bought a 1988 Chris Craft 17' with a Mercruiser 3.0 Alpha one outdrive. I would like some help with what would be involved if I were to replace the u-joints in my shop.I have skills doing mechanical work on cars,trucks and such never with boats. I do understand that I need a special spanner wrench to remove the shaft but then I'm not so sure from there.
    Thanks for any help

  2. #2
    Join Date
    Nov 2006
    Posts
    661

    Default

    It's a little tough to explain, especially while typing on a phone, but I'll give it a shot. Once you have the proper spanner wrench, loosen the spanner nut. It may be neccassary to pull the shaft out while loosening it. Once it is all the way unscrewed, the shaft will pull out along with the upper bearing pack and drive gear. Be careful, there are some shims and a spacer in front of the bearing pack which sets the gear location. If you loose these, it will require a special shim tool to get it located correctly. Then lock your spanner tool in a vice and place the assembly in the spanner tool. Use a long flat head screw driver and insert it into the unions to hold it while you loosen the nut on the gear. One the nut is off, the shaft should fall out, it may be neccassary to give it a little tap to pop out. Now you can change the u-joints like any other. Going back together gets a little tricky. The two bearings are set to a certain rolling torque. There are two methods depending on the age of the bearing pack. The old way, the bearings had a small and large spacer between them. This set the rolling torque, so it was only neccassary to tighten the nut to 80 foot pounds. The newer way is to use the nut to pull the bearings closer together as you tighten tighten the nut. making sure not to go to far, or you have to pull it apart and start over. To get the bearings off, you will use a press. Once they are apart you can check the bearing type by looking for the small spacer. It is also a good idea to change the seal since you are right there, and inspect the yoke that the seal rides on for a groove, if it is badly grooved, you may want to change it. When assembling the unit back together, the torque on the spanner nut is 200 ft lbs, but the spanner wrench throws a kink into the torque wrench setting. If your using a standard 17 inch long 1/2 torque wrench, you want to set it at 117 ft lbs.

    Please let me know if you need more details. It would probably be helpful to get a manual.

    Tech Support

  3. #3
    Join Date
    Dec 2011
    Posts
    2

    Default

    Thank you. I feel better about this process now. I"ll give it a try.

  4. #4
    Join Date
    Nov 2012
    Location
    Bastrop County Tx
    Posts
    2

    Default Hey

    Quote Originally Posted by mrpavement View Post
    Thank you. I feel better about this process now. I"ll give it a try.
    I was wondering about you Chris Craft,,is it a Scorpion series???

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Sterndrive Engineering, Inc. (SEI) manufactures a stern drive designed to replace Mercury Marine's MerCruiserŽ Alpha OneŽ, R, MR, Gen II and Bravo OneŽ stern drives. MerCruiserŽ Alpha One, R, MR, Gen II and Bravo OneŽ are trademarks of the Brunswick Corporation. SEI has no affiliation with the Brunswick Corporation. Consequently, any warranties governing products and or sold by Brunswick Corporation will not apply to products manufactured and or sold by SEI, or to products damaged due to the operation of an SEI product.