18 speed trans issue a lot of play in the output shaft

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Prohemi500, Apr 5, 2019.

  1. Prohemi500

    Prohemi500 Bobtail Member

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    So I bought a 18 spd Eaton out of a 09 peterbilt. Truck had 900k miles and the trans had no problems. I had a buddy rebuild the transmission replacing the top gear set and all other wear items. (He also rebuilt my 10 spd and it has worked flawlessly). Here's the issue- I just got the trans bolted up and I'm finishing up the job with the yolk and driveshaft install. I tighten the yolk on the the output shaft and I have a lot of up and down and side to side play in the output shaft, a full 360 degree worth of it and the nut is tight! Now there is very little or no in and out movement of the yolk (shaft) but probably 1/2-3/4 inch up and down at the U joint. The yolk, nut, and sensor ring are all correct, the nut is not bottomed out on the shaft, so I am figuring the is a problem with the shaft somewhere inside the rear box.. maybe a spacer or something that's been left out?? I have no idea. I forgot to look at the trans tag at my shop before posting this, so forgive me that I don't have the model number of the trans at the moment. Any ideas are greatly appreciated.
     
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  3. joey8686

    joey8686 Light Load Member

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    Jul 1, 2014
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    Washer behind the yoke nut,maybe need a thicker one ? Might be able to shim it somehow to take up slack, I had a diff that had play in it like that n mechanic said was normal so I ran it like that for hundreds of thousands of miles n no troubles haha
     
  4. Tombstone69

    Tombstone69 Road Train Member

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    Is the yolk moving on the shaft or is the shaft moving up and down. If it's the shaft it could possibly be a bad bearing in the main box, not the auxiliary box.
     
  5. Tombstone69

    Tombstone69 Road Train Member

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    Just Google18speed Eaton repair manual, download the pdf and it will tell you everything you need to know.
     
  6. speedyk

    speedyk Road Train Member

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    Yolks are pretty soft. Try a yoke and see if it tightens up. :^)

    What does the rebuilder say about it? I'm hoping you'll follow up on what you find.
     
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