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Thoughts on single piece driveline on extended cab...

Discussion in '6.9L IH & 7.3L IDI Diesels' started by laserjock, Jun 25, 2019.

  1. laserjock

    laserjock Almost there... Supporting Member

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    So as I thought I was about to wrap rally prep on the truck tonight I found something troubling.

    IMG_7211.jpg

    IMG_7212.jpg

    IMG_7213.jpg

    So here’s the deal. The drive shaft is pulled backward stretching the carrier bearing instead of slipping at the slip yoke. It’s a brand new slip yoke but I had a hell of a time putting it together. The driveline shop that shortened and balanced this thing told me someone had stripped the blue coating off the splines and it needed replaced. Granted there was no coating on the splines but it felt rock solid. They wouldn’t cut and balance without doing it so I let them. They just replaced the male end. This was an aftermarket shaft I bought off a guy local so I don’t know if it actually was supposed to be coated or not. It will not slip. I beat it apart with a BFH far enough to bring it to length but I’m essentially running a 1 piece because it won’t slip. I can try to press it apart and hope the carrier bearing is okay (or replace it) or I can use this as an opportunity to upgrade.

    Hence the title. It seems like I’ve seen longer wheel base pulling trucks use single piece shafts. Does anyone know the “accepted length limit” on a 1 piece? I’d have to measure to see what it needs to be. I don’t remember anymore.
     
  2. chillman88

    chillman88 Supporting Member Supporting Member

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    I don't know what the limits is but I know it depends on "rotating mass" and I've been told you can use a longer aluminum shaft than steel due to the weight difference.

    Might try calling Dennys Driveshaft in Buffalo, NY. I've heard good things about them and they should at least be able to give some insight.

    Personally I'd take it back where you got it and tell them some choice words, possibly escalating to leaving the driveshaft in an unpleasant place with the owner if they are too disagreeable LOL
     
  3. The_Josh_Bear

    The_Josh_Bear Full Access Member

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    I'm no driveline expert but my slip joint was all rusted up years ago, so bad I needed ratchet straps, hammers, and penetrating oil to get it apart.
    Long story short it wouldn't slide in and out, and I was not financially able to swing replacement. I used sand paper and a lot of elbow grease to strip down the male end and I lubed it with moly grease, been fine ever since. I have re-greased a few times since but it's always fine.

    As for the long single it also depends on how much torque you're putting down. Best find an expert on that one... sounds expensive though.
     
  4. subway

    subway be nice to the admin :D

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    from what i remember most places wont make a shaft longer than about 70" to 72". to make a shaft longer it needs to start getting larger in diameter to stay stable. then the larger in diameter you get the more swinging weight and harder to fit and work with everything is. that is what i read anyway.

    2 smaller shafts of the same size are more robust and stable than one long shaft the same diameter.

    i am no expert but every other drive shaft i have messed with the slip yoke on the transmission or shaft itself moved. it should be snug but movable by hand.
     
  5. catbird7

    catbird7 Full Access Member

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    The info folks are providing here sounds accurate. I checked out pricing on single driveshaft several years ago and ironically I think it was Denny's. Don't recall exact price or size however wanna say $700.00 and 6" diameter. Also agree with "josh bear", I'd consider removing and hit the slip area with a wire wheel on a hand held angle grinder, then grease the crap out of it.
     
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  6. laserjock

    laserjock Almost there... Supporting Member

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    This is the road we are going down. Wish me luck.
     
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  7. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    I think this may be the real key to longevity here. I give mine a couple of shots of grease every time I grease the rest of the truck. I figure that the fitting's there for a reason.
     
  8. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    Lots of driveshafts don’t have the grease zurt there, if yours doesn’t I would drill and tap it for one while it’s out. Lots of high power diesels running single piece driveshafts with longer wheelbases than what you have, driveshaft angle is your main concern. For me, a single piece has half as many failure points to worry about so I’m a big fan of them.
     
  9. laserjock

    laserjock Almost there... Supporting Member

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    So this is what it took to separate it.

    IMG_7215.jpg

    It’s ratchet strapped between the post and the truck. Then I put tension on it and had to BEAT IT apart with a BFH. Yeah, so much for slip joint.

    This is what it looked like coming out.
    IMG_7217.jpg

    Then I cleaned it up.

    IMG_7219.jpg
    IMG_7220.jpg

    I don’t know how I missed this when I put it together. I guess I was in too big a hurry. Anyway, bottom line is this isn’t working. Coating is all chewed up. Screw it.

    IMG_7222.jpg

    Yes. I know. You aren’t supposed to do this.

    Based on the back story on this piece I don’t think the original spline shaft was supposed to be coated. Anyway, long story short, it was no good the way it was. If it causes a vibration now I’ll do something about it. But I’d rather have a little vibration than have it wipe out the carrier bearing and transfer case slip yoke going down I-81 because the driveshaft keeps shrinking in length.
     
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  10. tjsea

    tjsea Full Access Member

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    If you need a driveshaft let me know. If we don't have what you need our local Ford junkyard has 5 school busses of drive shafts in various lengths.

    Sent from my SAMSUNG-SM-G890A using Tapatalk
     
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  11. laserjock

    laserjock Almost there... Supporting Member

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    Thanks man! I had a hard time finding one before. Wish I would have thought of you guys.
     
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  12. tjsea

    tjsea Full Access Member

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    The only downfall is he doesn't have them marked well so you need to know the lengths and then start measuring. I actually may still have the drive shafts Jason gave me from his extended cab. I was going to put them on my truck when I swapped in the BW1356, but after breaking my BW1345 last year I'm going a different route with custom shafts or at the very least shafts from a newer psd truck.

    Sent from my SAMSUNG-SM-G890A using Tapatalk
     
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  13. subway

    subway be nice to the admin :D

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    Chris and Alex have been a God sent for helping with truck parts! I try not to bug them to much lol but they have helped me a bunch of times!
     
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  14. tjsea

    tjsea Full Access Member

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    Well I mean that is the point of this forum and being friends, right? Haha! Gotta help each other out when we can.

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  15. david85

    david85 Full Access Member

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    I did the dual to single piece drive shaft conversion on a ranger extended cab once. In that case it was an easy swap because later rangers went to single piece shaft anyway. The flange coupling on both ends made it an easy swap.

    My F250 has developed a bit of a vibration in the last year so I might have to do something about it in the future.
     

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