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Thread: driveline U-joints question

  1. #1
    Join Date
    Aug 2015
    Location
    Portlandia, Oregon USA
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    202

    Default driveline U-joints question

    I found that the front and rear driveline u-joints are a little different.
    They have the same bearing cap diameters and the distance across the caps from side-to-side is also the same, but the width of the bearing caps are different: The front driveline cap is narrower on the right in this pic and and rear is wider, left. Looks like its easy to match the rear ones exactly with the modern ones from Spicer, but the smaller front ones are harder to find.

    Anyway, I'd like to use all the same U-joints on the truck so my question is if its okay to replace them all with the wider U-joint used in the rear like the Spicer 5-153x? Any problems with that plan?

    Thanks,
    Bryce



  2. #2

    Default

    every u-joint I,ve ever seen in a 715 is a 1310 or 369 joint.

  3. #3
    Join Date
    Sep 2014
    Location
    Wichita Falls, TX
    Posts
    603

    Default

    I've used the Precision joints with the 369 # from O'Reilly's and they were too big, but don't remember which shaft that was on. (was doing a bunch at once)

    But I've also gotten the Duracheapo brand from Autozone for Gladiator application, same part # front and rear, and they worked in both shafts with no slop.

  4. #4

    Default

    I,ve put a lot of 369,s in and zero problems.

  5. #5
    Join Date
    Sep 1998
    Location
    North Central Wisconsin
    Posts
    11,520

    Default

    This has been documented in the past...some of the early trucks did have a different u-joint setup...the use of of all the same u-joints was, for no known reason, not standardized until somewhere in the middle of 1967...I dont have a part number for the odd ones unfortunately.

    That being said, what is your trucks VIN number and/or date of delivery...with that I can give a good estimate if yours might be affected by this...if not, then I would think that the ujoint or ujoints was/were replaced before and one of them was not a match for the stock part...thus allowing you to now return to the factory setup of all being the same!

    From what I remember...this os over a decade ago when we have a couple show up with the issue...all 3 sets of u joints were different...the ones on the tcase stub shaft from the trans being the largest, the ones in the tcase to rear axle being medium sized and the ones in the front axle to tcase shaft being the smallest...and by enough that it wasnt as close as what you are showing in your pics...
    Lord send your Holy Ghost into our hearts and make the desire of our hearts Your Will.

    Pro-choice, that's a LIE, babies don't choose to die!!

  6. #6
    Join Date
    Aug 2015
    Location
    Portlandia, Oregon USA
    Posts
    202

    Default My 725 u-joints

    Thanks Jon. Great history on this question.
    My VIN # 12045

  7. #7
    Join Date
    Sep 1998
    Location
    North Central Wisconsin
    Posts
    11,520

    Default

    Yours is early enough to be one of those...unfortunately...

    Are all 3 different sizes? If so, it is one of the odd early ones...if not, then I would still think it was a replacement that wasnt exact to the original...
    Lord send your Holy Ghost into our hearts and make the desire of our hearts Your Will.

    Pro-choice, that's a LIE, babies don't choose to die!!

  8. #8

    Default

    The important dimensions are the cup diameter and the overall width of the joint with the cups installed.

    The rest of the dimensions will vary depending on manufacturer and design. It's always a balancing act between ultimate strength and bearing life. For example the joints with the shorter needle bearings probably have shorter bearing life but they will probably be able to withstand higher torques before breaking.

  9. #9
    Join Date
    Aug 2015
    Location
    Portlandia, Oregon USA
    Posts
    202

    Default

    Quote Originally Posted by MrNeutron View Post
    The important dimensions are the cup diameter and the overall width of the joint with the cups installed.

    The rest of the dimensions will vary depending on manufacturer and design. It's always a balancing act between ultimate strength and bearing life. For example the joints with the shorter needle bearings probably have shorter bearing life but they will probably be able to withstand higher torques before breaking.
    Yes, that helps and it looks like the yokes are all the same and I should be able to use the same u-joint across all three shafts now.
    Tho . . . I was thinking that the longer needle bearings would last longer AND take more torque because it's spread over a larger bearing surface? Right?
    Bryce

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