1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Third member issues...Save my Axle!

Discussion in '40- & 55-Series Tech' started by jhaha, Feb 21, 2007.

  1. jhaha

    jhaha

    Messages:
    322
    Likes Received:
    0
    Joined:
    Sep 14, 2003
    Location:
    Yorktown, Va
    Alright folks,

    I have symptoms the same as Herb here: <https://forum.ih8mud.com/showthread.php?t=138449>

    A clunking and obvious "rubbing/grinding" sound, but only sometimes. Other times it is quiet and no problem. So I took off the driveshaft and everything up to and including the speedo housing to inspect for anything wrong. Also to install my mudrak housing. (which work AMAZING by the way) Nothing there.

    So then I took off the diff cover and found not to much(first picture). No metal fragments, no unusual wear anywhere. However, some slight wear is noticed in the second and third pictures, on the most central piece (don't know it's correct name) in the same place where Herb had a nice wear pattern. In addition, the stake nut on the flange where the driveshaft bolts looks to be ok, and doesn't look like it has moved or loosened up. (fourth picture)

    Additional info - I did have to swap the flanges when i put a 4 speed tranny/transfer in, so the nut came off, flange swap, nut back on, but nothing was moved or opened up. Also did a rear disc swap, so axle shafts out and back in, no issues there. Lastly, I have been driving this thing for about 300 miles with no problems following my frame off build, then this noise and such started.

    So....

    1) Do i need a new third?
    2) If not, what actually is wrong and how do I fix this? (vague, but you all are pros)
    3) This axle (from a 73' 40) has 3.73 gears, right?

    On a lighter note, please give me a reason to pull the third so I can spring-over it! (not really)

    Thank you all in advance!
     
    Last edited: May 9, 2007
  2. jhaha

    jhaha

    Messages:
    322
    Likes Received:
    0
    Joined:
    Sep 14, 2003
    Location:
    Yorktown, Va
    Fourth Picture:
     
    Last edited: May 9, 2007
  3. John Smith

    John Smith In the garage

    Messages:
    4,172
    Media:
    6
    Albums:
    2
    Likes Received:
    207
    Joined:
    Jun 7, 2004
    Location:
    Maryland
    What value did you torque the pinion nut to when you installed the new flange? It is hard to tell from your last picture but it does not appear the nut is staked real well.

    You have 4:10 gears unless you swapped in some 79 or later FJ40 3rds.
     
  4. jhaha

    jhaha

    Messages:
    322
    Likes Received:
    0
    Joined:
    Sep 14, 2003
    Location:
    Yorktown, Va
    John, the best idea I can give you for a value is "tight." I know that doesn't really help, but yea. And I also know that is a bad answer, and one derived from ignorance on my part at that time.

    So can I just torque the nut to the proper torque?
    (145-173 ft/lbs from Charlie's article in the tech links?)
     
  5. Herb

    Herb

    Messages:
    628
    Likes Received:
    15
    Joined:
    Dec 16, 2005
    Location:
    Virginia
    Yep, you've got the same marks on your carrier that I have. Either my pinion came loose and got sucked into the gears, or my bearing fell apart and got sucked into the gears. (I haven't dug into it far enough to tell yet).

    It seems to me that one of these issues is your current issue as well.
     
  6. Poser

    Poser Oh...Durka Durka Durka. s-Moderator Supporting Vendor

    Messages:
    20,223
    Media:
    17
    Albums:
    1
    Likes Received:
    492
    Joined:
    Oct 1, 2003
    Location:
    MN
    That is junk.





    Locate a 4.11 third member, pre-1979 US 40 series all had 4.11's from the factory, preferably from a front axle as it should have far fewer miles on it compared to the rear, as long as it was in a truck that had lock outs and they were unlocked most of the time, swap out the center sections, and call it good.
     
  7. John Smith

    John Smith In the garage

    Messages:
    4,172
    Media:
    6
    Albums:
    2
    Likes Received:
    207
    Joined:
    Jun 7, 2004
    Location:
    Maryland
    Poser, what do you see in his pictures that make you believe his diff is toast? I can see what appears to be a pinion pattern on the carrier (may be reflection) but if there are no broken teeth on the R&P gears could he not torque the pinion nut to the proper setting and the pattern would return to normal?

    Edit, Is it the ring gear teeth? They look a little funky now that I study the picture closer. So... Improper pinion nut toque and the pattern gets out of whack and wears down R&P so they won't mesh into a proper pattern again?
     
    Last edited: Feb 21, 2007
  8. nuclearlemon

    nuclearlemon not an addict Moderator

    Messages:
    15,947
    Media:
    87
    Albums:
    4
    Likes Received:
    751
    Joined:
    Jan 30, 2003
    Location:
    meh-ico, colorado
    not if it's the stock gearing. it's 4.11s. in the third pic, is there a chunk out at the 7 oclock location? can't tell from teh pic. wear pattern does look too low, but not horribly low. how loud is the noise?
     
  9. Poser

    Poser Oh...Durka Durka Durka. s-Moderator Supporting Vendor

    Messages:
    20,223
    Media:
    17
    Albums:
    1
    Likes Received:
    492
    Joined:
    Oct 1, 2003
    Location:
    MN
    You can see where the pinion has contacted the ring gear carrier many times. Are you going to simply tighten the pinion nut back up, and run it in your junk? I sure as hell would not. Do you know that the pinion teeth are not damaged or cracked?

    I have seen what this does to the pinion teeth, and typically it damages (cracks along the root or the tooth, or chips in the tooth section) them beyond what I would consider reusable.

    A complete center section can be had for under 150.00, many times, a lot cheaper than that…


    I would not put my name on a ‘tighten the pinion nut and run it’ repair, or even suggest that; Only to get your butt home, and then fix it properly by replacing the worn/damaged components.


    I am not going to sit out here and say run that, only to have it leave him walking someday, and have him or someone he knows come back out here and tell me how wrong I was to even think of suggesting something so stupid.


    Again,

    The proper repair is not that fing expensive.

    Do it correctly the first time, and be done with it.


    :beer:
     
  10. John Smith

    John Smith In the garage

    Messages:
    4,172
    Media:
    6
    Albums:
    2
    Likes Received:
    207
    Joined:
    Jun 7, 2004
    Location:
    Maryland
    I did not even think about the shockload on the ring and pinion and stress cracks. Good Point. I agree that a retorque on the pinion nut would be a half assed get you home trail fix and the R&P would stand a much greater chance of failure. And you are correct, I would not run it in my truck except to get home.

    jhaha, now is the time to buy a locker if you want one.
     
  11. jhaha

    jhaha

    Messages:
    322
    Likes Received:
    0
    Joined:
    Sep 14, 2003
    Location:
    Yorktown, Va
    First off, thank you all for your comments, I will be putting in a new third.

    A couple of things though...

    John, even if I were to go with a locker, isn't ring teeth strength what is an issue here? Not trying to make you look dumb or anything of the sort, just is there something I am not understanding about what a locker typically is and that is does not deal specifically with with ring and pinion?

    Also, suppose the flanges on my "new" third need to be changed, what would I need to do? Could I then take off the nut, swap the flanges and MAKE SURE that time that I set the nut to the proper torque? Or in loosening the nut am I compromising the setup of the pinion and need to do something else to ensure that this does not happen again?

    As an ending note and something that doesn't also have to really deal specifically with this thread; although any advice I get on here is far more informed than any opinion of myown, I would never think to take the advice of a mud member, try something that doesn't end up working, and come back and blame the person that told me to do it. I think that would be slightly immature and irresponsible. However, I do understand your feelings on this issue. Poser especally.

    Thanks again
     
  12. John Smith

    John Smith In the garage

    Messages:
    4,172
    Media:
    6
    Albums:
    2
    Likes Received:
    207
    Joined:
    Jun 7, 2004
    Location:
    Maryland
    The stock ring and pinion are very strong. You should have no worries about running a locker and damaging the ring and pinion. The stock thirds use a solid spacer instead of a crush sleeve so as long as you retorque the pinion nut to the proper spec the gear pattern will stay the same. If you want to install a lunchbox style autolocker (replaces side gears and spider gears only) it is very easy, an ARB or Detroit that replaces the carrier will require setting up the gears and is much more complex.

    If you can find a fine spline 3rd member from a 78 FJ40 you can run a nifty aftermarket flange that is drilled with all of the different Toyota driveshaft patterns and the fine spline pinion is stonger than the coarse.
     
    Last edited: Feb 21, 2007