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FIXED****HELP 14FF QUESTION*****FIXED*****

Discussion in 'The Garage' started by 87BrnRsd, Oct 23, 2003.

  1. 87BrnRsd

    87BrnRsd 1/2 ton status

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    Well, im going to pick up my truck in a few minutes. My friend, who I took my truck to, said that the rearend was fine. He said that my driveshaft (slip yolk 208) needs to be longer by 2 1/4 inches. Other than that, he said everything was fine. So, tomorrow, I am going to a truck store around here, and getting a new driveshaft made. Then I will be ready to go. /forums/images/graemlins/thumb.gif Thanks for all of your help guys. /forums/images/graemlins/thumb.gif
    -Harrison


    Alright, this is driving me crazy!!! I have a 14ff with 4.56 gears and a detroit locker in it. It is brand new (dont say take it back to where I bought it from, because I already tried that and they wont honor their warranty, so I have to fix it myself.) Anyways, I put the axle in last weekend, and filled it with 80-140w gear oil. I went for a testdrive only to find that it makes a horrible grinding noise from the differential after about 35mph, but only when I let off the gas. If I hit the gas, it sounds fine, but when I let off, it grinds.
    ---So, I took off the cover for an inspection. What I found was a magnet full of metal shavings and little metal balls. They look like the little round molten balls that you get on the floor after you weld, because if you squeeze them between your fingers, they crush into a million pieces. I inspected the ring gear, and it looked perfectly fine. So I re-filled it with new gear oil and put the cover back on thinking I would take it somewhere because I dont know much about rearends.
    ---Yesterday, I decided to take the pinion out to inspect the pinion bearings. I noticed that even after I only drove the truck 1 mile (just to hear the noise again), that 1.5 hours after I parked the truck, I got the pinion gear out, and the pinion bearings closest to the yolk, were still pretty hot. After I got the pinion out, and the bearings pressed off, I inspected them, and they looked fine to me. I took them to a gm rearend tech who works at a chevy dealership near my house, and he said they look fine to him too. He said the crush sleeve may not have been preloaded right. So I pressed the bearing back on, and set the preload right, and test drove it on jackstands. The noise was still there.
    ----So today, I decided to take the whole carrier out, ring gear and detroit and all. After I got it out, I inspected the ring gear once more, to find tha it was still fine. I also inspected the carrier bearings and they too looked fine. The races did not have any scars on them as well. I also noticed that the magnet had not collected any more metal shavings, even though I drove it the day before. So, I put that all back in, and set the backlash (I remembered exactly where the two round things on the side of the diff were, and turned them back exactly how they were.) I checked the backlash and it was fine, so I bolted everything up, and put the cover back on. I filled it with oil again, and test dorve it on the jackstands, and the noise is still there.
    ----I gave up, so I drove the truck maybe 200 feet into a field near the shop and parked it. I noticed that the gears didnt clunk or anything, so the backlash was set properly. I also noticed that the detroit was locking and unlocking properly as well. I think I am going to end up taking it to that gm rearend guys house, since I am friends with him, to see if he will fix it for me for cheap.
    ---The metal specs in the oil, and the hot pinion bearing indicate to me a bad pinion bearing. I think the reason it looked fine was because it has been driven maybe only 6 or 7 miles, and is not showing the wear yet. Whats is yall's opinions on this matter? It is really driving me crazy!!
    Thanks for looking,
    -Harrison
     
  2. Don

    Don 1/2 ton status

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    Re: HELP!! 14FF QUESTION!!!! KIND OF LONG THOUGH

    Wheel/Hub bearing's ok? Brake shoe's toast? Drum's toast?
    How about all the brake hardware? Is it churning around in one of the drum's?

    I had a 14 bolt 10 year's ago, made a hell of a racket, turn's out it was the retaining pin's for the shoe's had broke, letting the whole shebang, grind around in the drum.
     
  3. 87BrnRsd

    87BrnRsd 1/2 ton status

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    Re: HELP!! 14FF QUESTION!!!! KIND OF LONG THOUGH

    All are fine. The noise comes from the center of the rear diff. It also disappears when I unhook the rear driveshaft, teling me that its something in the diff. /forums/images/graemlins/thinking.gif
    -Harrison
     
  4. justhorsinaround

    justhorsinaround 3/4 ton status

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    Re: HELP!! 14FF QUESTION!!!! KIND OF LONG THOUGH

    I've been told many times that I'm an idiot so I don't feel bad in suggesting the u-joint. Maybe next time you have it off the ground maybe try turning the diff and feeling for grinding vibrations. Good luck to ya.

    Allan
     
  5. fortcollinsram

    fortcollinsram 1/2 ton status

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    Re: HELP!! 14FF QUESTION!!!! KIND OF LONG THOUGH

    Well you've done a great job trouble shooting it, IMO...Did you check the pinion support bearing at the snout of the pinion? Maybe try some marking compund and seeing if the pattern is spot on...Do the carrier bearings fit snugly in the housing? Just some thoughts!

    Chris
     
  6. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    Re: HELP!! 14FF QUESTION!!!! KIND OF LONG THOUGH

    Check your back lash again and tell us what it is. Not that it is just "ok/fine". If I remember correctly, spec for backlash on 14b ff gears is .006-.010. Check the pattern and take pictures to post here. Did you pull the pinion support housing out of the diff housing? Pull it out and spin the pinion in the support housing by hand on the bench. Does it "feel" ok? Do you feel any resistance? Did you crush the crush sleave to the correct spec? Spec is 20-35in/lbs. Finding the proper torque wrench to do this job correctly isn't easy. It takes something rediculous like 500ft-lbs of torque to crush a new crush sleeve. Also, once a crush sleeve is crushed, you can't re-use it. A new one is required each time you pull it apart.



    [ QUOTE ]
    The metal specs in the oil, and the hot pinion bearing indicate to me a bad pinion bearing

    [/ QUOTE ]

    That means that pinion bearing preload was too much- Crush sleeve crushed to far. Which leads to a bad pinion bearing of course.

    And like others have said, be sure that the pinion support bearing in the housing is in good shape. Sucks if it isn't, cause that little bastard is expensive. /forums/images/graemlins/eek.gif /forums/images/graemlins/thinking.gif
     
  7. supersize75

    supersize75 1/2 ton status

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    Re: HELP!! 14FF QUESTION!!!! KIND OF LONG THOUGH

    According to tort law, the manufacturer/vender, is required to make good with a consumer so long as the product is sold and purchased with the assumtion that it is in working order.

    A vender is defined as selling 5 or more a year.

    This is regaurdles of vender/company waranty, if you purchase a phone and it doesn't perform you can take it back even after their time period has exspired, as long as it didn't do what they promised/ or advertised.

    I have more info on this if you need it, tort law is very interesting and also unknown to alot of managers and venders.

    The fact that you took it apart is regaurdless too, your taking it apart didn't make the product stop working s the problem is still there...go fight your fight /forums/images/graemlins/thumb.gif /forums/images/graemlins/usaflag.gif
     
  8. burbBoy

    burbBoy 1/2 ton status

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    Re: HELP!! 14FF QUESTION!!!! KIND OF LONG THOUGH

    Here is an idea for ya. Pull the cover and with it drained run it on jack stands to make sure the noise is present and maybe get a better look at what is making the noise. Next pull the carrier out and run it again on the stands. If the noise is there you know its in the pinion bearing area and if not you can look into the carrier bearings and detroit. Hope this helps.
     
  9. tarussell

    tarussell 1/2 ton status

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    Re: HELP!! 14FF QUESTION!!!! KIND OF LONG THOUGH

    I agree with the earlier reply about what was the actual back lash . Post some pic's of the wwear pattern ( drive & coast ). What is the resistance of the pinion rotation ( how many inch pounds does it take to rotate it ) .
    Eventhough the bearings looked good to a mechanic they might not be in good shape ( I mean no disrespect to your buddy at GM ) a lot of technicians only think a bearing is bad when it is horrible condition. If in doubt take your bearings to a true industrial bearing supply house and talk to a knowledgeable person. It is my opinion that if your rear axle was filled with small metal pebbles than your bearings are toast - no matter what !
    It sucks that you have this problem but I don't think it will be fixed until you put "new" bearings in it .
    Good luck , Tom
     
  10. 87BrnRsd

    87BrnRsd 1/2 ton status

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    Re: HELP!! 14FF QUESTION!!!! KIND OF LONG THOUGH

    Thanks for all of your help guys! The backlash was .008". I was going to replace all of the bearings, but decided against it because I dont have the money to spend, if it turns out that it wasnt them and still had to buy something for it. I know its not the u-joints because I have already looked at those. I felt the pinion support bearing for resistance, and it seemed fine to me as well. I also re-used the crush sleeve. I was told by the rearend tech at the chevy dealership I always go to that you can re-use them. He has never given me wrong informatino yet. He said, at the dealership, they always re-use them. He just said torque it to about 140 pound feet, and it will be fine.
    --Oh, and supersize75, I would like some more informtaion on that tort law. Sounds like it may be what I need.!
    I dont know the possibility, but I have been told that it may be the driveshaft angle. It looks perfect at the 14ff yolk, and is not at any extreme angle there. It does however, look to be at quite an angle where the driveshaft goes into the transfer case. (slip yolk np208) I dont know the effect this would have on the differential, but could this be a possibility?
    --I am going to mees with it some more this week, but if I cant figure it out, I think I will take it to my rearend friend. He will do it at his house on the side for me and not charge much at all. He also needs to install my 4.56 gears in the front for me next weekend too.
    Thanks for the help yall, and I will check some of that stuff this week.
    -Harrison
     
  11. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    Re: HELP!! 14FF QUESTION!!!! KIND OF LONG THOUGH

    [ QUOTE ]
    I also re-used the crush sleeve. I was told by the rearend tech at the chevy dealership I always go to that you can re-use them. He has never given me wrong informatino yet. He said, at the dealership, they always re-use them. He just said torque it to about 140 pound feet, and it will be fine.


    [/ QUOTE ]

    That information is wrong. Period. You cannot reuse a crush sleeve. Well, you physically can, but you're not supposed too. And no where in the pinion set up process is a ft-lb torque wrench involved. (except support housing bolts.)There is no torque spec for a 14b at 140 ft-lbs. You need an in-lb tension/bar type that will read 20-35 in-lbs. If this guys dealership always reuses crush sleeves...remind me not to have any rear ends set up by those guys... /forums/images/graemlins/eek.gif
     
  12. 87BrnRsd

    87BrnRsd 1/2 ton status

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    Re: HELP!! 14FF QUESTION!!!! KIND OF LONG THOUGH

    [ QUOTE ]
    You cannot reuse a crush sleeve. Well, you physically can, but you're not supposed too.

    [/ QUOTE ]
    Looks like you just contradicted yourself. You cant but you can??
    Your not supposed to do a lot of things, but you can, and they can work just fine. If you knew the guy that I talked to, you would quickly change your opinion. He isnt one of those "well I know this guy who works on chevys" guys. He knows everything about every part on chevy trucks and has never been wrong. He told me that the myth aoubt not reusing crush sleeves, is just that, a myth. Not only has he told me this, but so did 2 other people at that dealership, 1 at another, and about 5 people on here. Its just like the myth about oil. You know, when its black, its old and needs to be changed. Black oil only means that it is doing its job, and is still lubricating just fine.
    -Harrison
    P.S. Im not trying to make anyone mad here, but I have known this guy for a long time, and have no reason to believe that he is telling me something that is not true. He has yet to steer me wrong in an direction about my truck, even when many other people have told me differently.
     
  13. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    Re: HELP!! 14FF QUESTION!!!! KIND OF LONG THOUGH

    Do you know the idea behind what a crush sleeve does? The idea is a black and white idea, no grey area, or room for debate. It's sorta like a one time use shock absorber to set the preload on the pinion bearings. I assume you know the definition of pre-load. As you tighten the pinion nut onto the crush sleeve it crushs at a controlled rate until the deired preload is reached. After it's crused, it stays like that. It doesn't "spring back" to it's original shape when you remove the pinion nut. Also, even with used bearings that don't need a "break in" period, the pre-load isn't gonna stay the same as it does when you initially set it. Take it for a drive down the road after setting the pre-load, come home and check it again. The preload will be less. This is from bearings/races etc "seating". The crush sleeve doesn't change after it is crushed. So if you use it again, it has already been used to the proper spec. Crushing it further will just over tighten and over pre-load your pinion bearings. That obviously will cause heat, which as you hopefully already know, is a bearing killer.

    I would change my mind if I met your friend? I certainly would not. I don't care what dealership he works for, or how long he's worked there, or how long he's been working on differentials. One big reason is this..

    [ QUOTE ]
    He just said torque it to about 140 pound feet, and it will be fine.


    [/ QUOTE ]

    Ask him where the hell he came up with that number. There is no bolt on a 14b ff, or any GM differential for that matter, that calls for 140 ft-lbs. About 140? I have no faith in a mechanic who thinks any nut or bolt, especially one in something as important as a differential, can be torqued to "about" anything.

    I understand the idea about myths, but this isn't one of them. Another thing, so going along with your myth, It's ok to not change your oil once it gets black? /forums/images/graemlins/thinking.gif /forums/images/graemlins/eek.gif
     
  14. thatK30guy

    thatK30guy 1 ton status Premium Member

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    Re: HELP!! 14FF QUESTION!!!! KIND OF LONG THOUGH

    [ QUOTE ]
    Ask him where the hell he came up with that number. There is no bolt on a 14b ff, or any GM differential for that matter, that calls for 140 ft-lbs. About 140? I have no faith in a mechanic who thinks any nut or bolt, especially one in something as important as a differential, can be torqued to "about" anything.

    [/ QUOTE ]

    I stand by that explaination, too. When I hear a "mechanic" say "about" especially the "140 ft. lbs." on a 14FF, simply turn around and walk away. Wait! No, RUN AWAY!!! /forums/images/graemlins/ignore.gif

    Gotta side with Joe on this one. Everything he is saying holds true to the 14FF. The crush sleeve and torque are measured by inch lbs. of rolling torque. No big ft. lbs. torque wrenches here at all. /forums/images/graemlins/ignore.gif
     
  15. tarussell

    tarussell 1/2 ton status

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    Re: HELP!! 14FF QUESTION!!!! KIND OF LONG THOUGH

    I am with Kidjethro and Wess on this crush sleeve deal . It is designed to create pre-load and should be a ONE TIME use .There is a difference in getting away with reusing something and doing it the correct way .
    Think about all that debree(sp) that was in your diff. all of that was in and around your bearings too. Please do yourself a favor and install ALL new bearings in your rear axle.
    Good luck , Tom
     
  16. 87BrnRsd

    87BrnRsd 1/2 ton status

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    Re: HELP!! 14FF QUESTION!!!! KIND OF LONG THOUGH

    Well, I know that I could probably mess with it some more, and end up getting it right eventually, but I dont have the time or the money right now to keep messing with it. I know another person, who just got back from service in Iraq as the rearend specialist there, who has told me that he can check it our for me next weekend too. He has new bearings and new crush sleeves, and just about every other axle part at his house, so he can diagnose it and fix it right there. I am going to be taking it to him next weekend, so I will update this post after he is done with it, and I will tell you what he found.
    --I have realized though, that through all of this, I NEED to get this company to pay for more than they are willing to now. I have gotten them to pay for parts, but they wont pay for labor. Im not worried about what is wrong anymore, because I am through messing with it, I know it will be fixed the right way next weekend. Do any of yall have any good suggestions on how to make this company realize that they need to fix this? Thanks yall.
    -Harrison
     
  17. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: HELP!! 14FF QUESTION!!!! KIND OF LONG THOUGH

    If you have the capability to take it apart, I'd go to the junkyard and pick up some used parts. I bet they'd be better than the crap that you've got now.

    I agree on the crush sleeve thing. Reusing a crush sleeve is a bad idea. Buying a new one is a pain in the ass though unless you've got a good torque wrench.
     
  18. 87BrnRsd

    87BrnRsd 1/2 ton status

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    Re: HELP!! 14FF QUESTION!!!! KIND OF LONG THOUGH

    Thats exactly why im letting someone else do it this time. I have done every bit of work on my truck so far, but im fed up with the little stuff like this. I will let him deal with it.
    -Harrison
     
  19. 87BrnRsd

    87BrnRsd 1/2 ton status

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    Re: HELP!! 14FF QUESTION!!!! KIND OF LONG THOUGH

    I talked to the rearend guy who told me the first time that it was ok to re-use the crush sleeve. He told me that he did not mean to say that its perfectly ok to do so every time. He told me that from what I had described to him, he thought that the crush sleeve had not been crushed enough, causing the front and rear pinion bearings to sort of "wobble" back and forth when they werent under torque, which in turn made them heat up. He said that he just wanted me to check the pinion bearings, and then tighten the pinion nut down to somewhere between 125-150 ft/lbs, which should set the preload on the crush sleeve close to what it needs to be (because he knew that I did not have a torque o meter or anything like that). He just wanted me to check to see if that made any difference on the noise, knowing that regardless of if it did or didnt, I would need to buy new bearings and a new crush sleeve. So that should solve that whole ordeal.
    P.S. When I put the ring gear back in, I am not 100% sure that I got the pinion and ring gear meshing perfectly. I know it is somewhere close and could be exact, but am not sure. Would it hurt to drive it with the gears not 100% correct for maybe 30 miles, if I disconnected the rear driveshaft and used front wheel drive, to eliminate torque to the rearend? I am not sure if just the turning of the tires through the axleshafts is enough torque to mess them up. Thanks.
    -Harrison
     
  20. MTBLAZER89

    MTBLAZER89 3/4 ton status GMOTM Winner

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    Re: HELP!! 14FF QUESTION!!!! KIND OF LONG THOUGH

    [ QUOTE ]
    He said that he just wanted me to check the pinion bearings, and then tighten the pinion nut down to somewhere between 125-150 ft/lbs, which should set the preload on the crush sleeve close to what it needs to be (because he knew that I did not have a torque o meter or anything like that).

    [/ QUOTE ]

    IIRC pinion preload should be 25-35 inlbs. Thightening the pinion nut until it takes above specified torque to rotate the pinion only (carrier removed). I guess if you were just troubleshooting tighten the nut until it takes about 2 ftlbs to turn the pinion. Tightening the nut to a specified torque is useless It can take up too 500 ftlbs to crush the sleeve /forums/images/graemlins/eek.gif Good Luck
     

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