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transfer case clunk

Discussion in 'Chevy Trucks' started by snowjoker, Apr 29, 2003.

  1. snowjoker

    snowjoker Senior Member
    Messages: 283

    My truck clunks when i put it into gear,sounds like a bad u-joint,but they are good. The truck is a 93 chevy 2500 w/ the 4L80E tranny. Could it be the chain in the transfer case that has stretched some? any help woud be appreciated Thanks Walt
     
  2. Chuck Smith

    Chuck Smith 2000 Club Member
    from NJ
    Messages: 2,317

    I had that same clunk you are describing on m 80 GMC. That truck has a TH 350 and NP 205 (gear driven) transfer case. The way I found the problem was my truck started smoking at highway speed, I mean bad. Drove straight to my buddy's shop when it happened. We found the transfer case overfull, and the trans low on fluid.

    There is a sleeve that connects the transmission output shaft, to the transfer case input shaft. When we dropped the T case we found that the sleeve was shredded. The splines were almost completely gone. Luckily the shafts were fine. The sleeve was about $125.

    If you want to "check" you chain, and replace it, it's easier with the transfer case out. If you want to check the coupling sleeve I am talking about above, you need to drop the t case.

    I think to find your problem I would begin by checking the sleeve. You t case is aluminum, and much easier to remove than a NP 203 or NP 205 cast iron case.

    ~Chuck
     
  3. snowjoker

    snowjoker Senior Member
    Messages: 283

    Chuck, the rear driveshaft has some play in it .It does it in both forward and reverse.I has done it since i have owned it (3 years) it sounds like i have another summer project on my hands now:( The tranny fluid is ok.I am also glad it is not that NP205 transfer case i know how fun they are to work with.
     
  4. TomatoRedGMC

    TomatoRedGMC Member
    Messages: 39

    I have the same clunk in my 81 K2500. it also humms going down the road a little, and my crossmember bolts keep comming loose, even with loctite. any ideas?
     
  5. wyldman

    wyldman Member
    Messages: 3,265

    TomatoRedGMC - yours sounds like a bad u-joint.That would cause your clunk,and cause a vibration as well.The vibration is also what is causing your bolts to back out,and come loose.

    snojoker - when you say the driveshaft has play in it,where exactly is this play ? Up and down,side to side,while turning it ? Some other things to check would be the differential backlash,loose or broken leaf springs.Loose u-bolts,etc,etc
     
  6. snowjoker

    snowjoker Senior Member
    Messages: 283

    Wyldman the play is when you turn it.There is about an inch or so play when you turn it. All the springs are good and the u-jounts are tight, how do i check the diff backlash?
     
  7. wyldman

    wyldman Member
    Messages: 3,265

    Well,an inch of play is pretty close to normal.

    The diff backlash involves dropping the cover and using a dial indicator on one of the ring gear teeth.Rotate the ring gear back and forth,and read the dial indicator.

    .008-.015 thou is prefferd.
     
  8. snowjoker

    snowjoker Senior Member
    Messages: 283

    Thanks for the info Chris I will hafto check that out when i get time Walt
     
  9. Arc Burn

    Arc Burn PlowSite.com Addict
    Messages: 1,139

    Chris,in one evening you have answered about every automotive question we have had here for a week!I still say you da man:salute:
     
  10. Chuck Smith

    Chuck Smith 2000 Club Member
    from NJ
    Messages: 2,317

    Walt, mine was clunking for 3 years before I shredded it. All my U joints were good, the splines on the t case output shaft were good. I too had about an inch of play. I ASSumed it was just worn parts (20 year old truck, t case and rear end, 130,000+ miles). I just had the front driveshaft rebuilt, and did the rear u joints. About 2 weeks later, the sleeve went. I guess I took up all the slack in the driveline (or some of it) and the sleeve was the next weakest link...

    ~Chuck
     
  11. snowjoker

    snowjoker Senior Member
    Messages: 283

    Thanks Chuck i guess i better check that out then,The transfer case shouldent be too bad to take out.I know it wont be as bad as my 84 with the cast iron t-c under it Thanks again for all the reply's Walt
     
  12. TomatoRedGMC

    TomatoRedGMC Member
    Messages: 39

    Well, thanks......I'm definatly not at knowledgable as you guys, but trying to learn. Last night I changed the Crossmember bolts with grade 7 hardened bolts. the u-joints are good, there is no play in the shaft. This truck came straight out of a junyard, it was a yard truck, so some of the parts are not OEM. heck the front shaft i found out is off a 86 RamCharger!!
     
  13. wyldman

    wyldman Member
    Messages: 3,265

    TomatoRedGMC - if the u-joints are good,then you may have a driveshaft balance or alignment problem.Check the alignment and pinion angle first,as it's easy.The angle of the tc output yoke,and the diff input yoke must be the same.If they are off,you will get a vibration.You can use any cheap angle meter to check them right on the truck (sitting on the ground,suspension compressed).

    You can remove the shaft and have it professionally balanced,or you can do it yourself,with hose clamps,to see if it helps.Find a factory service manual (for any car or truck),they usually have detailed instructions on how to do an on-vehicle driveshaft balance.

    Also double check your slip yokes (if equipped),if they get sloppy,it will also induce a vibration.If it has slipo yokes,double check that the end yokes are in phase,or lined up with one another.If they aren't you will have to slide the slip yoke apart and line them up.This will vibrate pretty bad if out of phase.


    snowjoker - I don't believe your transfer case has that sleeve Chuck is reffering to.It was only used on the older 203 and 205 cases.The newer units,it's all part of the input shaft for the transfer case,and rarely goes bad.

    I would block the truck,and have someone shift it fron drive to reverse and back,and get underneath,and follow the clunk.It's very common to see the leaf springs slapping,or the rear diff clunking.At least you will have a better idea of exactly where it is coming from.
     
  14. snowjoker

    snowjoker Senior Member
    Messages: 283

    Ok Chris, I am very thankful for all the info, I have a neighbor that is a certified gm mechanic,but dont like to bother him about my prolbems,unless i cant figure it out.I will have someone help me to try and diagnoss this issue. One more question about my driver side window, the track on the bottom has rotted out and needs to be replaced, do you know how to remove this with out breaking the window? I am glad that there are so many good people on this web site to answer all of our prolbems :salute:
     
  15. TomatoRedGMC

    TomatoRedGMC Member
    Messages: 39

    thanks guys! I agree with snowjoker....there are so many really cool people here, I'm glad i found this site. I'll check out the shaft and yokes here soon. I'll keep watching and try to help out when i can. thanks again everybody.
     
  16. wyldman

    wyldman Member
    Messages: 3,265

    That piece is part of the window itself,and you have to buy a complete window to get it.They are cheap from GM (less than a hundred bucks),and even cheaper aftermarket.

    The window glass isn't to hard to change,you could probably do it yourself.Or,most auto glass shopd should be able to do it for less than an hours labour.
     
  17. TomatoRedGMC

    TomatoRedGMC Member
    Messages: 39

    Well, thought I'd let everyone know the driveshaft was out of balance.....stuck a hose clamp on per my uncles instructions and the vibration is gone......very cool. now, does anybody know where to get a 350 4-bolt? trying to find one around here is like trying to find a piece of gold at the bottom of the ocean!:waving:
     
  18. wyldman

    wyldman Member
    Messages: 3,265

    Good 350 4 bolts are getting hard to find.I have 5 or 6 stashed away,but I am keeping them for my own projects.Try some wrecking yards,sometimes they have them sitting around,or still in an older vehicle,and they don't even know it.