Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

FRIKKEN RING GEAR BOLTS AGAIN... HELP !!!!!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Thumper, Mar 25, 2002.

  1. Thumper

    Thumper 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    1,582
    Likes Received:
    0
    Location:
    Alberta Canada
    Well, had a trail run this past Sunday, so Saturday did my usual end to end on the truck. This check was different cause I wanted to take a peek into my rear diff to see if things were holding together since the last escapade with the bolts. Much to my dismay, they were loose again, and one had busted off, and took a small chunk out of my pinion gear. !@#$%^%^^&&
    OK.... for some history. It all started 3 yrs ago. I bought a set of diffs from a guy (with reciepts) that were rebuilt by a reputable shop in BC with 4:56 gears, and a rear Trutrac. I bolted them in. Worked great for about 1 1/2yrs. Then, one day on my way home from work, a loud crunch and an oil leak from the rear pumpkin. Inspection showed that ALL of the ring gear bolts were loose, and one had backed all the way out and got caught in the tooth of the ring gear and punched thru the cover. I repaired the cover, closely inspected the entire diff, and finding no damage reinstalled the remaining bolts (with red locktite) and torqued them.
    Time warp ahead 6 months.
    We are on a trail ride far from home. Driving down a tame part of the trail, the truck behind me calls on the CB and says I am leaking oil. We stop, and find that a bolt had punched thru the cover again. This time, it damaged the ring gear taking off about 1/2 of one tooth. ALL of the remaining ring gear bolts are loose again. So, I do a trail repair on the cover, and tighten all the bolts in again with a wrench, fill it with oil and carry on very gently. I get home, buy a used gear set with new bolts. Install with red locktite and torqued down.
    Time warp ahead 6 months.
    Routine check/ fluid drain after a water crossing trip. What do I find? ALL the ring gear bolts are loose. A couple are within 3-4 threads of coming out. So, remove the carrier again. Most of the bolts are damaged from the ring gear shifting around, so I go downtown and buy new bolts again. I clean the Trutrac carrier with brake cleaner, blow dry with air, install new bolts with red locktite, star lock washers, and torqued.
    Time warp ahead to Saturday March 23 2002
    Routine check and fluid change. Guess what? ALL the ring gear bolts are loose. One had come out and took half of one of the teeth off my pinion gear. Also a small hole in the cover. It was up high tho so it wasnt leaking out noticeably. So... I have no new bolts, its Saturday night, so I clean the carrier again, red locktite, whats left of the star washers, and tighten the damaged bolts in as much as I dare without twisting them off. I tenderfoot my way thru the run yesterday with no problems. I havent pulled the cover yet, but I want some help.
    My questions:
    1. What the h*ll is causing this?
    2. Has anyone else had this trouble?
    3. If I rebuild the whole diff, (pinion bearings, carrier bearings, axle bearings, seals, new gear set etc., except the Trutrac) is this likely to stop my trouble?
    4. What else can I do to hold these bolts in? (anything better than Locktite?, drill the bolts for lockwire?)
    5. Could it be the Trutrac somehow messing things up? I chased the threads in the carrier and they seemed good, but maybe they are enlarged? If so, what can I use to repair the threads that will hold?

    Info:
    The diff is a GM corp 12 bolt. It has 4:56 gears with a Detroit Trutrac unit. My driveline has been experiencing a few vibe problems lately, as I have been going thru many lift combinations (3" blocks, 4" blocks, shackle flip etc. but I dont really think that could cause my troubles. I have never broken an axle, and on jackstands everything seems to run smoothly and round. I am running 35" x 12.5" 15 radial mud tires, that are brand new. I have a TH400 and a NP205 t-case behind a mild 327.

    Any and all input is appreciated.
    Thanks.
    Mike
     
  2. jimmyjack

    jimmyjack 1/2 ton status

    Joined:
    May 11, 2000
    Posts:
    2,290
    Likes Received:
    0
    Location:
    Tucson Az
    Is the Truetrac a whole diff unit or does go into the 12 open carrier? If thats the case I would replace the carrier. Can you buy a londer bolt and like you said wire lock it or put a nylon locking nut on the back side of the carrier? You have me wanting to go open my diff cover and peek inside now.
     
  3. Thumper

    Thumper 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    1,582
    Likes Received:
    0
    Location:
    Alberta Canada
    The Trutrac is a unit. It replaces the stock carrier. The ring gear bolts onto the Trutrac and they are blind holes, the bolts dont go (or cant ) through.

    Mike
     
  4. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

    Joined:
    Jul 23, 2000
    Posts:
    36,170
    Likes Received:
    1,376
    Location:
    E-town baby!
    I'd guess the threads in the Tru-trac are too loose. Probably going back to the first loose bolt episode that was probably caused by insufficient torque at the time of the original axle build. I never used loc-tite on my 14 bolt ring gear bolts and haven't had a problem...

    Rene
     
  5. jimmyjack

    jimmyjack 1/2 ton status

    Joined:
    May 11, 2000
    Posts:
    2,290
    Likes Received:
    0
    Location:
    Tucson Az
    Maybe you could coat the threads with a coat of JB weld and crank them in again. Are all ring gear bolts left hand threads????
     
  6. reddog64

    reddog64 1/2 ton status

    Joined:
    Nov 9, 2000
    Posts:
    3,325
    Likes Received:
    0
    Location:
    Federal Way, Washington
    I hope there not left hand threads...
    hehe...
     
  7. mike reeh

    mike reeh 1/2 ton status

    Joined:
    Jul 23, 2001
    Posts:
    752
    Likes Received:
    0
    Location:
    San Diego, CA
    how deep are the threaded holes? like tRusty said, I bet when they came loose the first time, and the ring gear was loose and you gunned it, it tried to rotate the ring gear on the carrier, shifting the bolts back and forth and effing up the threads... now they're too big.. man what a PITA but you could drill & retap new bigger holes and use bigger bolts. this time tack weld each bolt /forums/images/icons/smile.gif or do the lockwire trick...

    mike
     
  8. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

    Joined:
    Dec 14, 2001
    Posts:
    22,060
    Likes Received:
    69
    Location:
    Pleasanton, CA.
    I agree with Rene, your problem is probably most definately coming from your first failure. When the bolts loosened the first time they wallered out the wholes in the carrier which is causing them to keep coming loose now. Sounds like you need to get a new carrier. Why not change diffs to a 14 bolt and never have troubles again? Yes you would need to buy new tires and wheels but you would never have trouble again. Also, check to see that the bolts are long enough. I am doing a gear and locker install now myself on a 14 bolt and the bolts that came in the genuine gear master kit are too short. I had to buy new bolts from the dealer. The bolts should enter the ring gear by at least 1/2" maybe even 5/8". Hope you get it fixed soon. Keep us posted as to what you finally do to fix it or if you decide to finally upgrade to that 14 bolt.
     
  9. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

    Joined:
    Jul 23, 2000
    Posts:
    36,170
    Likes Received:
    1,376
    Location:
    E-town baby!
    LOL Aaron! I think you'd know by now.../forums/images/icons/smile.gif

    Just thinking a bit more, the ring gear itself has the threads, and the ring gear has been replaced once already with the same results.

    Mike, are you using a torque wrench or ? If you are using a torque wrench when was the last time it was calibrated? Maybe the ring gear isn't seating properly on the carrier before the bolts are getting torqued? One thing I've noticed on the 14 bolt carriers is that the bolt holes in the carrier itself are very tight. Most of the bolts won't fall out even after it's been unbolted. How does the Tru-Trac compare to that?

    Rene
     
  10. Thumper

    Thumper 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    1,582
    Likes Received:
    0
    Location:
    Alberta Canada
    Well, thanks for the inputs so far.
    As far as the 14 bolt goes, its out of the question financially right now. I cant justify spending $$ for the axle, wheels, tires, rear discs, and a locker to get where I am right now with an axle that serves my purpose just fine for now. Maybe eventually...
    Tack welding the bolts... trust me it crossed my mind. But if it is the threads that are enlarged, welding or wiring or jb welding the bolts in is a temp fix.
    Drilling and tapping the holes larger... hmmm guess I could. Would it be a noticeable loss in strength? The bolts are 3/8 now, so I guess it wouldnt be bad to go one size up. I would have to drill the ring gear out to the new size as well, cause the bolts have to slip thru it first before threading into the carrier. Any inputs on this option?
    What about just repairing the threads the size they are? Is there any decent way to do this? Helicoil or sumthin?

    Thanks for the replies so far!

    Mike
     
  11. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

    Joined:
    Dec 14, 2001
    Posts:
    22,060
    Likes Received:
    69
    Location:
    Pleasanton, CA.
    The 14 bolt was only a suggestion that i figured you wouldn't go for but i mentioned it anyways. First of all the ring gear has the threads in it not the carrier. Second, i do not think you would ever in a million years be able to drill out the ring gear and tap for a larger size. The ring gears are heat treated after the holes were tapped and they are very very hard. (Experience here) The ring gear bolts on a 10 and 12 bolt torque to 50 ft. lbs.
     
  12. Thumper

    Thumper 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    1,582
    Likes Received:
    0
    Location:
    Alberta Canada
    OK, that changes things then... upon reflection, you are right. The threads are in the ring gear. Therefore, thats not the problem. Cause its the second ring gear that it happens to. So, back to question #1. Where do I look for the problem??

    Mike
     
  13. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

    Joined:
    Dec 14, 2001
    Posts:
    22,060
    Likes Received:
    69
    Location:
    Pleasanton, CA.
    Your problem is one of two things. Either your carrier is now bad because of the first failure or your ring gear bolts are too short. My guess is that your carrier is shot. You could try a third attempt i guess at installing another R&P set and new bolts but i will put money on it that it fails again. You should buy a new carrier, R&P, and new bolts and make sure you use a known good torque wrench set at 50 ft. lbs. and you should then finally be set again. Make sure that you do use red loctite on the bolts as you have the past two times.
     
  14. Thumper

    Thumper 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    1,582
    Likes Received:
    0
    Location:
    Alberta Canada
    Sheesh, I got everyone all backwards now....
    The other post was correct. The threads are in the ring gear. And its the second ring gear, so I am going to eliminate enlarged threads as a potential problem. And as the other poster said (Im crappy with names... sorry) the ring gear is hardened. What is the possibility of the bolts enlarging the holes anyways?
    Rene: Yes I use a torque wrench to put the bolts in, and its got a fairly up to date calibration on it. Military spec actually. /forums/images/icons/smile.gif and as far as the bolt holes in the carrier... they are the right size, but the bolts dont fit tight. The second ring gear seemed to seat down very tight when I did it. If I remember right, I used 50 ft-lbs for the torque... but its a while ago I did it.
    So, I guess there is still a possibility of lockwiring the bolts in since I can assume the holes in the ring gear are OK. It will be a new gear set anyways.

    Well, this has really got my brain thinking. I love these bulletin boards especially when willing guys are online to help out!
    So, keep the responses coming... Im not out of the woods yet!
    Mike

    edit: replacing the carrier will be a last resort. The Trutrac is a 400.00 USD touch that the wallet wont take especially after a gear set and installation/ bearing kit. The holes in the carrier appear to be fine.
    M
     
  15. mike reeh

    mike reeh 1/2 ton status

    Joined:
    Jul 23, 2001
    Posts:
    752
    Likes Received:
    0
    Location:
    San Diego, CA
    good call on the threads being in the ring gear thing /forums/images/icons/smile.gif

    personally if it were me, Id tighten the F out of the bolts, and put a bead of weld around each one. install cover, install gear oil, and forget about it! next time you have it apart will be to swap in the 14 bolt /forums/images/icons/smile.gif

    whats the contact pattern like on the gears? you say you replaced the ring gear, did you replace the pinion? youre not supposed to mix and match gears... just some food for thought

    mike
     
  16. Thumper

    Thumper 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    1,582
    Likes Received:
    0
    Location:
    Alberta Canada
    Yeah they were replaced as a set. The pattern was real good considering the fact that I did it myself. Do ya think that could be a problem? I dont really see how, but I am open to anything right now.

    Mike
     
  17. K10ANDYKHAMNIC

    K10ANDYKHAMNIC 1/2 ton status

    Joined:
    Sep 17, 2001
    Posts:
    1,962
    Likes Received:
    0
    Location:
    Western CO
    get eome new grade 8 bolts by a good mfger and lock washers , there are many things i would check but i dont know if you could understand what im saying , not you just that im not very good at giving directions ...
     
  18. ntaj*ep

    ntaj*ep 1/2 ton status

    Joined:
    Feb 4, 2002
    Posts:
    3,248
    Likes Received:
    1
    Location:
    Evergreen state
    Just a shot in the dark here. Where are you getting the bolts for your ring gear? I've used bulk bolts before, like lows, home base, and had the same thing happen. But when I use the "correct" bolts from Randy's R&P, or some other diff. shop I've yet to see a problem in 5yrs. now. Plus all the other diffs I've done. Just a thought.
     
  19. Triaged

    Triaged 1/2 ton status

    Joined:
    Feb 21, 2001
    Posts:
    3,808
    Likes Received:
    0
    Location:
    CA (LA/OC area)
    I don't like the idea of tack welding the ring gear bolts. They are heat treated to a very strength and that will be gone if you weld them. I would safty wire them...good luck drilling them though! You might look into getting some AN bolts. You could get the ones that have a oversized shank and drilled for safty wire already. They make a few different classes of bolts (all of them stronger than grade 8!) and I know there is one that will work...but it is going to cost you. The ones to look for would have ANS, 3003, a triangle with a dot in it, X, and E stamped on the head. Than you would just have to find the right length. This bolt is made out of 160,000psi steel. You would then have to ream out the carrier to fit the bolt (I am not exactually sure what size the shank is but the E stamp on the head means that it is a over-size). Then use threadlocker #262 (it has 15% greater breakaway torque than the #271standard red stuff). I am not saying this is the best thing you could do...just what I would try. Good luck (not like your luck could get any worst /forums/images/icons/smile.gif )
     
  20. 79Beast

    79Beast 1/2 ton status

    Joined:
    Dec 9, 2001
    Posts:
    1,155
    Likes Received:
    0
    Location:
    Georgia
    USE SAFETY WIRE. Your best bet is red locktite doesn't hold (assuming you put it on clean metal and gave it time to cure before adding gear dope) Drill the bolt heads, safety wire them......If you don't know the proper way to do this, Email me or get a tech manual/ friend who KNOWS how. The bolts will not come loose if properly wired. Trust me on this. We safety wire EVERYTHING on AH-1W SuperCobras and UH-1N Hueys (helocopters). These things vibrate like the devil and are subject to severe temperature cycles. The key to safety wiring is to have to proper pattern for the thread direction (RH or LH) and to have the wire TIGHT. Invest in some safety wire pliers....save you lots of time and frustration.
     

Share This Page