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Thunking T-Case?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 73CowBlazer, Jul 25, 2000.

  1. 73CowBlazer

    73CowBlazer Registered Member

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    I have a 73 Blazer with minor mods 35's and 2" body lift. A bit of cowprint about the truck ala gateway hence the name. Teenage daughter drives it. Problem is bad thunking increasing in frequency with speed, but close to one thunk per second. Doesn't happen in reverse in any t-case setting. Changes character with different t-case gears. Any ideas prior to towing to tranny shop???
     
  2. collegeK5er

    collegeK5er Registered Member

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    sorry i can't help you, somebody here can but just thought i'd say it's nice to see some more people from houston
    chris

    Doin' it all on a college budget
     
  3. Boss

    Boss 1/2 ton status Author

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    What transfercase do you have? NP203 I would assume, but check your U-joints first. Bad U-joints makes a horrible sound everytime the front drive shaft rotates.
    Boss
     
  4. Canuck

    Canuck 1/2 ton status

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    I would have to concour. It is probably your u-joints. Had the same problem, was more of a vibration than a thunking. Get under and give them a back and forth movement a check for play or "thunking".

    Canuck

    Go Wide or Stay @ Home
     
  5. Boss

    Boss 1/2 ton status Author

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    When my U-joints were bad, mine made a "Thunk-squeek" sound, like they needed greese. It sounded really bad. Thunk-squeek, thunk-squeek, thunk-squeek as I rolled along.
    Boss
     
  6. 73CowBlazer

    73CowBlazer Registered Member

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    It's a 205 and I checked the u-joints by jerkin' em around under there. The strange thing is it does it in 2wd and 4wd but changes the noise. I guess it could still be one of the u-joints on the rear drive shaft but I sure didn't feel any play.
     
  7. Boss

    Boss 1/2 ton status Author

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    In 2WD, make sure your Tcase is in 2hi and not just your hubs unlocked. Sometimes when I shift from 4Hi to 2Hi it really aint in 2hi, but I think it is. Then I go and drive and it feels like everything is normal, until I get under the truck and try to turn the front drive shaft and I can't. Then I realize that I'm not really in 2hi. Anyways, the front drive shaft still turns freely when you are in 2WD. Is the noise quiter in 2WD (like really quiet), but in 4WD really loud?? if so, definately Ujoints
    Boss
     
  8. 73CowBlazer

    73CowBlazer Registered Member

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    Took it to tranny shop and Jeff just called and said he had a piece of ring gear in his hand out of the original 12 bolt rear end. I guess a rebuild or something to swap in is now in order. What is the cheapest way to go? With one daughter just starting a Texas Tech I need to save all $ I can.
    Broke 73 Blazer
     
  9. MICHIGAN BLAZER

    MICHIGAN BLAZER 1/2 ton status

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    call around your area for prices on a junk yard special

    <font color=red>MICHIGAN BLAZER
    <font color=green>89 Fullsize Blazer
    87 Cherokee
    65 IH Scout
     
  10. blazer72

    blazer72 1/2 ton status

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    12 bolts are getting hard to find any place any more but the gears are easy to find I'd put in a new gear set and go on should cost you less than 500.00 to have the shop so the work and buy the parts

    I understand the jeep thing I drive a BLAZER!!

    Ken
     
  11. Canuck

    Canuck 1/2 ton status

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    Sorry to hear that Cowblazer dude. I'm sure you would havge prefered a bad u-joint!!

    Canuck

    Go Wide or Stay @ Home
     
  12. hpfire7227

    hpfire7227 Registered Member

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    HA HA!!! I was going to say REAR END, but I read this post too late. Oh well. My 89 did the same thing when the 10 bolt grenaded. Bad news, beleive me, I feel your pain. Just make sure a reputable shop does the rebuild if you go that route. Rear-ends can be difficult to get right. And remember the break in period for the new gears.

    10 BOLTS O' FUN
     
  13. bablazer73

    bablazer73 1/2 ton status

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    can you use just a ring and pinion set? I have a 12 bolt I am pulling out of my truck. no problems that I know of, just upgrading to a 14 ff. it has 3.08 gears. I can ship the gears or the carrier and gears.

    your right. I don't understand the jeep thing!
     
  14. Big B

    Big B 1/2 ton status

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    hey man i live in fort worth and can meet you half way or so and you can have the 12 bolt out of my 80 model just got a new 14 bolt this week you would not have to pay shipping just gas and a little cash for the axle let me know and it is your my email is bigb4x4@hotmail.com.

    bigb4x4.coloradok5.com
     

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