my truck

Discussion in 'Trucks and Trailers' started by elcam, Mar 28, 2000.

  1. elcam

    elcam LawnSite Member
    Messages: 4

    I have a '78 Chevy 1/2 ton short bed. it's got a 12 bolt rear end that's got a problem. It dosen't make any whining, grinding or moning noises, BUT on about 50% of the starts from a stop the driveshaft does about 1/4 turn as if there where nothing inside to stop it. then it catches makes a clunk and off we go. There's a locker in there of an unknown type. i haven't looked yet so i can't tell which one. is there any possibility that the clutches are so loose this is the result? i've had lots of cars and trucks but never one with a locker and none that did any thing like this. You can actually stand next to the truck, look at the driveshaft and see this happen.<p>----------<br>pete<br>
  2. John DiMartino

    John DiMartino LawnSite Silver Member
    Messages: 2,555

    Have you had the cover off?Any teeth missing?If not it sounds like its time for a new carrier/locker.The splines couldnt wear that much,but id check em if there out.<p>----------<br>John D<br>
  3. frahmie

    frahmie LawnSite Member
    Messages: 46

    i recently had to replace my rear end. i broke about a 1/4 of the pinion gear off. and 9 teeth off the ring gear. i moved but did something similar to what yours is doing. the only thing you can do is take the cover off. it isn`t that hard anyway. frahmie<br>
  4. Captkaos

    Captkaos LawnSite Member
    Messages: 88

    You might also want to check to see if the pinion gear is &quot;walking&quot; out of the ringgear.<br>I had one the nut on the pinion was coming off.<p>----------<br>Chris Lucas<br>
  5. yortengel

    yortengel LawnSite Member
    Messages: 216

    I have rebuilt many GM rear ends in trucks. Better pull the cover and inspect the contents. Sounds like you may have somthing comming apart. I have also seen the Differential Carrier brake at the bearing/race. This caused the same type of problem you have. also made the rear end steer. Didn't make any other noise.<br>Good Luck.
  6. elcam

    elcam LawnSite Member
    Messages: 4

    Here's an update! I took off the cover and there's no locker at all, guess the previous owner just thought there was. What i found is: There dosen't look like there's any problem with the ring and pinion, but there's lots of wear on the differential pinions and the shaft they are on. Also alot of movement at the splines of the side gears and the axles. I think this is where all the movement is coming from. Now i need to find some axles that have good bearing surfaces and splines. I'll also put in a new pinion shaft and new thrust washers on all four gears. Hopefully this'll do it without replacing the gears too. Let me know if it sounds like i'm on the right track.
  7. yortengel

    yortengel LawnSite Member
    Messages: 216

    Sounds like your talking about the spider gears. you can get a new kit with all the parts from the dealer, you might also check a rear end shop for a price on the kit. I have gotten a better deal from the dealer in the past, so better call both. You might want to find some one local to take a look at the rear end. some play is normal in the spider gears. I have seen this cause a lot of back lash in a rear axle, but not quite the problem that you have discribed. Does your truck have a manual transmission? that might explain why the shaft wood spool up every time that you started off.

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