bad chatter sound HELP

G

gmc00z

Active member
Jan 23, 2011
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N Ft Worth, TX
What i thought was some bad u-joints, turns out they were, is causing a bad chattering sound. Best i can describe it is piston slap that never goes away but its alot louder. Gets progressively louder under throttle and continues to chatter until i come to a complete stop. Since its not an exhaust leak or the u-joints anymore, makes me believe its either the transfer case or rear end. What can cause this? I've been told bad bearings in the axle. Transfer case seems to have enough fluid although it does have a leak somewhere (autotrac, the skid shows signs of leak) so im not sure what can cause this noise if it were the transfer case.
rear is 3.73 open 10bolt.
I just recently installed spring clamps to help resolve the yoke clunk but i do not recall if it was making this noise prior to installing these.
Thoughts? What to check?
 
yes they did, removed them at lunch to see if that was the culprit. They were NOT. Brought it to a tranny/gear shop, sounds like the rear end. Will bring it by monday and let them look at it. 3.73 has served me well enough for the time being and will more than likely take the lift off after this set of tires so i won't bother regearing to a lower gear and be overgeared in the future.
 
My buddy's truck started doing the same thing out of the blue this weekend. Turns out the tail shaft seal on the transfer case was leaking and had been for months. It was almost bone dry and chattering like a mofo. This was like 3pm saturday and all dealers were closed so we couldn't get GMs "autotrac II" shit. Just threw some GM Dex/Merc ATF in it and it went away. He's gonna drain and swap in the proper stuff later this week.
Your seal may not seem like a bad leak, the underside of his truck wasn't overly covered in fluid, but it could be very low on fluid nontheless
 
thanks Huck, i'll pick some up asap to see if that fixes my probelm. Does anyone know how much the auto trac II fluid is from the dealer? I saw summit has it for $7 a quart. Hoping the dealer isnt that much more.
 
:shake: Sure thing bud. Couldn't tell ya a price tho, I swear, GM techs around here are dumb as rocks. They didn't even know what I was talking about when I was describing the issue and the fluid we needed. They couldn't wrap their heads around the fact that the Autotrac case takes special fluid :nono: So they sure couldn't tell me how much it was...
 
got the fluid changed, chatter still there however. It seemed to quiet it down a good bit but its still there. Gear shop it is i guess
 
Hmmm, his went away after we drove it around a little. Could be yours got chewed up worse than his, we just happened to catch his right when it started to happen. Never made a sound till he was trying to back out of our friends back yard in 4wd and started making all kinda noise, so he never really drove on it like that.
 
turns out it was my axle, got it back on thursday of last week and she's back up and running. Rides so much smoother with brand new gears in it. It's nice to have a truck that doesnt make any pops/creaks, finally up to date on all the maintenance on this thing. Definitely enjoying it.
 
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