"Clunk" From the Front End in 4WD

[Korban_Dallas]

Hey Evreyone,

I have a 2000 GMC Sonoma ZR2, and when I put it in 4WD and roll a few feet it will be a loud Clunk, but then it may do it again instantly or it may roll 10 feet and do it again, I replaced the RF Half-Shaft cause at first it sounded like it was coming from there but it still does it, after lisitening more close it souds like it may be from the Transfer Case, and Clunk I mean it sounds like the front end is gonna fall off when it clunks. So anyone have any Idea's?

[dt4ts3]

Does it ever quit clunking? I'd be inclined to thin something is wrong with the internal hub that locks and unlokcs the diffy.

[Korban_Dallas]

Nope, when ever I am in 4WD its happening, it never goes away and the faster you go the worse it gets and it sounds like it's going to destroy the front end.

[Korban_Dallas]

Well it's been forever since I updated this but, I have been doing some work and have narrowed it down.
Over the past couple weeks the front Axle has been out and rebuilt new bearings seals etc. and a new gear that engages the passenger side axle, That was ground all to hell when I left vacuum line off under my dash when the floor heater door broke...:rolleyes: I also replaced Both CV shafts and the front drive shaft. (Bought the beefier one from synergy off-road)

But back to the real issue of this thread, the “Clunk” It is in the transfer case, exactly what in there I’m not sure I haven’t taken out yet, I have been told that the vacuum switch on top of the case can go bad, so I replaced that and it still makes the noise, so it’s something internal in the transfer case, not sure exactly yet, could be a loose chain, could be a broken tooth on a gear, not sure yet. I’ll provide another update once we get it taken out and get it apart.

[Blazer69]

probably a bad gear.

[dbcustoms]

i have a 92 blazer that has the same clunking noise you are describing, i assumed it was a cv joint like you did, but now thats got me wondering what would be the cause.

i do have a bent mainshaft in my trnsfer case(due to breaking a driveshaft off) and i wonder if that has now destroyed my t-case? it just started doing it the ohter day though when i had it out behind the house and we were down in a creek and it started when i tried coming out and up the bank. do you think that could have made something break inside the t-case?

[Korban_Dallas]

Yeah a bent output shaft on the transfer case could definitely be making the clunk sound you are probably skipping teeth on a gear and that's where your getting the sound from, personally on mine I don't know what the issue is or when it happened, when I bought the truck it was FUBAR'ed and like I said before I am getting around to taking it apart to see what's wrong.

[dbcustoms]

what i dont get though is it just started doing it and the shaft has ben bent for a while now