Stupid Posi question

[gjk5]

I have been worrying about this clunk-clunk coming from the rear as I take off from a dead stop. I was just able a look inside the glove box (long story involving a mirror and flashlight) and found that the 12 bolt is posi and was wondering if the posi engaging could be that sound? I don't know anything about posi-trac, but it seems to clunk and then catch, and proceed smoothly from there. This is in a '72 K5, 12 bolt, 3.73.


Someone ease my mind.

 

[diesel4me]

when does it do it most??

Most posi's only make noises or "klunk" when going around a corner,when the clutches in them have to slip or unlock to allow the tires to turn at different speeds while cornering..noises when you accelerate from a stop going straight ahead might be coming from other sources,like worn spring bushings,a broken center bolt in a leaf spring,cracked leafs in the springs,loose U bolts,a U-joint thats worn badly,loose or binding spline couplings,or slip joint on the rear driveshaft often make a "thud" when you release the brakes after coming to a stop,or when you first take off again if they are binding because they are devoid of grease,or worn enough so the cant slide smoothly...motor mounts and tranny mounts can cause klunks and thuds if they are loose and or broken too...so can body mounts!..

If you havent already,try pulling the cover off the rear end(good time to check what ratio it is,if you dont already know!)-- and refill it with new gear oil,and buy some "Posi" lube additive from a GM dealer--I've had a few posi's in chevelles and el-caminos that klunked so bad I thought they were junk,but after adding the lube additive it went away completely!---I think the genuine GM additive works the best--I used AMALIE additive and it still had some noise in one truck I did--the owner had me change the fluid again a few weeks later, using the GM additive,and it was much better...

 

[pauly383]

Before my 10 blot Gov Loc blew , it was acting like a locker around corners , and banged sometimes going forward .

Then it went KABOOM . Something broke , caught the window on the carrier , and tore it up . When we pulled it the broken pieces wedged in there were only things holding shaft and c-clips .

Do yourself a favor , and at least pull the cover to look at it , and if there are lots of particles , pick up an open carrier now instead of later .

 

[gjk5]

Thanks guys. It only clunks for a second and I did roll it in neutral on a hill and it only does it under power, not gravity rolling. It also seemed to be a little more pronounced on gravel and dirt last weekend, just when taking off. As far as it going out completely I'm almost prepared, I have a whole 'nother '72 that I am cannabilizing for parts, sounds like I'm starting with the axles.