HELP

[ngarman123]

after a long rest. (about 1 year) finally got my truck back on the road this weekend. runs good and all seams well untill i get a little bit of speed. lets say 20mph. i get a terrible noise coming from under it. it is not a grinding noise its more a bell sound like "ding" like something is hitting a moving surface. it goes away then comes back and gets worse then goes away?  it does not matter if i am braking, accelerating, coasting, 2wd, 4wd. took the truck back and removed the rear rotors. nothing looks out of the ordinary. jacked up the truck turned all four tires nothing seams wrong. looked and looked at everything i could trying to find anything that could be hitting. it does not pull or jerk the truck really does not seam to have an effect on how it drives but just sounds awful! since the truck has been drove last i have replaced the front rotors, bearings, seals, pads. i cant really think of anything that would be hitting and making such a loud pinging sound. the transfer case and fuel tank was also out since drove last. does anyone have any ideas to look for? i know it could be any 1 of 100 things but i am kind of at a loss. thanks!!

[Buddy]

Check your U joints

[Grim 82]

Make sure your exhaust isn't hitting anything.

[1984k30]

I would also start with the drive shaft.  check the joints and make sure nothing is touching the drive shaft.  I know if something  is touching the drive shaft it makes a pinging sound.  My buddys once put a couple zip ties around my drive shaft for a joke.  You may also want to put the rear end on jack stands and have some one put it in gear and listen for the noise.

[Irish_Alley]

My 94 did that but under a load at first then randomly on a take off thought it was the transmission then I got under it and notice one ujoint cap was sticking out about 1/8 inch. It was a stock u joint so the plastic gave away allowing it to slide out that caused all the needle bearings to fall out causing about 1/4 of a inch slop in that cap replaced the joint and AOL is well

[ngarman123]

thanks guys i will start with the driveshaft/u-joints and go from there.

[TexasRed]

spare tire?

[ngarman123]

found the problem!! but got some more questions? the rear pinion seal dust cover it rubbing both the seal and the yoke. i removed the drive shaft, pinion nut washer and removed the pinion flange. it looks like the back side of the dust seal is rubbing the flange of the seal. the dust seal that is attached to the pinion flange. it spins? is this normal? also there is a gap between the seal and the axle housing. like it is not seated all the way but i can not get it to go in any further. i hope i am making sense! i looked up the seal installation in my haynes manual and it says something about counting threads and use a in/lb torque wrench for semi-floating axles. how do i know if i have  a semi-floating axle or not and does it make any difference? thanks

[756man]

What model truck ? All 1/2 tons are semi-floating. 81-87 3/4 tons are semi-floating unless they came from the factory with a 454.

[Irish_Alley]

http://forum.73-87chevytrucks.com/smforum/index.php?topic=12306.0
cant help you with the pinion nut and all but I do know you are supposed to mark it so you put it back on in the right spot the tq is more for a new setup

[ngarman123]

i think the frame and rear end is a 73-74 1/2 ton it has a 12 bolt in it. i did not mark anything when i took it apart so i am going to put that in the old memory bank of things not to do again but i still need to get this thing back together and correctly.