i was sitting in the jack n da box drive through and noticed a new loud clunk every time i put my truck in drive to move forward. its never done this before. i used to get the normal quiet clunk thats expected but this is louder than usual. it only clunks loud when going to drive, and has the normal expected clunk when going from drive to reverse. a buddy of mine said its the rear end getting sloppy and its about to go but its just too loud to be inside of the rear end IMO. its more of an announced sound than a baffeled sound i would expect the gears to make being they are inside and full of fluid. im not sure about his mechanical skills either, but it did worry me a little since im getting new noises on deceleration which ill get to in a minute.

how many u-joints are there to be replaced, how hard is it, and do i need to rebalance afterwords? ive never done u-joints before but im not afraid to tackle the job. do these noises and clunks sound like they are the joints or the gears to you guys?

onto my driveline noise. about a month ago i noticed a slight howling noise on deceleration when holding 3rd gear. as soon as i give it a little gas it would stop, or if i put it in drive it would not whine as loud, or if i dropped it to neutral it would stop howling. can u-joints make these kinds of noises? im pretty rough on my truck so i wouldnt be suprised if the rear end is all of the problem.

 

sounds like that 10 bolt is ailing...

the U-joints arent hard to replace, if they are the original ones though, you'll have ot get a torch to burn out the plastic sealer in the yokes. heat it up and it pops like the juciest zit ever LOL.....

make DOUBLE and TRIPLE sure they give you the right U-joints, I went through 3 before I got the right ones from the parts house....

there's the one at the trans, one at the carrier bearing, and one at the rearend... 3 total.
Hope this helps

 

It sounds to me like your slip yoke. Mine did the same thing...everytime I'd shift from drive to park or from reverse to forward gears it would "clunk". GM has a Technical Service Bulletin on this and they reccomend to replace the slip yoke with an aluminum on and a new designed U-joint. I did this same repair and it did take the "clunk" out.

 

ive been going 60000 miles without any problems...i was hoping it was just the U joints needing to be replaced. what is the slip yoke and whats a guestimate price? im pulling the cover to check the gears this weekend. man i hope they look good that would be my cam money + some lol. 4.10's would make 12's on stock cam more of a reality though

 

Slip yoke - from not being greased enough. You can get under the truck, with it in neutral, and push up and down on the slip yoke, there should be hardly any free play.

u-joints - There's three, non grease able kind. The bomb prof ones to replace them with are Spicer. The correct way is to hammer them out with a socket, and brace the bottom with out hitting the ears. Balancing is a must. You can check each one at one time by twisting the d-shaft back and forth, there should be no slop at all what so ever. MUST BE DONE WHEN COOLED OFF. Those suckers get hot.

Rear - pop the cover, if you have spider gears it's pretty easy to tell. Flop the tires back and forth, and look for slop.

If it's humming on decel, then I'll bet that it's the rear

 

ive had the axle out 3 times in the last 2 months and ive never greased the yoke. the u joints have 60,000 HARD miles on them. rear end was replaced around 13,000 miles, but then again theres been some hard miles on the 3.73 g80 combo.


do i need to take the driveshaft to get rebalanced if i change the U-joints?

 

Do you mean the drive shaft? How did you remove it. Did you keep the shaft together as a whole, or separate it at the slip yoke? There's some green Teflon coating at the slip, and it MUST be on there. If it's not then you're get a nice vibration, and a clunk. The coating is not replaceable.

You're supposed to, but you don't have to. It'll make them last way longer, and you can have a slight vib if you don't. It's kind like balancing your tires.

 

i meant my driveshaft...

when i pulled the drive shaft i left it all intact but pulled it out from the transmission. thats the slip yolk right? if not im thinkin of the wrong part.

 

its just the yoke, the one on the transmission, there's no slippin . . . .

Have you tried checking the u joints, and the center slip yoke, after the carrier. Put the truck on some ramps, jack stands, or the curb. Lock the parking break, and but the trans in neutral. Push up and pull on each of the joints, and see what moves.

 

i was out doing that when you were posting. i wish i had someone who could put it in drive and reverse while i was under there...all of the u-joints seem solid, i cant even turn the driveshaft forward and backword to make noise. the center yoke seem solid but is that hanger thingy in the middle suposed to have any play? when i push up/down or side/side i can get that to move.