Clank!

[GMC 1500]

Whenever I put my truck in D from park it clanks as the gear is engadged, it also sqeaks as you accelerate until it shifts up.
Could anyone tell me what this may be. I think it may be a bad u-joint. THANKS

[gldevall]

The clank is due to wear in the rear end. This is a problem that plagues these trucks. I had it in mine and whenever I changed to a posi untio and new gears it quit. So, I'm not sure if it is in the chunk or the gears themselves. The squeak may be a lack of lubricant. BTW welcome to the board. Great place for info and a great bunch of guys and gals.

[Free88]

Could also be a bad u joint maybe.

[Jonboy]

sounds like a u-joint to me, too.

[Grim Reaper]

U-joint for sure on the squeek and get it fixed soon before you screw up the ears on one of the yokes. Some of the clank might be gear slop like gldevall said.

[1985K10]

My clunks too, my spiders look pretty worn, but changed the U-joint anyway, didnt help...

[MylilBowTie]

Could be just enough slack in the differential (worn out) to clunk. I can tell on mine when doing about 35-40 and tap the gas. It clucks when it tap the gas to accelerate then it does it again when I let off. I was hoping for the best but these things happen when you get a complete unknown mileage rear end.

[1985K10]

Mines been doin the same thing for a while now. Hasn't blown yet....but when it does Im gettin Posi!
I think a little bit of the clunk might be from the output shaft on the transfer case.

[GMC 1500]

Thanks ya'll. I asked a mechanic and he said it could be rear differential slack or bad u-joints. He said that it shouldn't hurt it driving without it fixed so I think I'll hold off on fixing it for a while. By the way it also leaks power steering fluid, any ya'll have this problem too?

[GMC 1500]

Thanks ya'll. I asked a mechanic and he said it could be rear differential slack or bad u-joints. He said that it shouldn't hurt it driving without it fixed so I think I'll hold off on fixing it for a while. By the way it also leaks power steering fluid, any ya'll have this problem too?

[Zilverado]

Originally posted by GMC 1500
Thanks ya'll. I asked a mechanic and he said it could be rear differential slack or bad u-joints. He said that it shouldn't hurt it driving without it fixed so I think I'll hold off on fixing it for a while...

I don't know about the diff, but as long as the u-joint(s) is not too bad, you should be OK for a while. I'd just hate to see you blow-up a u-joint doin' 70+ mph on the highway. Even slower wouldn't be pretty. And if it's the front one that lets go, you just have to hope the drive shaft doesn't catch the road and pull the rear of the truck right out. Well, then at least you wouldn't need to worry about slop in your diff... :p

In all seriousness though, for the price of the u-joints, I'd suggest you replace them before they get to that point.

Just my $.02

[1FaastC10]

welcome to the board GMC1500, where are you from?

[GMC 1500]

So basicly if its the u-joint... thats bad huh? How do you tell if the u-joint is bad?

P.S. im from Colorado

[Zilverado]

I didn't mean to be overly dramatic about the u-joint failure. I haven't heard of too many catestrophic failures as I was talking about, but I know they can come apart, and that would not be very good. I'd just encourage you to change them out before they get too bad - - it's cheap and relatively easy to do.

As far as checking them out, just get under the truck (mine is high enough I don't have to jack it up) with it in park. Now grab the drive shaft and wiggle and turn it. If you see any movement in the u-joint, it's gotta go. I've even replaced them when I only suspected trouble, due to squeaking and clunking (but no obvious movement), and found them to be completely dry inside.

Hopefully you'll find the problem. There are also many other, more experienced guys (and gals) on this forum that will maybe give you more diagnostic advice. This is just my experience.

Have fun.

[MylilBowTie]

Driveshaft loops are a good thing, pole vaulting your truck isn't. I would go ahead and have the universal joints replaced. Then if its still there that leave the free play in the differential.

[Short-Fuse 72']

Might want to check your driveshaft carrier bearing, if you have a two peice driveshaft.

[Tom]

I've seen two chevy 73-87's this year with dropped driveshafts due to u-joints. DO NOT screw around with these things. I had the front one pop on me in my 78 once, lucky it didn't drop the whole shaft.

[86k10]

I agree if it's a u-joint which it sounds to me like it is, replace it. From my experience the first thing u joints do is freeze up and they make sort of a snap or popping sound when you put them in gear and then do the squeaking thing while you drive. A bad joint is hard on the rest of the gear train when they are froze up and will not flex, the rest of the driveline has to absorb it.

[Grim Reaper]

$12 ujoint totals truck. Happens a lot more then you would think.

I ran accross a C10 in the Junk yard one time with a aluminum camper shell on it. One of the back wheel just about touching the back bumper and the drive shaft sticking strait up through the camper shell.
Bet that was a hell of a ride. $12 u-joint .

[MylilBowTie]

I like spicer u-joints if available, Im not sure of any other "good" ones.