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Help with hum/droning noise on freeway

One u joint had a little lateral movement, so I replaced both. I learned that the shop that repaired the driveshaft welded two 1350 yokes...they must have done this on the slip yoke too. One u joint went on fine...it was tight fitting but a few hammer taps loosened it up. The one near the axle was tight too, and I couldn't seem to loosen it much. This was the same one from before that I said the snap ring wasn't seated all the way. I seated it, now it's a bit tight! I got on the freeway and the noise is still there. I was careful not to lose any needles, I greased them well, the slip yoke was in the same order...this was discouraging.
 
Are your front hubs locked? Is the tcase in 4hi by accident? My 208 hums at high speeds if I leave it in 4hi or I have the front hubs locked.

Take a look underneath and check the front shaft. See if it rotates freely and easily. Check the ujoints for any play or loose straps. Also if your slip joint has some slop to it that can be make a hum.

The reason I'm saying front shaft is that even with the hubs unlocked and in 2hi it can still spin at speed through fluid friction in the tcase. Just another idea for you to look at.
 
Certainly not locked or in 4hi (I have done that though, lol). I marked the front shaft to see if it spins while driving (spins easily by hand). There is a noticeable amount of play at the slip joint on the shaft when pulling perpendicular to the ds. The shop replaced this too, as a gift for shafting me (pun intended). My guess? They replaced it because they effed it up too. I will do a test run while I pick up a 30mm socket since they over tightened the fill/drain plugs. Ughh.
 
So I greased the front shaft and that seemed to take up the play. On a freeway trip, it also didn't spin, or landed exactly as I marked it. Still hummed. I tried 4hi, hubs unlocked. Still hummed.

Lifted front wheels, spun and shook them both, they seem fine. There might be a mm of play at the tread with a top-bottom shake, consistent on both wheels.

I hope it's not in the transmission or transfer case...

Other ideas? Does it seem possible that my rear driveshaft wasn't repaired well?
 
It is possible that the balance on the driveshaft isn't quite right. As for the hard 1-2 shift, check the TV cable setting first. The vast majority of shifting problems are caused by improper setting.
 
TV is good. Went to a driveshaft shop, we drove it and put it on blocks and he inspected it. He thinks it's in the transmission or transfer case. Yay.
 
Ever try messing with the T-case lever a little while cruising to see if the noise changes? You might just need new shift pads or forks in there. Or the T-case might want bearings. The T-case is relatively easy to tear down and inspect.
 
I did try that. Made no difference. I think I will get an opinion from a recommended tranny shop before I attempt to tear down the transfer case.
 
My K5 had a resonance for a long time that turned out to be the exhaust hanger making metal to metal contact. The pipe resonance was transmitting to the body. The resonance came slowly in and out at speeds above 50-55 or so. It's easy enough to check.
 
I assume the driveshaft shop checked to see that the yokes are properly phased ?...I've seen guys just slap the splined yoke on without looking to make sure the u-joint caps are properly aligned front to rear,not all trucks had them 90 degrees from each other,some had to be offset slightly--others had a keyed spline that only goes together one way--correctly..

I remember a truck with a 2 piece rear shaft coming in my friends shop years ago to get the u-joints and hanger bearing replaced..after it was done,the test ride showed a bad vibration around 50-60 mph..he tore his hair out thinking it had a u-joint with a needle that fell into the cap,etc,ended up taking it all back apart,nothing was wrong with them...

It turned out after consulting a service tech at a GM dealer nearby,the splined section of the rearmost shaft had to be set at 4 splines "off" from 90 degrees ..once he did that,it ran smooth as glass!..the guy also said some trucks needed a 1/2" thick spacer added to the hanger bearing mount,there was a recall (I know this doesn't apply to your truck,just thought I'd throw that in)...

I noticed on my chevy van after I swapped in a different rear axle,and I didn't out the thin plastic or teflon "pads" between the axle housing and the springs,that the axle seemed a lot noisier than it did in the van I removed it from,and had test driven before I bought it to make sure it was good..
 
diesel4me said:
I assume the driveshaft shop checked to see that the yokes are properly phased ?...I've seen guys just slap the splined yoke on without looking to make sure the u-joint caps are properly aligned front to rear,not all trucks had them 90 degrees from each other,some had to be offset slightly--others had a keyed spline that only goes together one way--correctly..



I remember a truck with a 2 piece rear shaft coming in my friends shop years ago to get the u-joints and hanger bearing replaced..after it was done,the test ride showed a bad vibration around 50-60 mph..he tore his hair out thinking it had a u-joint with a needle that fell into the cap,etc,ended up taking it all back apart,nothing was wrong with them...



It turned out after consulting a service tech at a GM dealer nearby,the splined section of the rearmost shaft had to be set at 4 splines "off" from 90 degrees ..once he did that,it ran smooth as glass!..the guy also said some trucks needed a 1/2" thick spacer added to the hanger bearing mount,there was a recall (I know this doesn't apply to your truck,just thought I'd throw that in)...



I noticed on my chevy van after I swapped in a different rear axle,and I didn't out the thin plastic or teflon "pads" between the axle housing and the springs,that the axle seemed a lot noisier than it did in the van I removed it from,and had test driven before I bought it to make sure it was good..
Click to expand...


I don't think this applies to me. The shaft was modified and rebalanced. It is a one piece and the splines on the transfer case have no keyed grooves. The yokes were welded on in phase.
 
Yeah,if you have no "fixed yoke" on the t-case and no splined slip joint on the driveshaft,disregard...

A long shot,but I've had a bent fan blade make a vibration/hum on a truck before...a solid bladed one,that eventually tossed a blade off it right thru the hood,and slashed the upper radiator hose in the process..:doah:..
 
if it were me, I would have that driveshaft checked out again. It doesnt take much vibe in a burb to make noise.
 
Black Dawg, the driveshaft shop says the source of the noise doesn't seem to be the ds. I took it to a recommended tranny guy, he said he's fairly certain it's a bearing in the transfer case...which is also what the driveshaft guy said. I'm taking it in Friday to have him open it up. I've rebuilt a tcase before, but I would rather a pro do a once over on the rest of the other shops work. People seem to do a good job when you tell them another place messed it up...
 
Turns out there was a bad bearing in the transfer case...runs smoother and a little quieter but still drones. My driveline angles were off by 11 degrees so I removed the angled shim in my spring pack. Angles are good now, but it still drones. The driveshaft guy stopped looking when he heard the bearing. I will take black dawgs advice and go back for a further diagnosis on the driveshaft and post back for curious minds and future searches.
 
So the driveshaft is jacked. The shop tried to get it fully balanced at higher speeds and it was a no go...it's better though, but not good enough. I plan to hit up the jy this week. The shop warned me about fork lift damage at the jy lol.
 
Thats weird. I have watched a friend of mine at a machine shop build driveshafts. Either replacing splines or yokes, or building some from scratch.
I don't remember ever seeing one he could not balance on his machine after he finished.
Some took more weight than others, some a couple of weights in different places, but they all balanced.
If yours won't, I suspect either the splines are badly worn if it has any, or the darn thing is bent.
 
Fordum, I think it's slightly bent...remember that after it fell out the other shop cut the yokes and replaced them but reused the shaft. I'm not sure of the splines, they look ok...
 
Yeah, if it won't balance, I'm betting on bent. The only way the splines would prevent balancing, is if they were worn to the point that the ends with the weights could twist enough to throw off the positions.

Or, if it were letting it sag like it was bent.
 
Good luck finding a driveshaft at a salvage yard thats not bent..ever since they started using forkloaders,driveshafts seem to be the hardest thing to find undamaged (next to lower body panels)...very few yards pull the shafts out before they unload the truck off a ramp truck or trailer any more...unless whoever scrapped it tossed the shafts in the bed or cab,chances are the driveshafts are junk...


You'd have better luck shopping on Craigslist or a swap meet,to find one thats not bent...having one made up from scratch isn't cheap,but might pay off in the long run..
 
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