wisdom needed...

[triophan]

I have an intermittent (sp?) hum.

I've searched and read and read and searched.
I've got new tires (balanced and checked by another shop) but it was happening with previous wheels and tires too
clean rallys
new front bearings
new ball joints
new 700r4 (well... less than 10K)
new cab bushings
new sway bar bushings
new trans mount
new brakes
just lowered 5" (happening BEFORE lowered)
recent alignment
new shocks all around

I have this hum that I begin to notice about 40mph (incorrect reading on speedo- but some reference point) thats at its worst around 55-60 mph.
I am replacing the u joints and balancing the shaft this coming week...
I guess my question is, is there anything in the rear end that would cause this?
Anything I should check to see if there is any play in my rear?
Could it be the frame being outta whack somewhere?
I really could use some input here. I'm trying to get this dang truck to go down the road smoothly FIRST and foremost.

Thanks in advance.
-david
here's a photo for good measure

[terryj]

Is it a hum or a whine, does it increase with speed? Typically a hum is caused by tires, a whine could be caused by transmission or rear end.

[3r!c84]

axle bearings and seals? pull off your drums and see if its coverd in gear oil. replace them both when you have it appart

[triophan]

its more of a 'owwowwwowoowwowowowow..." if that makes sense. low noise, low frequency, to the rear, but i can feel it throughout the truck, and every once in a while it shakes the bed and makes it chatter.

Maybe I will just pick up another 10-bolt at the junkyard and build it in the shop with new goods... kinda learning experience... see if that solves it.

[3r!c84]

check your rear end out before you go threw the trouble

[1LowToy]

A wowowo like you have snow tires on but don't? Are you tires showing cupping wear? Check axle bearings or and carrier bearings.

[triophan]

ok. the repair manual I have says nothing about checking the rear. Any pointers? I'd like to get a book thats got some good drivetrain info, as I eventually want to do rear discs and go up to a 3.73. This would be a good start.

1lowtoy- no, its not that consistent. as I go faster, it slows down or speeds up. I've not gone above (speedo reading inc.) 55-60. and I can't hear/feel anything below 35-40

[Jonboy]

Sounds like a u-joint problem to me.

[3r!c84]

Put the rear on jackstands. Chock the from Tires. Put it in drive and Let the wheels spin. Look under and see where the sound is coming from
Posted via Mobile Device

[triophan]

a local spring shop told me 2 days turnaround for U-joints... at $12 a pop, I can do 'em probably 4 hours total. Seems like no one around here doesn't suck.
We'll make it through the weekend and get the joints done and see what happens. I'm working the truck from ground up... so its not killing me to LIVE under it for now.

Gonna be sooooooo sweet though...

I'll keep you fellas posted. If anyone has any other ideas, or "while you're down there..." bring it on.

[mooseknuckles]

u-joints or bearings....I'm leaning more towards bearings tho.

[triophan]

well how do i check/replace bearings?

[silvereagle07]

My original truck rearend was making that noise. I put it on a lift and found out it was the pinion bearing. I just found a used rearend with better gears (3.42's)

[lakeroadster]

Originally Posted by 3r!c84

Put the rear on jackstands. Chock the from Tires. Put it in drive and Let the wheels spin. Look under and see where the sound is coming from
Posted via Mobile Device

And if you do this make sure somebody is in the truck while you are looking under the truck so they can hit the brakes if something goes wrong. I personally would double up on the jackstands too.

Safety First

[pkbinplano]

check exhaust also. Make sure everything is secure. Check exhaust manifold heat shields if you have them. While you are under there check your motor mounts and tranny mounts. I had a "thunk" for a couple of months and then it's like "doh" motor mounts. sure enough. Check your front brake dust shields. What I'm sayin is check all the free stuff first. ( something loose)

[rayfinseats]

thats at its worst around 55-60 mph.
Im thinking wheel balance or driveshaft balance !

[502ss]

Originally Posted by triophan

its more of a 'owwowwwowoowwowowowow..." if that makes sense.

Sorry man but this is the best post I have seen in a while!!
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[3r!c84]

Originally Posted by 502ss

Sorry man but this is the best post I have seen in a while!!
Posted via Mobile Device

haha i hear that sound but its not coming from my truck!!

[junkyardjohn]

OWOWOWO.. WOO WOOO WOO... PING.PING.PING.... YOU GUYS JUST MADE MY SUNDAY MORNING ENTERTAINMENT. JOHN

[triophan]

Glad I made a couple dudes days!

Lucky for me the two hour job of changing the u-joints has become a 14 hour thing, as I have specialty "conversion" joints. Luckily, with the help of another board member, I was able to find the cross-part numbers at the part store after trying 8 different ones in comparision to the ones I have and a lot of internet searching.

So, the 1st one was in stock, they ordered the rear- which should be delivered from the warehouse this morning...

Ahhh... this truck thinks he can defeat me. But I am bound to win this battle with a little patience!

Headed to the junkyard today to try to find a spare 10-bolt (maybe find one with 3.42s or 3.73s) to rebuild on the bench. After that, I'm taking a week off of working on this heap to save some money and do something that doesn't require being under the truck.

[sumran]

Sorry you are having extra trouble. Good to hear that you are not going to let it beat you. Makes for a good story later, but it stinks while you are in the middle of it.

Sounds like you will be ready for quiet, quality cruising soon.