Lifted rear now I'm having problems

[-Jake-]

Ok I got my F150s rears installed last weekend and took it for a spin and it vibrated BAD and when I let off he gas or throw the trans in neutral it makes a growling sound.  I pulled the rear shaft and drove around in 4wd just to isolate the rear shaft.  Sure enough it was the rear shaft.  I checked the u-joints they were a little sloppy so I replaced them.  No change at all.  Starts from a stop and gets a little better but still vibrates all the way up to 60.  I'm wondering if the driveshaft is WAY out of phase or is my transfer shot?  It almost sounds like it is coming from the transfer.  If I get going 60 and throw it in neutral is starts growling immediately.  I dont know if it from unloading the driveshft and u-joints or if the rear shaft is pulling on the output of the transfer.  I am lost guys.  HELP!!!

[micahturner]

How does your pinion angle look?

[79coyotefrg]

your wondering if the shaft is out of phase, go look and see

[-Jake-]

Pinion angle isn't too bad.  I ran the F150s backwards and I made shackles that are 6.5" from center to center.  Its probably pointed up 3*-5* or so.  The angle at the transfer is fairly steep though.  I'd guess the 150s gave me about 4" of lift.

[-Jake-]

your wondering if the shaft is out of phase, go look and see

Ok I *think* it might be out of phase but would that cause a growling when coasting?

[Cheesemaker]

Do you have a CV joint in the front of the d-line?  And the pinion must be pointing to the t-case output. 
Is it possible that the d-line is out of balance, or slightly bent? 

[-Jake-]

Do you have a CV joint in the front of the d-line?  And the pinion must be pointing to the t-case output.  
Is it possible that the d-line is out of balance, or slightly bent?  

Nope but I am starting to think I am going to have to pony up the money to have a shaft built with a cv.  Haven't torched off the old spring perches yet probably need to do that too.  The driveshaft could be out of balance but is definitely not bent.  BTW it is a pretty violent vibration and growling people stare when I drive by.

[79coyotefrg]

post a pic of the driveshaft

[-Jake-]

It'll be a while before I am able to sorry.  I kept it at my parent's place because I live 150 miles away and I wasn't about to try to make it home with the vibrations.

[79coyotefrg]

why did you mount the f150's backwards??

[-Jake-]

If I ran them forward then I would have had to added something onto the frame to weld on new shackle hangers

[88_Pathy]

why did you mount the f150's backwards??

So you don't have a huge over hang

[micahturner]

My money is on the pinion angle. I had the same problem when I installed my 63" Chevy leaf springs. I would try some shims in the back to see if that eliminates the vibrations. If that solves the problem you know you need to turn your pinion.

[84t0y]

you neesd to have a cv joint at the t case side, do you have one of the two piece driveshafts? if so thats definetly your problem, get a one piece with a cv.

[79coyotefrg]

So you don't have a huge over hang

i dont have huge over hang,  my shackle  only moved rearward 4 inches from stock

[79coyotefrg]

you need to have a cv joint at the t case side, do you have one of the two piece driveshafts? if so thats definetly your problem, get a one piece with a cv.

i didnt need a cv , and its only got a slight vibration at 80 mph or more

[84t0y]

you have a one peice drive shaft dont you?, with a two peice you need to change it, with a one piece you probably wont.

i didnt need a cv , and its only got a slight vibration at 80 mph or more

[-Jake-]

yeah i have a one piece

[Steve_925]

did the axle move back? maybe the slip splines are almost pulled apart

[-Jake-]

did the axle move back? maybe the slip splines are almost pulled apart

nope it is dead center looks like the driveshaft slip is out 1/2" farther then it was.  Whats your guys' thoughts on a 5* shim or thereabouts?

[84t0y]

if you can see the splines you should get it lengthened.

[-Jake-]

definitely no splines showing

[ROCKO]

grease your driveline and if the noise goes away a little then its defently your drive line...i had the same problem and ordered a new drive line

[86turboyota]

Mine did something very similar before i added a CV joint to the rear driveline and it did again when i had a bad ujoint.

[-Jake-]

I greased it up and replaced both u-joints.  My plan is to throw some angled shims in it and see if that corrects it.  I know the CV plus new perches would be the *right* way to do it but I'm poor so shims it is!

[germ]

As I recall, the angles at either end of the shaft have to be within about 1 degree of each other or you will get a killer vibration. The closer the angle, the less vib. CV joint is basically a way to cheat this rule of physics. I'd also check the phase of the D-shaft.  I had a LC, and the guy accidently pulled apart the shaft, and when he slid it back together the u-joints were out of phase, and it shook like Elvis on speed. Put it back together correctly, and it went away.

Erik

[79coyotefrg]

you have a one peice drive shaft dont you?, with a two peice you need to change it, with a one piece you probably wont.

i have a 1 piece shaft since my truck is a shortbed

and it is stock,  1 ujoint at each end,  F150 springs in the rear 5 inch allpro's up front

[-Jake-]

Figured it out!  It was out of phase as I suspected.  I had the yokes lined up like this | -- instead of | | made a huge difference no vibrations at all now.  Also got my new wheels and 37s picked up.  Next weekend/week is RUFs, high steer, body lift, tube bumper and mount my 8274.  Woo Hoo!

[-Jake-]

Crappy cell phone pic

[germ]

Sweet! glad it was so simple.