Spooky after new axles! Help!

[slickemhoundd]

I put my rear axle in first after sending back fronts for standard rotation. Put them in monday taking it easy all week had NO problems at all, that weekend i went to the shore and anything above 60mph (GPS) i get this sound and feeling through the truck like dragging a mallet across spray on bedliner, seriously like no vibration ive ever felt. lasts for 2 seconds and stops for 2 seconds over and over. One week later put in the front axle, drove around everything tip top. go to the shore same thing again!! But it seemed as if the truck would chug a bit. Get to the shore driving around not a noise to be heard as usual. Get on the highway heading home there it is again! I drove 5 miles jumped off and took back roads home. I dont know what it could be, its only over sixty. Im thinking being regeard and cruising at the higher end of overdrive that it could possibly be a driveshaft issue? I also just put in new ujoints a few weeks ago BUT set the shackles at extra inch when installed rear. Could it be the pinion angle? But only high speeds?

 

[boominXplorer]

Did you set up the gears? Any pics of the pattern? If I had to guess either your driveshaft bolts are not tight enough or you didn't tighten the pinion bearing preload enough.

 

[slickemhoundd]

I didnt set them up my self but my buddy that has done my strip cars set them for me i do trust his work/judgment granted there could be a mistake. Ive heard bad rears and shot r/p's but this is quiet 100% of the time until 60. Actually the previous vibrations i had high way driving are completly gone but now i have this issue, as i said it sounds/feels as if a mallet is dragging across herculiner every 2 seconds. But also curious about setting shackles an extra inch high. Was going to throw the wedges in just incase but figured itd just lower me back down (sua). Is there anything i could check with out pulling the carrier? Also i did see the patterns and they seemed by my eye DEAD ON (meant to take pics). Also i installed the axles myself just not the gears, i know all bearings,seals were replaced in the spare axle that was built. As far as pinion preload how would i check that/effect drivability

 

[boominXplorer]

To check your pinion preload on the super quick all you have this..... block your tires front and rear, put trans in neutral. Climb under truck and turn the driveshaft back and fourth, there should be some "slop". Now grab the pinion flange/end of driveshaft and try to move it up and down(toward floor of truck and ground), there should be zero play.

By your hammer / herc discription it also could be that c/v joint in the front driveshaft. I would remove it and see if anything changes.