Trying to figure out why the rear 5100's got so bouncy so soon. No leaks, and still have decent compression, but they failed the bounce test. Swapped them out with KYB, and noticed an immediate improvement in both ride and diminished vibrations.

Is it possible that the vibrations from the bad pinion angle caused them to fail sooner than they should have? With 600 or more in the bed, when I came to a stop the truck would rock back and forth several times before settling, and after swapping to the KYB the rock went to once and done, a clear indication of worn shocks. When I had 1120 in the bed and it was on the alignment rack I saw first hand how much bounce the truck had when the tech bounced the truck hard several times and the truck kept bouncing 6 more times when he let go, but bounced once and done in the front like it should be, I have 5100 in the front as well, all installed at the same time. He did the test a few times as neither of us could believe it. Prior to replacing the shocks the pinion vibrations were quite noticeable, and with the KYB they are clearly diminished. For the inspection by the ASE mechanic for the LL suit, I am going to put the 5100 back on only so the vibrations can be clearly felt.

 

So you're going to put defective shocks back on to try and identify a problem? How do you even know they weren't defective to start with?

Why Ford won't cover warranty issues with aftermarket products installed in starting to make sense now.

 

I'm assuming Bilstein will replace the worn shocks under their lifetime warranty? Wonder if warrantied shocks come from a different pile than the backordered regular stock.

Well.. just realized everyone now has them in stock, so that doesn't matter anymore.

 

Putting them back on to prove that there is indeed a vibration issue that the new shocks now mask. Doesn't take rocket science to figure that one out. And I already stated that they failed the bounce test, or did you not read the entire post?

Yes, already have the RMA number, but not in a hurry to send them back just yet, once the inspection is done, I will take them off and put the KYB back on and send them in.