Hey ! I like that drillin and tappin Zerk idea!

Smokie

 

With mine all i can explain is. Bumper to ground was say 18".. Bags at 0. Hitched up the 5th wheel. The weight dropped the truck to 15". Pumped up air bags to get it back to 18"=80psi. I noticed a distinct shudder just leaving a full stop. I jumped out and lowered my bag pressure to 50psi. . Shudder was gone the rest of the trip. When i got to where i was going i measured 16" Bumper to ground and bags still at 50psi.. But was the ground flat? Unsure. I know my Truck likes 50psi with the 5vr on its back. On way home, Pumped up to 80 again. Shudder returned. Back to 50psi it and the was shudder gone again.. shudder was repeated.
I also want to check my slip joint for grease and possibly change my universals before the Myrtle beach trip in September.

Edit. Note. With bags at 50, No trailer hooked up. The back end is 'up there'. High rider.. Still no shudder. I think it had to do with the heavy load and the angle it was at. Just guessing though.

 

I'm consulting with one of our engineers about this. His theory is that under load, you are experiencing more axle wind up and that is increasing your pinion angle. So, add the wrap up to the extended ride height and the shudder comes from timing inbalance between the two u-joints. Axle wrap up is a very common consideration for us but I have never heard of it being an issue with this product. I hope this helps.

 

I would check to see if it does it worse while turning sharp from a stand still,could be time for a rear diff. oil change,if so be sure to use an oil that has the friction additive,or get some and add yourself,check the slip yoke too as others have said...