New member, thanks for having me.

On to the questions..... 1999 Ram 1500, 5.9, 4x4. Yes, I read and searched the forum, but peoples descriptions/symptoms seem kinda vague.

I have a vibration that manifests itself quite frequently. Happens at all speeds, engine on or off(rolling down hill) Not constant, it will start small, rise to a crescendo(at which point my cup holder is bouncing up and down, spilling the morning lifeblood) and then fade away for a while, rinse, repeat, rinse, repeat...... 2WD or 4WD, same thing.
I feel it in the body of the truck, feel it through the seats, I see stuff bouncing up and down in the cab, it's not wheel balance, nor is it the dreaded DW (lotsa experience with that, also have a jeep.....)
Granted, the front end needs some work, but it's definitely not the front end. Not the brakes. It almost feels like the driveshaft is out of balance, but I checked the u-joints for play and they seem ok. It;s almost like a couple of things are syncing up and then it starts until the sync goes away. I did find a bad front hub bearing(replaced on the side of the road somewhere in SC during a road trip- did I mention I'm a semi retired mechanic-and always carry tools?) That wasn't it. Literally, I could make a milkshake in the cab when it starts. And I'm kinda tired of all these guys on my lawn.....
I'm at a loss of where else to check, This has gotta be a Ram thing. Anyone? Bueller? Bueller?.....

 

Might be a dry u-joint...... heat makes them do silly things. I have also seen having the rear brakes adjusted up too tight cause similar problems...... drum heats up, and you get a nasty vibration. But, those usually don't go away until you stop, and let it cool for a bit.

 

It does it rolling down a hill, meaning low speed. I would put the four corners on some solid blocks or ramps with block of wood on them then put it in 4x4 and drive then let the wheels roll while I was under it looking at the wheels/axle shafts/drive shafts to see if it'll show me something that ain't right. I would also put my ear to the transfer case while things are spinning.

HeyYou mentioned rear brakes, I had a blown wheel cylinder and it made that tire lock up at low speed on gravel when I breathed on the brake pedal. Brake fluid makes those pads really grabby.

 

You say it's not your front end but I think that's where you should start. A lot of loose components and stuff can start causing vibrations, shakes etc. Take your driveshaft out and inspect the joints. Replace with Spicer joints if they are bad.

I just went through chasing a vibration on mine and replaced a lot of stuff I knew was wore out...track bar, sway bar bushing and end links, shocks at all four corners, had the tires balanced, wheels aligned and a few other minor things and that took care of the vibration 99% (i think my 10 year old cupped tires are the other 1%).

 

Planning on pulling the driveshaft tommorow, right after I pull a trans out of an S-10 with a suspected blown rear freeze plug......
Thanks for the tips

 

Gotta check the rear brakes, I think they are way out of adjustment, but who knows what I will find when I get in there, the PO was a bit of a kludge....Had to pull a BobCat the other day, noticed the brakes seemed off. Fronts are good, just did them. Prolly upgrade to a DOT 4 fluid while I'm in there, I have a Vacuum bleeder so it's a quick job, and I like having that extra bit of temperature resistance, I tow, a lot.

 

You should get a 2500 then.

 

Check to see if front driveshaft was removed and put back in out of balanced, that happened to me. I have been chasing a vibration for 2 years now and replaced everything even took it to a shop they had it up in the air running and they said everything was good. It's a Ram thing

 

It's a good idea to adjust the rear brakes at every oil change since the stock adjusters don't do their job very well. You don't even need to take the wheel off to adjust the brakes if you have the knock outs replaced by rubber plugs on the back of the drums, you just need two flat heads and a jack.
Which pads did you put on there? I learned my lesson to not get ceramic or Wagner Thermoquiet pads.
Since you tow a lot then helper springs or airbags would be a good investment. I have add a leafs and they make the ride pretty stiff unloaded but they're great when I load the truck down because it barely squats.

 

The factory adjusters are pretty much useless, coupled with the fact the are designed to operated when you use the parking brake(who here with an automatic uses the parking brake?- Show of hands?) I used the Advance brand pads, (carquest now) usually middle of the line, I have a commercial account with them, my side work is as a mobile mechanic, and I can generally get them to deliver wherever I am. Definitely want to add a helper, running 18 inch rims with 275/70 tires and a 2 or 3 inch lift, and the back squats pretty good when I load up. I was toying with the idea of just bolting some 2500 springs in, but they are pretty hard to find used around here. When I figure out how I will put up a pic of mine.