Rough Ride

I own a 2004, 2500 HD Duramax, Crew Cab, 4x4, short bed. Wanting bigger tires, but having height requirements, I had my truck leveled. I was told they only replaced the Alignmnet CAMs and brackets and did NOT tweak the torsion bars. I also added after market wheels and 285x75x16 tires Anyways, my truck starting riding rough. Really rough on concrete roads. It seems to vibrate mostly an 45 and 75 mph. I took it in to have the tires checked and they we really out of balance. They rebalanced the tires and no longer then one week later, the truck starting vibrating again. After several tires rebalances and a front end alignment, the tire store graciously swapped out my tires for another set/different brand. Anyways, my truck still vibrates. Any ideas on what might be causing my truck to vibrate? I checked the front end and can't find anything unusual

I don't know for sure, But I read that with the Duramax you can have all sorts of driveabilty problems with large tires. Maybe it isn't actually the tires vibrating.

Was the front suspension lifted at all, fi so the front drive line angle may have increase and that causes a front vibration from the front drive shaft, I know most Chevy HD lifts require you get a new longer front drive shift

Like the whole cabin literally vibrates, or is it more of a sound than actual vibration? The torsion bars not being tweaked could easily be the problem, but why wouldn't they tweak them with the other susp. parts? just wondering.

I was told that tweaking the torsion bars for lift is a big no no since it will alter the alignment and the way the suspension reacts in that it takes away some upper travel and may top out on the frame stops instead of letting the suspension cycle properly. Thats what I was told by suspension "specialists".

I don't know much about it, so im not ganna lie and say some big words or mumbo jumbo, but he said it would alter alignment, and if your alignment is a problem maybe he is backwards...haha. And letting the suspension cycle properly? And by being lifted wouldnt the travel be better? I don't know what kind of lift there is or anything on it, but im just blowing air out my ass pretty much lol. Sorry i can't help.

Funny thing is it does add "lift" to your suspension but doesn't mean if you have a 6" lift you have 6 mor inches of travel! On my truck I have a 6" RCD lift, The upper arms remain in the stock location due to the knuckles being extended and the lower arm mounts are 6" lower but, If you look at your front suspension there are stoppers on the upper arms to keep them dropping too much just as there ar stoppers to keep the suspension from allowing you to bottom out. Between these two points is where the suspension needs to be in order funtion the way engineers designed it to work and your truck to be safe on the highway. Lifted ot lowered the suspensions has to always be able to "cycle" Sorry for being long winded!

I know what travel is and how suspension works. I have a 3" Travel upgrade on the rear of my truck. I don't remember the name of the brand but my uncle and I put on new shocks on along with the travel lift. I just never heard of a suspension cycle.