I have a 2006 KR Crew Cab with the long bed. I have a 4" BDS lift kit on it and for as long as I can remember the truck has had a "bounce" to it. I first thought it was due the tires I had (BFG Mud Terrains 35's) but with the recent purchase of different tires, the bouncing is still there.

Is there a way to stiffen the ride of the truck?

 

Bouncy seems more like a shock problem. Is it the whole truck or just front or back.

 

It seems to be the whole truck.

I also get a little shaking in the steering wheel between 35-40mph, it goes away after 40mph.

 

Might be a drivetrain shake. Does it get worse with more speed? You might have something bent.

 

Did you shim your carrier bearing? If not that can be the source of the vibration.

 

It could still be the tires as well. Confirm even tire pressure as well as correct pressure. if you get similar vibes at a higher speed it very well could still be the tires but as you have shimmy, confirm all your front end components are in good working order especially ball joints and the crap ford shocks. SD's can go thru these quicker than you may think. Reconfirm tire balance as well as alignment.

Trash the junk OEM stabilizer and replace with a higher quality, even a dual with your 35's if you haven't already.

 

I have not shimmed the carrier bearing but I will now take a look at that and see if that stops the vibration/bouncing of the truck.

Thank you for the advice.

 

ours was doin the same thing then got new shocks, and got an alignment. solved our problems.

 

I also have a 2005 crew cab long box and the bounce is ridiculous. I thought it was the box but now comfirmed that it is the cab that is bouncing. When I look in my rear view mirror it looks like the box is about to fall off but if I look behind me you can see the box is stationary and the rear of the cab is boucing up and down. I installed Bilstin shocks (as people suggested) and nothing changed. I am contemplating changing my cab mounts but they are almost $1000.00. If I knew it would fix the problem I would do it but I still cannot be sure if that will do it. It looks like the cab is pivoting (front of cab is stationary but rear of cab is bouncy). Thoughts???

 

That is frame flex, I think the purchasing dept at Ford ordered spring steel for the frame rails that year.
I do support for Baja races with my 05 and, at least, the flexi-frame gives good traction!
I get tire bounce with my 35's running lower pressures, its a pretty unavoidable tradeoff for ride quality and traction.
Your tires are a suspension component that shocks can't control.

 

That only helps u-joint binding on acceleration.

BTW, you can make the shims yourself out of 1/4" strap; should take about 4-5 to get rid of the binding. Stock bolts should be long enough.

That carrier bearing spacer SHOULD have come with the lift kit, did you do it yourself or have a shop do it?
I'd look at the parts list for the kit to see if it was supposed to be included.