My truck. vibrates real bad at about 70 MPH. It rides a lot better at about 55 and 80 mph.

It was a lot WORSE before I got an alignment, but now that I got an alignment, it's still pretty bad- I mean my teeth literally chatter at 70 MPH (60MPH on the speedo b/c of 35" tires)

My instincts first said "tire balance"- however, I feel the same vibrations (although much subtler) at extremely slow speeds (like roll from stop uphill at 0.002 MPH. In these situation, I get tons of "shakes" without even getting a full tire rotation.

It also seems "worse" if I turn my steering wheel slightly to the right (like shifting lanes from the left to the right on the highway- it gets much worse).

Any idea what it could be?

New Wheel bearings and front ujoints (was doing it before these were replaced). New front axle seals too. Alignment done today.

I doubt camber could have anything to do with it, but my camber is way off- -1.3 degrees front left, -.09 degrees on the front right, but those aren't adjustable.

 

?....how is the camber not adjustable....when i got my alignment last year they gave me a print out, and the toe-in and camber was changed, because they were both off....


and that def. sounds like misbalanced tires.....with my new tires, they have come out of balance a couple times. Its not an out of the ordinary thing.....id have them rebalanced, and make sure you have the same PSI in each tire...for front and rear....i mean you can have 50psi up front and 60 psi in rear, but make sure the fronts match, and the rears match

 

your camber is only changed by offset ball joints. how about your rear u joint.

 

did they play me at the alignment place? im being honest the print out showed before and after and my camber was changed.....hmmmmmm

 

Camber can change SLIGHTLY from changing the Toe, but the toe is the only thing adjustable on these rams.

So if it changed from .3-.5 or something like that, it makes sense that is from the tow adjustments. If it's -1.6 to .03 or something, I'd be a little worried about what the alignment place did!

 

I checked all my ujoints. Look solid. I replaced the two fronts because they were both shot (and both front wheel bearings because one was shot).

Clearly the only other thing I can think of is that it's the drive shaft, but besides a tiny (and I literally mean tiny) bit of rust, there are no gouges or dents or anything that I can find.

Are there any Ujoint "tests" besides trying to turn them side to side to see if the bearings are shot? (it's possible one of the Ujoints is "going"- not turning well), but then the heat build up should cause it to "go out" very soon, and I've put over 1500 miles on it and I've had that vibration issue since I bought it. (I thought it was the front Ujoints when I bought it).

The only other thing that looks "funky" is the Toe for the rear tires- not adjustable besides moving the axle on the leaf springs, but the left is .46 and the right is -.08. Thats fairly significant?

 

Side note, how do you select your PSI for your offroad tires?

I've got 20 PSI based on the fact that the "max load rating" is at 20PSI on the side of the tires. Should I increase the PSI anyway towards 40 PSI or so?

they are pro comp all terrains.

 

20??????? Are you sure you aren't reading that wrong?

 

My old 35x17.5 x15Mickey Thompson Baha Belteds were 20 PSI too.

These pro comps are 35x12.5x16s, and its 20PSI Max load rating. There is no max PSI rating however. Seems pretty common with straight up offroad tires. If I can safely increase the PSI for onroad driving I will. I've got a 1200 mile trek coming up in a week and a half, so that might help my gas mileage too!

Anyone have any idaes?

(Side note, "HeyYou" was the name of the guy who used to always help me out on the 3kgt forums. Kind of ironic that you share his name)

edit:
OK, I accidently lied. The new trick (Pro Comps) are 35 PSI, and I have them loaded accordingly. The old MTs were devinately 20 PSI. I have a photo of of the load rating from when I sold them.

Same question though- 35 where its at or can I push that?

 

Just a thought: Those MT's of yours are pretty wide, like 315 mm or so if I figured right. I don't know if you're in snow country or not, but if so, you'd probably agree that those tires won't do very well in it. Maybe try to locate a cheap set of "normal" sized tires and rims for winter use, and see if the vibration goes away with them on. Might just be those tires - they've gotta be harder to balance than something like an LT235/85/16, and make more trouble if they throw a big-a$$ weight.

If you're not in snow country, it still might be nice to have one set for off-roading, and another set for everyday driving. They might just pay for themselves if (when?) gas finally hits five bucks.