Okay, this has fooled everybody I've talked too, but it seems it must be simple.

Vibration starts at ~30 mph and continues to ~45 mph. Not very violent but you can notice it easily. Every part of the truck shakes, I feel it everywhere.

Thought it was a miss in the engine cause pressing the clutch caused it to stop. Then I realized pressing the clutch caused the truck to slow down and that stopped it. Speed up and press in the clutch and it vibrates

Thought it was tires. Took them to schwabs and had them rotated. They checked them and told me they were in balance. All inflated to 34 psi cold (per door jamb).

Any ideas? I don't want to pay $$$$ to have a tech look at it.

 

could be flat spots on the tires, or loose driveshaft components.. get underneath and see if there is any play in the joints.

 

Flat spots in tires, driveshaft out of balance, bent rim, trans tailshaft or stub shaft, or axle shafts..

 

If it was flatspots it would be throughout the the drive not just 30mph+ right? Do what CJM said and see if your rim is bent if not my money is on driveshaft.

 

For bent rims or rear axle shafts, lift the rear end in the air on jack stands and run the engine at idle and let it turn the wheels (block the front wheels well). Hold a pointer up to the tire face and see if you get any radial run out. If so, move the pointer to the lip of the rim and repeat the test. If run out is found there, check the brake drum/hub and see what it looks like.

Other option is the rear driveshaft, see below for some tips:
- http://www.4crawler.com/4x4/CheapTri...FixingProblems

 

thanks for the ideas guys I'll try them today

but Les Schwab checked the rims and didn't mention they were bent

 

i'd also start with a better inspection of the tires and wheels.... les schwab is pretty hit and miss when it comes to decent tech's. the other thing they do that bothers me is when balancing tires they don't remove old weights, they just keep adding more and more.

if your driveshaft has no play, try replacing your rear shocks. one may be bad.

Al

 

hmmm another thing I didn't think of was I didn't notice this before I aired up the air shocks. Might try lowering the pressure and see where it goes

 

I'd take off the air shocks, you'll probably get rid of the vibration and get a lot better ride with even cheapo gas charged shocks.

 

no way, I love the air shocks. You can easily adjust them depending on your load.

 

I have seen tires seperate internally .. what I would do is borrow , or use another set of tires and rims .. install them , and run and see if it eliminates the problem ..


.

 

hmm will try

 

didn't you just add a lumber rack on your truck? did you have anything on it? Just a shot in the dark but when I was working construction the racks on our work trucks played havoc with what ever aerodynamics the truck had.

only thing that I can think of since the other ideas have been mentioned...

 

Sounds like you driveshaft, I had the same problem, and i figured it would be alright for a little while until i could get my garage cleared out to fix it, and the front of the drive shaft dropped out while i was driving (30km/h), just make sure your bolts are good, and there is no play in your universals

 

any luck narrowing down the source of your vibration?

 

Try taking the mowing deck off.......











































But if it's your truck you are referring to.....









































I'm replacing my U JOINTS tomorrow(4Runner). And you're symptoms sound identical to mine. But I also have a Squeek at low speeds accelerating up hill, or getting up to speed, then when I hit about 20 MPH, the squeek stops, but the vibration starts, but after about 40-45MPH, all is quiet.

 

well tried it with different wheels and tires and got the same results. Airing down the air shocks helped quite a bit, so I'm not as concerned about it now. Thanks for all the suggestions.

Oh, and stormin, the deck has not worked since 2004

 

I would go with bent rim or out of balance tire. I have the same problem with my nissan truck after I swapped over the tires from my 4runner. The wheels on the 4runner had worn a weight on the inside of the wheel from rubbing on the caliper when I swapped them over to the nissan the vibration only shows up in 4th gear at the bottom 35mph to about 40 something.

 

Never thought of that becuase my truck did the same thing, but i put new rancho's on it, hopefully she'll ride smoother since both old ones were *$#@#%. Hav't had a chance to drive it since though

 

Not sure if you ever figured it out but I will give my .02

The first thing, when describing a vibration (especially on the web) its important to mention the frequency of said vibration. You mentioned "vibration" and "shake" in the same sentence. To me, those are 2 different things.
A low frequency vibration would feel like a washing machine out of balance and would indicate something out of wack with tires, rims, rotors ect. A high frequency vibration feels kinda like a D.A. sander does in your hand, usually indicates a driveline problem. I would start with the rear drive shaft assuming the vibration is still there with the t-case in 2WD and the front hubs unlocked. A common problem are the slip-splines on the drive shaft. With the trans in neutral, try to wiggle the the shaft at the splines. If you get movement, its probably your problem. This would also explain why the problem goes away when coasting with the clutch in.
Im assuming you have checked your u-joints, but are they "in phase"? Out of phase u-joints would cause the vibration to come and go at different speeds.