LB7: LB7 Shaking/vibration issue

[jonathancasey19]

Need some help figuring out what could be causing a heavy vibration/shaking feeling most noticeable at high speeds approx. 70-80 mph? It's so bad you can hear your voice shutter, radar detector can't stay on windshield, whole cabs squeaking.

Tires were just rotated this week and front end alignment. No clunking or binding. Just horrible vibration. Checked balance rates this evening. Four injectors are out of spec + - 6 in D. Oil pressure seems fine, all temps okay.

 

[ripmf666]

any fuel in the oil?

 

[bullfrogjohnson]

Whens the last time you had your tires balanced?

 

[MACKIN]

Whens the last time you had your tires balanced?

x2 Probably a bad tire ,belt or balance.

 

[DIESELMAFIAPER.LB7]

X3 tires or possibly u joints I would check the u joints to be safe, sounds like you'll need some Injectors though

 

[jonathancasey19]

I've been meaning to replace the injectors at some point. No fuel in oil (second time cross fingers). I thought bad injectors would result in a rough idle not at high speeds.

Travis, the tires were balanced using internal beads. Could they be out of balance anyway?

U-joints are very old. No squeaking but it wouldn't hurt to replace. I could start there.

Thanks

 

[MACKIN]

Not Travis but I'd have the tires 'checked' I'm not a big fan of the beads. They're probably good at low speeds but at the speeds your talking I'll bet that is the culprit

 

[RENODMAX]

The stick on weights have always been fine for me. Good tires shouldn't take much to balance. Is your truck doing anything else
strange? Smoke at idle etc

 

[jdlover1]

Is your tires cupped any?

 

[MuscleTruck03]

does it do it only under a load or just cruising at that speed?

 

[DuraTitus]

I agree.
Sounds like tires.

 

[jonathancasey19]

Jordan- Nothing else strange that I know of. No smoke or other injector symptoms except few bad balance rates. I was worried it could be a motor mount?

Wade- Tires have definitely been under inflated but not sure if they are "cupping". That would explain the vibration. These mickey thompsons are great tires. I love them, second set actually. You would think if I were having a cupping issue, the mechanic would have mentioned something when he did the alignment last weekend.

MuscleTruck- It is most noticeable cruising only at high speeds in excess of 65 mph.

I'll take a better look at the tires tomorrow.

 

[Chevy1925]

is its like a bucking sensation like when goin down a bad freeway or is it like a high speed vib that you feel in the floor board/seat like your phone is on vibrate?

 

[RENODMAX]

You can pull the motor mount easy I'd yank the driver side if you think it's bad. Does your truck shake when you shut it down?

 

[sparepartsracing]

what tire pressure you run at..... any play in the front end on anything?

how cranked are your torsion keys?

 

[jonathancasey19]

is its like a bucking sensation like when goin down a bad freeway or is it like a high speed vib that you feel in the floor board/seat like your phone is on vibrate?

Definitely a high speed vib. It gets so bad your vision is affected...

You can pull the motor mount easy I'd yank the driver side if you think it's bad. Does your truck shake when you shut it down?

Oh yeah of course....but I figured all diesels do that lol
I read a thread on here somewhere ab an easy motor mount fix. How do you know if it's bad?

what tire pressure you run at..... any play in the front end on anything?

how cranked are your torsion keys?

Running 50 lbs in front and 52 in rear. Tires are not cupping. Torsion keys are barely cranked with this cognito lift. All angles are great. Front end is in good shape (pitman/idler, wheel bearings, tie-rods, ball joints etc..).

I'm at a lost here. Aggravating as hell.....

 

[DIESELMAFIAPER.LB7]

Did you check u joints it sounds just like Mine when I lost some u joints

 

[wdino73]

Also check your driveshaft make sure your weights are intact, that's my 2 cents... Good Luck

 

[MuscleTruck03]

I hear ya man, my truck has a vibration too but its only from about 70-85 and its the worst at 75, except my truck only does it under a load. Ive done u-joints, tires, transfer case, trans.... all that stuff has been replaced so I dont know what to tell ya! also mine doesnt shake like yours, mine just gets a noisy humming and vibrates the whole truck. let me know if you figure anything out as im frustrated as hell too!

 

[RENODMAX]

Wheel bearings, and ball joints may be a culprit too. But id start simple with the tires.