Aggressive unidentifiable shake.

[Quinlan_C-E]

Aggressive shake in truck.

I bought this truck (94 eclb idiT 4x4) 4 months ago, ever since I bought it it's had an aggressive vibration that Is annoying as hell and I can figure out what it is, so far this is what I've changed to try to solve it

-new rear driveshaft, all new Spicer U-Joints.
-4 new bilstein shocks
-new front leaf springs, hoping it would bring the front end up and potentially make driveline angle better.
-Pulled cover for rear diff, no metal, looked in good shape
-Pulled rear half of transfer case and thoroughly inspected
-replaced all 4 tires
-replaced 1 rim that had a small bend in it
-inspected, repacked front wheel bearings


The vibration is worst around 60kmhr and Is felt at every speed above 40, it feels like driveline mixed with an unbalanced wheel but I don't know what else to change since it's all been replaced.

I'm about 3k into parts and countless hours trying to fix it and am at the point of selling the truck and taking a loss. I don't want to spend more money on a diff and transfer case and still have the same problem.

Any ideas are welcome and appreciated.

 

[Quinlan_C-E]

Also I shut the truck off and put it in neutral going highway speed and the issue persisted.

 

[nelstomlinson]

I usually figure the Ford shakes are bad suspension bushings. New springs would include new spring bushings, right? You probably had someone check the alignment after the springs? Are the tires wearing funny?

 

[Nero]

Did you have the driveline balanced, or just slide new u joints into it? An out of balance driveline sounds like what you got going on

 

[Quinlan_C-E]

Yes I had a driveline shop cut out a dented section, weld In a new tube and balance the whole assembly, aswell as replace the U-Joints.

 

[Quinlan_C-E]

Yes new spring bushings. Also replaced the drag link and tie rods with moog parts and had it professionally aligned as well, no funny wear in the tires.

 

[nelstomlinson]

Does the vibration impair driving? Sounds as if you're not damaging anything, if you can drive it safely, drive on.

 

[MIDNIGHT RIDER]

Could be a bad drive-shaft slip-yoke.

Could be a bad carrier-bearing.

Most mechanical stuff vibrating that bad will soon show itself - which is actually cheaper than trying to find the problem.

If stupid radial tires, that is the first place to look --- but, you replaced the tires and the shake is still there.

Did the new tires change the shake in anyway ?

Did the new tire place put some sort of balance bead foolishness in the new tires; if so, you may have just got rid of a bad shaking tire and replaced it with four new shaking tires.

Point the thing toward Aunt Rhodie's and get the tires up off the ground and get in there and drive until it starts shaking while an innocent bystander observes from a safe place.

 

[Quinlan_C-E]

Thank you all for the advice, I've had it on jack stands with the front of the truck chocked against my tractors tire and ran it up. That's how I determined the driveshaft was bent and the one rim was bent. I had it full speed in 5th gear but couldn't determine any problems after replacing those.

My brother and I both replaced the tires ourselves at a local shop we have access too so there's nothing funny there, all the new ones balanced out good. It didn't seem to change the shake at all. I did notice after changing the driveshaft that the vibration was reduced, which points me towards the driveline still.

Also I forgot to mention, carrier bearing is new as well as the slip yoke, as one of the ears where the U-joint cap seats was slightly damaged.

The vibration appears to be not damaging anything but it's bad enough the dash and every panel in the truck makes noise.

The truck is a 4x4 so what if I removed the rear diff entirely and got it up to speed to see just running with the front axle to take that out of the equation?

 

[Cant Write]

That’s exactly what I would do, drop the front shaft and go drive it.

If shakes persist, then reinstall and drop the rear shaft and go drive it, if still persist, then scratch your head....cause I’m not sure what to do about the slip yolk in the transfer case if the front half of the rear shaft would cause your problem.

Does it dog walk down the road?

I hate the shakes, all cases

 

[Quinlan_C-E]

It doesn't seem to be dog walking, but ill pull a driveshaft and run it in fwd and rwd and update here if anything changes.

 

[KansasIDI]

It doesn't seem to be dog walking, but ill pull a driveshaft and run it in fwd and rwd and update here if anything changes.

Those transfer cases have slip yokes, so by removing the rear driveshaft you are unsealing your transfer case essentially…

 

[Cant Write]

Those transfer cases have slip yokes, so by removing the rear driveshaft you are unsealing your transfer case essentially…

I was thinking he might be able to run it with the front half of the rear shaft still in place due to the slip yolk. Is that not possible?

 

[Quinlan_C-E]

Right, I disconnected the shaft after the carrier bearing as to not loose fluid and make a big mess under my truck, the vibration is still there but so much less if you didn't know to pay attention to it you wouldn't even notice. This leads me to believe rear diff?

I'll removr the cover and pickup some gear marking compound and run a pattern and see if it's all out of whack. The cover has some paint marking on it as if it came from a junk yard so maybe someone just slapped a junk yard diff in and sent it.

 

[Black dawg]

Is the rear driveshaft phased correctly?