Symptoms of a bent axle shaft? (1 Viewer)

[hammerheadfistpunch]

I just replaced my shocks (ICON) and front driveshaft with a double cardan and while much of the vibration and grr is gone, there is still some there, especially at freeway speeds. I am going to balance my tires (again) tonight but Im wondering if maybe I have a shaft runout problem, what kinda of symptoms does a bent shaft cause?

 

[nukegoat]

I just replaced my shocks (ICON) and front driveshaft with a double cardan and while much of the vibration and grr is gone, there is still some there, especially at freeway speeds. I am going to balance my tires (again) tonight but Im wondering if maybe I have a shaft runout problem, what kinda of symptoms does a bent shaft cause?

It wont bolt to the hub very easily

 

[hammerheadfistpunch]

It wont bolt to the hub very easily

Front, not rear.

 

[nukegoat]

Front, not rear.

Oh

 

[gummycarbs]

there is still some there, especially at freeway speeds.

Still some vibration, or some grrr, or both?

 

[LINUS]

Did you change your springs or change the caster?

You could swap back your old non-DC unit & see if it still acts like it did prior.

Shocks alone aren't going to change caster, so without knowing if you did springs the old shaft/same behavior may be worth a try.

It's a heck of a drive, but I just found a new DC FR shaft when cleaning last weekend from my old LX450 spares days. Still has a sticker on it.

 

[hammerheadfistpunch]

Did you change your springs or change the caster?

You could swap back your old non-DC unit & see if it still acts like it did prior.

Shocks alone aren't going to change caster, so without knowing if you did springs the old shaft/same behavior may be worth a try.

It's a heck of a drive, but I just found a new DC FR shaft when cleaning last weekend from my old LX450 spares days. Still has a sticker on it.

Just shocks, the front PS was shot because of the vibes (rubber bushings destroyed). The vibe is still there and the castor is the same, I am about 2-3 degrees off of perfect for a DC shaft. The old shaft was much worse. I just wonder if its a balance issue in the shaft? a bent axle shaft, or out of balance (old) tires.

 

[hammerheadfistpunch]

Still some vibration, or some grrr, or both?

Same vibes, but much less. Kind of a bearing noise on power. I still need to replace the rear DS with one I have and that may do it but it sounds/feels like its coming from the front.

 

[hammerheadfistpunch]

Still some vibration, or some grrr, or both?

Same vibes, but much less. Kind of a bearing noise on power. I still need to replace the rear DS with one I have and that may do it but it sounds/feels like its coming from the front.

 

[LINUS]

A bent axle shaft (as in the inner shafts of the FR) - you'd either be doing the birf soup or doing it real dang quick, plus you'd hear the sound of schrapnel in the axle shell, short of a quick drain of the diff juice & looking for the pretty sparkles.

Maybe get the tires rotated FR to RR if you're already up on a hoist getting balance work. Isolate them out of the picture.

 

[richardlillard1]

It’s probably not the front shaft that makes the noise. On mine it’s the tcase end of the rear which is angry.

 

[hammerheadfistpunch]

It’s probably not the front shaft that makes the noise. On mine it’s the tcase end of the rear which is angry.

Methinks the T-case front output is unhappy. probably from many many miles of bad vibrations.

 

[-Spike-]

None of the axle shafts are load-bearing, it would be tough to bend one.

 

[BILT4ME]

Can a DC shaft be Out-of-phase?

 

[-Spike-]

Can a DC shaft be Out-of-phase?

Nope, but it can be at bad angles. The single u-joint technically should have no bend to it at all. That's a rare occurrence, and many 80's don't have perfect geometry for a DC drive shaft. Slight angles often don't vibrate enough to bother the owner, but every truck and every driver are different.

Normally, the 2 u-joints in a drive shaft counteract each other- when one joint gets longer, the other gets shorter, back and forth. A dual-cardan joint works the same way, the two joints counteract each other. That leaves the single joint on its own, so if it has any angle to it it's constantly getting longer and shorter as it rotates, which causes the assembly to vibrate.

One method of troubleshooting is to remove the front (or rear) driveshaft entirely, lock the CDL, drive it and see if the vibration is gone. If not, the driveshaft isn't the issue. Unfortunately, if the problem does go away it doesn't necessarily mean the driveshaft is to blame, but it does indicate you're in the right area.