Frustrating dana 30 cyclic front end noise after regear+truetrac.

[aplchn_mtngoat]

1996 Jeep XJ Dana 30 reverse rotation axle. I recently did a front end regear (4.56) and installed a truetrac as well as upgrading to 35s. Did other small things like axle seals, hubs, and axle ujoints.


I now have an obvious front end noise which sounds similar to a wheel bearing, but does not change with weight shift (steering). 50/50 noise/vibration. It is hardly noticeable at speeds below 35mph, but increases noticeably with speed above that. I can also feel light vibration from the pedals. It is also hard to distinguish between driver or passenger side, if I had to choose, more passenger.


It is very cyclic (louder, quieter – following tire speed) especially while through a turn. The odd part is once out of the turn, the noise will remain steady at the same pitch when the Jeep is straight, and then varies slightly with small steering adjustments. I have tried to get a recording of the noise but the Jeep is too loud. Example, if I leave a turn and the noise is in its quitter cycle, I can continue to drive with almost no noise, opposite when leaving a turn in the louder cycle, until steering adjustment.



I was worried it was the pinion and replaced the bearings and reshimmed it, but resulted in absolutely no difference in noise. When I pulled the diff apart, there was some metal particles, but I’m assuming from the truetrac breaking in. Bearings showed no excessive or odd wear. Short of just letting whatever the problem is wear out or blow up, I’m completely stumped. :banghead:



Any ideas based off of the behavior of the sound?

 

[maxbraketorque]

Have you tried different tires? Each brand/model/size of tire has its own unique sounds. New tires I recently put on one of my other cars has a distinct hum that develops right at 70 mph. On another topic - did you replace the axle bearings?

 

[Tim_MN]

As already suggested are you sure the noise is not the tires ?

Are you sure the gear set-up is correct and has a proper pattern ?

Some lesser priced gear sets are said to have some pretty significant noise.

 

[aplchn_mtngoat]

Have you tried different tires? Each brand/model/size of tire has its own unique sounds. New tires I recently put on one of my other cars has a distinct hum that develops right at 70 mph. On another topic - did you replace the axle bearings?

I actually just swapped on fresh treads today to test that. If you're referring to the axle hub bearing, yes. Brand new Timken units, and today I also swapped out the passenger side bearing to something different to check that as well. No difference with the tires and bearing.

 

[aplchn_mtngoat]

As already suggested are you sure the noise is not the tires ?

Are you sure the gear set-up is correct and has a proper pattern ?

Some lesser priced gear sets are said to have some pretty significant noise.

I'm positive the gears are set correctly and they have a good contact pattern. To cross the gears off the suspect list, my backlash was slliiightly changed when I redid the pinion, but the noise did not change at all. Gears are a G2 set. I also have a set in the rear 8.8 with no issues. I took a passenger along today and confirmed the noise was definitely coming from the passenger footwell, so not likely the gears.

 

[whitexj98]

Going straight shit into 4 hi and see if the noise changes. I had a bad setup on gears and loading them would change the noise they made.

 

[Vince]

Do you have directional tires? If so, got one running backwards?



Back in the 90's a friend of mine that was running directional Yokahomas had to use his spare on the 'wrong' side of his Jeep. As with all mounted directional spare tires they have a 50% chance of being used on the correct side. There was a noticeable difference in noise from the tire that was running backwards. I have avoided directional tyres ever since.

 

[maxbraketorque]

I actually just swapped on fresh treads today to test that. If you're referring to the axle hub bearing, yes. Brand new Timken units, and today I also swapped out the passenger side bearing to something different to check that as well. No difference with the tires and bearing.

If you're sure its from the right front passenger side, you're running out of options on what it could be. Seems like the only thing left is something rubbing or flapping in the wind. Doesn't go away when stepping on the brakes?

Another comment is the the source of a noise can be deceiving. I've had passengers along in my other toy to help identify the location of a noise, and quite often they identify a different location than what I thought, and in more cases than one, neither myself or the passenger correctly identified the source of the noise.

 

[Evan03]

What about brake dust shield rubbing rotor.

 

[aplchn_mtngoat]

Going straight shit into 4 hi and see if the noise changes. I had a bad setup on gears and loading them would change the noise they made.

Currently running no front driveshaft. Waiting for rear spacers to fit my 35s on and also did WJ rotor/caliper upgrade so my old 32s on 15s don't fit.

 

[aplchn_mtngoat]

If you're sure its from the right front passenger side, you're running out of options on what it could be. Seems like the only thing left is something rubbing or flapping in the wind. Doesn't go away when stepping on the brakes?

Another comment is the the source of a noise can be deceiving. I've had passengers along in my other toy to help identify the location of a noise, and quite often they identify a different location than what I thought, and in more cases than one, neither myself or the passenger correctly identified the source of the noise.

I did have a passenger confirm the front passenger side for the noise. No change with brakes, only speed and turning. I can't imagine it being something rubbing or flapping, there's not too much there besides the rotor and caliper. No dust shield or inner fender well.



I jist picked up an axle shaft and I'm going to swap that out when I get a chance.. Its the only other mechanical component I haven't replaced on that side as a diagnosis.

 

[aplchn_mtngoat]

Do you have directional tires? If so, got one running backwards?



Back in the 90's a friend of mine that was running directional Yokahomas had to use his spare on the 'wrong' side of his Jeep. As with all mounted directional spare tires they have a 50% chance of being used on the correct side. There was a noticeable difference in noise from the tire that was running backwards. I have avoided directional tyres ever since.

Running Falken MT/01s. I don't believe they are directional.

 

[aplchn_mtngoat]

I just swapped out the passenger axle shaft. Noise has been reduced by almost 80% and no longer sounds like it is coming from the passenger side, mostly right under my feet.


My theory:

I'm assuming when I busted out my rusty ujoints, I managed to slightly knock the axle shafts out of alignment. When going through a turn, the shafts would go in and out of phases against eachother, increasing or decreasing the vibration. Perhaps the truetrack amplified this effect.


I could easily be wrong, but I'm going to swap out the driver side shaft to see if the rest of the noise/vibration goes away.

 

[aplchn_mtngoat]

Update:


So I broke my breaker bar at the boneyard trying to pull the driver side shaft, went to Lowe's and grabbed another, broke that one too I left in frustration and ordered a fresh set of chromoly shafts and full circle clips.


While it solved specific front end vibrations, apparently my rear end was hiding in the perceived noise/vibration, reverberating through the unibody/cab and sounding like there was a heavy front end issue.


Now onto more problems... I just want to wheel already!! Thank you all for your help.