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Noisy front Axle
- Thread starter natesjeep
- Start date
mcnamaag
NAXJA Forum User
- Location
- Red Lion, PA
Wheel bearings? U joints? There's about 20 different things that could make noises in the front of a jeep.
93blackxj
NAXJA Forum User
- Location
- New Port Richey
Sounds more like you have a loose pinion gear. Generally bearings make noise all the time where gear set noises come and go with throttle. If the gear isn't broke, you should be able to tighten up the pinion nut with some lock tight. May make noise still, do to the fact that the gear set is ruined from the pinion gear being push and pulled from driving around loose. Two reasons pinion gears can come loose the pinion nut backs off or the pinion bearings fail. If you decide to get by on the old gear set for the time being. Tighten the pinion nut down just past taking all the play out of it. If you over tighten the pinion nut this will make the pinion bearings fail at a faster rate.
wavingpine11
NAXJA Forum User
- Location
- Central PA
I'd like to throw in my recent pinion bearing experience. I bought a used set of axles, a HP D30 and a Chrysler 8.25, to take advantage of the stock 4.10 gears in them. Before I installed them on the vehicle, I swapped out the carriers and readjusted the carrier shims to arrive at a decent backlash and good gear mesh patterns.
As soon as I installed the axles, I noticed that:
1) If in Full-Time or Part-Time 4wd
AND
2) Pressing on the accelerator
THEN
I would hear a noise that sounded like a metallic scouring noise.
In 2wd I would never hear it, and I never heard it unless I was actively pressing on the gas when the front axle was engaged. After doing some research recently, I learned that that combination of factors does point to bad pinion bearings as a cause.
When I pulled the front axle shaft, there was obvious in and out and side to side play in the pinion assembly. After I pulled the axle apart, I found that there was no measurable pinion preload when using dial-type inch-lb torque wrench. I also found that I could not tighten the pinion nut to any amount of torque to actually get a measurable reading. I believe in my particular case that whoever had last been in the axle before me had replaced the pinion bearings and possibly just replaced the original preload shims and torqued the pinion nut to spec. I suspect they ended up with the noisy axle and unloaded the set on me, thus making their problem go away.
I drove on the axle with the loose pinion bearing preload and 5 or 6 years later came to suspect the pinion bearings were worn out. The most amazing part of this is that I replaced the bearings, readjusted the pinion height and backlash, and then after switching from the setup inner pinion bearing race to the press fit race, ended up with the pinion height being a bit high given the gear mesh pattern I was seeing. I didn't have the factory tool that would be used to pound out the inner race and I was pretty uncomfortable with how the previous one had come out crooked when a friend of mine pounded it out with a punch, so I simply readjusted the backlash and ran it as such. Amazingly, the gear noise that I had to listen to for years, despite years of improper wear and a slightly nonideal current setup, is now absent. I'm feeling extremely lucky given the circumstances.
Most likely, you have pinion preload shims in your high pinion Dana 30. If you torque the pinion nut back down to 160 ft-lbs (according to my 1998 FSM), you may have relief from the symptoms you are experiencing. However, if the bearings are bad, or the pinion depth shims are not correct, you will need to dig deeper to sort out the problem. The pinion depth shims determine how closely the outer bearing can be pressed towards the inner bearing, and it is this critical value that determines the preload experienced by the two sets of bearings. This value cannot be measure with the carrier still in the differential housing, because the carrier's resistance to movement would be added to the pinion value, and further, so would the axle shafts if they weren't already pulled.
I would recommend pulling the carrier and checking the preload. Almost anyone can do those simple tasks (you will need a beam or dial type torque wrench that ranges from 0-30 or so inch-lbs), and being able to find out the pinion bearing preload will help you diagnose the problem you are experiencing if a culprit is not found in the u-joints or wheel bearings that you can inspect as you are tearing down the axle.
In my case, I came to suspect the pinion bearings because the scouring noise, which was almost like the distant scrape of a snowplow on a snowy road, had upgraded to a clicking noise that only occured under the same conditions. I did a lot of work to deal with the pinion bearings, and the clicking initially got subjectively worse. It turned out that the clicking was at least in part if not wholly coming from the front drive shaft. I only began to suspect the shaft when I went to reconnect it and one of the caps fell off and it looked like there was muddy water inside rather than grease. I regreased the u-joint and attached the shaft. I didn't notice any play in the u-joint caps, oddly enough, but the clicking continued and only after swapping that shaft out was the clicking noise eliminated, so clearly there was a bad joint in the shaft.
It is worthwhile to note that removing the shaft alone, in my case, would never have allowed me to point the finger at the pinion bearings, because as 93blackxj has noted, gear noises come and go with throttle. In my case, they only came and went when some of that throttle was being pushed through the front axle, however. No shaft, no noise, but no resolution of the actual problem either. A known good shaft swapped in for the suspect one would have allowed me to observe the clicking go away (if the bearings weren't also clicking) but would have retained the scouring noise which was definitely coming from the loose pinion assembly.
As soon as I installed the axles, I noticed that:
1) If in Full-Time or Part-Time 4wd
AND
2) Pressing on the accelerator
THEN
I would hear a noise that sounded like a metallic scouring noise.
In 2wd I would never hear it, and I never heard it unless I was actively pressing on the gas when the front axle was engaged. After doing some research recently, I learned that that combination of factors does point to bad pinion bearings as a cause.
When I pulled the front axle shaft, there was obvious in and out and side to side play in the pinion assembly. After I pulled the axle apart, I found that there was no measurable pinion preload when using dial-type inch-lb torque wrench. I also found that I could not tighten the pinion nut to any amount of torque to actually get a measurable reading. I believe in my particular case that whoever had last been in the axle before me had replaced the pinion bearings and possibly just replaced the original preload shims and torqued the pinion nut to spec. I suspect they ended up with the noisy axle and unloaded the set on me, thus making their problem go away.
I drove on the axle with the loose pinion bearing preload and 5 or 6 years later came to suspect the pinion bearings were worn out. The most amazing part of this is that I replaced the bearings, readjusted the pinion height and backlash, and then after switching from the setup inner pinion bearing race to the press fit race, ended up with the pinion height being a bit high given the gear mesh pattern I was seeing. I didn't have the factory tool that would be used to pound out the inner race and I was pretty uncomfortable with how the previous one had come out crooked when a friend of mine pounded it out with a punch, so I simply readjusted the backlash and ran it as such. Amazingly, the gear noise that I had to listen to for years, despite years of improper wear and a slightly nonideal current setup, is now absent. I'm feeling extremely lucky given the circumstances.
Most likely, you have pinion preload shims in your high pinion Dana 30. If you torque the pinion nut back down to 160 ft-lbs (according to my 1998 FSM), you may have relief from the symptoms you are experiencing. However, if the bearings are bad, or the pinion depth shims are not correct, you will need to dig deeper to sort out the problem. The pinion depth shims determine how closely the outer bearing can be pressed towards the inner bearing, and it is this critical value that determines the preload experienced by the two sets of bearings. This value cannot be measure with the carrier still in the differential housing, because the carrier's resistance to movement would be added to the pinion value, and further, so would the axle shafts if they weren't already pulled.
I would recommend pulling the carrier and checking the preload. Almost anyone can do those simple tasks (you will need a beam or dial type torque wrench that ranges from 0-30 or so inch-lbs), and being able to find out the pinion bearing preload will help you diagnose the problem you are experiencing if a culprit is not found in the u-joints or wheel bearings that you can inspect as you are tearing down the axle.
In my case, I came to suspect the pinion bearings because the scouring noise, which was almost like the distant scrape of a snowplow on a snowy road, had upgraded to a clicking noise that only occured under the same conditions. I did a lot of work to deal with the pinion bearings, and the clicking initially got subjectively worse. It turned out that the clicking was at least in part if not wholly coming from the front drive shaft. I only began to suspect the shaft when I went to reconnect it and one of the caps fell off and it looked like there was muddy water inside rather than grease. I regreased the u-joint and attached the shaft. I didn't notice any play in the u-joint caps, oddly enough, but the clicking continued and only after swapping that shaft out was the clicking noise eliminated, so clearly there was a bad joint in the shaft.
It is worthwhile to note that removing the shaft alone, in my case, would never have allowed me to point the finger at the pinion bearings, because as 93blackxj has noted, gear noises come and go with throttle. In my case, they only came and went when some of that throttle was being pushed through the front axle, however. No shaft, no noise, but no resolution of the actual problem either. A known good shaft swapped in for the suspect one would have allowed me to observe the clicking go away (if the bearings weren't also clicking) but would have retained the scouring noise which was definitely coming from the loose pinion assembly.
