rear axle problems

[DF5152]

Hi all. Here is the deal, my truck has 85,000+- miles on it has always had a rear end noise but it has been getting worse over the last few weeks. Put a trailer on the back not to long ago and it made it really bad. I serviced the fluid with synthetic and the noise got worse over the next few day. Put the truck in the air you can hear a noise from the pinion. So I changed the U-joint thinking maybe it was going bad and thats easier then the pinion. noise is worse now. So I pulled everything apart expecting to find a bad bearing and EVERY THING LOOKS GOOD. So... I dont want to spend anymore money then necessary to fix this but not sure what I should replace. any Ideas was thinking that the synthetic fluid was to thin and transmitted the noise better. rear went from factory fill to Valvoline at about 40k then just recently within the last few hundred miles mobile one... Tired of all these problem with this truck lately was good till I got it paid off #@$%!



HELP.

 

[DMattice]

Hi all. Here is the deal, my truck has 85,000+- miles on it has always had a rear end noise but it has been getting worse over the last few weeks. Put a trailer on the back not to long ago and it made it really bad. I serviced the fluid with synthetic and the noise got worse over the next few day. Put the truck in the air you can hear a noise from the pinion. So I changed the U-joint thinking maybe it was going bad and thats easier then the pinion. noise is worse now. So I pulled everything apart expecting to find a bad bearing and EVERY THING LOOKS GOOD. So... I dont want to spend anymore money then necessary to fix this but not sure what I should replace. any Ideas was thinking that the synthetic fluid was to thin and transmitted the noise better. rear went from factory fill to Valvoline at about 40k then just recently within the last few hundred miles mobile one... Tired of all these problem with this truck lately was good till I got it paid off #@$%!



HELP.

Those Pinion and thrust bearings "look" good, but when they are worn or slightly pitted, but the noise is terrible. They get that way with a lot of towing and not changing the rear end fluids regularly. They also go bad when moisture gets in the case and the steam heat changes the grease. I suspect that you need to fork out for some new bearings.

 

[SRadke]

How hot does it get on say a 20 mile freeway trip?

 

[DF5152]

i can still touch it...

 

[SRadke]

Sounds normal. The first sign of bearing issues is excessive heat. Warm is expected but you should be able to hold your hand on it.

 

[HBarlow]

When you say "rear end noise" and "getting worse" what do you actually mean? All differentials hum or whine a bit. If your hearing is particularly sharp or you're driving on smooth blacktop surfaced roadway with the sound system off or volume down you may hear a hum or whine. Some gear noise is normal and doesn't necessarily indicate you have a problem.

I installed a Mag-Hytec cover on the AAM axle in my '06 Ram when it was new and ran it 230k miles with only 50k mile fluid changes using brand name synthetic lubricant. The truck towed more than 50% of those miles, often towing in excess of the factory gross combined weight rating. I never experienced any metal dust in the fluid or any mechanical problems.

 

[Jim W]

What weight of gear oil did you put in? What weight of gear oil where you using? Did you switch to a different gear oil weight this time? I see that Mobil One offers two different types, LS 75W-90 and LS 75-140.

In your post you stated that you have pulled everything apart. Are you stating that you pulled the differential out of the differential? If you did what does the tooth pattern look like? Is there even wear around the pinion gear teeth, any chipped teeth?

I think knowing what gear oil weight you are using would help also.

 

[DF5152]

the fluid was mobile one 75-90w the gear pattern look good the noise was definately a bearing noise and got louder the faster you went and I would get a drive line vibration at hwy speeds. Everything is apart now and everything looks good do these carriers go bad?

 

[Jim W]

Yes, a bearing can go bad. I do not know if you have ever heard about B10 life of a component. This is an engineering term were 10% of the components will fail under the projected life of this said component. An example would be one of the bearings in the differential could have a B10 life of 100,000 miles. This means that 10% will fail before the average bearing reaches 100,000 miles and some will go over this life target.

When engineers design components they design to a life target and each component has a life target assign to them. This life target is for normal operation and using the specified lubricants at the proper change interval. Otherwise we could not afford to buy our trucks if everything was designed for infinite life.

I am not saying that the differential should or should not last till 100,000 miles. I do not know the design targets for Dodge components, I am just using the 100,000 miles as an example.

Hope this helps you understand how items are designed.

 

[DF5152]

yeah its called planned obsolescence ... ... or in my case these days Murphy's law that which has not broken yet will just before u need it to work

And just so everyone knows the dealer has the market cornered on the parts for these things and they are expensive... .

 

[jelag]

You might try this... while its running take a screw driver or long extension and put one end to your ear and touch the rear end with the tip... as you move closer to the cause of the noise you'll hear the noise increase... this should lead you to the cause...

Do you know how to put blue dye on the ring gear and pull the pinion through and test the pattern... this will tell you if the gears are making the noise. .

I agree with SRadke, in that if you have hold your hand on the housing after 30-40 min down the road you don't have a bearing problem... unless the noise is at the wheel end and its wheel bearing...

You might also get a point and shoot infrared thermometer and see if you have any hot spots... I'd look for any area that might be 50-75*F. higher than any other spot. .

 

[JWadford]

also if you had a bearing problem you would have dust or flaking on the magnet

 

[cerberusiam]

And just so everyone knows the dealer has the market cornered on the parts for these things and they are expensive... .

I had to rebuild mine on a trip when it ate a carrier race. The bearings are expensive but NAPA got me eveyrthing I needed. Don't think the dealer is the only source.



Also got the some parts at CarQuest.