[nojo]

i have a strange noise, the best way i can describe it is that it is very much like the sound of a hard ball rolling around in a metal drum or barrell, it only happens at about 25-28 ,mph and does it in either second or third gear, it i am accelerating past that speed, you don't hear anything, it's only when i am holding speed at 25-28 mph, it seems to be coming fromthe rear end, it isn't the exhaust banging around on the axle or anything, and i had wheel bearings checked when i changed tires, i don't hear very well, so it is difficult to pin point where in the rear the sound is coming from, but i would guess passenger side rear end?

 

[340SHORTY]

u joints ?

 

[Elwenil]

If it's when you coast or at neutral throttle (meaning not accelerating or letting off completely, but holding engine speed with the wheel speed) then it's more than likely the rear axle.

 

[nojo]

the u joints don't have any visible signs of wear, no play or shavings or anything like that, the sound is very specific to that speed, and it is regardless of whether i have light throttle, no throttle, or coasting in nuetral down hill, if it is the axle, would that mean i would need to replace my entire rear end?, or is rebuilding/replacing parts a possibility...it would most likely be work i would not be able to do myself so it would be cool to have an idea heading into the mechanic...

 

[Elwenil]

IF, and I do mean if, it is the rear axle, yes you can have it rebuilt.  Chances are it would probably be easier and cheaper to just swap in another axle from a junk truck.  The problem with that is that the used axle may have the same issues or develop them in time.  The problem with rebuilding an axle is that they require special tools and knowledge and it's usually not real cheap in parts or labor.  I personally do not like the Chrysler 9 1/4" rear axle because problems are very common with them and usually return even after a rebuild.  A lot of people deal with the typical "Dodge clunk" and other pinion and backlash issues and get many, many miles out of the axle but I've had a few fail and now I refuse to own a truck with one in it.  The issue with swapping a different model axle under there is that you will normally have to swap to 8 lug axles or do something custom.

Now having said all of that, your problem may not necessarily be in the rear axle.  It is possible for a ring and pinion to make noise at a particular speed but usually it changes with speed and is there in some way regardless of speed.  It's very possible that the noise is related to something else but honestly it's very hard to diagnose these things over the Internet.  It could be something as simple as a catalytic converter that has failed and has broken pieces rattling around in the exhaust or it could be a transmission, axle wheel bearing or transfer case bearing going bad or a hundred other things.  I wouldn't rule out the axle bearings just because someone "checked" them when putting tires on.  Unless the bearing has already started destroying itself, there isn't much that can be determined without pulling the axle shaft.  Basically without some piece of info that would help pinpoint the problem better, you are probably going to have to diagnose it further by process of elimination or take it to a knowledgeable mechanic to diagnose.

 

[nojo]

i understand what your saying, it is a very vague description to try and follow up on through the web,  i am debating over whether or not to dig into this issue right now, or let it go for a while and see if the noise declares itself in another way, hopefully i won''t damage something else, but that seems like it could be a possibilty also, seeing as how i have no idea what the issue is...

 

[moremopars4ed]

detonation?

 

[nojo]

so i finally get the rc out of town onto some dirt roads.. and the same sound that i get at the specific speed i get pretty much consistantly on dirt roads and definately occurs when i hit bumps, potholes, anything like that.. so i'm going to get under it tomorrow and hopefully i will find something, maybe in the brake system, that is loose or rubbing? i'm hoping to find something external and simple to fix.... but i imagine it could still very well be internal and not so simple...