I just replaced the transfercase, transmission, and the rotoflex joint on my 95 discovery. I also replaced the diff fluids and no metal was found. I had a bearing lock up in the transfercase which got so hot it locked the governor in the trans up. I had this noise before I replaced these parts but seems a little worse now. I am getting a decal noise when I take my foot off the throttle. It happens mainly at higher speeds and goes away as soon as I hit the gas again. It is a rattling, rumbling noise from the rear driveshaft area. At least that is where is sounds like it coming from. I noticed that all the u-joints had been replaced. The front u-joint on the rear driveshaft has a tight spot. It is light but you can feel it when you move the joint around. I am not sure if this would give me the noise. I have done so much I am getting sick of working on it. Just want it reliable. Thanks

 

tight spot replace it, are they greasable? just cause they look replaced does not mean they are, replace with good ones and grease well, they are cheap

 

Listen to Tom Sounds like the beginning of my Tranny blow up. Had that same noise at the same times Ignored it until the draftshaft came off and destroyed the tranny

 

Yes they can be greased. However this one wont take grease. I understand that it should be replaced. But I have never had a u-joint make this kind of noise. It is more of a slightly rough spot that a tight spot. I will replace it. I was able to grease all the front ones. I have heard this same noise out of a pinion bearing. Loaded no noise, unloaded noise. But they feel fine and no metal in rear.

 

Think around the following terms:

1. When the engine drives the propeller shaft and the propeller shaft strains one side of the differential main gear teeth, which in turn puts a force on one side of the final satelite gear teeth which drive the wheels you get no noise.

2. When the wheels drive the differential main gear you get the noise.

3. This principle goes into the universal joint couplings as well.

The proper amount of grease into the universal joint may help you to isolate the problem.

Help me please: Does the American term "tranny" refer to the gearbox (transmission), or to the transfer box which connects the front propeller shaft into the drive train?

 

Yes I understand the principle. I cleared the zerk fitting and was able to grease the u-joint. The noise seems to be gone for now.


"Tranny" is a slang term for transmission, or a he/she.......

 

If the noise is gone replace all joints you just put a very temporary band aid on it, the little needle bearings in u joints are shot, any tight spot also shows bad joint

 

Since the u-joints are newer my guess is they damaged the bearings installing it. Either way new ones are on the way.

 

If that doesn't do it it could be the rear pinion bearing. My 96 had a growl at speed when you let off the gas that would go away when you stepped on the gas. When I swapped in a 3rd member with an ARB it went away.

 

That is what I first thought it was. But it comes and goes. Usually a pinion bearing get louder the hotter it gets. Although my pinion seal started to leak a little. I will probably pull it apart and check in a few weeks.