Help with strange grind/rattle in the driveline

So I have had a strange noise in the driveline recently and I have been trying to figure it out on my own for a while but I'm stumped. It sounds like a grinding/rattling. It started by only doing it when I was slightly on the gas but now it does it then and when coasting. I crawled under my truck after my 38 mile commute this morning to check the pinion bearing (which had no play) and noticed that my third member was very hot to touch. Next time I'm home I'm going to jack up the rear and see if it will do it with no load (it should since it does it while coasting) Anybody had anything similar?

 

Carrier bearing maybe

 

When you say hot to the touch, are we talking hot enough to burn your hand, or just really hot?

I suggest checking your fluid level in the rear diff, and perhaps lift the truck up in the back on jack stands (Safety!!) and run the truck on the jack stands while listening for the noise. If it is not in the rear diff, then you should be able to pinpoint the noise from there.

 

I had a similar noise of grinding/vibration when I let off the gas and was decelerating that started a month or two ago. Changed out the carrier bearing last weekend and problem solved. The old one had 177k on it and was getting some axial play in the bearing.

 

Id say the diff gets hot under normal use..how hot, Idk.

 

That was my first thought because it does sound like a dirty/bad bearing but every carrier bearing I've seen go bad has squealed not rattled. It also started after I got it muddy which also makes me think it's bearing related.

I could hold my hand on it for 3 seconds before it burned bad enough to snatch my hand off.

Good to know! How much did you pay and where did you get it?

 

Oh I'm sure but like you, idk how hot but it was much hotter than I expected. I don't think it's the problem but I did notice it when checking the pinion bearing

 

Instead of throwing lots of money at a problem I was unsure of, I bought a DEA brand bearing off Amazon for $30 (Rockauto has it too). Sure enough that was the problem. If and when it goes bad (presumably soon), I'll fork out the $150 for the OEM one.

 

That is too hot. I have rebuilt differentials for years, and even ones that come right into the shop from the road were hot, but never THAT hot. I suggest as I mentioned, to lift the rear diff and check for noise as well as correct fluid level. Sounds to me like a pinion bearing is worn.

 

mine rattled like no tomorrow when mine went out, it was pretty noticeable too when I would let off the gas at highway speeds it would rumble and shake the truck pretty good.

 

check your U joints too.

 

Idk if it's possible but it sounds like it's coming from the rear section of the driveshaft itself. There's no vertical or horizontal play in the pinion bearing and I put my finger on the carrier bearing and it didn't feel like it was coming from it so idk...

 

Listening to that video I am sticking with my belief that there is a problem in the rear diff. Either the gears, side bearings of the differential carrier, or the pinion bearings.

 

I guess I could pull it on a weekend just to double check. Shouldn't be that hard. Drain diff, slide the axles out, disconnect the driveshaft, then pull the third? That's it isn't it?

 

ya probably the diff or the rear u joint. angle on the ujoint is horrendous.

 

Yeah I know the pinion angle is bad but I will have to redo the lower shock mounts to shim it since they are welded on... didn't think that one through. I guess I'll pull the diff next weekend and check it out. If it's bad there's a complete elocker axle on craigslist for $550

 

Just put a new carrier bearing in. Old one is def shot and the new one helped with my drivetrain rattle I have been having but it's just masking the source which could very well be in the rear end (pinion bearing or r&p). I can't get the new one to stop squealing no matter what angle I mount it at either. Any ideas?

 

What is your rear operating angle at the last u-joint, where the 2nd half of the driveshaft, and rear diff meet?

Ideally, you will want it to be around 2*

 

It's nowhere near that but I can't shim it since my lower shock mounts are on the axle so for now I'm stuck. The new carrier bearing helped a lot but the noise is still there. Something in the rear end

 

The aggressive angle at the last u-joint may have killed your pinion bearing. You're going to want to fix that angle. Perhaps re-welding the shock mounts is in order.


Easy way to diagnose pinion bearing problems in the rear diff, is with a magnetic base dial indicator. You can check for runout at the companion flange, so you don't have to tear apart your rear axle.



It indicates to check the inside lip and face, because its not exposed to corrosion, so its surface will run true

http://www.youtube.com/watch?v=RfGQjhIvAFo

^ if your pinion has this much play, your teeth are probably toast.


Heres some reading on the noises

http://www.ringpinion.com/technicalhelp/ContentFrame.aspx?FilePath=~%2FContent%2FHowTo%2FGeneralInfo%2F%2FDiagnosing_Noise_(Part_1).inc


Have you ever done a re-gear of the rear end?
Does it make a "whirring" noise while driving
Have you changed your rear diff fluid? Look at it and see if theres metal in it
Does is do it in reverse? If it doesn't, that removes the bearing problem, as the R&P re-align and mesh better in reverse (forward often likes to walk the pinion up the ring)
How are you're U-joints?