T-case noise?

[Maverick]

I got this whining sound coming from my truck upon deceleration, most noticable from 25 MPH and down. It happens with the clutch in/out in gear/out of gear doesnt matter. It slows as the truck slows so im thinking it has to be something in the t-case. I pulled the t-case out to reseal it and noticed while it was apart that the ring the planetary spins around on is discolored from heat. Doesn't the planetary only spin when in low range though? Anybody have any ideas or have had the same experience? My truck is an 02 so the front driveshaft spins all the time.

 

[MAKG]

Yeah, the planetary spins only in low.

The transfer case would be the LAST place I looked for such a noise. The first would be the brakes (disk brakes are in contact with the rotors whether they are applied or not, and they can make some really odd sounds when worn).

Anything in the driveline from the transmission mainshaft backwards spins at road speed.

 

[Hahnsb2]

I wouldnt rule out t-case failure. Me and my father have both had t-cases take a dump on us.

 

[Maverick]

Yeah, the planetary spins only in low.

The transfer case would be the LAST place I looked for such a noise. The first would be the brakes (disk brakes are in contact with the rotors whether they are applied or not, and they can make some really odd sounds when worn).

Anything in the driveline from the transmission mainshaft backwards spins at road speed.

The front brakes were just replaced by me, and it's been making the noise since I bought it. It's definately a gear/bearing whine of some sort. I brought the tranny to a shop to get checked out while it was out (lost the slave assembly) and as far as they could tell there's nothing wrong with it.

 

[MAKG]

HahnsB2, I'm not ruling it out. I'm saying to start at the brakes and work toward the engine. It's not impossible for a transfer case to blow. It's just the sturdiest part of the drivetrain (by a lot).

If the brakes are known good, the next thing to check is the axles and differentials. Look for floppiness at the differential flanges and at all four wheel/axle bearings (with the parking brake off).

Do check the REAR brakes as well. I've chased phantom noises to brakes before, after confusing them with bearing howls. One of them even did it only on turns, so I was CONVINCED it had to be front bearings. It was a wear indicator....

 

[4x4junkie]

The planetary gears ALWAYS spin, there's no load on them unless you're in lowrange though.

Does the case make the noise if you spin it by hand (out of the truck)?

 

[Ranger5.0]

the bluis colour could be from a factory heat treating process..

 

[AllanD]

The planetary turns with the input spline.

The female input spline is one-piece with the "Sun" gear of the planetary

The sun gear turns the planet gears and since the ring gear is a
press fit into the case it cannot turn...

What CHANGES between hi-range and Low Range is what is turning the output.

In High range the output is engaged to the sun gear and the planetary
is spinning, but "just along for the ride".

In Lo-Range the output is engaged to the planetary "cage" thus the
output turns at the slower rotating speed of the cage

I can't believe that any "overheating" of the T-case could turn the
planetary outer ring gear "blue" from heat without MELTING the far
smaller planet gears, especially since the ring gear is coupled to a big
aluminum "heat sink".... the t-case main case.

I don't have a T-case open at the moment to look at the gear, so I'll provisionally vote for the heat treatment theory...

AD

 

[Maverick]

The planetary gears ALWAYS spin, there's no load on them unless you're in lowrange though.

Does the case make the noise if you spin it by hand (out of the truck)?

I didn't think to try that when it was together. My new problem is some how I managed to break the locating pin off the end of shifting mechanism that attaches to the electric shift motor. A manual transfercase swap is looking better and better.

 

[Sasquatch_Ryda]

It only makes this noise when you're off of the gas pedal (no load)? Does it go away as soon as you give it any throttle? If so it sounds to me like gear whine from the rear differential on the coast side of the gears.

 

[Evan]

I don't think it's your t-case. I would look at either the tranny or rear end.

 

[Maverick]

Nothing wrong with the tranny, had it checked out. Maybe I'll pull the diff cover and take a look at the pattern.

 

[Maverick]

So I tore the t-case all the way down today. Everything seems fine, the discoloring on the ring is definately factory heat treating at a closer look. Time to pull the diff cover.

 

[maritimeranger]

could it be maybe just a bad u-joint? i had that problem with the grinding noise and that was my problem

i know it is weird but that was my problem lol