Engine/Transmission (1994 - 1998) 47RE - Whine in OD

[charlessmith]

I've got a '97 2500 4WD with the 47RE automatic, 100,000 miles, Suncoast TC and VB. Manual TC lockup switch. I haul a 3400# slide in camper.



I've started to hear a whine while the transmission is in OD. With gentle no load acceleration the whine starts when the OD shift takes place. The whine is audible most of the itme. For example, at 45 MPH with the TC is unlocked, it is a bit louder under gentle load or at trailing throttle. It's quite audible at 55 or 60 MPH at steady cruise. My first guess is that it sounds like a ball bearing whose race is getting pitted.



I've got a fluid & filter change scheduled next week, but I'd be interested in your thoughts on the problem.



- Is this just going to get gradually worse, or is something likely to break and leave me along side the road?



- Is this likely a repairable problem, or should I be thinking of replacement with a performance built transmission? I don't want to "fix" it if some intrinsic weakness will make it happen again in 30,000 miles.

 

[HoleshotHolset]

The 47RH in my '94 makes all kinds of racket in OD. BUT, I don't have any carpet or insulation covering the floor... AND my 4x4 shifter boot isn't bolted down to the floor... you can lift it up and see the transmission.



The NV-4500 in my '98 makes a crapload of racket... only in OD and especially when I've got my foot into it. That truck is fully carpeted/insulated... so I don't even want to know how noisy it would be without carpet/insulation.



I've never had a problem with OD in either truck... knock on wood!



Matt

 

[STripp]

mine too...

I am sure mine whines like crazy. However, My tires are so loud and my straight pipe sounds so good I just can't hear it :-laf , And I am on my original trans (47RH) with 202,000 miles and going :--) . No slips and no problems... other than having replaced about 250 or so TPS's. Boy is that aggravating!!! :-{}

 

[JoeBioDiesel]

There is a bearing that is in front of the 4th clutch piston. It is called the overdrive thrust bearing. It bears the entire force of the piston when it applies, releasing the direct clutch pack. That spring has about 800lbs of force. I'm surprised that bearing survives as long as it does. Anyway, when that bearing begins to go it starts making a noise in 4th only, that will grow louder over time. Eventually it fails and it's time to rebuild at least the overdrive unit.

I'm not sating that's what your problem is, but that is the most common problem I have found when these trans' make noise in OD only.



Joe

 

[rrl989]

OD Whine

I also experienced a whine while in 4th OD only, Grew louder and noticable very quickly. Problem was exactly as Joebiodiesel stated above. No whine at all with the OD locked out. I spun the Thrust bearing in the OD case. Had to get a new case and bearing. This problem left me never wanting to buy another Dodge again. I told the DC morons to check the $49 OD bearing first (As stated in the service manual) when diagnosing the problem, I put in in writing and spoke to the Manager, well $1800+ ($270 in parts) and after a week of diagnosing $$, I got my truck back repaired !!!!

I called around and found that I could have gotten an entire new DC OD unit for $1300.



Ron

 

[JoeBioDiesel]

I've got another one of these on the bench right now. The direct clutches in the OD unit are toasted bad, and that bearing is noisy too. Forgot to get a new one when I ordered the overhaul kit. Transtar now makes a matched bearing and thrust washer. I've had good luck so far with them, but I've only been using them since the beginning of the year. If you have your trans apart, or have the OD unit off REPLACE THAT BEARING!.

My 2 cents.

Joe