Manual Tranny Whine while coasting

Discussion in 'Tech Info' started by TheBlackMambaXD, Sep 26, 2016.

  1. TheBlackMambaXD

    TheBlackMambaXD Junior Member

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    I recently got an 01 1500 5 speed. I believe it has the NV4500 transmission. Anyway it shifts fine, drives great, until I let off the throttle. As soon as I loose positive power it starts to whine. Not a grind, just a noisy whine. Sometimes it lurches a touch. Anyway maybe related it had a pretty bad transfer case output seal leak, and after getting the truck I checked the levels and it was REALLY low. Fixed that and it seems to be better than before. Any thoughts? Thanks a ton guys.
     
  2. dudeman2009

    dudeman2009 Senior Member

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    My truck is neither manual or 4x4, however I have quite a bit of experience with 4x4 systems on chevys, and manual trans on Semis.

    Seeing as the noise quieted down after filling the transfer case, and you determined it to be low, it is likely that is where a majority of the noise is coming from. If it was run too low on oil, the clutch assembly may be the source of the noise, primarily the bearings on the dog (assuming that dodges use a dog and not a friction type clutch in theirs) The chain may also be a source of some whine due to lack of lubrication if the front driveshaft isn't disconnecting.

    Just fill the transfer case to the proper level with ATF+4 transmission fluid. Do not put any additives in except those specifically listed by Dodge.

    A bit of whining can be expected from the manual trans, most of this is just gear noise. For most of the transmissions life power and rotation are being applied primarily in one direction, the direction that moves the vehicle forward (the output shaft and countershaft are the only ones that reverse direction under normal forwards and reverse driving, the input shaft always spins the same direction) Less than 5% of most transmissions lives are spent in reverse, and then only the reverse gear on the input and countershafts as well as the idler gear see any load, the rest are relatively unloaded. When two metal surfaces meet and rub against each other, they wear in a specific pattern. This pattern wears in such a way as to provide the most contact between the two gears, this results in quieter and more reliable operation. Because all of these gears only ever see load in one direction (given that no engine braking has ever been done on the transmission, the clutch is either engaged or its put in neutral) only one side of the gears ever wears together. When you coast in gear with the clutch depressed, the gears for the range selected are now being driven by the drive shaft instead of the engine, this forces the 'non-mated' sides together and can cause quite a bit of noise. Even if you put it in neutral, the selector only disengages the input shaft from the gears on the input shaft. All the gears are still being driven by the drive shaft, there is just slightly less 'load' on them from the input shaft bearings. Coasting in gear with the clutch engaged, also know as engine braking, will result in quite a bit of noise even in a high gear where the engine may only be at idle speed as the drive shaft is now backdriving the engine, and all the friction from the engine systems is putting load on the gear range selected.

    I wouldn't worry about the trans, just make sure its filled up. As for the transfer case, if you want, you can do a fluid change to remove any debris from it (I have no clue if it has a filter, I would expect that it does, but I don't know) that may help. However, whatever damage has been done, is irreversible. As best, it just has a reduced service life, at worse, the bearings are damaged and may cause premature failure under high load. You will know if the bearings are bad or going bad though, the noise will get continually worse. But a little bit of whine is expected, just not so much that it sounds like a Honda backing up.
     
  3. TheBlackMambaXD

    TheBlackMambaXD Junior Member

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    Haha thanks, didn't expect such a detailed answer. I've had the truck just for a few weeks, and I've already fixed the leak and filled it up with ATF. And it really could be that the previous owner didn't do much engine braking. Me I live in the hills so I engine brake constantly, and notice it constantly. X). BTW the transmission was filled to the plug with oil.
     
  4. dudeman2009

    dudeman2009 Senior Member

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    Just dont beat the piss out of it like those Ford boys and it will last a good long time. Its funny too, most of the older fords around me are all beaten down and just piles of garbage, run like a half dead cow too. I don't see any old chevys. But there are a lot of old Dodges that look good and run great, thats gotta mean something.

    Good luck to ya
     
  5. Jimmy68

    Jimmy68 Senior Member

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    Dude, ?. ATF4? Does the transfer case really give a shit? Just thinking cost wise. I used regular Dex III in my 01 T-case.
     
  6. dudeman2009

    dudeman2009 Senior Member

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    It may not. But I do things by the book, if the service manual specifies a certain type of fluid, thats what I use. Could you use any type of anti seize on brake components, sure, but high temp anti seize it proper albeit slightly more expensive.
    The exhaust stack on Semis specify grade 8 bolts, do they need that, not really they could get away with grade 5, but grade 8 is whats specd out.

    As far as cost goes, I know i'm not as knowledgeable as the engineers who designed these things, when they specify something there is usually a reason. Sometimes there isn't and its solely for convenience, but i'm not qualified to make that determination. One fill of ATF+4 is worth both the peace of mind and the avoidance of potential problems down the line.

    Just my 2 cents.
     
  7. dapepper9

    dapepper9 Senior Member

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    Atf is best if you wish to avoid potential problems. Pretty sure the main concern is with the auto trans if the seal between the 2 should ever fail you're buying a transmission.
     
    Last edited: Sep 29, 2016

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