+ Reply to Thread
Results 1 to 9 of 9
  1. #1
    Curt
    Guest
    Location
    , ,
    Member No: Curt's Avatar


    Yes | No

    Unbalanced driveshaft - how can I tell?

    In the past 30 days, my drive shaft has been shortened (don't know if a balance was done) due to a 4 - 5 speed conversion and I've switched differentials. The 5speed conversion was professionally done and my neighbor and I did the diff swap.

    If something is out of alignment, how can I tell?. All seems well so far but I'm wondering if there are certain symptoms that I should be aware of. The idea would be to catch a problem early to minimize the damage / repair costs.

    Is it simply body shake, rear gringing noises, and a pool of oil all that I should be sensitive of?



  2. #2
    K.C.K.
    Guest
    Location
    , ,
    Member No: K.C.K.'s Avatar


    Yes | No

    My best guess.

    I have been driving around with one hand on the shift tower mount, just below the shift lever boot/cover. It's the black mount that the shift lever ball sits in. I figue that if something is out of alignment I would feel it there because it's directly attached to the trans.
    Just my thoughts.
    K.C.K.

    In the past 30 days, my drive shaft has been shortened (don't know if a balance was done) due to a 4 - 5 speed conversion and I've switched differentials. The 5speed conversion was professionally done and my neighbor and I did the diff swap.

    If something is out of alignment, how can I tell?. All seems well so far but I'm wondering if there are certain symptoms that I should be aware of. The idea would be to catch a problem early to minimize the damage / repair costs.

    Is it simply body shake, rear gringing noises, and a pool of oil all that I should be sensitive of?



  3. #3
    mikeS
    Guest
    Location
    , ,
    Member No: mikeS's Avatar


    Yes | No

    Should be kinda' obvious...

    An unbalanced driveshaft should feel like an unbalanced or distorted guibo, which is really easy to feel. At certain speeds you'll feel or hear a vibration, without even having to put your hand on the shifter.

    Mike


    In the past 30 days, my drive shaft has been shortened (don't know if a balance was done) due to a 4 - 5 speed conversion and I've switched differentials. The 5speed conversion was professionally done and my neighbor and I did the diff swap.

    If something is out of alignment, how can I tell?. All seems well so far but I'm wondering if there are certain symptoms that I should be aware of. The idea would be to catch a problem early to minimize the damage / repair costs.

    Is it simply body shake, rear gringing noises, and a pool of oil all that I should be sensitive of?



  4. #4
    Curt
    Guest
    Location
    , ,
    Member No: Curt's Avatar


    Yes | No

    Hear a vibration - what would it sound like?

    I have been trying to track down a sound that I hear only when the car is driving that occurs within a fairly small RPM band (a couple hundred RPMs same range in multiple gears).

    I think it is from the heat shield in the tranny tunnel (because the band has changed with the 5 speed conversion and it's now in the 2000 RPM range instead of 3000), and the shield metal was bashed pretty good with the conversion - as was the tunnel.

    I wish I knew what a bad guibo sounded like.


  5. #5
    Rob S.
    Guest
    Location
    , ,
    Member No: Rob S.'s Avatar


    Yes | No

    if driveshaft wasnt balanced...

    You might want to get it done. If you feel VERY stupid and fearless, you could put the car on stands on level ground and have a friend go through the gears while you lay on the ground NEXT to the car with a flashlight or video camera... hell the video camera would be the safest thing because you could just videotape it with the camera sitting on something pointed up and you safe inside the car. Just watch the tape inside the house and see if you can see anything moving, especially at the REAR of the driveshaft since it seems like the vibration has survived the shortening of the front of the shaft. You could actually take seperate close ups of the guibo and center section and rear section, and even the back of the diff. If you did do this, make sure to use plenty of light and .. FOCUS!!! ;)


    -Rob


    I have been trying to track down a sound that I hear only when the car is driving that occurs within a fairly small RPM band (a couple hundred RPMs same range in multiple gears).

    I think it is from the heat shield in the tranny tunnel (because the band has changed with the 5 speed conversion and it's now in the 2000 RPM range instead of 3000), and the shield metal was bashed pretty good with the conversion - as was the tunnel.

    I wish I knew what a bad guibo sounded like.



  6. #6
    mikeS
    Guest
    Location
    , ,
    Member No: mikeS's Avatar


    Yes | No

    Same range, multiple gears == Motor.

    If you are hearing/feeling a vibration at the _same_ rpm range in multiple gears, it's probably motor-related, not driveshaft-related. The driveshaft rotational speed is proportional to the car's speed. Actually, when you are in 4th gear, the motor RPM on the tach is the driveshaft RPM (assuming overdrive 5th; if 5th is 1:1, tach RPM=driveshaft RPM in 5th).

    Generally an out-of-balance or out-of-round vibration has its peak at a small range of RPM of the thing that's out of balance. Thus if the vibration you are feeling occurs at several different driveshaft RPM but one range of motor RPMs, it's something related to motor speed. This does not necessarily mean it's the motor, though; as you note, your heat shield might be vibrating in sympathy to a motor vibration.

    I don't have a heat shield on my car. I don't recall that there ever was one. Generally I remove things like heat shields, sound insulation, etc. But on other cars that I've owned, a loose heat shield causes a tinny, metallic rattle when it vibrates in sympathy to the motor. Generally heat shields are sensitive to motor vibrations because they are often connected to an exhaust pipe or pipe bracket, and exhaust pipes transmit engine vibrations very well.

    When my guibo goes whacky, I generally feel a vibration in the seat, in the gas pedal, in the steering wheel, etc. You can even look over at the empty passenger's seat and see that the head rest is vibrating a bit. These vibrations occur at around 2000 driveshaft rpm (2000rpm in 4th). Generally with balance/roundness vibrations, the more out-of-whack the part is, the lower the vibrational frequency. Thus if you seriously misalign your driveshaft (e.g., move the center bearing over to one side, or shift the differential over), you will feel a "whump whump whump" at lower speeds, and it seems to lessen in severity at higher speeds. If you get the alignment a bit closer to true, but not quite, you might not feel the vibration until 50mph or so.

    Mike


    I have been trying to track down a sound that I hear only when the car is driving that occurs within a fairly small RPM band (a couple hundred RPMs same range in multiple gears).

    I think it is from the heat shield in the tranny tunnel (because the band has changed with the 5 speed conversion and it's now in the 2000 RPM range instead of 3000), and the shield metal was bashed pretty good with the conversion - as was the tunnel.

    I wish I knew what a bad guibo sounded like.



  7. #7
    Curt
    Guest
    Location
    , ,
    Member No: Curt's Avatar


    Yes | No

    stupid and almost fearless here

    I'm going to be putting the car back on stands this weekend (check diff bolts) and will run it through some of the gears. I have been thinking about this as the problem does not occur in neutral.

    I'll have the car pointed out the garage, just to be on the 'safe' side.


  8. #8
    Jerry '72 tii
    Guest
    Location
    , ,
    Member No: Jerry '72 tii's Avatar


    Yes | No

    Check exhaust, may be some loose parts there.

    There is supposed to be a bracket from the tranny to the exhaust. If it's gone, get one. Don't bother with the rubber grommets, though. Just bolt it up solid.

  9. #9
    Curt
    Guest
    Location
    , ,
    Member No: Curt's Avatar


    Yes | No

    The exhaust - tranny bracket's there & tight


+ Reply to Thread


Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

     

Similar Threads

  1. UNbalanced chamber-help
    By vdo in forum BMW M3 Forum (E36 M3)
    Replies: 1
    Last Post: 05-19-2002, 04:20 PM
  2. Wheel alignment & Unbalanced tires?? (m)
    By mikebrawn in forum BMW M3 E46M3 (2001 - 2005)
    Replies: 0
    Last Post: 05-13-2002, 11:57 AM
  3. question for all... new tires and rims unbalanced?
    By wade in forum BMW 7 Series Forum (E23)
    Replies: 1
    Last Post: 08-06-2001, 12:24 AM
  4. Unbalanced hood, greasy windshield
    By Shane in forum BMW 5 Series Forum (E39)
    Replies: 7
    Last Post: 02-26-2000, 11:04 PM
  5. Unbalanced wheels .....
    By Costin in forum BMW 5 Series Forum (E39)
    Replies: 0
    Last Post: 06-11-1999, 12:25 AM

Bookmarks

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
1e2 Forum