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Diff whine

Discussion in '"Stock" Alpine' started by clhiller, Aug 1, 2020.

  1. clhiller

    clhiller Silver Level Sponsor

    During my refresh this winter, I was able to replace the existing 4:55 Rapier rearend with a 4:22. All the bearings seemed in good shape, I was concerned about the amount of backlash. A mechanic buddy checked it out with the Mark I eyeball and pronounced it "good enough". Now when I drive, in 3rd, 4th and OD, there is a loudish whine from the rear area of the car. It stops when I let off the gas and coast, and is quieter when I am hard on the gas. It is loudest when just cruising.

    Is that indeed the sound of a sloppy differential? I am prepared to live with it until the winter when I can remove and dial it in correctly. Or could it be the wheel bearings, or the transmission? I did not replace the wheel bearings when I had it apart (dumb), but I did use the two that were smoothest and quietest and were acceptable in my opinion.

    I did have the transmission rebuilt by a reputable British car shop and it was run on their test bench with no issues. There is no vibration coming through the gear shift and no vibration in general when cruising at 65 mph. Just the whine (and not the good kind!).

    What is everyones' opinion?
     
  2. 260Alpine

    260Alpine Silver Level Sponsor

    Too much backlash.
     
  3. alpine_64

    alpine_64 Donation Time

    When you pull it the ring gear bolts have washers that compress amd go loose. This keads the bolts to loosen and causes bad sound and also increses wear.. Worse they can lead to failure of they come out.

    Replace with new bolts and locktite them in
     
  4. clhiller

    clhiller Silver Level Sponsor

    I checked all the bolts when I swapped the diff into my S1 rearend, ( the diff is out of a S3). All the bolts were Nice and tight.
     
  5. alpine_64

    alpine_64 Donation Time

    If the diff was from a series 3 you should check the ratio again. S3 was the only series where both 4 speed and OD cars ran the 3.889 diff.

    If the one tou swapped into your car has a 4.22 ratio it was changed at some point
     
  6. alpine_64

    alpine_64 Donation Time

    Also i would say if you have OD and the 3.889 thats a great combination for cruising.. I run that with 195/65/14s on the back and the car eats miles beautifully
     
  7. clhiller

    clhiller Silver Level Sponsor

    It is definitely a 4:22. I went from a non-OD with a 4:55 rearend to an OD with a 4:22. It is like night and day. I’ll keep my eyes open for a 3.89, but for now I’m happy with what I have. (Once I get rid of the whine!)
     
  8. alpine_64

    alpine_64 Donation Time

    Yes the OD and 4.22 was used on all series I/II and IV/V .. Gives a goosld balance of acceleration and cruise. With a 4.55 it would have been howling at 60mph.

    Interesting someone had swapped the diff in the donor s3.

    Good luck with sorting the whine... If you can get a decent 3.889 from any non OD car ( Barring stateside SV) that would be an even nicer upgrade
     
  9. RootesRooter

    RootesRooter Platinum Level Sponsor

    "All the bolts were nice and tight"? That makes you part of the lucky 1%. Did you bend the washer tabs down before you tried to check the torque? Did the washers look like someone else had previously bent them down and then back into place?

    Once the gears start to whine, has anyone been able to get rid of the whine by adjusting the backlash? I'm not aware of any success stories offhand.

    One other thought: its been a while since I had a bad u-joint in my Alpines. I can't remember if it howled under under acceleration, off-throttle, or both. U-joint whine isn't as 'grindy' as a bad diff, but it is loud.
     
    Last edited: Aug 3, 2020

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