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Thread: 98 R1100RT alternator belt help?

  1. #1
    It's a way of life! oldnslow's Avatar
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    98 R1100RT alternator belt help?

    I've read and researched and now confused myself. With what belt should I replace my stock alternator belt I hear talk of some ELAST belt or such, but it takes 'special' pulleys? ? The bike has 19000 miles on it, and I'm sure its the stock belt. Also, tips and instructions on replacement would be appreciated. PM to me or post here..thanks.
    Mike Davis
    "Old n Slow" It's a way of life!
    1985 K100RT

    1998 R1100RT

  2. #2
    Nickname: Droid
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    I got so many miles on the original belt that I didn't even think of it till the miles really racked up. Then I finally replaced it at 100k and installed a Dayco exact replacement belt. Been in there now for another 70k with no issues. Just get the belt designed for the bike and you'll be fine in my opinion.

    Oh, and my 94RS has the original OEM pulleys in it since day one. No need to change to any belt that requires a special pulley based on my experience. Besides, if it makes you feel better, just change out the standard belt at 40k and stash the old belt under the bike somewhere as a backup. I carry an extra Dayco belt on my RS in the storage area behind the taillight, I think I paid $17 per belt.

  3. #3
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    Max BMW

    # Part Number Description lb Qty Each

    04 12 31 1 341 779 RIBBED V-BELT 0.11 1 $23.42

    4PK611 was also stamped on my old belt.

    This is what fit on my 98 R1100RT.

    I also purchased and used the BMW preload tool.

    I do not think you need the special tool but it may make getting the proper belt tension easier and more accurate.

    Mark

  4. #4
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    belt

    Your bike doesn't need the elast belt. I use a Dayco belt of the proper length on my '98 RS (611 mm, I believe) that I bought from NAPA, but everyone carries them.
    To tension the belt you can use various methods (including the '1/4 turn' test and the 'lever under the alternator' method), but if you buy an acorn nut (or if you double-nut it) you can put it on the end of the adjusting bolt and use a torque wrench from the front of the engine. The proper method, of course is to use a torque wrench on the head of the bolt (from the backside of the mounting plate), but that is more trouble. And, just so you know - you have to use the torque wrench in the 'leftie loosie' direction if you do it from the backside of the mounting plate.
    BTW - don't be alarmed if you loosen the three nuts and the alternator belt doesn't loosen up. The alternator sometimes gets stuck in position, and you just have to persuade it to drop down to loosen the belt.

  5. #5
    Registered User lkchris's Avatar
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    There's a new BMW tool that facilitates torquing from the front side. Much easier.
    Kent Christensen
    21482
    '12 R1200RT, '02 R1100S, '84 R80G/S

  6. #6
    aapasquale
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    tool

    Quote Originally Posted by lkchris View Post
    There's a new BMW tool that facilitates torquing from the front side. Much easier.
    sent you a pm about this tool, but others may be interested as well. Do you know the BMW # for this tool?
    thanks,
    Tony

  7. #7
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    BMW part # 90 88 6 123 551 I paid $43.25 a couple of years ago. Do not remember where.

    Mark

  8. #8
    RK Ryder
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    Quote Originally Posted by ANDYVH View Post
    Oh, and my 94RS has the original OEM pulleys in it since day one. No need to change to any belt that requires a special pulley based on my experience. Besides, if it makes you feel better, just change out the standard belt at 40k and stash the old belt under the bike somewhere as a backup. I carry an extra Dayco belt on my RS in the storage area behind the taillight, I think I paid $17 per belt.
    Andy, what is the part number for your Dayco belt? It's a job I've been considering doing when I take the Tupperware off in a couple of weeks.

    Thanks.

    Paul
    Paul
    Retired and riding my RTs, the '87 K100 & the '98 R1100 !
    Treasurer of the Forest City Motorrad Club #159
    Knights of the Roundel #333

  9. #9
    Registered User lkchris's Avatar
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    The following article is definitive as regards Oilhead alternator belts

    http://www.bmwra.org/otl/belts/

    The "new" tool is shown in use and contrasted to original method in left/right photographs.
    Last edited by lkchris; 03-21-2013 at 04:13 PM.
    Kent Christensen
    21482
    '12 R1200RT, '02 R1100S, '84 R80G/S

  10. #10
    2UP RIDER snookers's Avatar
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    Paul......I adjusted the tension on the alternator on my bike.....I noticed it was a "Dayco".....the part number for it.....at least the number on the belt is 4PK0620 in one
    line and 5040240 directly below it.
    Hope this helps
    2000 R1100RT
    Niagara BMW Riders #298

    BMWMCO #45

  11. #11
    RK Ryder
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    Quote Originally Posted by snookers View Post
    Paul......I adjusted the tension on the alternator on my bike.....I noticed it was a "Dayco".....the part number for it.....at least the number on the belt is 4PK0620 in one
    line and 5040240 directly below it.
    Hope this helps
    Thank you, Snookers!
    Paul
    Retired and riding my RTs, the '87 K100 & the '98 R1100 !
    Treasurer of the Forest City Motorrad Club #159
    Knights of the Roundel #333

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