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Alternator belt life?


Beembish

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I am 2 hours from my nearest dealer and what a drag to have the service performed. I have to arrange an overnight stay to have anything much done.

 

My question... I recently had the valves adjusted and throttle body synch done. I was told if the belt has not been changed , if they had time they would do it. It was not done and I am just about to turn 29K. How important is this to get done right away?

Rob

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It seems a crap shoot. A number have had them fail at or below that mileage. I changed mine at 50k and it looked perfectly fine. I stuck the old one under the seat and won't change it again until I see signs of wear on the installed belt.

 

If it has you concerned, it isn't difficult to check the belt. Remove the fairing side. Remove the "shark fin" the fairing attaches to just in front of the cylinder. Remove the belt cover and inspect the belt.

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ElevenFifty

Change it - mine was fraying at 32K ... it's an easy job. As with most service, the most time consuming part is removing the tupperware.

 

Tupperware off

Port side shark fin off

Cover off

Loosen alternater retaining bolts

new belt on

CAREFULLY lever the alternator to tension the belt

tighten the retaining bolts

Ride 600 miles and Repeat the above steps

 

The belt is tensioned when you can grab it in the middle of it's longest run and then just barely twist it 90 degrees with your thumb and forefinger.

 

Lots of folks on this board cut the cover in half on the horizontal axis so that they can remove it without taking off the shark fin.

 

Have fun

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How important is this to get done right away?
Not critical at all, especially if service appointments are a PITA for you. While there are examples of some bikes having problems with alternator belts at low mileage, in general the belt should (and usually does) last well beyond BMW's specified replacement interval. Just have it done at the next service, or as was mentioned it's not a difficult job to do yourself.
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Had mine done by the dealer at 40K+ miles, for $100 plus belt. Old one showed no wear so it is under the seat to ward off wear on the new belt.

Lways carry spares. Seems you never need the part you have with you.

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Bill_Walker
Lways carry spares. Seems you never need the part you have with you.

 

Which doesn't mean you won't have a related failure! My headlights went out in Torrey. I had spare bulbs and spare fuses... neither of which were the source of the problem! Turned out it was a loose (and burned) ground connection.

 

I replaced my alternator belt when I did the 24K service, because inspection showed it to have some holes in the outer casing, presumably damage from one of the many tiny rocks I found in the bottom of the cavity (which I assume came in through the vent holes). If you do any riding on unpaved surfaces, I'd encourage you to check for this at every service.

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I've run several past 50K, my current one has 56K. I ride on all surfaces. I always carry a new spare. Your mileage may vary!

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I checked mine at 24K miles with a strong maglite; it looked okay- which means it will now disintegrate on a rainy night someplace away from home. Do have a spare in the rear; I wonder now why when I had the tupperware and shark fin off; I didn't replace it right there (in hindsight). I started thinking about it; mine's a '98 so it's almost a decade old, and we know rubber degrades with time. Sort of like the 15-year-old timing belt on a mazda that was supposed to be changed at 60k, but it was driven by an old lady only on Sundays and only has 59K...

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Keep in mind that the BMW tool kit is missing a wrench needed to replace the belt eek.gif I believe that it is a 4 mm allen wrench thumbsup.gif

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Charles Elms

Tupperware off

Port side shark fin off

Cover off

Loosen alternater retaining bolts

new belt on

CAREFULLY lever the alternator to tension the belt

tighten the retaining bolts

Ride 600 miles and Repeat the above steps

 

On my 97 RT there is one more step. You have to remove an oil breather tube before you can remove and install a belt. No big deal, just one more step and parts you don't want to drop.

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According to Beembish's profile:

 

 

Bikes(s): Black 2000 R1100RT

 

 

I wouldn't worry about it unless you're planning a trip anywhere near Amarillo, TX dopeslap.gif

 

My experience has been that the R1100's don't eat belts like the R1150's do. The list of respondents here would seem to also corroborate those findings. smirk.gif

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  • 3 weeks later...

I've got 42,000 miles, 2003 R1150RT, had fuel pump problem, checked my belt and many chucks of the ribs were gone. I do tend to run fast which of course does not help.

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When the little red battery light goes on and stays on, you know you waited too long. Happened here at 28000 miles give or take....

Again, YMMV....

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I wouldn't worry about it unless you're planning a trip anywhere near Amarillo, TX dopeslap.gif

 

I'll bite, Why do you say this?

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John Dickens

I've just changed mine as per the 36,000 mile service (actually 35,000 as I'm going away on it soon) and it was in perfect condition, but I'd hate to have to replace it at the roadside so I'll change it again as specified at 72,000.

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Mine just failed this week...

 

2003RT

34,000 miles.

mix of commuting and highway, nothing aggressive.

 

Shredded to pieces (fortunately very close to home).

 

Mike O

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My belt pretty much blew up at 30kmi. I started hearing the chirping, and had 100mi to get home, and did get home. There were only 2 ribs of the belt left on the pulleys. Very near total failure.

 

Be sure to use needle nose pliers and compressed air to get all of the belt fiber and rubber chunks out of the alternator vents, or you'll fry the alt shortly after.

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Jerry Johnston

You live in the Northern states and don't put a lot of miles on your bike, I'm betting yours will look new. I replaced mine at approx. 42k and it looked new. It was a very easy job to do as already stated. If you pull the front cover off you could easily inspect it yourself. I think the life depends a lot on if you live in a very high temperature southern state and if you ride half the miles in town where you're stopping and stating continuously. I would imagine stating the bike in very cold weather when your oil is thick won't help it either. All these factors will give you a variety of answers from our group.

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Stan Walker

I've never had a belt fail. I replace them at the 36,000 mile interval and they look used but perfectly good for many more miles when removed. No fraying, no cracking, no missing chunks. That's with 160,000 RT miles worth of belt changes on our two bikes.

 

Much depends on how you use the bike. High rpm running, jack rabbit starts, heavy electrical loads, and high temperatures will all reduce the life of the belt. Since we don't routinely do any of those things our belts last and last and last.

 

Also, correct belt tension is important!!! Too tight and you risk the alternator bearings, too loose and the belt slips on the pulleys and self destructs over time.

 

Stan

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daveinatlanta

I took a look at my belt at 32K and it looked identical to Jim Von Baden's picture above. So I changed it. I followed the procedure outlined by ElevnFifty above and everything was quick and easy - EXCEPT I took a REALLY stupid shortcut to tension the belt. I didn't buy the $50 BMW tool to tension the ratchet behind the left alternator mounting bolt and I was in a hurry - so I just propped a stick on the floor with the top of the stick on the front of the alternator shaft and slowly rocked the bike (which had the front wheel off the floor) forward to push the alternator up - thereby putting an upward force on the alternator pulley and shaft. dopeslap.gifdopeslap.gif I knew this was a bad idea but did it anyway due to time.

 

Luckily it seemed to work, no strange bearing noises from the alternator. Yet.

 

I've since read (but have not tried) of a safer, simpler, solution -- buy a cap (acorn??) nut that fits over the adjusting stud, put a socket on it and rotate the alternator up until the belt is tensioned properly.

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Certain things hasten a belts demise.. Obviously high mileage is one of them. Along with grit or other debris on the belt/pulley’s.. Excess heat is also a belt killer (not normal operating heat but extreme heat).. Alternator load in itself won’t necessarily kill a belt but alternator load coupled with a loose belt will.. One of the big factors in belt life is ozone (ozone of a definite belt killer).. Oil on the belt will really shorten it’s life also.. Belt flex is another belt killer with small tight radius pulleys & high RPM’s being hard on a belt.. Vehicle prolonged storage is probably about as hard on a belt as anything as the belt conforms to the pulley & kind of takes a permanent set then is forced to flex when started after storage.. Pulley rust from storage can also effect belt life.. High engine RPM’s on a very cold belt can also make it’s life much shorter..

 

Side fraying is usually an alignment or rubbing issue,, rib cracking is usually from over flexing, or dried out belt material , or high temps (see dried out belt material).. Ply separation can be from running overtight, or an alignment issue, or just old age..

 

Drive belts are difficult to figure.. I have seen some automotive serpentine belts go over 200,000 miles with others failing at 25, 000 or less..

 

The auto companies are shooting for 100,000 mile service free operation in the future with belt life being a big factor in that area.. As of now we are getting close with the engine oil change being the limiting factor at the moment..

 

Twisty

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Certain things hasten a belts demise.. Obviously high mileage is one of them. Along with grit or other debris on the belt/pulley’s.. Excess heat is also a belt killer (not normal operating heat but extreme heat).. Alternator load in itself won’t necessarily kill a belt

 

I guess I can see why my belt died at 30k:

 

- I've ridden a decent number of dirt/gravel roads.

- I sport ride in the Deals Gap/Suches, GA corridor (high rpm)

- I commute almost daily, sitting at red lights with the servo brakes on probably puts a good load on the alternator.

- I enjoy twisting the loud handle (jack rabbit starts)

- The summer commute is 3-4 months of afternoon heat in the mid-90's, with high humidity. Add stop and go, little airflow, and I bet it gets hot under that cover.

- The winter commute can involve morning temps in the 20's.

 

I guess my riding conditions are NOT conducive to long belt life. I'm changing the next one out after 24k.

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Certain things hasten a belts demise [ . . . ]

 

[ . . . ] high mileage is one of them

[ . . . ] grit or other debris on the belt/pulley’s

[ . . . ] Excess heat [ . . . ] (not normal operating heat but extreme heat)

[ . . . ] alternator load

[ . . . ] ozone is a definite belt killer

[ . . . ] Oil on the belt will really shorten it’s life

[ . . . ] Belt flex is another belt killer with small tight radius pulleys & high RPM’s being hard on a belt

[ . . . ] Vehicle prolonged storage is probably about as hard on a belt as anything

[ . . . ] Pulley rust from storage can also effect belt life

[ . . . ] High engine RPM’s on a very cold belt can also make it’s life much shorter.

 

 

[ . . . ] Side fraying is usually an alignment or rubbing issue

[ . . . ] rib cracking is usually from over flexing, or dried out belt material , or high temps (see dried out belt material)

[ . . . ] Ply separation can be from running overtight, or an alignment issue, or just old age.

 

[ . . . ]

 

Twisty

Well let's see:

 

--My belts never reach "high mileage"

--I DO ride through a lot of sandy cross winds (if you look at the pic posted above you can see the sand embedded in the grooves already)

--I ride through the deserts every summer--hot, dry, windy and if the ambient is 114*F, then the heat down near the black asphalt and in the front of the engine where the alt belt is has got to be a LOT more

--I run Signal minders that turn the signals into running lights front and back, I run with fog lights, 100W of Motolights all the time and high beam during the daylight hours (the rest of my farkle package doesn't draw that much)

--I'm sure the city driving I do almost every day is through air with elevated ozone levels

 

Yup, I guess that explains it--I change mine every 24k miles now. I retention it at 6k after that, check at 18k and change it again at 24k. Even with the modified cover, I'm sick of doing it on the side of the road. tongue.gif

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