Poly V-belt installation

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omg1010
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Re: Poly V-belt installation

Post by omg1010 »

Hi John,

as said earlier, note the ref which is printed on the old one and order a new one with that ref. That is the smartest and easiest way to avoid troubles! :roll:

Kind regards
Oliver
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Re: Poly V-belt installation

Post by dgates »

OK, trying not to beat a dead horse here but...

I have an 04 (manufacture date of 02/04) ~38,000 miles.
The top pully (on the alternator) is the solid drum style.

The OEM belt on there has the reference number:
11.28-7681841-692637 4 pk 592
The replacement I bought from the dealer yesterday:
12.31-7681841-692637 4 pk 592

The new belt would NOT go on no matter what I tried. Too short!
Put the old one back on with no problem. Dealer closed until Tuesday 7/7.
I read this thread and I'm consfused. I figure if 592 is the length in mm, then it should fit, right?
Do I need the 4pk611?
Thanks and happy 4th!
Doug
omg1010
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Re: Poly V-belt installation

Post by omg1010 »

Hi Doug,

why don't you compare the old and the new belt (put one on top of the other)? Yes 592 indicates the length and if 4 PK 592 was printed on the old one then a new belt with the same ref should fit ...

Brgds
Oliver
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Re: Poly V-belt installation

Post by dgates »

omg1010 wrote:Hi Doug,

why don't you compare the old and the new belt (put one on top of the other)? Yes 592 indicates the length and if 4 PK 592 was printed on the old one then a new belt with the same ref should fit ...

Brgds
Oliver
Did that. Very slight difference with the original slightly bigger. The amount of difference, I thought, was due to normal wear/ stretch. I guess I'll have to see what the dealer parts guy has to say.
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Re: Poly V-belt installation

Post by CycleRob »

After trying and failing to install one of these stretchy, way too small belts I now understand why everyone is having a difficult time installing those belts. That belt stretches a LOT!!!

Here goes. The new belt numbers match identical to the old belt, yet the new belt is noticeably smaller!! We try to put it on using the bottom pulley by turning the engine. It keeps slipping and does NOT want to go on!! Using a screwdriver was suggested, but no, that would force a damaging sharp bend with a heavy tensile load. We couldn't stop it from slipping on the lower pulley. Then I tore off a 2" square piece of sandpaper (any grit will do) folded it in half, grit sides out. Placed it on the pulley at 3 O`Clock position on the pulley belt groves where the belt pinches it. Turn the crank CW with a 16mm socket wrench, making sure the belt stays in the top alternator pulley grooves. Watch as the belt is pulled around the bottom and up into place. We all just looked at each other as if we had just witnessed childbirth. Cool.

That was easy.
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dgates
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Re: Poly V-belt installation

Post by dgates »

Tried the sandpaper trick. I couldn't get the belt to grab over the lip of the crank shaft pully. I think I had too rough of grit sandpaper? I used a small screwdriver and was able to pry that belt over the lip as I cranked the engine with a 1/2" 16mm socket wrench. Bottom line, belt is on :D . I will check the tension the next 6,000 miles or so.
Doug
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Re: Poly V-belt installation

Post by omg1010 »

Hi Doug,

I changed my belt about 4 weeks ago and the old one got off easily as well as the new one got on easily ... I applied the tension, fixed the screws and took a ride. All well. Whole exercise was 30 odd minutes (took me a bit longer as I have the oilcooler installed in front of the belt cover ...). If the new one is of the same length as the old one the new one should get on as easy as the old one off. Hence I am curious to understand what has caused the difficulty you have experienced ... Changing the belt is a very easy excercise.

Kind regards
Oliver
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Re: Poly V-belt installation

Post by rdsmith3 »

I changed mine a couple of weeks ago. The old belt came off easily (and I will save it, Cyclerob). The new belt went on without a hitch. The problem I had was getting it tight enough. Applying 8 Nm torque on the one bolt did not seem to give nearly enough tension to the belt. I could turn it about 180 degrees. So I carefully used a lever to move the alternator up more to get more tension. I used the 90 deg rule of thumb.

I have to remember to check it in a few thousand mile.
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Re: Poly V-belt installation

Post by Boxer »

Applying 8 Nm torque on the one bolt did not seem to give nearly enough tension to the belt. I could turn it about 180 degrees.
Bob,
Just correct me if I assume wrongly, but it sounds like you are putting 8nm of torque on the bolt head. The 8nm of torque is applied to the adjusting nut on the back side of the right bolt on the front. You can not turn that adjusting nut 180 degrees.
The way you did it works fine also. I've done that before when I couldn't/didn't have access to the adjuster nut back in behind the alternator.

Edit: It just occurred to me you were referring to the belt twisting technique with the "180 degree turn". The adjuster on the back can get it very tight. You may have had an unseen blockage to your wrench as you were turning.
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Re: Poly V-belt installation

Post by rdsmith3 »

I could have written it better.

Yes, I applied 8 Nm to the backside of the bolt. It did not seem to tighten the belt enough, but I was probably doing something wrong. With this method, I could still twist the belt at least 180 degrees, so I was guessing it was too loose.

I have the BMW training video on how to use a torque wrench to tighten the belt, so I thought I was doing everything correctly, but I guess not.
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dgates
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Re: Poly V-belt installation

Post by dgates »

omg1010 wrote:Hi Doug,

I changed my belt about 4 weeks ago and the old one got off easily as well as the new one got on easily ... I applied the tension, fixed the screws and took a ride. All well. Whole exercise was 30 odd minutes (took me a bit longer as I have the oilcooler installed in front of the belt cover ...). If the new one is of the same length as the old one the new one should get on as easy as the old one off. Hence I am curious to understand what has caused the difficulty you have experienced ... Changing the belt is a very easy excercise.

Kind regards
Oliver
I have the same questions you are asking. Both belts are 4pk592. The only differences are the first four numbers (11.28 OEM and 12.31 new belt). As I noted earlier...
In fact, once I was able to pry the new belt on over the lower pully (with a screwdriver while cranking the engine with a 16mm socket wrench), the belt tension was tight so that I could only twist the belt 90 derees with two fingers. This was with all three screws loose. I did tense it up a bit and locked down the screws and I was still able to twist the belt 90 degrees.
I have yet to get a clear answer in my mind, but I am thinking that this new belt is more elastic and stretchy than the OEM. It seems to be working fine. I plan on rechecking the tension in ~1000 miles and maybe these really strecth out over time, hence the difference in length from the OEM and new belt??
Doug
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Re: Poly V-belt installation

Post by omg1010 »

Doug,

this sounds strange but anyway if you are able to twist the belt 90 degrees with 2 fingers the tension should be fine. Under normal circumstances these belts should not stretch in length over time (or only in an unnoticable way). I must admit however that I don't have experience with the elast version of the belt as I preferred to stick to the "old" non-elast version which has worked fine for 8 years and 60 000 kms and hence I suppose the replacement will also work fine ... I kept the old one (which shows no wear and tear) as a replacement in case of emergency.

Brgds
Oliver
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Re: Poly V-belt installation

Post by Boxer04 »

Hi all,

I used the CycleRob method about a year ago (at 60,000km). It took some effort. I had to place myself on the right hand side of the bike; place the sandpaper under the belt (abt 3 o'clock); use a socket wrench and (the hard bit) push like hell on the belt when turning the motor over to make dure the belt did not move forward and slip off towards the front of the pulley (using rubber glove to save the pinkies is a good idea!). No sharp implements should be used as this will leave a mark on the lower pulley - could cut the belt during rotation. Also do not use a lever to move the alternator up to tension the belt as the hall effect wires run through that area (under the alternator). They could be severed.

I use a 8mm threaded rod joiner and thread it on the alternator adjusting bold(botton right); I then screw a 8mm bolt in until it touches the altrnator bolt. I use a 13mm ring/socket to tension the belt (turning clockwide). Turning clockwide from the front raises the alternator and tensions the belt; you cal also get a tension wrench on the bolt head easier than working from behind the alternator as in the manual.

Regards
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rdsmith3
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Re: Poly V-belt installation

Post by rdsmith3 »

Boxer04 wrote: Also do not use a lever to move the alternator up to tension the belt as the hall effect wires run through that area (under the alternator). They could be severed.
oops! I did that. It seemed very straightforward and simple.
Bob
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Re: Poly V-belt installation

Post by billbeemer »

just replaced my '03(build date 10/02) r1150r belt yesterday. took the old belt to one-stop, he typed in the reference numbers and came back with a Dayco for $13.00. i tightened to 90 degree rule and will check again in a few thousand miles. easy on and easy off for the R front cover. i'm just coming up on 40k miles. old belt looked good, but a small amt of rubber in bottom cover. :badgrin:
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Re: Poly V-belt installation

Post by towerworker »

Recently I replaced the original belt on my '04 with the new one that everyone is having trouble with. I had the same problem getting it to stretch over the crank pulley. Even with an additional pair of experienced hands we had trouble. I took a small piece of this material (http://www.dycem-ns.com/) leftover from my time in a rehab facility 4 years ago. It's a non-slip material that when placed between the belt and crank pulley allowed me to slowly turn the crank with a wrench and pull the new belt in place. It literally turned a 2-hour fight into a 2 minute job!

You can get a free sample from the above site plus you could probably go to most hospital rehab facilities and find some. It's also available on eBay and Amazon.
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billbeemer
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Re: Poly V-belt installation

Post by billbeemer »

i just replaced my alternator belt on my '03 r1150r. the one that came off my bike(original) had a bunch of official looking bmw numbers on it, but was a continental automobile belt. i took it off and went to one-stop where the guy plugged in the numbers, brought me a dayco belt same size and charged me $13. it's funny the bmw people say change at 36k, same belt on auto says 60k. is somebody pumping dealer revenue here? unbelievable.............
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