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Sourcing an alternator belt


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Heya,

 

The belt for our leisure battery alternator is knackered so we need a replacement, and I'm struggling to identify the belt so I can get a new one online

 

It's a beta 43 engine, and the belt is 10mm wide. There's a few codes and numbers on it that are a bit worn, but from what I can make out they're 3108, 13AY1087, 661 1130 54940 161 and FA1 AUTOMOTIVE <something> - pic below

 

I've found this one at midland chandlers, but it doesn't match any of the codes on the belt so I'm not sure it's the one...

 

Any ideas?

 

Cheers,

J

 

image.png.21ead793266d00b47f6da315d549f0a1.png

 

 

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10mm wide means its "Z" series.

 

Measure the length witha piece of string / rope, in millimeteres and that should match one of the numbers you can see.

 

EG Z 1018 would be 10mm wide by 1018 mm circ.

 

Z is a common size for cars so any car shop should be able to supply you with one simply on the circumference.

 

 

ETA As tony says,it may be 12mm wide in which case thats an "A" series.   Not so common at car shops but you never know.

Edited by jake_crew
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"A" section is more popular on marine and plant engines. I would expect it to be a 1130 mm circumference "A" section cogged  ( notched )  belt. Some are marked in inches rather than MM

Take it with you to the factors. On line could be more difficult, you don't say where you are so I can't suggest a local supplier. Bearing suppliers near by?

That Midland Swindlers one is massively priced!

 

This one on ebay may be correct     

 

https://www.ebay.co.uk/itm/124059264329?hash=item1ce2822549:g:FY8AAOSwcB1eKvTg

 

 

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As the OP may not know. V belts drive on their sides, not the bottom, and they should NEVER reach right to the bottom of the pulley groove. The V profile is different between A & Z belts so although the wrong one may drive it is also likely to suffer excess wear.

 

For marine use, always use cogged/notched belts because these grip on smaller diameter pulleys such we typically have on the alternator.

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13AY 1087 is the best ref to get a match, 13 mm A profile, 1087mm long. When you find the replacement, buy 2, they don't eat anything and you'll have a spare. Whilst looking, if you've not got a spare for the service alternator, it's worth getting one of those too.

Edited by Ex Brummie
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2 hours ago, Tony Brooks said:

As the OP may not know. V belts drive on their sides, not the bottom, and they should NEVER reach right to the bottom of the pulley groove. The V profile is different between A & Z belts so although the wrong one may drive it is also likely to suffer excess wear.

 

For marine use, always use cogged/notched belts because these grip on smaller diameter pulleys such we typically have on the alternator.

Just for info I drive an v belt on the bottom and it’s fine. There is a wedge pulley on the 70A alternator and then the belt goes round the JP flywheel on the flat face…no machined groove. It works well and has done for 30 plus years. Change belts about every 1000 hours or so as a precaution but the take off belts are fine. The belts are solid…not notched. No slip even when the alternator is in full output. 

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46 minutes ago, frangar said:

Just for info I drive an v belt on the bottom and it’s fine. There is a wedge pulley on the 70A alternator and then the belt goes round the JP flywheel on the flat face…no machined groove. It works well and has done for 30 plus years. Change belts about every 1000 hours or so as a precaution but the take off belts are fine. The belts are solid…not notched. No slip even when the alternator is in full output. 

We drove big alternators like that on the Ailsa Craig engine, with the massive diameter of the flywheel it works fine but you cannot run on the inside face on the alternator pully, it has to sit tight in the vee without bottoming.

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53 minutes ago, frangar said:

Just for info I drive an v belt on the bottom and it’s fine. There is a wedge pulley on the 70A alternator and then the belt goes round the JP flywheel on the flat face…no machined groove. It works well and has done for 30 plus years. Change belts about every 1000 hours or so as a precaution but the take off belts are fine. The belts are solid…not notched. No slip even when the alternator is in full output. 

 

Yes, but there is no way that has any relevance to conventional V belt and grooved pulley drives. Your flywheel is what - about 18" or more in diameter, with the belt wrap over at least 75% of its circumference. It would be surprising if that configuration did not drive well enough. Its, it is different to an 8" or 2" pulley with only 30% belt wrap. Especially if it has a 150 Amp plus alternator hung on it. However, that should have twin or polly-V belts.

 

I doubt the belt manufacturers would condone that, although we know it works.

Edited by Tony Brooks
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