Alternator belt/fan belt random size for a Type 1?

Hello all

I have tried and failed to replace my fan belt tonight on my 1600 Type 1

When the engine was rebuilt I remember the builder having some issues with getting a belt to fit, now I see why.

For whatever reason a standard Optibelt 11.3 x 912 does not fit, as it is to loose, even with no shims fitted between the pulley.

I had bought a V belt which was 11.3 x 912 as I was told they where slightly thicker ??

Anyways, currently fitted by the engine builder and working is a Dayco 10A0905C with no shims. There has never been any shims fitted between the pulley, only stacked ontop.

I have a Genuine VW alternator pulley, Genuine VW crank pulley and the original and Genuine VW alternator stand, so unless the pulleys are the wrong size for the engine im stumped as to what to fit?

Obviously another Dayco 10A0905C can be fitted, but with no adjustment that's far from ideal!

Thanks all for your time

 

Your local bearing factor can supply you belts in a size to suit. They'll be cheap too.
Just make sure you tell them what you want to do with them.
Try an A900 to start.

 

BTW I'd suggest you have the wrong pulley, do you have photos and sizes?

 

after a bit of research it would seem that the engine may have been converted years ago from a dyno to an alternator, in which case VW heritage recommend running the 9.5 x 905 belt still designed for the dyno even with the conversion kit

 

but you can get a 10 x 900 continental belt so I may give that a whirl

 

This sounds similar to ours (only running a shim or two), I might give that size a go.

 

Just a quick update on this, today I bought a 10x900 notched belt, not sure what it's actually for but it's fitted, with 3 shims between the pulley which is 3 more than I had before, and alls well so far.
They could have ordered in an 11x900 but the 10x900 was off the shelf.

 

And it cost £2.87

 

Bit of an old thread, but I’m just about to buy a belt for my bus that I’ve added an alternator to. Why are there two size belts listed, one for alternator and one for dynamo? The top and bottom pulleys are the same, and the alternator has the same centreline as a dynamo, so why a longer fatter belt for an alternator?

 

I found the toothed belts and the solid belts, although the same size and make were completely different. The solid belt fits fine with a few shims, whilst the toothed belt is too loose with no shims. Work that out because i can't

 

With a stock steel pulley top and bottom, my alternator needs a 910mm belt. With an aluminium pulley, that is too long and so a 900mm dynamo fan belt is needed.
Even then the toothed belt starts at about 4 shims between the pulley halves.

The correct belts are 11.3mm wide. Some belts are 10mm wide so they sink down into the grooves a bit further.

 

Nothing is simple ...
There are various stock top and bottom pulley combinations and then there's the added complication of previous owners messing around trying to get better cooling etc ....
Basic should be 900 BUT if the crank pulley is stamped with a 'D' this is a later factory mod for the yank market and is a slightly larger circumstance for extra cooling , needing a longer belt - 912 if I remember ??





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The 50 or 55 amp alternator belt pulls more power than a 30 or 38 amp dynamo - looking at the listings, the dynamo belts are 10mm wide, the alternator belts are 11.3mm wide.

Use what fits, note it down and buy the same.

 

Thanks all, pot luck then. Im using an ally crank pulley, so i'll try a generator belt, see what happens
Lasty, interesting info and makes sense.

 

At least you are forewarned that it could take a couple of tries.
When I did this for a living, at one point I hung old belts on a nail on the wall. When I got to about 15, every single one was different. To be fair that would have included alt, gen and type-4 engines but still...

 

So maybe as short as a 900.. this is on a 75A alternator..