Alternator belt size?

[68_early_bay]

Hi guys

Noticed the fan belt was a bit loose, so thought I'd move a shim from between the halves to the outside. But they are already out, no probs I thought the belt must have stretched/worn so ordered a new one, new ones came today fitted it and it's exactly the bloody same if not looser.... there's about 20mm deflection in the belt and I can spin the belt with out the top pulley moving....


It's an 11.3x912 belt I have an alternator is it the right size?? Every where I've read says it's right,

Cheers Shaun

 

[mike202]

Yea that sounds wrong. Should be the right fan belt for an alternator fitted to a type 1 engine though.

You should only be able to turn the fan belt 90 degs with your thumb and fore finger, or alternatively about 10-15mm deflection.

I also think(?) that you should usually, still have one or two shims between the two halves of the pulley wheel.

So somethings not right, don't be offended but have you mated the two halves of the top pulley wheel together properly?

Otherwise to try the 905 smaller belt is all I can think of.

 

[subheatadey]

Should be the right size I think there is a 909 belt but that's not enough to make a difference, make sure you use the shims you take out and place them on the the side so it pulls up and as you tighten it spin it to seat the belt

 

[68_early_bay]

Cheers for the replies guys, the two halves of the top pulley are both mated together properly, and the shims are all put under the nut and washer so that it pulls up correctly when tightened, just seems a bit loose with the 20mm deflection but strangely enough when I do the twist test it does only go to 90degs no more

Will keep an eye on it and hopefully pick a slightly smaller belt at skegvegas this weekend

But also came across this page when I was looking

http://vw.zenseeker.net/FanBelt.htm" onclick="window.open(this.href);return false;

With a few recommendations for smaller sizes :mrgreen:

 

[Nugsy]

Got a similar issue and done a bit of reading lately, apparently the bigger belt 912 is also wider, reason being when upgraded to a alternator the thinner Genrorator 900 belt kept breaking.

However as your pulley wears, when you put the bigger belt on it slipps down a bit and ends up loose.

Best idea is to find a smaller belt 900 that has a wider width, to give the required strength, and means it will need shims back in for the new width.

Not the best explanation but it makes sense in my head....

 

[ozziedog]

Next time you have your belt off, try wiggling the alternator pulley, just to rule out a dodgy bearing. You can compensate for this but the alternator is on a self destruct mission if the bearing is shot. A new bearing versus a new alternator ?? Just a thought but might not be the case with this one. Is everything else completely stock do you think or original ? That`s the bit that gets harder as these dudes get older. :mrgreen:

Ozziedog,,,,,,,,,,Keep us in the loop :mrgreen: