bmohr

got it sorted out. Sourced 3 new allen bolts from true value for 3 bucks(6mmx30mm) put everything back with a better understanding of the shim system and it's running smooth. thanks everyone 4 the help

bmohr

This is embarrassing but please bear with me. I'm looking at the parts diagram for the belts/pulley system and it shows a very thin shim in between the alternator pulley halves. I have an overtight alternator belt and I'm trying to loosen it, but I don't understand how putting a thin shim in between the two pulleys will loosen it up as the shim isn't thick enough to widen the spacing. Am I missing something here. The shim and position in question is number 15 in the diagram shown here:

FeralComprehension

Sure it is. You move the sheave halves apart the shim thickness and the angle of the sheave walls allow the belt to ride just a bit lower, lowering the tension.

I just took mine apart; 4 shims each for alt and fan.

elbeee964

+1, what feral says.

If the pulley face is inclined, say, 10 degrees away from the belt center line, then for every unit of increased gap lowers your belt contact point 2.84 units on the pulley surface.
That's nearly a 3:1 multiplier effect!

(And if the pulley face is 'steeper' than 10 degrees from vertical, then that multiple is greater. And shallower, less.)

bmohr

hmmm, i don't see it, but i'll follow the rules and advice To my vision the cap is nearly4-6 shims at least wide so the whispy thin shim would just be floating around in the middle basically worthless. But i'm going to put one in there anyway to just to experient and follow the good advice of you all who have loads more experience than me.

Edit this, i think i'm actually visualizing what was said here guys and I think i got it. I'll report back. Danke!

911Jetta

I recently replaced my alternator. Here are a couple random pictures I found in one of my web albums of the shims.

FeralComprehension

I think maybe we're not actually communicating; we just think we are. To alter the belt tension you need to adjust the number of shims between the paired pulley halves. Adjusting the number of shims between the pulleys will merely move the fan pulley in or out, depending.

On my car the setup from rear to front was: Nut, cone, fan pulley half (rear), shims (x4), fan pulley half (front), spacer, alt pulley half (rear), shims (x4), alt pulley half (front), cone. Going from 4 shims to 3 would increase tension; to 5 would decrease it.

Bloody clever, IMO.

bmohr

yes, this is what I got from your original post and it's what I think I will need to do for my setup...2-4 spacers in between my alternator halves, not between the pullies. It's what I'm going to try first. Right now I have none and the belt is very tight and I can hear the bearings are stressed, not outright squeeling, though I know i probably shortened their lifespan a bit