Recently, a potential customer called, needing a Generator Pulley. His, he told me, had self-destroyed! “Do you have any?” he asked.
I replied that I did have a stack of Pulleys but that he should bring his Pulley so that we could match it.
Destroyed was an inadequate description of his Pulley and its parts. As we surveyed the parts, the customer explained what had happened. I never fully understood what had happened, but…
I think that it was incorrect placement of the Spacing Shims (washers) so that the Pulley Nut could not be properly tightened. Take a look at the damage:
The first thing which I noticed was that the Pulley was a chromed after-market version. Chromed surfaces are not just smooth—they are slick so that attempts to properly torque a bolt or, in this case, a nut, can be inexact.
Powder-coated surfaces pose the same problem. I made the mistake, once, of sponsoring the powder-coating of engine components, including the Generator Pulley. The resultant difficulties cured me of powder-coating Pulleys of any kind.
I’ve been chastened for saying that, but if I save one person from the problems of chrome and powder-coating—I’ll die happy!
What did I do for this customer? We sorted genuine German Pulleys until we found a really nice, used Pulley which was going to get the job done. Also, a Woodruff Key (shaft key), 8 good Shim Washers, a good German Pulley Coned Washer (or collar) and a Pulley Securing Nut.
I want to say something here about the Shim Washers. I have accumulated a box of Generator Pulley Shims over the years and draw from them when I need some. Over time, I noticed that some Shims are quite flimsy and are easily bent. They appear to have been stamped from thin sheet metal which has left raised edges. I prefer the less flexible Shims (see specifications at the end of this discussion).
Let’s look at a Genuine German Pulley which would have come on a 1967 Beetle Generator.
In the Owner’s Manual, the Glove Box Edition which came with each VW, Volkswagen has a good illustration, with instructions, for installing and adjusting the Generator Pulley Belt. This should be The Standard when installing a 1967 Beetle Generator Pulley Belt and related parts.
1967 Beetle Owner’s Glove Box Edition Manual—Page 29
The Belt for a Generator always should be a V-Belt with NO notches. Notched Belts are for the Alternators in mid-‘70s air-cooled VWs.
- Be certain that you have the correct Pulley and Belt to install onto your Generator. Having the wrong Belt will lead to frustration when Belt Tension will not adjust properly. Having the wrong Pulley can result in the failure of Pulley, Belt and Generator.
Be certain that the Crankshaft and Generator Pulleys are properly aligned. If the Generator Pulley is not in line with the Crank Pulley, strain will be placed on the Belt and Generator that can lead to Belt and/or Pulley failure—or perhaps worse! The Belt could flip off and the loss of ability to cool could cause pretty rapid Engine Failure through overheating. This may seem to be an unlikely scenario—but, I have seen misalignment of Pulleys.
The number of Spacer-Shims: There always should be 8. The Shims are to be placed between Pulley Halves to alter the Tension on the Belt–more Shims causes the Halves to be separated farther and the Belt to “fall” farther between the Halves as a result. Fewer Shims between the Pulley Halves means that the Belt will ride higher between the Halves (because the Halves will be closer together). So, you need to adjust and check, adjust and check, until the Proper Tension is reached. Proper Tension can be determined by depressing the Belt at mid-point, on the side towards the carburetor/fuel pump. If the Belt can be depressed about 5/8ths inches (a little more than a half inch), proper Tension has been achieved. You don’t need to put much pressure on the Belt in order to check this deflection. Just a firm thumb on the Belt, depressing the Belt at mid-point. Test yourself several times and you’ll get the idea.
Now, let’s suppose that it takes 5 Shims between the Pulley Halves to achieve proper Belt Tension. What becomes of the “extra” Shims? They should be placed on the Outside of the Outer Pulley Half, between the Outer Pulley Half and the Coned Washer, which will be secured with the Pulley Nut.
But are these “extra” Shims really “extras”? “Not at all!” says Barry Blythe, the local VW Mechanic. These “extra” Shims serve to take up slack between the Pulley Coned Washer and the Outer Pulley Half. Examine the Generator Shaft End and you will see that the Threads do not extend past the Generator Pulley Halves. There are Threads sufficient to accommodate those few “extra” Shims and the Pulley Coned Washer and Nut. The “extra” Shims fill the void that will be left between the Outer Pulley Half and the Pulley’s Coned Washer and Nut. Otherwise, there would be a little slack between the Nut and the Outer Pulley Half and Coned Washer so that when the Nut is tightened (to the extent of the Threads), the Outer Pulley Half would be allowed to wobble. This would not be a good scenario! In short, the wobble would turn into a nightmare for the Complete Pulley Assembly, ultimately resulting in Pulley and Belt Failure and likely would damage the Generator. So, be sure that you keep those “extra” Shims and put them where they belong–between the Outer Half of the Pulley and the Pulley Coned Washer!
- More on Tensioning the Belt: Okay, so you have the Belt positioned between the Pulley Halves and are tightening the Pulley Shaft Nut. Seems tight, so you let it go at that. Wait! You now need to turn the engine by hand (use a wrench). You are going to find that the Belt will “seat” between the Pulley Halves. You may have to repeat the Adjustment Procedure several times until you have the Correct Number of Shims between the Halves so that the Belt rides properly between the two Halves and the Deflection at mid-point is about 5/8ths inches. Each time, after tightening that Pulley Nut, turn the Engine manually to “seat” the Belt in order to check for proper Tension! This is very important.
Why spend so much time discussing this Pulley and Belt and associated parts? Because—the life of the Engine depends upon these simple elements.
And, a well Adjusted Belt will see that the Battery remains properly charged.
Treat these components with care and your Volkswagen will return the favor in long-life and lots of enjoyment!
David Brown, our Go-To Parts Consultant supplies the following VW Parts Information:
- The Pulley Halves are sold as a set of Inner and Outer Halves with the Original VW Part Number of 131 903 109. The correct Pulleys for 1967 are the ones with two “tabs” on the Outer Half and two “slots” on the Inner and with a round Center Hub.
- The “Cone Washer”…..VW calls it “Special Washer”, is VW Part Number 111 903 183
- The Shims (0.5mm thickness) are 111 903 131 A. VW calls them “Distance Washers” and the number required is noted as “x” which means “as needed”.
- The Pulley Nut is 111 903 181
- The Woodruff Key is N 012 705 1. These “N” Part Numbers are standard DIN parts and are 3mm x 5mm in size. The other Key on the Fan end of the Generator Shaft is the same.
These all are Original VW Part Numbers. The Pulleys, themselves, have been superseded a few times but the rest of the parts have kept their Original Numbers.
By the way, the Belt always has been 111 903 137 A for both 6v and 12v from 1955 up to when the Alternator replaced the Generator in mid-1973. How many other car makes have used the same Fan Belt for 20 years? (Note—the same Belt now is being sold as 111 903 137D)