Fan Belt/Pulley adjustment

[Lenny Santora]

I've recently had a few issues with the fan belt & pulley and hope that someone can assist.
The issue first began when I pulled away from a light and as soon as I hit second gear I heard a bang from the rear and saw the generator light come on. I immediately pulled over and shut it down. Opened the engine compartment to find that the outside pulley half had split and tore the belt.
A few people have told me that this was because the pulley was chrome plated and that affected the metal.
Replaced the pulley with one from Stoddards.
After replacing the pulley I put less than 100 miles on the car and while driving I started to smell rubber and before I could pull over the generator light came on. Quickly shut it down and then found that the inside pulley was completely worn away from the center out.
After removing the pulley I found that a small screw on the face of the generator had backed out. I believe it may have been rubbing on the inside pulley which I did not notice when I replaced it.
Any insight or thoughts are most appreciated.
BTW I just purchased another pulley set and two belts.

[John Brooks]

COUNT YOUR SHIMS

[Vic Skirmants]

COUNT YOUR SHIMS

You need ten total to be sure the pulley halves are clamped properly.

[Lenny Santora]

Thanks..I bought ten shims..Based on the work shop manual that I have I need to have four between the pulley halves on a new belt.
Please correct me if I'm wrong.

[Vic Skirmants]

Depends on the belt. You have to install it and see what the tension is. Add or subtract shims to make it right.

[Doug McDonnell]

viewtopic.php?f=1&t=42075&hilit=fan+pulley See Rainer's comments in this link.

[Geoff Fleming]

...and use a good spray-on belt lubricant. It will keep the belt pliable and lower the friction-induced heat. As Vic mentions, each engine is different. The factory specs are simply a starting point. You will probably need additional shims...or even fewer. Snug it up nicely and re-check after driving a few miles and again after about fifty miles.

[Dick Weiss]

You must have 10-shims to make sure the nut gets tightened correctly!

Just adjust the belt somewhat snugly for checking the parallelism of the belt between the pulley face-edge to the inner pulley 1/2 and adjust the shims to suit the final tightening; A new 9.5 x 825 belt (notched or OEM plain V) will be kinda short and don't tighten the pulley 1/2s until the belt is in the V and NOT the flat faces--this would cause the later warp/cracking of the flat-sided hole!! You should squeeze the belt (between the pulleys) which makes the belt a little longer when snugging up the nut and proper tension would be checked by twisting the belt approximately 90 degrees w/your fingers, or depressing 1-side of the belt to about 1/2-3/4" and the engine growth w/get it tighter

After running the engine for 25-75 miles, recheck the belt's tension as it'll get stretched w/use.
You shouldn't need any dressing on the belt.

[WilliamVaughan]

When in the process of tightening the nut on the generator shaft, always let the pulley halves rotate and slip against the belt. This encourages the belt to change its radius on the pulley halves and reduces the likelyhood that you will distort the pulley halves.

Buy the Fanschers 912 generator pulley spanner wrench. It makes the process so much easier.
https://fanchers.com/shop?olsPage=produ ... ocus=false

[DonCichocki]

Attending Chuck Stoddard's seminar at Akron he was adamant that you check your belt tension AFTER the engine has thoroughly warmed up. There should be slight play at the midpoint of the belt when hot, if not it will put added stress on the generator bearings. From my own experience if you tighten the belt to the book specs when cold it will be extremely tight when the engine is hot...Chuck knows!

[Dave Wildrick]

Having the belt too tight is worse for the bearings at the pulley end than a little bit too loose.
Electrics/generator guru Joe Leoni told me that if the belt is adjusted properly, you should not be able to easily turn the crank pulley by rotating the generator pulley nut.

[Steve Proctor]

One other thing, some times when the pulleys let go due to lack of clamping force or too few shims, the pulleys have "worked" back and forth, grooving and / or otherwise compromising the hub that is keyed to the generator shaft. If the hub is damaged, life of the replacement pulleys will be adversely affected.

[Wes Bender]

After you get the belt installed, place a straight edge on the rear face of the engine pulley and sight down it to see if your belt is parallel with it. Too far from parallel and the belt and pulley halves will wear prematurely.

+1 on Dave's advice per Joe Leoni. When my belt is adjusted properly, I can only turn the engine over with the pulley nut by pushing on the belt a little. Otherwise it slips.

[Fred Lawrence]

I've had the same issue with the pulley halves; the person who rebuilt my Speedster's engine last fall put only six spacers total (five between the halves and one outside against the nut. The inner half lasted less than fifty miles. The hub was also damaged to the point that a new inner half disintegrated after about 100 miles, even with ten spacers in place. I have not been able to remove the hub; any suggestions on how to do so would be greatly appreciated.

[David Jones]

Use a big half inch impact wrench. It does not impart a constant torque so is less likely to damage the generator shaft. Good item to have and iff you don't have a compressor Harbor freight sell an electric one that works well. I have had mine for 10 years and it gets used often removing lug nuts.
https://www.harborfreight.com/12-in-hea ... 68099.html