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Sun Nov 22, 2009 11:16 am

morymob wrote: Going to a smaller crank pully won't make fan run faster.

I got a "D" in physics, but I thought that the larger the driving pulley, the slower the driven pulley, which would mean that the smaller the driving pulley, the faster the driven pulley. Explain please. :-k

Sun Nov 22, 2009 11:57 am

Ken J wrote: morymob wrote: Going to a smaller crank pully won't make fan run faster.

I got a "D" in physics, but I thought that the larger the driving pulley, the slower the driven pulley, which would mean that the smaller the driving pulley, the faster the driven pulley. Explain please. :-k

no, backwards.... to keep it simple, if your driven pulley(gen/alt) is 1/3 the size of the drive pulley(crank) your driven pulley will make three revolutions for each revolution of the drive pulley... make the drive pulley smaller, say to twice the size of the driven pulley instead of three times the size and the driven pulley slows down to 2 revolutions per revolution of the drive pulley(that is twice the size)... that is what the theory behind a "power pulley" is, to slow the fan down, thus using less HP to turn the fan

Sun Nov 22, 2009 3:51 pm

Had to go to my shed and think about it. Got it. :idea:

Wed Jul 14, 2010 8:53 pm

This topic sure took off..hadn't pulled it up since the problem has been solved. I run the fan belt looser, I've always like the solid V belts for some reason and I've only had to replace them in the past year.

My engine is running a tad bit hotter (all cooling tin in place, thermostat working, aux air valve, etc...read up on it on here). I did the tennis ball trick and it's helped with the dipstick temp and the engine lid getting baked. It is about 106 heat index around here and it seems like that tennis ball keeps the top end cooler. I hope it keeps the cooling system operating properly or even more efficiently.

I still have a dim low gen light at night, after cleaning all the ground contacts. I checked my voltage and it's fine, just seems to be some feedback in the wiring, but causing no real trouble.

My crankshaft endplay (about 1/8 in while really pulling on it) I have put over 140,000 on this engine that I never had trouble with. I'm trying to find a NOS FI case (FI works great, convert to carb and larger motor later). Time for a rebuilt in the next 6-8 months.

Thu Dec 16, 2010 11:32 pm

[quote="jhvw1976"]This topic sure took off..hadn't pulled it up since the problem has been solved. I run the fan belt looser, I've always like the solid V belts for some reason and I've only had to replace them in the past year.

I have an aluminum "stock size" (approximately 6 7/8 inches in diameter) crank pulley and an aftermarket "stock size" generator pulley (1972 Super Beetle), and the stock 9.5mmX905mm belt is too loose- even with no shims between the pulley halves (like others on this topic thread).
It has been suggested to use a thicker and/or shorter belt, but I have not seen exact numbers to suggest what might work. :(
I found a 11mmX200mm at an auto parts store and wondered if anyone has tried this or any other than the stock size and what they used. I would prefer original German stock pulleys and not have this problem, but that is not an option right now (unless someone has a set they can part with?)
Thanks,
Manoteal

Fri Dec 17, 2010 12:34 am

Ken J wrote: It seems to me that what we're actually dealing with is a fan that was not designed for the ultra-high rpms. The cogged belt and serpentine systems appear to do their jobs. I don't know of any other cars where you want the belt to slip. We want it to slip to protect an over-stressed fan assembly. That's really a "Mickey-Mouse" way of looking at the problem. I've been running my Bully's Pulleys for about 6-7 years now and never had a problem. Of course I don't turn pavement vibrating rpms

How do we know that the regular belt starts slipping above a certain RPM and saves the fan? I doubt that revving the engine while it's parked gives a factual duplication of a strip-run under load. Maybe it slips fine while the car is stationary, but doesn't during a run and the fan usually handles the stress and only explodes once in awhile, maybe due to being an unbalanced or poorly assembled fan assembly. Just a thought.

I do love the statement about anyone screwing with the original German engineer's designs will be condemned to working on old Yugos with Harbor Freight tools in hell. But we've moved into a different plane here. The engineer's never expected our little "people's cars" to be running at the rpms they are today, so I don't think we're really screwing with their design. We're trying to take it a step further.

With all the VW brain-power here, I'm surprised that no one has come up with a solution, Maybe it would be made of stainless steel, aluminum or carbon fiber. Maybe a system that automatically disengages the fan above a certain rpm. That way it would work normally on the street and disengage for the strip runs. Maybe eliminate the stock fan completely and go to an electric one with some sort of thermostat or kill-switch. Maybe some sort of round collar like an over-sized alt/generator strap that completely encloses the fan assembly to keep it intact.

When a fan-grenade goes off, does anyone know exactly what happens? Do the blades fly off, does the housing crack and fly apart? Does anyone know what the actual weak part is, or does the whole thing blow up so thoroughly that we can't tell?

I'm sure if someone threw enough money at some design-engineers, they'd come up with something. The bad aspect is that the initial design and prototype costs would be horrendous and hard to recover with our small market. Most "streeters" wouldn't be interested, because they don't run those high rpms and blow up their fans. So that leaves us with the racers, an even smaller segment of the market.

Furthermore, of that market, it seems that the large majority haven't had their fans explode. I get this feeling from statements like, "Well, I've never seen one blow up, but my ex-girlfriend's 3rd cousin on her mother's side met a guy at the McDonald's drive-up who said a friend of his saw one explode.....or was it his nephew?"

Kind of joking around there, but who has actually seen or had one explode and looked at the engine-compartment results right after it happened? To me, this sounds like a solvable problem, but maybe not worth the investment.

I think this is the most intelligent post Ive read to date.

Fri Dec 17, 2010 7:26 am

I would like this post to get back to the issue of the fan belt shredding. Is it misalignment? Is it poor quality belts? Or What?

Now to the subject of exploding fans. Any substance that is in a solid state, steel that has been fabricated from a flat sheet originally made with no concern it is going to have get centrifugal force an extended period of time is going to have structural problems. Image a ball of clay on a potter's wheel, as it spins the sand (grog) particles migrate to the exterior of the ball because they are denser. It is the same principle as a salad spinner. So any material in a solid state is not absolutely stable- the particles are migrating to the exterior over time. When the bugs were made 30-40 years ago, Germany was using some of the highest quality steel ever mass produced. Ask any blacksmith they look for the stuff for the raw material. And now when have much cheaper made and cheaper quality metal of course there are going to be impurities present so the likelihood of the metal 'exploding' over time is greater. When is do to the driving, the metal and the temp that metal gets to on a regular basis.

Fri Dec 17, 2010 8:31 am

Bodyzoom wrote: I would like this post to get back to the issue of the fan belt shredding. Is it misalignment? Is it poor quality belts? Or What?

Now to the subject of exploding fans. Any substance that is in a solid state, steel that has been fabricated from a flat sheet originally made with no concern it is going to have get centrifugal force an extended period of time is going to have structural problems. Image a ball of clay on a potter's wheel, as it spins the sand (grog) particles migrate to the exterior of the ball because they are denser. It is the same principle as a salad spinner. So any material in a solid state is not absolutely stable- the particles are migrating to the exterior over time. When the bugs were made 30-40 years ago, Germany was using some of the highest quality steel ever mass produced. Ask any blacksmith they look for the stuff for the raw material. And now when have much cheaper made and cheaper quality metal of course there are going to be impurities present so the likelihood of the metal 'exploding' over time is greater. When is do to the driving, the metal and the temp that metal gets to on a regular basis.
If your crank pulley is rusty or pitted this will eat up belts very quickly. It will rust when the car sits up for a while. When you run it the rust and the pits caused by the rust eats at the belt and wears it very quickly. Replace it or sand the groove until smooth. Other wise miss alignment as mentioned before will do it.

Sat Dec 18, 2010 6:20 am

Greezy Joe thanks.

If the wear is do to misalignment how can you adjust the pulleys. I replaced the alternator a year ago and do not remember any way to adjust wear the pulley. Mine seems to be too far towards the front of the car and needs to be pulled out a little bit. However I just replaced the belt and I have so many shims in there I can only get the nut so the nut and the shaft are flush. It makes me feel a little uncomfortable that it will come off by itself. Can the crackshaft pulley be adjustd?

Sat Dec 18, 2010 7:29 am

Add a spacer washer to move the fan fulley rearward to align. Get a different fan belt so you don't need as many shims on the rear of the pulley (your extra ones).

Fri Sep 23, 2011 8:35 am

From my website (www.BullysPulleys.com).

Tom turning over 7500 RPM with Bully's Pulleys spinning his blower
and tearing up the asphalt!

"I made 5 passes on the motor. All seems to be working fine. I saw 16psi on the boost gauge at 7,500rpm. The belt has lost no tension and there is no wear that I can find. There is no wear on anything. The belt is cool to the touch after making a pass.
Right now, it's the least of my worries."

Tom Simpson
Simpson Racing

Click to Watch:

http://www.youtube.com/watch?v=n0rJJS70jIc&feature=related

I didn't see anything shredding or exploding with the cogged (no-slip) pulley system.