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I have a cleveland and when I get on it hard it throws the v belt for the alternator. I've done everything I know how to ensure its aligned, I don't want to spend thousands on a serpentine belt kit. It doesn't do this under normal driving, however I built this to have fun, any suggestions would be a big help!
 

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In the above statement you never said the belt was actually aligned.... You only said that you tried to ensure that it was aligned... Get pictures of your setup please.

I think that you're getting a heavy load put upon the alt when you hot rod it. that's what causes one side of the belt to get longer and the alignment is off or the belt would stay on.

What ignition system do you have?
 

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I used to have that problem until I put a smaller pully on the crank to slow it down a little bit.
 

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Hell I thought that was a chebby thing, with the long belt spans pulley to pulley... lol
 

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+1. If it's aligned and the belt is coming completely out of the pullies (not just flipping) then make sure your tension is correct. Proper tension for this type belt is 3/16" defection per foot of span at 4 pounds of pressure. Too much and it overloads the bearings. Too little and it can crawl or flip out of the pulleys. The easy method I use is to press with my pinky finger at the middle of the belt as hard as I can without it hurting. That's right about 4 pounds for most people. If the belt is 12" from one pulley center to the other, then it should deflect 1/64" per inch, or 3/16" per foot. If the span is more or less, the deflection should be relative (6" span = 3/32" or 24" span = 3/8", etc.). Some run a bit loose at 1/4" deflection, but only if loads are low (no squealing, glazing, or hot pulleys after running to indicate slipping), spans are short, and it doesn't try to jump out. Don't forget if it's a fresh belt that they stretch in the first 10-20 minutes of running and need re-tensioning.

If the belt is found flipped sometimes, or the thrown belt is twisted, then it's a mass thing. Some belts are heavy at the small part of the V, and at speed, they try to flip over. If that's how yours are jumping out (flipping and then throwing), then try a low-mass belt with the slots or grooves (cogs) at the small part of the V to reduce the tendency to flip at high rpms.

David

Measuring belt span:


Examples of standard and low-mass (cogged) belts:
 

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I used to have that problem until I put a smaller pully on the crank to slow it down a little bit.
aligned perfect and correct tension . still would flip and throw the belt .

like yours a smaller crank pulley was the only cure
 

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I have a cleveland and when I get on it hard it throws the v belt for the alternator. I've done everything I know how to ensure its aligned
Either a manual cut-out switch for the ALT hot wire or a WOT cut-out switch when the red light competition bug bites. It will also reduce drag on the engine. Same with AC.

Post a photo if you can.
 

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I knew a stripper in Jax., N.C. when I was in the Marines that had that problem..But hers was a "T-belt"...

It took a Bigger crank pulley I guess..

Sorry...I had to say that...:rolleyes:
 

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I had a vette that threw belts so I installed deep groove pulleys. I don't know if you can get those for a Cleveland.
 

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Make sure you have the proper belt width for the pulley grooves you are running. 3/8 belts for 3/8 grooves etc. Usually once a belt twists and it throws it off that belt is junk.
 

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Discussion Starter #13
wow just got home from work can't believe all the responses. What I ment by I'm sure its straight, is I checked it and I'm satisfied..hell I've had ones that were no were near as straight and didn't come off. These all look like good things to check...even the stripper! I'll ask one more question and I'll get out of every bodys hair (provided you have some). What do you think of a gilmer belt set up? prices are reasonable, it looks cool, appears the water pump and alt will now be driven by the gilmer ( cog style) and the power steering will be driven by a single v belt. Anybody here use one of these? Thanks everybody!
 

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I had a 351 that I shifted at 9000 to 10,000+ never tossed a belt. It was a daily driver. Used factory pullies dont know of any aftermarket stuff back in the early 70s.
 

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R U using ADVANCE (but won't) AUTO CHI-COM belts or a quality product?
 

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I had a 351 that I shifted at 9000 to 10,000+ never tossed a belt. It was a daily driver. Used factory pullies dont know of any aftermarket stuff back in the early 70s.
factory one I used came inside a larger multi groove pulley.

as ask by Klutz , yes the quality of belt is important
 
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