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> throwing belt..., alternator belt keeps flying off??
crash914
post Jun 2 2006, 05:37 AM
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anyone have this problem?

It all started when I replaced my gas tank.. before that I never had a problem.

Now I have thrown the belt 3 times in 3 days....

I did advance my timing a little bit. Could I be revving too fast?

this is not a stock motor... I just don't know if there are shims or other things to look at. Fan is tight and balanced..

I guess I could back off the timing, but what fun would that be...
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davep
post Jun 2 2006, 05:46 AM
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It could be the belt is loose or damaged. More likely would be the alternator alignment or perhaps the alternator bearings.
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crash914
post Jun 2 2006, 05:54 AM
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reply would not take...

I threw the old belt and the new belt twice. I thought that I did not have it tight enough...but not the second and 3rd. time.

The alternator seems ok, spins ok and smooth.

I run it up to 6500 rpm. i did this before I advanced the timing with no problems very frequently. Now with the advanced timing, I am thinking that it spins up more quickly. thus the problem. I am guessing but at 6500 engine rpm, the alternator must be spinning at close to 12000 rpm...anyone? anyone?
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VegasRacer
post Jun 2 2006, 05:59 AM
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I had the same problem on my 4 cyl. race car. I could toss the belt at will at 7K RPM. My solution was to add a tensioned roller. Never had the problem again.
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GBallantine
post Jun 2 2006, 06:58 AM
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I had the same problem on my race motor. Tried all kinds of size belts no cure. Finally removed the alternator and ran an Odssey 8 lb. dry cell battery. Just charge up at the end of a track day.
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Bartlett 914
post Jun 2 2006, 07:07 AM
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My belt kept coming loose. I have the motor out and I can see the pulleys are not aligned correctly. It looks like the alternator bracket is holding the altenator crooked. Check to see if both pulleys are in line and straight.
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Matt Romanowski
post Jun 2 2006, 07:31 AM
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Hey Herb,

I don't know if you remember, but I had this problem at NHIS. My car actually broke the long bracket that goes up to the fan shroud. It must have been cracked for a while and moving around before breaking. Hope this helps.

I've also talked to a few people that soak the heck out of the belt with dressing. It weakens it enough to keep it on.

Matt
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draperjojo
post Jun 2 2006, 08:14 AM
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I think Bartlett nailed it. Generally when you start throwing belts you need to look at belt tension, belt condition, alignment, and condition of pulleys. In this case you would probably need to check alternator bearings also, and it sounds like you've done that. After a number of years, the belt profile in the pulley wears and the belt doesn't ride where it should, it rides lower in the groove. The horsepower is carried through the sidewall contact in the pulley, not by it bottoming out in the bottom of the pulley groove. Throw road dust into the picture and its like polishing compound. Someone else mentioned checking the brackets for fatigue and alignment. Good idea!
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Mark Henry
post Jun 2 2006, 08:39 AM
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All of the above plus I also found I always threw belts that had the ribs on the outside, I use the gates belt with no ribs.
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davep
post Jun 2 2006, 10:26 AM
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The pivot hole in the alternator can get worn out and ovaled. So can the pivot bracket and the pivot pin. Then the alternator does not sit straight and the belt walks off of the pulley.
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crash914
post Jun 2 2006, 12:19 PM
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Thanks all! good ideas and it seems that I am not alone...

Now why would this occure after replacing my gas tank?

I think that it is a little bit of a red herring...

hi matt! just to let you know, throttle bodies are still in sink and this motor runs like stink...I am using it for my daily driver down here....
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Matt Romanowski
post Jun 2 2006, 02:26 PM
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Herb,

I HATE you!! Not really, but my car isn't done yet. I'm heading up this weekend and should have everything on the chasis done. Then over to Mark's to finish the motor.

Matt
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KenH
post Jun 2 2006, 02:50 PM
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I had the same problem till I got the CORRECT meteric sized belt.

FLAPS belts are not right.

Have not lost one now in years.

Ken
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Dave_Darling
post Jun 2 2006, 04:40 PM
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At one point my car started doing that, too. I futzed with the alternator bracket, and then it would only throw them at the rev-limiter. I futzed with it again, and it would throw them all the time. I futzed with it again, and they started staying put. No problems since then.

I got really tired of trying to get a wrench in between the alternator and the body. And of halfway-removing the alternator...

--DD
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Cire
post Apr 27 2009, 05:25 PM
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QUOTE(davep @ Jun 2 2006, 04:46 AM) *

.... or perhaps the alternator bearings.


How could it be the alternator bearing? Is there a way to test that?

My belt has popped off 3 times now as well.
BLEH!

Eric
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McMark
post Apr 27 2009, 05:45 PM
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Old Thread REVIVAL!!!! (IMG:style_emoticons/default/mueba.gif)

Installing your alternator pulley on backwards will pop the belt off at random times.
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