why does it keep throwing power S. belts!?
Thread Starter
Instructor
Joined: Mar 2009
Posts: 209
Likes: 1
From: Denver CO
why does it keep throwing power S. belts!?
I have a 74 L-82 SB, and no matter how many times my friend and i put a new power steering belt on at some point (usually during flat out redline runs:o) it throws the belt. Is this a common issue, a poorly designed system? all of the bolts are tight-- two in front of block and one back by motor mount. and then there is the single adjusting bolt on the tilt. This is frustrating because belts are expensive and often times my fan chews them up. i am at the point of using blue lock tite on the adjusting bolt/nut to keep my belts on or is there a better way?
Race Director
Joined: Sep 2002
Posts: 10,362
Likes: 5
From: San Diego - Deep Within The State of CONFUSION!
Only two things cause this: Out-of-Alignment syndrome, or bent pulley syndrome ... 
Look to make sure the pump pulley is perfectly vertical from every vantage point you have. Over it, next to it, and from opposite side of car. If the pulley is perfectly straight, then next you need to make sure it lines up perfectly with the pulley on the crank. If the balancer has slipped or moved, it's possible these pulleys don't line up.
Next make sure the pulleys are not BENT. If you drop a pump during installation I guarantee you the pulley is bent. Or if the pulley on the balancer was ever dropped, it will be bent. Look for places on these pulleys that the belt area is narrower than others. If there's a spot where the belt area on a pulley is narrower than the rest of it, this will cause a belt to be tossed.
Let us know what you find.
Look to make sure the pump pulley is perfectly vertical from every vantage point you have. Over it, next to it, and from opposite side of car. If the pulley is perfectly straight, then next you need to make sure it lines up perfectly with the pulley on the crank. If the balancer has slipped or moved, it's possible these pulleys don't line up.
Next make sure the pulleys are not BENT. If you drop a pump during installation I guarantee you the pulley is bent. Or if the pulley on the balancer was ever dropped, it will be bent. Look for places on these pulleys that the belt area is narrower than others. If there's a spot where the belt area on a pulley is narrower than the rest of it, this will cause a belt to be tossed.
Let us know what you find.
Burning Brakes
Joined: Jun 2008
Posts: 1,086
Likes: 1
From: Michigan
I had the same problem on a '70 4 speed I had back in the early '70s. It would only happen if I missed a power shift or over revved the engine for some reason.
It turned out that the alignment was o.k. but the pulley had a "wobble" in it as it wasn't running true. At high rpm only it would throw the belt which caused a lot of expensive other collateral damage.
Going by memory I can't recall if the belt path has a guide positioned just above the belt to prevent it from experiencing a severe up/down travel at high rpm. I know my alternator belt path has this guide.
It turned out that the alignment was o.k. but the pulley had a "wobble" in it as it wasn't running true. At high rpm only it would throw the belt which caused a lot of expensive other collateral damage.
Going by memory I can't recall if the belt path has a guide positioned just above the belt to prevent it from experiencing a severe up/down travel at high rpm. I know my alternator belt path has this guide.
Race Director
Joined: Apr 2000
Posts: 17,676
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
First make sure you have C3 specific pulleys, there is slightly different spacing for '68-82 Corvette than any other chevy small block pulleys allot of guys don't know that. You can't just use any ordinary small block pulley on a C3. You can't even tell buy eye unless you put them side by side, it's only a fraction of an inch difference. The different spacing aligns the power steering pump either in or out further I can't remember than an ordinary small block pulley.
My guess is you have an ordinary crank pulley on there that doesn't line up correctly with the power steering pump pulley and at high RPM's the mis-alignment throws the belt
My guess is you have an ordinary crank pulley on there that doesn't line up correctly with the power steering pump pulley and at high RPM's the mis-alignment throws the belt
Last edited by MotorHead; Jan 15, 2010 at 12:56 PM.
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Melting Slicks
Joined: Jul 2006
Posts: 2,286
Likes: 487
From: Salmon Arm, BC
I had this happen on my stockcar. have a look at your power steering pump, mine seemed to go into hydraulic lock at RPM's above 6000 and always threw a belt. I solved it with a reduction pulley, but you can remove the pressure relief valve on the backside of the pump and inspect for debris or component failure. Take the pressure line off, and then remove the fitting that the line screws into
Race Director
Joined: Sep 2002
Posts: 10,362
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From: San Diego - Deep Within The State of CONFUSION!
Safety Car
Joined: Jun 2004
Posts: 4,371
Likes: 223
From: Beecher Illinois
What size belts have you been running?
For my years, 78-79, specs call for either 3/8" X 36"(Dayco 13360)or a 7/16" X 36 1/2"(Dayco 15365) for the power steering.
I run the narrower belt as it rides lower in the pulleys.
For my years, 78-79, specs call for either 3/8" X 36"(Dayco 13360)or a 7/16" X 36 1/2"(Dayco 15365) for the power steering.
I run the narrower belt as it rides lower in the pulleys.
Thread Starter
Instructor
Joined: Mar 2009
Posts: 209
Likes: 1
From: Denver CO
well i found out the problem and im not sure if anyone has heard of this before or as to why it may have happened. The stud coming out of the back of the pump that goes thru the bracket was completely snapped off. thought about welding another one on but i just might get a new pump and pulley to be safe. that was weird!
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
well i found out the problem and im not sure if anyone has heard of this before or as to why it may have happened. The stud coming out of the back of the pump that goes thru the bracket was completely snapped off. thought about welding another one on but i just might get a new pump and pulley to be safe. that was weird!
