All engine belts off - expert advice needed!
Thread Starter
Racer
Joined: Aug 2016
Posts: 271
Likes: 16
From: Raleigh NC
Sorry To be late to this game, But I figured I'd add my two cents;
The Secret life of Belts by Unkahal
V belts are terribly misunderstood; As a mechanic and mechanical engineer, I see this time and time again.
1. Belts are 'driven' by the V, that is the two outside V edges of the belts ARE THE DRIVEN BEARING AREA....NOT the bottom of the pulley,nor the bottom of the belt.If the belt is running on the bottom of .the pulley =FAIL!
2. Belts generally when fitted and sized correctly run just at the surface edges of the pulley grooves...this is not only to maximize the bearing/ driven area, but so when the belt wears it wears down toward the bottom of the pulley evenly.
3. If the belt is running on the bottom of the pulley it will FAIL....it's not designed to do this!
4. If the pulleys are glazed, Take an old belt turn it inside out and wrap some 100 grit sandpaper around the belt and then insert this into the pulley grooves and DE- GLAZE the pulley.
5. Needless to say proper sizing is KEY here.
6. Buy VERY GOOD quality belts, for sure this is 'safety-of-flight' GATES/DAYCO and my favorite CONTINENTAL.....whats $4.00 on a $25,000 car?????
7. PROPER belt alignment is SUPER CRITICAL....having all the pulley running in EXACTLY the same plane is CRUCIAL. {After years and years of various and sundry 'Bubbas' working on your car...washers and spacers get left out....PERFECT PLANES!
8. We all remember the LT-1 'story' of why LT-1 (70-71's) had no A/C..because they would THROW THE BELTS OFF at 6000 rpm. Belts EXPAND with RPM's, this is pure centrifugal force. Belts get Hot and expand and get 'rubbery' and zzzzt! there goes the belt.
9. Revisiting the belt tightness is important after installing new belt or as the course of a 'tune-up'.
10. The 1/2" total deflection across the long axis of the belt is the standard...Making the belt TIGHTER is deleterious to the belt life, and causes water pump and alternator bearing failure. Tighter is NOT better.
11. If the belt is too wide for the pulley, it will fail and get ejected from the pulley grooves.
So now you know what the belts do when you close the hood!
Unkahal
The Secret life of Belts by Unkahal
V belts are terribly misunderstood; As a mechanic and mechanical engineer, I see this time and time again.
1. Belts are 'driven' by the V, that is the two outside V edges of the belts ARE THE DRIVEN BEARING AREA....NOT the bottom of the pulley,nor the bottom of the belt.If the belt is running on the bottom of .the pulley =FAIL!
2. Belts generally when fitted and sized correctly run just at the surface edges of the pulley grooves...this is not only to maximize the bearing/ driven area, but so when the belt wears it wears down toward the bottom of the pulley evenly.
3. If the belt is running on the bottom of the pulley it will FAIL....it's not designed to do this!
4. If the pulleys are glazed, Take an old belt turn it inside out and wrap some 100 grit sandpaper around the belt and then insert this into the pulley grooves and DE- GLAZE the pulley.
5. Needless to say proper sizing is KEY here.
6. Buy VERY GOOD quality belts, for sure this is 'safety-of-flight' GATES/DAYCO and my favorite CONTINENTAL.....whats $4.00 on a $25,000 car?????
7. PROPER belt alignment is SUPER CRITICAL....having all the pulley running in EXACTLY the same plane is CRUCIAL. {After years and years of various and sundry 'Bubbas' working on your car...washers and spacers get left out....PERFECT PLANES!
8. We all remember the LT-1 'story' of why LT-1 (70-71's) had no A/C..because they would THROW THE BELTS OFF at 6000 rpm. Belts EXPAND with RPM's, this is pure centrifugal force. Belts get Hot and expand and get 'rubbery' and zzzzt! there goes the belt.
9. Revisiting the belt tightness is important after installing new belt or as the course of a 'tune-up'.
10. The 1/2" total deflection across the long axis of the belt is the standard...Making the belt TIGHTER is deleterious to the belt life, and causes water pump and alternator bearing failure. Tighter is NOT better.
11. If the belt is too wide for the pulley, it will fail and get ejected from the pulley grooves.
So now you know what the belts do when you close the hood!
Unkahal
Melting Slicks
Joined: Feb 2017
Posts: 3,232
Likes: 1,232
From: PHX AZ
Great question that I don't have a SPECIFIC answer to.
Corvette Service manual.
Internet 'spec' sheets from MVMS?
I have many German car owners manuals that actually had the belt sizes in them (one was wrong! lol)
Measuring the 'old belt', converting that in what you think is 'near the dimensions'. usually height of belt and width of belt at top x length.
Bear in mind that some metric belts MAY, when you do the maths equivalency numbering, fit better.
It's been so long since I've had to THINK about this....cant even tell you what is in the 69 or the 82.
I always carry a 'good old' belt set ; H2O pump and PS pump 'set' in the jack tray area. I'd much rather spend a 1/2 hour by the side of the road, than call a tow truck!
Best of luck sleuthing around...maybe others can be more SPECIFIC.
Unkahal
Corvette Service manual.
Internet 'spec' sheets from MVMS?
I have many German car owners manuals that actually had the belt sizes in them (one was wrong! lol)
Measuring the 'old belt', converting that in what you think is 'near the dimensions'. usually height of belt and width of belt at top x length.
Bear in mind that some metric belts MAY, when you do the maths equivalency numbering, fit better.
It's been so long since I've had to THINK about this....cant even tell you what is in the 69 or the 82.
I always carry a 'good old' belt set ; H2O pump and PS pump 'set' in the jack tray area. I'd much rather spend a 1/2 hour by the side of the road, than call a tow truck!
Best of luck sleuthing around...maybe others can be more SPECIFIC.
Unkahal
1967 Pedal Car Champion
Joined: Mar 2020
Posts: 9,147
Likes: 4,259
From: US-PNW
You can find the belt your '69 needs above and then reference the chart below to see length. I believe they are all 7/16" wide (3V belt profile I think).
There are 16 pages of way more than this for other years starting at:
http://www.gmpartswiki.com/getpage?pageid=52041
Le Mans Master
Joined: Jan 2001
Posts: 6,746
Likes: 1,387
What does "C.A.C." stand for?
nevermind....searched around and found that it stands for "car air conditioning". http://webinfotech.tzo.com/Boss%20No...nformation.pdf
nevermind....searched around and found that it stands for "car air conditioning". http://webinfotech.tzo.com/Boss%20No...nformation.pdf
Last edited by carriljc; Jul 11, 2020 at 12:26 PM.
