Topic: Thought I was being smart saving money...
in Forum: C3 Engines
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Former Member
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Frederick, MD - USA
Joined: 9/8/2003
Posts: 3398
Vette(s): 1969 convertible L71 427/435 4-speed black interior
I've owned my '69 427/435 for nearly ten years and have barely changed anything under the hood. I noticed the alternator belt had a slight split in it so I felt I should replace it. Since the air pump belt has to be removed first I figured I should replace that at the same time...no big deal.
I checked around for new belts...reproduction GM belts from the suppliers ran about $35 and $24 for the two belts. I checked with local suppliers and Dayco belts run half of that for the application. Dayco is a good quality belt and these belts were their Top Cog premium line. I bought what I needed at Pep Boys...Advance Auto and Auto Zone carried the same belt but Pep Boys was closer and less expensive.
I installed the belts with no issues. I ran the engine to make sure everything was fine. A day later I drove the car to gas it up and found no problems.
This past Saturday I took the car to a Corvette show...less than a thirty mile drive. When I got there and opened the hood for display I noticed the alternator belt had flipped inside out! It was still tight but flipped on the pulleys. I drove home with no issues and turned the belt to how it should be.
I realized the problem...the belt only filled the pulley about half of the groove. There simply wasn't enough surface area to grip the groove. What Dayco and other companies are doing for such older applications is to consolidate part numbers and eliminate as many numbers as possible. The length on the belt was perfect but it's still wrong for the car.
I called the local Chevy dealer and they couldn't help me at all. I ended up ponying up the money for a reproduction belt from Zips. It was a GM licensed reproduction belt and it fit perfectly...it fills the pulley groove like it should.
Just a heads up for everyone else here...give serious consideration to just pay the extra and get the GM licensed belts for your cars...it pays in the long run.
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That's good to know, Bruce! It seems like A LOT of things for the older cars you gotta poney up for the reproduction parts because the regular ones don't work!
Barry
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Ormond Beach, FL - USA
Joined: 7/28/2012
Posts: 19
Vette(s): 77 coupe, yellow, auto, L series, A/C, T top, Grey leather interior. It is about 75% & matching #'s. The miles are 117K & intend on restoring bit by bit to enjoy Cruises & rallies in Florida , & maybe some shows ?
I know you have to be careful about getting inferior products to replace OEM sometimes. But I will betja the replacement belt you recieved was not the proper width. Even though it looked the same side by side, you probably ended up with a 4L width belt & in order to fit the pully to the top like it should be, it probably should have been a 5L width belt. An old school parts guy would have spotted it if he could have compared them the right way. Check out the old - new belts together carefully, & see if it aint so. Report back on the thread to us.
Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
One other issue is that the newer belts are made way more pliable than what they used to be...meaning they have more flex. A lot of v-belt made now are designed to "flop" in the middle. They're more like a rubber band than an actual belt.
I bought a full set of the Dayco Cog belts for my '74 years ago, and they worked fine, but they definitely did NOT fit all the way down into the grooves of all of the pulleys as they should. I bought a complete set of original Gm belts from a friend that had taken them off of a '73, and that's what I have had on it for about 10 years now, with no problems.
You're right about part # consolidation...."One size Fits All".....right....
|UPDATED|8/15/2012 7:23:08 PM (AZT)|/UPDATED|
I bought a full set of the Dayco Cog belts for my '74 years ago, and they worked fine, but they definitely did NOT fit all the way down into the grooves of all of the pulleys as they should. I bought a complete set of original Gm belts from a friend that had taken them off of a '73, and that's what I have had on it for about 10 years now, with no problems.
You're right about part # consolidation...."One size Fits All".....right....
|UPDATED|8/15/2012 7:23:08 PM (AZT)|/UPDATED|
Joel Adams
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Former Member
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Frederick, MD - USA
Joined: 9/8/2003
Posts: 3398
Vette(s): 1969 convertible L71 427/435 4-speed black interior
kendo2 said: I know you have to be careful about getting inferior products to replace OEM sometimes. But I will betja the replacement belt you recieved was not the proper width. Even though it looked the same side by side, you probably ended up with a 4L width belt & in order to fit the pully to the top like it should be, it probably should have been a 5L width belt. An old school parts guy would have spotted it if he could have compared them the right way. Check out the old - new belts together carefully, & see if it aint so. Report back on the thread to us.
There's no question that the new Dayco belt was more narrow at its top...since it only fit halfway down in the pulley it had to be narrower. While it fit length wise it was simply the wrong belt for the purpose, regardless of the application guide.
I wouldn't call Dayco belts an inferior product as far as their construction, it was a problem of specifying a correct length belt with insufficient width and depth for the specific application. That was most likely a business decision on the part of accountants and planners at Dayco to reduce product numbers for such old applications. Good in concept...lousy in practice.
Former Member
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Frederick, MD - USA
Joined: 9/8/2003
Posts: 3398
Vette(s): 1969 convertible L71 427/435 4-speed black interior
Adams' Apple said:
One other issue is that the newer belts are made way more pliable than what they used to be...meaning they have more flex. A lot of v-belt made now are designed to "flop" in the middle. They're more like a rubber band than an actual belt.
I bought a full set of the Dayco Cog belts for my '74 years ago, and they worked fine, but they definitely did NOT fit all the way down into the grooves of all of the pulleys as they should. I bought a complete set of original Gm belts from a friend that had taken them off of a '73, and that's what I have had on it for about 10 years now, with no problems.
You're right about part # consolidation...."One size Fits All".....right....
I bought a full set of the Dayco Cog belts for my '74 years ago, and they worked fine, but they definitely did NOT fit all the way down into the grooves of all of the pulleys as they should. I bought a complete set of original Gm belts from a friend that had taken them off of a '73, and that's what I have had on it for about 10 years now, with no problems.
You're right about part # consolidation...."One size Fits All".....right....
The Dayco did seem to have a lot of "flop" in the middle...plus being a pretty long belt exaggerated that. I expect that's what led it to twist inside out. The new air pump belt I purchased was a Top Cog as well but it's doing just fine. It's a much shorter length than the alternator belt and has very little ability to "flop"...I don't think there will be any problems with it.
Just about the only belts I buy for everything are Gates. I buy the premium belts, and I have for years, and they have never failed me. They are not cheap, but they are VERY good.
Lifetime MemberManteca, CA - USA
Joined: 11/20/2005
Posts: 3623
Vette(s): 1978,two tone,Metalic Rootbeer & gold
1975 L48 4 speed
I am constantly experiencing belt squeal when I punch it hard so I keep tightening the belts but I'm very much aware of too much pressure shortening the bearing life of adjoining components. I've thrown away my belt goop from what we've learned here on the forum and I've heard of pulley wheels being worn smooth on the inside walls, and looking at them, you can plainly see that it's true, but I'm more inclined to go with what you're saying about belt quality. 
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I'm in ! Thanks for sharing.Jimmy B.
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Overland Park, KS - USA
Joined: 7/9/2003
Posts: 914
Vette(s): 1973 Orange Metallic Coupe (orig owner), L82, 4 spd (WR), PS, (A/C & PW (I installed from wrecked 73)), leather, AM/FM Stereo, ran with '65 FI unit earlier & will again some day.
2023 Accelerate Yellow HTC Stingray
Bottom line no matter which brand you get is that the belt has to fit the pulley.
Most, if not all, Chevy HP engines used deep groove pulleys to prevent throwing belts at hi rpms. Therefore the proper belt should sit well below (but not bottomed out) the OD of the pulley whereas the belt on standard engine pulleys should just be slightly below the pulley OD.
Most, if not all, Chevy HP engines used deep groove pulleys to prevent throwing belts at hi rpms. Therefore the proper belt should sit well below (but not bottomed out) the OD of the pulley whereas the belt on standard engine pulleys should just be slightly below the pulley OD.
1973 L-82 4 spd
in Forum: C3 Engines
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