Which v belt do i need

Zebbman

Not-quite-so-new-guy
Mar 13, 2021
21
13
Hello. I am changing belts on my 1986 Cutlass Supreme with a 307 and a/c. All original and complete. My issue is the a/c belt. The one I purchased is a Dayco 15520 and I also have a Duralast 15520. Neither will go all the way over all 3 pulleys. The one I took off has a 15525 number on it. Everywhere I have searched says the belt I purchased is correct. I just can't get it on. Seems to short. Can anyone tell me if I have the correct belt and if not what belt do I need. First time changing them on this car but not the first time ever changing belts so any help would be appreciated. Maybe I'm missing something
 

g0thiac

G-Body Guru
Sep 6, 2020
547
63
Hello. I am changing belts on my 1986 Cutlass Supreme with a 307 and a/c. All original and complete. My issue is the a/c belt. The one I purchased is a Dayco 15520 and I also have a Duralast 15520. Neither will go all the way over all 3 pulleys. The one I took off has a 15525 number on it. Everywhere I have searched says the belt I purchased is correct. I just can't get it on. Seems to short. Can anyone tell me if I have the correct belt and if not what belt do I need. First time changing them on this car but not the first time ever changing belts so any help would be appreciated. Maybe I'm missing something
See my other post.
 
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565bbchevy

Geezer
Aug 8, 2011
8,649
113
Michigan
The new 15520 should only be about a 1/2" shorter but could be too small to fit.
Dayco lists a 15525 belt if that is what you removed.
 

565bbchevy

Geezer
Aug 8, 2011
8,649
113
Michigan

g0thiac

G-Body Guru
Sep 6, 2020
547
63
That is 5 inches shorter
I just realized it was for the alternator (Google is a dumbass and apparently doesn't know when I type AC I mean AC lol)
 
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g0thiac

G-Body Guru
Sep 6, 2020
547
63
Hello. I am changing belts on my 1986 Cutlass Supreme with a 307 and a/c. All original and complete. My issue is the a/c belt. The one I purchased is a Dayco 15520 and I also have a Duralast 15520. Neither will go all the way over all 3 pulleys. The one I took off has a 15525 number on it. Everywhere I have searched says the belt I purchased is correct. I just can't get it on. Seems to short. Can anyone tell me if I have the correct belt and if not what belt do I need. First time changing them on this car but not the first time ever changing belts so any help would be appreciated. Maybe I'm missing something
Nvm what I posted before, this is what will work.


 

565bbchevy

Geezer
Aug 8, 2011
8,649
113
Michigan
I just realized it was for the alternator (Google is a dumbass and apparently doesn't know when I type AC I mean AC lol)
Sounds like my stupid smart phone that likes to auto correct me when I use an automotive term
 
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g0thiac

G-Body Guru
Sep 6, 2020
547
63
Sounds like my stupid smart phone that likes to auto correct me when I use an automotive term
Auto correct haha, don't even get me going on that lmao.
 

g0thiac

G-Body Guru
Sep 6, 2020
547
63
Hello. I am changing belts on my 1986 Cutlass Supreme with a 307 and a/c. All original and complete. My issue is the a/c belt. The one I purchased is a Dayco 15520 and I also have a Duralast 15520. Neither will go all the way over all 3 pulleys. The one I took off has a 15525 number on it. Everywhere I have searched says the belt I purchased is correct. I just can't get it on. Seems to short. Can anyone tell me if I have the correct belt and if not what belt do I need. First time changing them on this car but not the first time ever changing belts so any help would be appreciated. Maybe I'm missing something
Since this is your first time changing the belts, this might help by the way.

 
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69hurstolds

Geezer
Supporting Member
Jan 2, 2006
5,901
113
Your 86 Cutlass VIN Y should be this belt-
9433757 7/16 x 52.5" - This A/C belt was used on the single belt P.S. pump setups along with the single belt from water pump to alternator setups for 307 Cutlass. (see the video- it shows a similar setup). You can tell easily by the single groove P.S. pump pulley and 2 different sized water pump pulley grooves.

9433756 7/16 x 52.0" - This A/C belt is called out for the DUAL belt P.S. pump setups with part of the alternator belt running around the front groove of the P.S. pump. This setup was used on SOME Cutlasses mid-84 production and up, mostly VIN9, and IIRC, the Diesels.

Some aftermarket belts come with the length size in their part number. Examples you gave was the 520 and 525 belts. 520 equates to 52.0" and the 525 equates to 52.5".

Obviously it doesn't have to be a GM belt, I'm just throwing the p/n's out there as to what the sizes of the belt are. Pick the one best for you, and you should be golden.

Good luck.

Edit: I went back and looked at the video and I thought I saw that A/C belt number was 15585. I'm like "dafuq"?? That seems weird. Then I realized it was likely a Custom Cruiser setup with the A/C belt driving the A.I.R. pump too. Errrgh. 86 Cutlass drove the A.I.R. pump via an extension pulley off the crank specifically for this, as did many others. Olds used about 43 different belts in the 80s and early 90s on the 307s.
 
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