Summit lists multiple lengths of belts for a 79. Not sure which to get...

What are the stock belt lengths for a 79 L82 AC/PS/Auto? I need 3 belts...alternator/water pump, AC/water pump, and power steering. The AIR has been removed.

Many thanks,
Steve

 

I forget where I bought my belts.
The fit perfectly.
they are one so I cannot measure them for you

Im wondering if the different lenghts refer to L48 vs L82 and early vs late 1979.

 

"Dayco" is the only way to go. One of the forum members is a rep for them Ill try to find out his forum name and he should be able to help........LT

 

Good luck! First let me rant! I've been trying to get a couple of "correct" belts for my 78SA and my black 79 for a while, now. Going by the vendor part no., I got wrong belts for both alternators. The one for the 78 fit the 79, one inch longer. OK, send me out a one inch longer for the 78, then. Wrong again, it was too wide! Finally gave up and bought the alt belt for the 78 off the rack at the auto parts store. Fit perfectly. At least now I knew the EXACT size I needed. Recently decided to try again getting "correct" numbered belts. Talked to the "tech" guy at Corvette Central, wanted to order 2 belts by GM part nos. First one was AC for the black 79. GM number and size both copied directly off the original belt(8K mile Vette). "That no. doesn't exist". I'm reading it right off the belt!! "No". OK, how about the alternator belt for the 78SA? Here's the GM number and size. "That's for an L48, are you sure you have an L82?" Duh!! Ordered that belt anyway. Got the belt, it was stencilled with the GM number and size, .380X53. But it wasn't. Was .440X53 which meant it would ride higher in the pullys and need to be a little longer. I had determined 1" longer if a .440 belt when I went with the generic belt. Right now I'm waiting on a specified .440X54" belt, but they seem to have a problem if not given THEIR part no.

Anyway, copied off the original belts on both of my 79s. One a 4speed, other an auto. Both are "late"79s.
AC, .500X55.0 This is the belt I was told by CC that doesn't exist. I THINK a .440X54 might work. Rides lower in the pullys so it can be shorter.
PS, .380X36.0 Was told a while back that .380 size is no longer made.
Alt, .380X52.0 Again, not made? BUT I do know that a .440X53.0 fits perfectly as I ended up with that size for the white79.
If you want GM/Dayco part nos. let me know. I just don't think they'll work any more.

 

So...if I read this right, for my early 79 I'll need a 55" for the AC/water pump, a 36" for the PS, and a 53 or 54" for the alternator/Water pump? How about width...Summit offers 7/16 or 17/32". Do I need to measure the pulley? How important is it that the belt is the propoer length, as long as it fits reasonbaly well and has the correct tension? Bear with me here..

Thanks Guys and Gals, S

 

The correct length depends on the correct width. The 7/16 is the same as the .440, so the alternator belt would be 7/16(.440)X53. AC would probably be the 17/32(little bigger than .500 width)X55. PS I would go with the 7/16(.440)X36. Except for the alternator size I stated, I can't be sure of the others because none of these sizes are EXACT as original, but I did have that size alternator belt fit perfectly. You may even need to add 1/2" to the length of both the AC and PS .
Now these are measurements for a late 79, so I'm not sure how they would fit an early79. Most of my looking shows "early"79 as being REAL early, before 8/78. Like the first month or so of production.
What I've found is that the correct belt,.380, or 3/8" rides low in the pully. Since ya can't get that size, ya move up to the .440, or 7/16" which rides higher on the pully. For a belt in the 50+" range, it means adding 1" to the length. I found that 1" short means not getting the alt belt on because the alternator hits the valve cover. 1" too long and it's at the very end of the adjustment, maybe even where ya can't get it tight enough.
If you're not interested in originality, why not go local and get Daycos from an auto parts place with the understanding that you can bring em back and exchange them if necessary? Take your old belts in and let them measure em with their handy-dandy belt measuring device.
This IS frustating! This is the only project i've had trouble with on my Vettes! I AM fussy in that I want everything adjusted to the correct location, not just close.

 

Will do...great detail and advice. Thanks for taking the time to clarify. My alternator belt is right at the limit of adjustment so I'll cut back on the length to get it more centered in the support. I'll let you know how I make out.
Steve

 

Here's something I noticed last nite. On my 78SA, the original PS belt is .440X36.5. Notice, there's that extra 1/2" added that I explained above when going from .380 to .440 width.
So, I would SUGGEST....
Alternator belt, .440(7/16)X53, which should put you right in the center of the adjustment.
PS, .440(7/16)X36.5
AC, .440(7/16)X 54, which because it's narrower than original it should be that 1" shorter.
If you go local and they have Dayco belts, numbers should be...
Alt. 15530 ("15/32"X53, get it?)
PS. 15365
AC. 15540
Good luck.

 

Hey- I'm dealing with this exact issue now and curious how you made out. I have an 80 L82 with no AIR and need all 3 belts. I have the PS but, the other 2 are toasted, broken, melted and I can't use them as a reference to measure for replacements). Can you tell me the brand and part numbers that worked for you?

Thanks!!!

 

All Dayco:
Alt. 15530
PS. 15360
AC. 17540

I could have gone 1/2" shorter on alt and 1/2" longer on AC. Still worked out fine as above.

Next time I'll use this if available:
Alt. 15525
PS. 15365
AC. 17545 or 17550

Good luck, Steve

PS Some advice: Buy a range of belts, especially for the alternator, and test them on the car. Just return the ones that were too big/small when you're done. I went to Autozone 3 GD times to get the "correct" belt and it still wasn't perfect since the alt securing bolt is right near the end of the bracket. I was hoping to get it to land somewhere in the middle to give some future adjustment when it loosens. PITA

 

The ideal match for belts and pulleys is to have the top or the outside surface of the belt flush with the top or widest part of the pulley groove. This creates maximum grip at the proper tension.

A lot of these older cars have had the wrong belts installed over the years so matching those won't help.

I found that first adjusting to the shortest setting, for example the alternator, and then using an old cut serpentine belt (flat side around all pulley tops) to measure the total distance. Then subtract 1" for the pully depth and you should be within range.

As Wuttin suggested, get them locally so they can easily be exchanged.