Serpentine Belt Double Sided?

KingChuck24

Active Member
So after buying a new replacement belt for 2.4l we realized that the one from zzp only had ribs on one side where the wheels on our engine have grooves for the ribs on both sides. The previous belt also had ribs on both sides. After looking around a little bit I couldn't find any double sided 703 5 rib belts. That is what we think we need. So if anyone knows anything about this that would be great. I am assuming it is not a good idea to put on the zzp belt that is not ribbed on both sides.
 

jirwin

Well-Known Member
I doubt you'll find a 703 belt. If memory serves (at least for Duralast at Autozone) the number is inches divided by 10. So 703 would be 70.3 inches. I think they usually come in 0.5" increments. Pretty sure on my supercharged 2.2 I'm running a 705 (70.5"). I'll check tomorrow morning.

Can't speak to the double sided as I'm not sure how your belt routing is setup
 

k.rollin

Goblin Guru
I think you're overthinking this. The ribs run against the crank pulley, A/C compressor (if applicable), and alternator. The tensioner pulley is smooth and runs along the backside of the belt, so ribs don't matter on the backside.
 

Gtstorey

Goblin Guru
I think you're overthinking this. The ribs run against the crank pulley, A/C compressor (if applicable), and alternator. The tensioner pulley is smooth and runs along the backside of the belt, so ribs don't matter on the backside.
He is running an add on supercharger so that might be why he needs a double-sided belt.
 

k.rollin

Goblin Guru
That's fair. I saw 2.4L and assumed naturally aspirated because I'm posting on mobile and didn't rotate my phone to landscape mode to make the signatures visible.
 

r3drckt

Goblin Guru
I’m assuming the SC just makes the belt run like it does on the LSJ. Easiest way to tell if it should be smooth or ribbed as it routes around a pulley is if the pulley is smooth or ribbed. Also posting a picture.

If it’s routed like the LSJ, I’m assuming everything is almost identical.
009BB0B3-6A99-4828-9131-ED05842A9241.jpeg


LSJ Serpentine belt replacement part number is 12585151, rock auto has them and they are also 70.2”
872230F8-61DC-41E1-923B-D98D472F4675.png

 

jirwin

Well-Known Member
I doubt you'll find a 703 belt. If memory serves (at least for Duralast at Autozone) the number is inches divided by 10. So 703 would be 70.3 inches. I think they usually come in 0.5" increments. Pretty sure on my supercharged 2.2 I'm running a 705 (70.5"). I'll check tomorrow morning.

Can't speak to the double sided as I'm not sure how your belt routing is setup
Yeah, its how I thought it was - 0.5" increments. K5 meaning 5 rib.

35657
 

k.rollin

Goblin Guru
I'm curious about the belt routing now, because a DIY supercharger add on using LSJ bits would make sense to use a double sided belt. The ZZP kit doesn't need a double sided belt, as jirwin and BAR-AIR have indicated based on prior posts/pics

 

Rauq

Goblin Guru
The LSJ setup has a 6 rib double sided belt and a one-way clutch on the alternator. NA conversions use a 5 rib belt and spin the stock (solid pulley) alternator in the opposite direction of an LSJ. That's why LSJ builds have to keep the AC compressor (for the pulley), and why the belt has to be double sided.
 

k.rollin

Goblin Guru
The LSJ setup has a 6 rib double sided belt and a one-way clutch on the alternator. NA conversions use a 5 rib belt and spin the stock (solid pulley) alternator in the opposite direction of an LSJ. That's why LSJ builds have to keep the AC compressor (for the pulley), and why the belt has to be double sided.
Right, but OP has a converted 2.4L that had a double sided belt with 5 ribs. His whole donor confuses me tbh, because a 2006 Cobalt LT would have been fitted with a Gen 1 L61, but he's got a LE5 which makes sense for a 2006 Cobalt SS/NA.
 

Rauq

Goblin Guru
I guess that makes sense if an LSJ tensioner and idler were swapped on and the L61/LE5 tensioner was removed. Key indication should be a 5 rib belt running on a 6 rib tensioner pulley.

I'm content to let OP chime back in before I continue speculating lol
 

KingChuck24

Active Member
Sorry I havent been responsive, been a long week.

Anyway, here is what I just bought. Thank you for all the insight on this but I just didn't want to have to deal with extracting the bolt from the wheel so I just bought the whole assembly new. The rubber things were wearing out anyway so it probably needed replacing soon. As for the belt it is a 6 rib double sided 70" belt. Thank you for pointing that out Rauq, I was about to order 7 for some reason. I am 90% sure these will work but I will update when they arrive.
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