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[VR-VS] How to fit Clarko's 20% underdriven pulleys onto a ecotec engine

Immortality

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Hi Guys

recently I completed a group buy for the Clarko's 20% underdriven pulleys, now I figure I better do a quick "how-to" so that everybody can see what is required to fit these great looking pulleys. Originally I fitted a set on my VN. I liked em that much I got another set for my missus VS :)

Ok, firstly, required tools

24mm socket and ratchet
15mm ring spanner
10mm ring spanner
8mm ring spanner
Hammer (I know you're wondering about this one)
Block of wood
Old serpentine belt
Cold brew

1. loosen the 4 bolts holding the water pump pulley (8mm ring spanner).
2. Loosen the 4 bolts holding the power steering pump pulley (10mm ring spanner).
3. Remove the Serpentine belt (push down on a 15mm spanner fitted on the tensioner pulley bolt).
4. Using a old serpentine belt, loop it around the harmonic balancer, double it over, around the idler pulley (under the dfi module) and wrap the other end around the alternator pulley doubling one end over (as per in the picture below) and using the 24mm socket/ratchet undo the nut holding the alternator pulley on.
133708d1328232011t-how-fit-clarkos-20-underdriven-pulleys-onto-ecotec-engine-img_3987.jpg

5. Remove old alternator pulley and fit new shiny alloy pulley.
6. wrap the serpentine belt around the alternator pulley in the opposite direction and tighten the nut for the alternator pulley.
7. Remove the water pump and power steering pump pulleys.
8. Because the new alloy power steering pulley is a larger diameter we are going to have to "adjust" the 2 steel transmission coolant lines that run under the power steering pump. I used a block of wood and hammer to gently "persuade" them to move. It's a bit of a "trial and error" method, you want to move them enough that they won't foul on the new pulley but you don't want to move them to far to either damage them or get a kink in them reducing flow (see pic below).
133709d1328232045t-how-fit-clarkos-20-underdriven-pulleys-onto-ecotec-engine-img_3988.jpg

9. Fit your new shiny alloy power steering pump pulley and fit the bolts finger tight.
10. Fit your new shiny alloy water pump pulley and fit bolts finger tight.
11. rotate the new water pump pulley buy hand a couple of times to make sure it's centred and running true (might need to do it a few times until you get it spot on).
12. Fit your new serpentine belt, I used a 6pk2815 belt (original belt was 6pk2720).
13. Fully tighten the 4 bolts for the water pump and 4 bolts for the power steering pump.
14. Double check that the power steering pulley clears the transmission coolant lines again.
15. Start engine and check that everything is running correct and true.
16. Enjoy a cold brew.

You should have something that looks like this,
133710d1328232107t-how-fit-clarkos-20-underdriven-pulleys-onto-ecotec-engine-img_3990.jpg


Cheers

Bart

Disclaimer: I have taken all due care to ensure that the above information is correct and accurate, I however accept no liability for any damage to you, you vehicle or any thing or any body else from you following these instructions.
 

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Last edited:

Munz

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lovin number 16


how does the car feel after the install...any difference?
 

Immortality

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I definitely think it's more noticeable on the VN with the manual trans, that one revs out a lot easier now. These days it will cruise in 5th gear at 60km/h (3.45 diff ratio) and it will happily accelerate without complaint with the slightest touch of the throttle. Only driven the VS once since fitting them so it's a bit early to say. Throttle response is certainly fairly good. Need to give it a good run so I can actually use some throttle, a good hill climb maybe :)

cheers
 

Immortality

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The under driven pulleys reduce parasitic power loss from the crank, basically the accessories are consuming less power from the crank because they are spinning slower. The pulleys were originally designed for high revving engines but work on standard engines too.
 

Immortality

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Ok, been on a few days now. In my opinion throttle response has improved. Gave it a decent boot coming up a hill and it accelerated very nicely indeed. Cruising now i'm using stuff all throttle.

Overall i'm happy with them :)
 

Immortality

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The group buy was $345 + postage.

Retail they are $405 + postage for the set now.
 

showbags

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As I see it the only mistake you made was step 16 should come after every second step:)
 
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