M122 Pulley & Idler Swap

synergydetail

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Hey all,

I’m looking to swap my stock M122 pulley out with the VMP 2.5” and 90MM idler. Car is a 12’ GT500. Never done it before. I have the VMP pulley removal tool but wondering how to access the idler and the best way to do it. Can’t find instructions or video anywhere. Appreciate any help! Thanks!


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PM-Performance

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I highly suggest to NOT use that VMP blower pulley. I cannot tell you how much money and aggravation their junk pullies have caused me.
That being said, yes the idler is pretty easy to do and should come with instructions. Plenty of videos on the pulley tool as well. I have one on my channel when i did mine as well
 
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axo250

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I highly suggest to NOT use that VMP pulley. I cannot tell you how much money and aggrivation their junk pullies have caused me.

I am surprised to hear of any issues with a pulley, specifically VMP’s setup that was referenced. I have run that setup for years without the slightest issue and know a number of others that have as well. Their pulleys look identical to the OEM pulleys and use the same bearings to my recollection.

What issue(s) did you have? Seems like a simple part that should be trouble free.
 

PM-Performance

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I am surprised to hear of any issues with a pulley, specifically VMP’s setup that was referenced. I have run that setup for years without the slightest issue and know a number of others that have as well. Their pulleys look identical to the OEM pulleys and use the same bearings to my recollection.

What issue(s) did you have? Seems like a simple part that should be trouble free.

the pullies were poorly designed. Not sure if it was just the press on, or if the modular ones were an issue as well, but my press ins were a constant problem chasing belt slip. Multiple belt styles and added $600 tensioner and belt size changes ect and nothing fixed it until I removed and went to a BPS pulley.

the ribs even after a short time were completely polished. I talked to BPS as well as others and they just laughed and said yea that’s a common thing due to poor rib design on those pullies.
 
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Nutty 5.0

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It’s pretty easy with that tool. They have a video or two on how to use it if you haven’t already watched them. I started out using the same setup on my 12 and had it done in about an hour but have done many 03/04 terminators before.

I’d recommend moving both the coolant and HE tanks out of the way. You don’t need to disconnect the hoses as there’s enough space to slide them out of the way. May be a good time to replace the other belt while you’re in there.


 

axo250

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How do I release the tension from the belt?


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There is a spring loaded pulley down in there somewhere that is called a belt tensioner. Find which one moves with a socket and ratchet and you’ll be on the game. After you pull the belt off the blower pulley, slowly release the tensioner back down so your belt will stay essentially in place.
 

axo250

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the pullies were poorly designed. Not sure if it was just the press on, or if the modular ones were an issue as well, but my press ins were a constant problem chasing belt slip. Multiple belt styles and added $600 tensioner and belt size changes ect and nothing fixed it until I removed and went to a BPS pulley.

the ribs even after a short time were completely polished. I talked to BPS as well as others and they just laughed and said yea that’s a common thing due to poor rib design on those pullies.

I’ll be darned. I have run a VMP 2.5 for a while now and never ran into any significant problems. I have seen a very small amount of belt slip as indicated by a little bit of black specks on the grey supercharger but have never noticed belt slip under acceleration. Nor have my pulley ribs worn.
 

PM-Performance

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I’ll be darned. I have run a VMP 2.5 for a while now and never ran into any significant problems. I have seen a very small amount of belt slip as indicated by a little bit of black specks on the grey supercharger but have never noticed belt slip under acceleration. Nor have my pulley ribs worn.

I mean. . . of course its something I am doing. lol. I am always the first person to experience these issues.
Thats what all the manufacturers tell me atleast until I hear from other people with the same problems.

That being said, I race my car and make a decent bit of boost. I can tell you I have logs out the wazoo to prove this and pictures and dyno runs showing the effect of boost loss.
Last step I did was add a BPS pulley at the recommendation of multiple people with the same issue and my belt slip is nill for the most part now. I only see a dip on the 2-3 shift when logging of maybe 1/2 to 1psi where before I would see 2-4 PSI loss with the VMP.
 

SCGallo2

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How do I release the tension from the belt?

There is a spring loaded pulley down in there somewhere that is called a belt tensioner...

Al you need is a common half inch ratchet end and hands like a raccoon to release the tensioner.

Looks exactly like this:

SC Belt tensioner.jpg
 

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