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Discussion Starter · #1 ·
I have an '04 Cobra motor with a Kenne Bell blower. Everything else is working fine, but I've been blowing idler pulleys (not the same one every time). They actually crack, start to split open, and then shred the belt off. I've never seen this before on other cars or applications. Anyone else? Causes? Aftermarket idler pulley solutions?? I'd like to run ones similar to the idler from KB that sits next to the blower pulley, but anything that someone has found that works would be great... if anyone else in the world has had this problem.
 

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I never expierienced this are you sure the belt size is correct. Also Billetflow makes really nice aux idlers as well as MetCO.
 

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I believe this happens on our cars, especially with aftermarket blowers. I upgraded to the four piece Billetflow system, but other companies including Metco make heavy duty idlers too.

Matt
 

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Scott, are you talking about the factory idlers? If so, they are notorious for breakage with non-stock boost levels. They are just not designed for the the additional forces imposed on them with that scenario. Billetflow is the most popular solution, but Reichard and Metco certainly have a share of the market as well.
 

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I have broken 2 factory idler pullies. They are junk. Usually the lowest pulley is the first to go. Go with an aftermarket pulley and forget about it. Good luck!
 

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Discussion Starter · #6 ·
More questions

You guys are all great; thank you. I saw some from Metco that I think will do. "Double Bearing Idler Pulley 100mm" say they are for extreme duty use. I do need the 100mm not the 90mm, right? I have the smaller pulley on the blower if that's important.

Also, can you tell me other problems I can expect to have that maybe I can take care of before it becomes a problem? I'd like to take it on a road trip this summer, but can't the way it keeps breaking down now.
 

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Discussion Starter · #7 ·
I also don't know how many and of what size I need. I thought I only needed 3 of the same size (100mm) but some pictures show 3 - 100mm and a 92mm. I don't believe I need a tensioner pulley, (think mine is aftermarket already) but you guys know better then me.
 

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The auxiliary idler should be the 92 mm from Metco and then the other three can be 100's.
 

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The Canadian Snowbra
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The stock idlers are garbage, they're just stamped metal. I'm only running a single 90mm aux idler, and a 2.75, and I'm just waiting for the stock stamped metal ones to give up.

We'll see how long they last, good luck to you!
 

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Discussion Starter · #10 ·
If yours haven't given out yet do yourself a favor and get the aftermarket ones now. It will save you the cost of the belt, the cost of the tow, the cost of overnight shipping (if you want your car back on the road quickly), and the inconvenience of having to replace them on their schedule, not yours. Had I known these were junk I'd have upgraded before I ever even picked up the car. Unfortunately, after the first one broke, all the guys at the shop informed me that it had to be a fluke as none of them had ever seen anything like it, so I replaced with the OE part. That's why I asked if there is anything else that commonly breaks on these so I can get it fixed now!
 
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