How do aftermarket idlers prevent belt slip, if so, how do I decide on idler size?

[FreddyFingers]

Proper decision on idler sizing?

I'm not necessarily having slipping issues. I just replaced my belt after 3 years of use before the thing started its squeal. I'm not grasping the concept that aftermarket idlers prevent belt slip though. Only that they are a necessity for higher boost running due to weaker bearings in stock idlers. I say that because in aftermarket idlers even when increasing the idlers size to 100 from the stock 90 you still have to increase the belt size. Maybe I'm slightly retarded, but I cant wrap my head around it. I'm just not sure on how to decide proper sizing.

 

[Quick Strike]

The snub idler and bracket adds an idler under the SC that wraps the belt further around the SC pulley. That is what reduces slip. The replacement pulleys will not blow up like the stockers tend to do when you add more tension (tighter belt and removal of the tensioner stop) and a smaller blower pulley. There are pictures of all and a belt sizing chart here.

 

[FreddyFingers]

So the 92mm eliminates the tensioner completely or does it mount to the tensioner arm just reversed(stock pulley faces block)? I'm still in the same place kinda. I like that kit but unsure of belt size as I have a 2.8 Steeda upper/ #2 lower and cant exactly afford to buy 2 or 3 different Gates to test. I do like that BF set though! It shows a stock belt useage for the 2.76 and #2 lower, would this still apply in my case?

 

[Quick Strike]

How do aftermarket idlers prevent belt slip, if so, how do I decide on idler ...

No, you keep the tensioner pully as is and replace the three idlers. The fourth idler is added to a bracket that is installed under the sc snout. That is the one that adds more wrap around the sc pulley. You select a belt depending on your sc pulley size, lower size and number of aftermarket pulleys added as listed in the chart on the website. Click on the pictures on that page. They even have one that shows where they all go by size.

 

[cj428mach]

This right here is all you really need.

http://www.lethalperformance.com/sh...3-04-cobra-snub-idler-bracket-and-pulley.html

The stock idlers on my old SB car had 80k of abuse on them with a 2.93 pulley setup and were still doing fine so you don't have to replace all the idlers but its not a bad idea. The aftermarket setups usually go with a larger pulley in some of the places so that slows down the idler speed so the bearing life is improved.

Billetflow and Metco both have information on belt suggestions but when it comes time to order belts you can get them from Rock auto for as $10-$20 a piece I've even gotten some as low as $2.XX. Although if you can't afford extra belts I'd suggest staying away from modding as it usually just ends up costing more money.

 

[FreddyFingers]

Ok, cool. Yep saw the pics, just couldn't distinguish if the one was replacing the tensioner. You guys really explained exactly what I was looking for. Tracking all, much appreciated. I can do 20 bucks a belt but at 60 bucks a belt, woohoo. lol, tracking the costs of modding for sure, just cant stand frivolous redundancies. Thanks gents!

 

[MG0h3]

I ordered belts from Oreilleys when I pullied down. I had an idea of what I needed so I ordered three. @30 bucks for the Gates. I just returned the two that didnt fit.