Belt & Tensioning help

[LGHTNGfeverUAE]

I have recently done some upgrades to my 00 L - namely adding a plenum and TB plus 4lb pulley which included a new belt.

The new belt however seems quite loose - it can be fairly easily bent with a thumb and forefinger near the SC and is nowhere as tight as the belt at the bottom on the block as a comparison.

What I wanted to know was:

* How tight should the belt be?
* Is the stock tensioner spring loaded (this is what my parts shop told me) - ie. can it be tightened more?

The belt was supplied by JDM and is numbered AT 25 - 080680.

I am concerned that i may be facing belt slip and a loss of power as the belt is too loose.

Any help or advice would be welcome

 

[LGHTNGfeverUAE]

Can anyone offer up some answers? Much appreciated.

 

[speed3198]

Try adding a set of billet idler pulleys. They come in 90 & 100 mm diameter sizes. This should eliminate the slack. Depending on mileage for your L it's probably due for them anyway

 

[65fastback2+2]

Belt is slightly too big. here's a chart I made you can view for belt sizing: Ultimate Eaton/KB Belt Chart

stock idlers are 90mm, so changing them to 90mm wont fix anything.

are you sure you have the belt routed correctly?

 

[speed3198]

My mistake, I didnt measure the stockers when I swapped them with the 100 mm ones. Im running a 4# pulley and the new idlers made the belt a tighter fit.

 

[LGHTNGfeverUAE]

Thanks for the info gents. If I understand this correctly a 100mm idler pulley will increase tension.

Would having the correct belt help too?

Alos I am presuming that a tensioner might be a good idea too..

 

[Robert Francis]

Having the right length belt for your pulley combination is what you want. If you had changed your upper pully to a smaller size, it may have been advantegeous to change your upper idler pully to a larger size (from the standard 90 mm to 100 mm).

The standard belt tensioner is internally spring loaded and "not" adjustable.

 

[LGHTNGfeverUAE]

Thanks for all the info, much appreciated. Ok, just got a confirmation from the supplier that they sent a belt for a 6lb pulley not a 4. I am aiming to change it up for the correct one.

I have one last question: Is it still viable to change up the idler pulley to a 100mm if the belt is the correct size?

 

[Robert Francis]

If you have the correct length belt for a 4 lb pulley and the standard size upper pulley, you shouldn't need a 100 mm idler.