Idler Pulley Sizes

[Terrorist 5.0]

Hi everyone, so I am having an issue with belts. Currently, I have no smog pump, no air conditioning compressor, and an ASP underdrive pulley. I put on a 2034MM belt, and upon putting it on, the tensioner marks were in spec, little on the looser side. Within a week or 2, after the belt had seated and all, the tensioner was beginning to knock from being too loose. I tried a 2020MM, and it looks like the tensioner is going to start knocking again soon. A 2018MM is too small. It seems nobody makes a belt between these sizes. I want to try to do this without buying the extra pulley. I figured I would change to a slightly larger idler pulley.

I measured the outer diameter of the stock pulley, and it looks to be 90MM. I confirmed this through other sources to solidly make sure I had the stock pulley. Does anybody make a pulley larger in diameter? I see there are plastic grooved pulleys, and they appear larger in diameter, but I don’t know how much that will change the belt tension, and how it will last, seeing that the smooth side of the belt rides on the pulley. I may try it for shits and giggles but I figured I would try the correct way first. Last thing I want is to have a belt snap on me.

Does anybody make a larger diameter pulley that will fit this car? Is there maybe a pulley from another Ford I could use?

Currently, I’m looking at other cars idler pulleys to see what will fit, but looking at Ford specifically, I don’t see anything that will help out. So far I see a 95MM pulley from a Hyundai with matching specs, but it is only 26MM wide. It will be close for the belt.

 

[95opal]

With stock pulleys it should be 82.7" or 2100mm. Not sure on the size siff in the ASP pullies but you could measure the diff. You may also try clocking the tensioner itself.

 

[Terrorist 5.0]

With stock pulleys it should be 82.7" or 2100mm. Not sure on the size siff in the ASP pullies but you could measure the diff. You may also try clocking the tensioner itself.

I’d rather not mess with the tensioner. I am trying a tensioner pulley off a first generation LS400 in the meantime. All the specs are the same but it is 10MM bigger diameter wise.

 

[duh09]

How olds the tensioner itself? Spring may just be a bit too tired.

Finding a larger diameter smooth pulley would be relatively easy with a catalog in hand. I'd dig through them tomorrow at work, but I'll be on the road all day going to grab a part for a customer.

 

[Terrorist 5.0]

How olds the tensioner itself? Spring may just be a bit too tired.

Finding a larger diameter smooth pulley would be relatively easy with a catalog in hand. I'd dig through them tomorrow at work, but I'll be on the road all day going to grab a part for a customer.

I have no idea about the age of the tensioner, but it doesn’t show any signs of wear. Doesn’t bounce around, make noise, nothing. I was looking online and the pulley I am TRYING currently off RockAuto, has an outer diameter of 102MM compared to the Mustang’s 90MM. So effectively, 6MM tighter fit to the belt. This may still leave it in the slightly looser range, but I also need water pump clearance too.