Idler Pulleys that last!

So your factory or cheap replacement idlers have bit the dust, ate your belt, or are just screaming for mercy? Don’t want to waste money on those cheap replacement idlers that die in a few months? There’s a solution for you!

Automotive idler pulleys! They have much higher quality bearings and seals in them. There’s a pretty good chance you can find them at any parts store. The only downsides i can think of for them is theyre a bit more expensive than mower idlers online (probably the same price as those junk tractor supply ones), and that the flat idlers need a bit more work to be usable as they need belt keepers.

For v idlers, you can find ones like this Dayco 89039- its about 3-1/16” diameter with a 12mm (just under 1/2”) bore. This is commonly used as an AC belt tensioner pulley on 89-95 toyota pickups. The 890XXX series of dayco idlers seem to offer a range of sizes of idler. Advanced Auto parts website offers the actual sizing if you type in the part number there.

https://a.co/d/6ysnqOG

Flat idlers are a bit more tricky- most automotive flat idlers dont have the lip around them to stop the belt from walking off. You have to make guides so the belt cant come off. Usually jusy an L shaped piece bent up with a hole to bolt it on works pretty good, like i have here on the lawn ranger.

If the belt rubs one keeper or the other as it tracks from side to side on the flat pulley, don’t stress too much about it, just make sure the belt isnt fraying. If your keepers have rounded edges it should be fine, your keepers shouldn’t have any sharp edges anyway.

Interestingly enough this serpentine idler probably had 100k miles on it before it was replaced and thrown on this tractor. It still feels as good as new with many hours of use and abuse. Really shows how good the quality is on an automotive idler.

You could also get a grooved serpentine idler, and turn the grooves down on the lathe. Then you would have a lip on each side.

Hey thats a pretty good idea! Someone could even do that with a grinder if they wanted to. I’ll have to look into it.

RichieRichOverdrive wrote:

Hey thats a pretty good idea! Someone could even do that with a grinder if they wanted to. I’ll have to look into it.

Yeah I have a wood lathe and use that all the time to machine things with a grinder.

RichieRichOverdrive wrote:

Hey thats a pretty good idea! Someone could even do that with a grinder if they wanted to. I’ll have to look into it.

There should be plenty of metal there to work with. Good range of sizes, too. All you'd have to do is cut the grooves down and smooth it out. I'd like to see pics if anyone tries this.