v-belt pulley and idlers

Still going through my '56 WIAD machine. One of my v-belt idlers is very worn, the motor drive pulley has worn unevenly such that the outer belt is tighter than the inner and the idler has also paid the price. Has anyone made an idler from round stock? Reading on the forum, it sounds like there was some significant engineering in the bearing, bearing spacer, hub liner and idler so I'm not sure I just want to wholesale replace it with a piece from billet.

I'm looking for one or two idlers in decent condition and a good condition 5.5" splined pulley for the gearbox.

My gearbox pulley could be trued up at a smaller diameter, but I've only got one lathe running at the moment.

Thanks in advance,
Ryan

Well... typically, the solution is 'matched belts', but that assumes that you don't have significant wear/erosion on one or both ends of one of the belts' sheaves.

You could just use TWO idlers... use some belt tensioners from a modern serpentine belt... one for each belt would solve the slack...

DaveKamp said:

Well... typically, the solution is 'matched belts', but that assumes that you don't have significant wear/erosion on one or both ends of one of the belts' sheaves.

You could just use TWO idlers... use some belt tensioners from a modern serpentine belt... one for each belt would solve the slack...

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I read several past threads where new owners purchased matched belts only to find that they had uneven wear on the drive pulleys or idlers. I was hoping someone would have one or a pair of idlers with low to moderate wear that I could turn down and use. If I can't find any I'll just make some new ones.

The automotive serpentine idler pulleys tend to be plastic and just not very classy. I have several laying around in various boxes - extras for some of the race cars I maintain, but I think I'll stick with metal. I was eyeing a piece of 3 1/8" 6061 on Ebay.

For the motor drive pulley I fully expect that any I'll be offered will require truing up.

Once I get all the pulleys sorted I'll buy a new set of matched belts.

Ryan

I don't remember what I built using idler pulleys last, but the application from whence I sourced them, I DO recall... Jeep Cherokee 4.0L inline six... it was used... some engine swap left it in my junk box. They're steel shells with bearing pressed in. I mounted it on a stud, with lever and spring, and they run really smooth and true...

But my thought was, that if you have separate idlers, it won't matter if there's groove wear or mismatched belts.

My 10EE only has one belt, and although one idler, it basically does nothing. Gates Polychain... toothed belt with 3:1 drive ratio, and VFD on the motor. ;-)

DaveKamp said:

I don't remember what I built using idler pulleys last, but the application from whence I sourced them, I DO recall... Jeep Cherokee 4.0L inline six... it was used... some engine swap left it in my junk box. They're steel shells with bearing pressed in. I mounted it on a stud, with lever and spring, and they run really smooth and true...

But my thought was, that if you have separate idlers, it won't matter if there's groove wear or mismatched belts.

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I see where you were heading, would add some extra complexity to create a mount for the "third" idler. I'll have to give that some thought.

DaveKamp said:

My 10EE only has one belt, and although one idler, it basically does nothing. Gates Polychain... toothed belt with 3:1 drive ratio, and VFD on the motor. ;-)

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I have read here on the forum that one belt would be sufficient and maybe I'm just be nostalgic but I like the two belt design. To be honest there are lots of design elements on these machines that I find fascinating, It would be something to have met the original Monarch Engineers.

Ryan

The idlers are not magic, at least on later ones they are castings (to remove weight), not sure if they are aluminum or ankle based but they do wear. Many people have mounted them up and taken a skim cut to even them out. I would have zero worries about making them up from aluminum, for bonus points you could make the actual wear surface stainless (or something relatively hard) if you have the stock on hand.

Would worry more about the uneven wear in the motor/back gear sheave. I would try to correct that first. BTW I still have several of these kicking around (spline version) should you be interested, but you should be able to fix what you have as well.
Paul

PaulM said:

The idlers are not magic, at least on later ones they are castings (to remove weight), not sure if they are aluminum or ankle based but they do wear. Many people have mounted them up and taken a skim cut to even them out. I would have zero worries about making them up from aluminum, for bonus points you could make the actual wear surface stainless (or something relatively hard) if you have the stock on hand.

Would worry more about the uneven wear in the motor/back gear sheave. I would try to correct that first. BTW I still have several of these kicking around (spline version) should you be interested, but you should be able to fix what you have as well.
Paul

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Paul,

Mine appear to be Zamak or similar pot metal castings. I can imagine the unit being run on a single belt would cause the wear pattern I’m seeing, heavy wear on one gearbox groove and one deep groove on the front idler.

If i go with making a set, I’ll use 7075 aluminum which is significantly harder than zamak. Stainless steel wagon wheel rims certainly sound interesting.

I will send you a PM with my email about gearbox pulleys.

Ryan

I checked the output shaft on my gearbox, it uses a 28 tooth spline.

Ryan

Hi Ryan,

I'll take a look at what I have tonight. I think I have 2 sizes and also at least one pulley that has the smaller V belt profile (Discovered that monarch used at least 2 different types of V belts - I noted it several times on the site.

Assuming I have one that fits up and you want to borrow it while you fix the original we can arrange that easy enough.

Paul