# Predator Repower needs new pulley



## Sarthos (Jan 5, 2021)

I recently began to attempt a repower on my old Toro 421 (model 38010) with the predator 212 engine that about 500 other people have done. I just have one little hang-up... It turns out the amount of rust holding the pulley onto the shaft was stronger than the pulley itself. So, obviously, I can't exactly re-use the pulley that's now in several pieces. I also found that while looking up the OEM pulley (toro 37-6720) that it's not only unavailable, but my pulley wasn't even OEM, it has neither a keyhole, nor the set screw the factory pulley is supposed to have. 

Now, the question is: since my pulley is toast, is the best course of action to hit up ebay, pay 70 bucks for what looks like the OEM pulley (but says 1" shaft even though I thought mine was 3/4"?) And buy an adapter to fit the oddity predator, or is there some other way of getting a pulley kit for the predator?

Thanks in advance


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## tpenfield (Feb 24, 2015)

Welcome . . .

Go to Tractor Supply or browse online Zoro.com and order yourself a couple of V-belt pulleys w/ 3/4" bore and of the approximate outer diameter of the drive and impeller pulleys. You will also need the shaft 'key', which I believe is a standard size. To 'lock' everything in place, you can get some 3/4" bore 'collars' of the thickness needed.

Your end result would look something like this . . .









Keep in mind that if you are going from the Tecumseh 4hp to the Predator 212cc, you can go for a slightly larger diameter impeller/auger pulley than the original, since you'll have the extra power.


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## tpenfield (Feb 24, 2015)

Also, with the Toro 3521/421/521 re-power using the Predator, you may need to add a spacer on the chute control where it attaches to the handle bars so that it clears the valve cover.


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## db130 (Feb 16, 2013)

On my _Predator 521_, I'm using a pulley from a Toro 524 that is 2.5" on the drive pulley side and 2.75" on the auger pulley side. I'm using it with a 3/4" to 1" crankshaft sleeve adapter.

I agree with @tpenfield that you should buy 2 new 3/4" bore pulleys since the Predator has a 3/4" shaft. 

Since the Toro pulley is so expensive in the used market, an alternative would be to buy a double pulley from an Ariens 924 series. They tend to be a little cheaper:









Ariens Engine Double Pulley from 832 Blower. Part # 02435700 | eBay


<p>Ariens Engine Double Pulley from 832 Blower. Part # 02435700. Condition is "Used". Shipped with USPS Priority Mail. One inch shaft , outside pulley 2 3/4, inside pulley 2 1/2 inches</p>



www.ebay.com





As that Ariens pulley has a 1" bore, you'd still need the crankshaft sleeve adapter:









7/8 X 1 X 3 Shaft Adapter Pulley Bore Reducer Sleeve Bushing & Step Key | eBay


Find many great new & used options and get the best deals for 7/8 X 1 X 3 Shaft Adapter Pulley Bore Reducer Sleeve Bushing & Step Key at the best online prices at eBay! Free shipping for many products!



www.ebay.com


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## Oneacer (Jan 3, 2011)

Just another thought, but when I was at Tractor Supply, they had a whole isle almost dedicated to a wide assortment of pulleys ... just sayin, might be worth a look.

If you have a Tractor Supply, might be worth browsing, and they also run some fantastic oil and lube specials.


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## Sarthos (Jan 5, 2021)

Perfect! I kinda thought after posting maybe there was a way to use two pulleys on one shaft, I've just never seen such a thing on a car or small engine before!

So, just to be positive, the measurements I should take are
1. The width of the belts, so I get a pulley for the right sized belt
2. The inner diameter of the drive pulley, match that so the blower goes at a reasonable speed
3. The inner diameter of the auger pulley. I can get a larger pulley to throw snow farther, but too large and it will bog down in heavy snow. I'm thinking maybe 1.3x the size would be reasonable?
4. Overall length from the start of the drive "pulley" to the end of the auger "pulley", the height of the new pulleys + collar should match this
5. It looks like you have an extra piece before the drive pulley on that image above. Is that something necessary to add as well?


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## Oneacer (Jan 3, 2011)

Just bring the double pulley with you that you need to replace, and a caliper. ... you might need a locking shaft spacer/lock ring as well.


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## tpenfield (Feb 24, 2015)

Pullyes are measureed by thier bore size (3/4" in this case) and the OUTER diameter size, which seem to be 2.5" and 2.75" in this case, as posted above. Your belt is probably going to be a 4L or 5L profile . . . so you can buy pulleys to match the belt.


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## tpenfield (Feb 24, 2015)

Also, measure the spacing that the original 'combo' pulley has/had between the belt centerlines. This will give you a dimension that the 2 separate pulleys (if you go that route) need to be apart. For that you can determine what spacers you might need (if any).


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## paulm12 (May 22, 2015)

I looked into the pulley set screws on 38010 machines before. The 1979 model (serial #9xxx) had a set screw, the 1980 model (serial 00xxx) had the set screw, and 1981 (serial 1xxx) did not. The ones without the set screw had bolts into the end of the crankshaft.

tx


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## Sarthos (Jan 5, 2021)

oneacer said:


> Just bring the double pulley with you that you need to replace, and a caliper. ... you might need a locking shaft spacer/lock ring as well.


I'm not sure I can get the pulley off the original engine unfortunately. I broke a few chunks off trying to remove it, and of course with chunks missing, it's even harder to remove than before. It's quite bizarre. And yes, I did remove the bolt into the crankshaft.



tpenfield said:


> Pullyes are measureed by thier bore size (3/4" in this case) and the OUTER diameter size, which seem to be 2.5" and 2.75" in this case, as posted above. Your belt is probably going to be a 4L or 5L profile . . . so you can buy pulleys to match the belt.


Yeah, centerline to centerline would work as well, I was thinking overall length but center to center is probably better.

So two pulleys and a spacer, that makes sense, obviously though I can't have the pulleys able to slide backwards or forwards on the shaft, I'm guessing


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## tpenfield (Feb 24, 2015)

was there and end bolt on the shaft? If so, with an end bolt and a sufficiently sized washer, it can keep the pulleys & spacers nice and tightly positioned on the shaft.

Post some pictures when you can.


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## Sarthos (Jan 5, 2021)

Top view (you can see the break in the pulley, also the keyway on the shaft that has no key)









Front view (you can see where the shaft is threaded, the bolt was taken off)









So yes, a bolt stops the pulley from being able to slide forward off the shaft, and assuming the new shaft is the same length that's perfect but as is it appears that nothing is constraining this pulley from spinning freely on the shaft (no key) and nothing constrains it from sliding backwards towards the engine.


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## paulm12 (May 22, 2015)

the pulley is (supposed to be) keyed. If the key is not there then you need to get one. The front of the pulley, where the bolt hits it, is smaller than the crankshaft diameter, so that is what stops the pulley from going any further towards the engine. 

tx


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## Toro-8-2-4 (Dec 28, 2013)

You are better off with two individual pulleys unless the Preditor shaft is not long enough. This way you can get the correct diamenters and center distances for both drives optimized. Becareful not to use the die cast alum pulleys at TSC. They are not made for higher horse powers and will not hold up. People have tried and have reported bad reliability with them. You may want to get an AK style pulley which is what is used in industrial applications. These will have standard keyways and have at least one set screw to hold it in place. This way you will not need a spacer. Check out McMaster Carr , Grainger, Bearings and Belts or just Google AK pulley. They are sized by their pitch diameter. Which is the diameter used to calculate the reduction ratio. It is about an 1/8 to 1/4 less than the OD. Also if you go too large you will have to modify your belt cover or fabricate a new one. Measure the wide part of the belts you now have. My guess it the tractor belt is 3/8 which is a 3L and the auger will be either 3/8 or 1/2 inch. The 1/2" will be a 4L. If it is cogged on the inside it may be a 3VX or a 4VX for a 3/8 and 1/2" respectively. Good luck and post some pics.


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## Sarthos (Jan 5, 2021)

paulm12 said:


> the pulley is (supposed to be) keyed. If the key is not there then you need to get one. The front of the pulley, where the bolt hits it, is smaller than the crankshaft diameter, so that is what stops the pulley from going any further towards the engine.
> 
> tx


Makes sense. Now, if I stack two pulleys it would be lacking that small front part of the pulley, so for my build I'd need some form of collar/set screw to put the thing into phrase


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## tpenfield (Feb 24, 2015)

The pulley is internally keyed as per the picture below. So, that is why it does not appear to have a key . . . but it does.










No need to worry about it, since you can buy separate pulleys and a key for less than the Toro part would cost. ($179 list, $90 ish on eBay)

It also looks like the drive and auger V's are just about the same outer diameter on the OEM pulley. I think the drive belt is smaller (3L maybe) (If I remember correctly) so it sits lower in the pulley when engaged.


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## tpenfield (Feb 24, 2015)

Also for future reference . . . pulleys tend to be 'stuck' on the crankshaft of an engine after 20+ years of age. You can heat the pulley (hot air gun or torch) to expand the metal, which will loosen its grip and make it easier to remove.


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## Toro-8-2-4 (Dec 28, 2013)

Sarthos said:


> Makes sense. Now, if I stack two pulleys it would be lacking that small front part of the pulley, so for my build I'd need some form of collar/set screw to put the thing into phrase


Yes, you can add a set screw by drilling and tapping a thread over the keyway. Usually a 1/4-28 thread should do it. Some have two 90 degrees apart. If you buy a new AK pulley it would be there already.


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## Sarthos (Jan 5, 2021)

tpenfield said:


> Also for future reference . . . pulleys tend to be 'stuck' on the crankshaft of an engine after 20+ years of age. You can heat the pulley (hot air gun or torch) to expand the metal, which will loosen its grip and make it easier to remove.


Yeah, I was hoping just PB blaster would do it, using a torch on the crankshaft was not something I wanted to do.

So, just something like this?








Standard V-Belt Pulley: 1 Grooves, 2.85 in Pulley Outside Dia., 3/4 in Pulley Bore Dia.


V-Belt Pulley, 3/4"Fixed, 2.85"OD, CastIron




www.grainger.com




For the auger and a slightly smaller one for the drive? The fact that it says 3L and 4L for the pulley I find a little odd. Beyond that, no need for any other spacers or collars to hold things together?
.


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## tpenfield (Feb 24, 2015)

I used those 'TB Woods' pulleys for my Troy-Bilt re-power. They seem decent. I did find that I had to sand the painted surface of the V groove a bit after some usage, as the paint within the groove caused some slippage after a while.

3L and 4L sized belts are often usable with the same pulleys . . . the 3L just sits lower in the pulley groove as opposed to the 4L.


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## Sarthos (Jan 5, 2021)

That makes sense, I'm more used to automotive belts sitting flat as opposed to the v-shape of the snowblower pulleys. And the general seeming witchcraft of the pulley not matching the diagram I had (no key, no set screw) had me kinda apprehensive. Looks like I know the way to go forward though!

On a semi-related note, I've read that, for snowblower use, these things might run a little lean and could use an aftermarket carb jet (like .30-32mm instead of .28 mm) It's a simple enough replacement, but when I search online for jets I tend to find more extreme aftermarket kits, like 38mm. Any good place to source a couple of jets?


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## tpenfield (Feb 24, 2015)

I used my 521/Predator straight up without a carburetor modification for a while and it was fine. The following year, I got myself a 0.030 drill bit and reamed the main jet slightly. It runs fine.

I think since the engine is well-powered for the size of machine, it runs OK on the factory mixture. You can always run a slight bit of choke if you need to go rich. On a 24" machine, it would probably 'want' the carburetor modification.


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## Oneacer (Jan 3, 2011)

I have my Predator 212cc on a 24 inch Ariens, it runs great, no mods whatsoever.


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## Sarthos (Jan 5, 2021)

Good to know! Just did not want to run into any other issues with this thing once it gets running. Having a snowblower decide not to run when you get around 12" of snow is... less than fun. And of course it just has to be a thing handed down in the family for generations, so I'm not allowed to just get rid of it and replace it. 

But so long as it tends to run fine we should be good! Might replace the impeller bearing as well, and at that point all should be well!


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## Toro-8-2-4 (Dec 28, 2013)

Sarthos said:


> Yeah, I was hoping just PB blaster would do it, using a torch on the crankshaft was not something I wanted to do.
> 
> So, just something like this?
> 
> ...


There are pulleys that can handle both 3L and 4L belts. The angle is the same for both v belts. the 3L sits deeper in the groove hence it has a smaller Pitch diameter. Remember, To get the reduction ratio you want, you need to work with the pitch diameter. Not the OD. Unless you are using it for a 4L belt, I would be concerned it may hit the belt cover. If you have access to a lathe you can turn the od down but you should be able to find a more suitable pulley. Look on McMaster carr. or Belts and Bearings. Good Luck


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