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Model 49 snowblower sprocket upgrade step by step

53K views 54 replies 21 participants last post by  MF Kat 
#1 ·
I decided to upgrade my snowblower to a different sprocket. I have seen many threads about this but no real step by steps. So I am going to attempt to do a step by step for you guys.

I was moving it into the shop in this picture



Here is the sprocket shield removed



This is the sprocket that needs removed



This is the master link in the # 50 chain, sorry it is hard to see



Here is the set screw in the original 40 tooth sprocket



This is after the sprocket has been removed, a good time to check all of your bearings on the auger.



This is the original 40 tooth sprocket removed




I think I am going to go with the 36 tooth it sounds like a good fit for my 322. I am going to order the sprocket on Monday hopefully, there will be more pictures of the chain link removal and the new sprocket install.
 
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#30 ·
I replaced my 40T with a 34T from Surplus Center. The only issue that I had was that the hub diameter is significantly larger than on the 40T that has a hub on both sides. The larger diameter hub on the 34T resulted in rubbing on the inside of the cover. The cone shape bump out on the cover isn't wide enough for the larger diameter hub. I ground the corner of the new hub at a 45 degree angle so that it wouldn't hit the cover. I didn't have to take too much off to get the clearance necessary.
 
#38 ·
This weekend I replaced my sprocket to a 30T from Surplus Center, and am not able to put the side cover back on. To get the chain to line up, I had to install the sprocket hub-side facing inwards, which may make a difference. Tonight I may try again, but flipping the sprocket and see if I can line up the chain.
 
#31 ·
gcaldicott - thanks for the tip, it doesn't appear that mine is going to hit but I will be sure to check it before I bolt the cover back on.

dan33klein - that makes two of us
 
#32 ·
I posted this on another thread discussing the same ?upgrade.

I have yet to see a GT with an engine big enough that a full bite of snow will not bog it down without reducing forward speed. The engine will only produce enough power to throw a given weight of snow a specific distance. A change in anything that is part of that equation will change the other values in the equation if the engine output remains the same.

More distance with the same engine means slower forward progress. Or, to put it another way, how far can you throw an engine? Now, throw it another 3' further without reducing its weight.

Commercial snowblowers are rated for tons of snow/hour that can be moved. If they need to move more than that, the engine has to be upgraded.

How well balanced is the impeller for your blower?
 
#33 ·
I saw your comment in the other thread as well Bob and it certainly bears consideration. I've yet to see a video or hear direct commentary from anyone regarding their results in deep/heavy/wet snow with the increased rpm's and would like to very much.

Another concern I have involves trepidation regarding the effects of the increased rpm's when finding a buried shoe or boot or wet rolled-up newspaper or even a curb with all that rotating mass spinning even faster than before. (It concerns me even at stock rpm's...) I fear the whole blower leaping into the air and smashing against the front of my hood, making a messy dent at the very best. I fear parts and pieces flying off the blower as it disintegrates at worst.

I tend toward the conservative side of things and may be concerned over nothing. An increase of 10 or 20% in rpm's probably wouldn't make any real difference in anything, but doubling it seems to me that it could get down right dangerous!

Thoughts anyone?
 
#35 ·
I saw reference to someone using a 22 tooth pulley. I didn't do the math but...

It was more rhetorical anyway. A 10% or even 20% increase isn't likely to result in any real changes either way. In order to realize any real gain in distance, something more will likely be required and that to me seems to be when things would start getting dicey.

The OEM's have to be concerned with product liability and thus err on the side of safety. There's something to be said for that...
 
#36 ·
I only wanted to increase my speed a little bit. And with such little change I am sure it may will work my 322's 18 horsepower yanmar harder but that is okay. As you mentioned in deeper snow you would have to slow down, well I would have had to go slower anyway. Just as with tilling the harder the ground the slower I have to go. I have seen a lot of guys do the upgrade and I just wanted to try it. I still have my factory gear in the even that I don't care for the performance. Here are the numbers for different sprockets.
40T = 88rpm stock
36T = 98rpm +11%
34T = 104rpm +18%
32T = 110rpm +25%
30T = 117rpm +33%

I agree that going to a 22 tooth would be crazy and there is no where near enough horsepower. Also has been stated in other threads these blowers were made for tractors with as low as 12 horsepower. I have 18 and an inline three so I should be okay with my 34 tooth.
 
#40 ·
I found that a 1" smaller drive pulley was a lot easier way to speed up mine. Works great.
 
#47 · (Edited)
I found that a 1" smaller drive pulley was a lot easier way to speed up mine. Works great.
The drive pulley is the one closer to the engine (prime mover).

The driven pulley is further from the engine.

Your statement gives conflicting information. A smaller drive pulley will slow things down. A smaller driven pulley will speed things up.

This is standard nomenclature in the mechanical trades and is used for clarity.
 
#43 ·
Nope. Smaller = faster. Just like everyone goes to a smaller sprocket to speed it up, whether it is the drive pulley or sprocket - it makes no difference. The only downside to doing the smaller pulley is that the gearbox also turns faster and could produce more wear. I wasn't concerned with that as it isn't that much faster and I don't run WOT that often anyway. My pulley was bend anyway, and had to be changed regardless. With my modern style spout mod, the snow flies great at 3/4 throttle.
 
#44 ·
> smaller sprocket to speed it up, whether it is the drive pulley or sprocket - it makes no difference

Not to belabor this, but to avoid future confusion it doesn't really work that way. Putting a smaller drive sprocket on doesn't speed up the 'gearbox' -- only the throttle can do that. (or some upstream gearing change) Make sense?

To increase final shaft speed: bigger drive gear/pulley or smaller driven gear/pulley, or both.
(all at the expense of torque)

/WW
 
#45 ·
He did not change the drive sprocket.
He changed the pulley on the gear box to a smaller one.
At least that is the way I understand it.
So he did speed up the gear box and auger speed.
 
#48 ·
That would be correct.
 
#50 ·
Hey TNT,
I was wondering how easily your sprocket change was? I am just getting around to changing my sprocket and have to admit the darn thing was very hard to get off. Used a gear puller to get the original gear off. I haven't installed the new gear but held it up and it seems will need to be pressed on. However I can't press it on while the shafts in the blower. I'm thinking of trying to tap it on with 2x4 over it as not to damag it. How did you install your sprocket?
 
#51 · (Edited)
Got a woodstove? Put the sprocket, hub down, on top of it to warm up for a half hour or more. Wear welding gloves to handle it after it's warmed up. It should slide right on.

Failing having a woodstove, make a rack out of a metal clothes hanger to support the sprocket over a heat lamp for an hour. Covering it with an old pot lid will help keep the heat from escaping.

A hub temperature of 370*F will give about 0.001" extra clearance for a 1" hole. An infra red digital thermometer is real handy for this.

You can't hurry the process using these low grade heating methods. It takes time for the heat to soak all the way through the hub, and there is a lot less risk for damage over using a torch.

Make sure that you install it the right direction and in the right place for chain alignment. That may sound dumb, but I've seen professionals install sprockets backwards due to focussing on the hot sprocket and just getting it on the shaft as quick as possible. They don't come off as easy as they go on, once cooled down.
 
#52 ·
Thanks tudor,
I held off until I got a response, I've used the old heating trick a bunch in the past with my oven. Only problem is it's far away from my work. I'll just have to cover it up to move it.
 
#53 ·
itsjojo - my sprocket wasn't to hard to get off or the new one on, I just tapped mine back on with a dead blow hammer and it went right on. The heating trick works good when I worked for Caterpillar we heated all kinds of gears all of the time to install them. A salamander heater can work also I have used one before when installing a timing gear on a 350 chevy engine.
 
#54 ·
Anyone use a 34 tooth on a 322 in wet heavy snow that can give a rundown on performance?

I have read lots of reviews, most state it's better after minimal testing in light snow. I can blow light snow moving very fast so moving it twice is not a problem. The heavy stuff is were I need additional throwing distance but at what cost...how much slower must I drive the tractor? I added the rubber mod (waiting for snow to test) and have a tall chute and tractor is at proper rpm...so a through deep snow review would be greatly appreciated by me and I'm sure other members.

Thanks
 
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