Most of the Hondas I've seen and worked on (over 100) have between 3/16" to 1/4" gap.

 

As with many things you get what you pay for. Honda housings are constructed to fit reasonably tight around the impeller which is not easy for a few reasons. But that precision comes at a price.

Other companies, though, are also able to get relatively close. A gap of 1/2" is, obviously, not very good and makes those snow blowers good candidates for impeller modification.

 

Exactly what I am doing to my Yard man !!!

 

When I made my impeller end gap modification, the greatest distance I found between impeller end and the housing was 5/16". It varied very slightly around the whole housing but that was the largest gap, which then told me how big to make the material to bridge that gap.

https://www.snowblowerforum.com/for....com/forum/honda-snowblowers/144101-honda-hss724aawd-impeller-modification.html

 

Just did my impeller mod, and to my astonishment I am able to put my index finger half way so I measured about 3/4 inch. Did not check all around just 2 spots near chute.

I will be adjusting the rubber flaps tomorrow to have least friction and have 1 or 2 mm gap. This should make major difference in snow being thrown.

 

depends on model. most I have done I can almost get my pinky in the gap. how's that for scientific?

on the older models like the 50-55 the gap is larger. I usually don't put them on 1132's because they don't need them for all the power they have. unless requested by owner.

 

pinky lol very scientific !!!!

I mesarured mine lol but 3/4 wow

 

New ones are tighter. My old hs 624 maybe 1/4 " ?

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Hard to see ...

 

Here's my mod.
The gap did vary from left side to top to right. Had to adjust the rubber mat with my grinder.

i used a mod flap from a big truck cie near me.

 

Mine was also 'cone' shaped quite a bit
In it's favor though that gap was consistent for the entire perimeter ..no egg shape at all.

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I know about the bearing but if it's rusted don't need to break my head about that one for the time being.

I know there is a gap on the right but
- this thing is spinning so fast that everything is going upward in a straight line.
- yes you're right there is liquid, but still going outward in a straight line.

I have seen guys just doing our mod going through water and slush about 3 inches and it just throws everything.

so adding the inside left in a second part next to it as close as possible will make a small difference. will it be noticeable ??? not sure but worth it !!!!.

Will do a video tomorrow and if I have the courage to do the second mod, will do second video.

Can't do one impeller as will be imbalanced and we're expecting close to 3 inches tomorrow mixed with small hail, ice pellets

so it's either all 3 or nothing !!!

 

Even if you don't mod..it a good idea to just just take the machine apart once in a while anyway...if not when the day comes everything will be stuck due to rust
Split it down the middle.. remove the pulley.
Remove the bearing retainers on the side of the bucket.
Hope your shaft isn't stuck in the bearing behind the impeller.
Pull it all out from the front of the bucket.
If your impeller is froze to the shaft...tap it off...shine everything up.
Clean up the auger shafts where they go into the retainers in the side of the bucket...Grease
Take off wheels..clean shafts.. grease...grease where they go through the bushings.
Clean and lube hex shaft.
Check everything for wear as well.
It sounds like alot of work..it's not though.. unless everything is stuck together.
We won't be able to match a Honda even with a good paddle mod..I have seen videos of them slinging some nasty stuff thirty feet.
But next time I mess with the paddle I am going to get the corners ..kind of a cup shape like some of the Ariens.
When the stuff gets nasty any little advantage you can give yourself is going to make a noticeable difference.
Although I haven't clogged yet I have had the stuff sticking to my plastic chute..it freezes on there under the right conditions..A higher velocity will help combat that as it will be knocking that stuff off itself.
I have been bombarded with small snowfalls on warm ground...worst kind..It's just a matter of time before I join the 'clogged' crowd.
I have had my augers and bucket clog up with the stuff..corners get packed ..and augers get the stuff packed in..that is with car wax from the summer..and furniture polish in between uses in the winter.. I will try something different next year




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U shaped spoon of belt or pad not sure.

When I thought of rounding the pad in the corner, I was afraid of vibrations caused by the rubber pad hanging in mid air not supported by direct contact of impeller.

 

Saw people use slippery stuff from DuPont others Pam for cooking lol that's what I will use. As for the pulley and bearing yes you're right. Have done everything outside in the cold from -3c to -12c lol. Changed belts all 3 greased and lubed everything both gears removed friction disk changed it removed wheels sanded rust greased the shafts beatings flange split the base in two changed augers cable replaced the skis removed carb and small clean twice did the mod impeller changed oil all that in the cold outside. Have two order 2 bearings around hex shaft as both are finished.

 

Of what I saw no lubing or maintenance had been done except maybe oil on my machine for quite some time.

 

Wonder what would be best Pam furniture polish or car wax ?? Was going with Pam as it's the second most popular stuff I saw guys used. First was DuPont stuff .

 

it's almost impossible to attain a perfect seal as the inside housing is NOT a perfect circle . You can get pretty close. and important step is breaking in your pads. if you do it "dry" the pads will melt from the friction and may be damaged , split , etc and may have to be redone.

so you should use some kind of lubrication ( i use fluid film but other lubes will work ) and proceed slowly at first so the pads will wear in. I have posted this before. I have two Honda HS80's that I experimented with. One with kit and one without and waited for a wet slushy snowfall.

we had about 6 inches of it so tried out both blowers. the one without the kit clogged up every 3 feet or so. the one with the kit threw the snow and water 10-15 feet. under dry powder conditions the results were similar. the one without the kit threw the dry powder very well as it always did but the one with the kit threw the snow further.

the efficiency is improved. you in effect have a water pump now.

 

Do you think the impeller mod is worth doing if you have about 1/4" gap?

 

I'm in my third season with my Husqvarna ST227P (254cc engine). It moved even "good snowman" snow fairly well, although too wet and I'd wind up re-blowing a lot of the snow in the wide part of the driveway outside the garage, where it flares out to pass also by the side of the garage. But after a storm that dropped an inch or two of snow and then enough rain to leave a half inch of slush at the bottom, I had to handle the mess with the push plow. Otherwise the blower would clog too often, and in between clogs the soggy mess would dump out just a couple of feet to the side. After stalling too long and putting up with doing the slushy jobs by hand, I bought the materials and did the impeller job.

Following a link from another thread on impeller mods, I bought a 3-ft roll of 4" wide 1/4" SBR; the label reads "70 S Shore A, Black, Smooth Finish, No Backing." I found a source of 40x80 mm stainless mending plates online, and from the hardware store I got 1/4" stainless bolts with locking nuts.The bolts are 3/4" long, but I should have used 1" to make it easier to get the nuts on in tight quarters. Below are pics I took this afternoon, with the chute removed. The top two pics show the bolt head side, as the impeller blade is about to pass the chute area. You can see how I bent each plate up to hold the rubber piece as it turns up the curvature of the blade. The first also shows where I notched the rubber where it passes over the chute bolts. The third pic shows the back side of the blade, where the nuts are fastened, and the stiffening groove in the blade. The groove was convenient for starting the bolt holes. I suppose drilling twice in the groove weakens the blade, but that would be offset by having the plate/rubber sandwich bolted on. I used a new 5% cobalt bit at slow speed for the drilling, with the chute off, with an old round cold chisel placed through a chute bolt hole to hold the impeller from turning as I leaned on the drill. A strong magnet was used afterward to clean up the bits of drilled out steel from the housing. The first and third pics also show that the rubber turns up the end of the blade, but not all the way to the tip. The end of the rubber does go outside the chute opening, so I'm not concerned about spillover there.


The last pic shows the can of spray stuff that Tractor Supply sold me when I asked about what they'd recommend to make the inside of the bucket non-stick. It seems to do the job well.


After finishing the job, I took the machine outside and started the engine. After a bit of warmup, I engaged the drive, and I did notice a brief bit of laboring as the impeller was driven around the housing. I didn't run it for too long that way. I figured that the roughness of the housing interior, due to small stones and other crud from two years of blowing, would file down the edges of the rubbers pieces in short order.


Given the snow drought we're having here in NH this year, the only test of the modified machine was in 4-5" of very light snow. Whether it performed better on that stuff is hard to say, as that type of snow sort of aerates quickly ten feet out of the chute and disperses. I'm waiting for something heavier to fall. We've had maybe 3" of light snow today, but tomorrow we're due for some sleet and freezing rain, then maybe back to snow at the end. I'll wait for the end of that, then see what happens to the combination of snow and ice.


An earlier post commented on improved chute velocity. I thought I'd add my own. With an unmodified impeller, snow/slush right at the tip of the impeller should be near the speed of the impeller itself. But right next to the housing, the drag of the housing would slow the speed of the snow considerably, to a fraction of impeller speed, notably when the snow is really sticky or slushy. In between impeller and housing, snow speed would be somewhere in between, falling off rapidly outside of the impeller tip. This layer of reduced-velocity snow/slush likely is what leads to increased chute clogging. Thus it's easy to imagine why having a rubber piece sweeping up snow right to the housing would nearly eliminate that low velocity layer and improve the throw. I doubt that the slightly higher velocity of the very tip of the rubber compared to that at the tip of the impeller blade has a lot to do with the improvement. I think it's mainly the elimination of the low-velocity layer that does the trick.


[Moderator: given that this thread has grown in length considerably and is mostly about impeller modification and not really specific to Honda blowers, should it be moved to the maintenance/repair forum?]

 

We arent working on the space shuttle they are just snowblowers.

Put some rubber on the impeller get it as close as you can and you will be fine.

It works wonders on all blowers I've done them on ariens, mtds, hondas. They all have noticeable improvement and no clogging.

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Hey guys, you can take my opinion with a grain of salt, I’m just a high school history and sciences teacher, not a rocket scientist!

My take is that under some conditions, a bit of an impeller gap can be beneficial ... bear with here:

Our engine can only produce a finite amount of power, and that power (amount of work accomplished over a given time) is a product of torque (force) and rpm (how often this force is produced every minute)

Now I can see how impeller gap effectively creates a “leak” in the pumping action where we are using engine power to push snow through a duct. For this effect we are trying to :
- accelerate the snow to maximum speed in order to obtain good throwing distance and avoiding clogging...
-maximize the quantity of snow we are removing from the auger box to avoid bogging and overspill as we move, ideally being able to take full swath as we go to fully use this auger width.


Now, although air and snow are consider fluids in mechanical science (I know, air is a gas, snow is a solid) we cannot fully compare our impeller with water pumps impellers...
Our snow blower impellers are more an hybrid between pump impellers and air screw (propellers). This means that a certain ratio of air in our impeller will not cause a drastic drop in pumping efficiency not any increases in cavitation. In fact, due to its very low density, a certain amount of air intakes allows to reduce load, effectively keeping the impeller RPM into its optimal working range. (Engine rpm as well since these two are mechanically linked by a belt)
You can compare the effect of air in the snow/air mixture here with a torque converter in your automatic transmission... (you might not like the mushy feeling of AT in your car, but there is no denying it does multiplies the torque force applied to wheels at low engine rpm!)

Now, can impeller gap mods be helpful? Yes! It can increase throwing distance, it can help prevent clogging (very wet snow behave more like water than dry powdery snow). This is very true in not so well engineered snow blower(I used to have a very bad craftsman )
The down side: you are now at risk of overloading your engine power due to the extra mass (pure snow is denser than snow mixed with air) of the snow that must be lifted and accelerated by your impeller at the passage of every impeller blades...

Would I recommend such a mod on Honda’s and Yamahas? Nope... not on mine... Honda engineers spent a lot of time balancing the ratio of snow/air (efficiency) of the impeller to make sure it grabs enough snow to empty the buck as fast as the auger can feed it while still sucking enough air to maintain rpm and accelerate the mixture to speed in the chute.

So how to know if you can benefit from such a mod?
Use these question:
Could I used extra throwing distance?
Is my bucket always spilling of the side as soon as I take full width swath?
Am I often dealing with water, extra wet snow?
If you answer yes to any of the above, chances are that increasing the scooping volume of the impeller would help you.

Last note of the throwing distance:
Increasing the impeller rpm (pulley ratio) would be more efficient as it will increase both the snow and air moved in the chute.. it will also avoid risking premature bearing damages due to improperly balanced impeller...

All right, I’m braced, you can flame me now...


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I will bite.[emoji1]
I will start with the torque converter comparison.
A torque converter redirects the fluid to another set of vanes to increase torque..
An impeller in our machines with snow going around the impeller would be a comparison to a slipping clutch.( Converts to heat as wasted energy)
Maximum work. Peak HP in theory is where we can achieve maximum work (moved snow).
Those tests are done in labs holding the governor open...In real life we have governor droop/ 10 to 15 percent is pretty common..A generator aims for less droop..the less droop however the engine is more apt to hunt.
But just for easy figuring we will use 10 percent droop..An engine set for 3600 will not fully open the throttle until the engine is pulled down 10 percent..Now the engine speed is 3240 RPM..our new peak HP..Is at 3240
Peak torque on most of the engines is 2400 to 2800 RPM..As we lug the engine from our 3240 RPM our twisting force increases until we lug below our peak torque.
Now here is where it gets interesting.
We are accelerating snow from 0 mph to say 50 mph... It takes four times as much power to double our acceleration.
Therefore more work can actually be achieved in theory with a slower Impeller as long as you are not overloading the impeller itself.. A slower impeller passing the same weight of snow in the same amount of time uses less power.. It takes four times as much power to accelerate the snow twice as fast.. As we can see if we use a smaller engine we can slow the impeller a little to make up for the lack of power...Our throw suffers as a result however.
Back to snow going around the Impeller.. snow getting worked around by the impeller and slipping it past generates heat.. that heat is wasted energy.. although it may have have helped keep the RPM up...we would have been better off slowing a better sealed impeller at a reduced RPM handling less of the same snow twice in the impeller.
Force..when we double speed..we have four times the force(stored )..Snow traveling double the speed has four times the potential(Just think of stopping distance on a vehicle) when our snow is moving faster is has much more potential to keep the sticky snow that just passed before pushed out of the way.
This is why when people raise engine RPM they are seeing a major improvement in having less clogs.. although the engine RPM increase may be only 5 percent.





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Our engine can only produce a finite amount of power, and that power (amount of work accomplished over a given time) is a product of torque (force) and rpm (how often this force is produced every minute)

While that's true of the engine, it's not true of the entire snow blower because speed/volume should also be considered.

Spawn.Qc, let me take exception to one component of what I think you're saying: the premise that the impeller modification relates to increasing the volume of snow moving through the snow blower. I don't think that's the issue particularly as the modification increases the impeller blade by only around 3/8".

The fact is that the volume of snow is related most closely to the speed of the snow blower. A snow blower moving twice as fast will handle twice as much snow so the user is always able to control volume, perhaps subconsciously. Likewise, at any speed, the snow blower handles the amount of snow moving into the auger irrespective of whether or not the snow blower has been modified.

So, it's a question of effectiveness, rather than volume. The modification improves the snow blower's efficiency and reduces clogging, which translates into effectiveness. In that way, I believe modifying the impeller also reduces stress rather than increasing it

 

While that's true of the engine, it's not true of the entire snow blower because speed should also be considered.

Spawn.Qc, let me take exception to one component of what I think you're saying: the premise that the impeller modification relates to increasing the volume of snow moving through the snow blower. I don't think that's the issue particularly as the modification increases the impeller blade by only around 3/8". The fact is that the volume of snow is related most closely to the speed of the snow blower. A snow blower moving twice as fast will handle twice as much snow so the user is always able to control volume, perhaps subconsciously.

The modification improves the snow blowers efficiency and reduces clogging. In that way, I believe modifying the impeller reduces stress rather than increasing it

A few points on this:

3/8th of an inch over the width of the impeller blade is a substantial area, multiplied by all three or four blade is quite something. At the outside of the the impeller radius is HUGE in terms of impact due to the leverage and blade speed effect.

Now let say: If you scoop 50grams of snow per impeller revolution at 2000rpm , you can move the same amount of snow at 1000 impeller rpm by scooping 100grams of snow per revolution but: the amount of mechanical stress is exactly twice on the parts and engine. Exact same work done, twice as stressful on the parts.. this is why shaft torque was closely monitored in airplane big radial engines.. I digress a bit.

I agree 100% with you that it will reduce clogging. I partially agree with you on the efficiency part. 3/8th of an inch gag or bigger? Yeah, might wanna reduce this gap... closing the gap completely? Not so sure.. some breathing space in that mechanical system is not necessarily an complete efficiency killer... i have faith Honda engineers could have designed those blower with near zero gap...there is a real need for “play” to account for various snow conditions...

Any how, I’m not trying to say that there is no application for the mod, It’s just not a 100% magical mod , as far as I understand physics at play...


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At any forward speed of the blower, the effort provided by the engine will ramp up to accommodate the load. I hear this when I move from a layer of undrifted snow into a drift several times deeper. A blower ought to handle the load well through a foot of dry snow, if only in low forward speed, with the engine delivering the necessary power. Otherwise the machine is underpowered in the first place. So it ought to move just as well through a 2" layer of wet/slushy snow having the same total water content and thus same mass as the dry foot, without overloading the engine. Trying to move the machine through a foot of sopping wet snow would be asking too much (unless the machine is really some beast built for it). Somewhere in between there might be a point where adding 3/8" to the impeller diameter would reach the point of overload.



It's interesting to compare this to centrifugal liquid pumps, for which a mfg provides pump curves. A range of different diameter impellers can be used within any casing. For any impeller diameter and rotational speed, the pump will operate on that curve, and pump head will vary with volume flow. As volume goes down, head goes up. Pump power requirement also will vary along the curve. In sizing a pump, one picks the appropriate curve according to volume and head requirements, and that determines the required driver power.

 

This is very interesting discussion and I love it.

So is it me or we can say that some aspect of impeller speed play for us, other against us? As for the gap, it reduce efficiency while not really helping much... so this brings a question.
Why aren’t they any tighter? It’s really not crazy precise manufacturing involved right?

Also, high impeller rpm doesn’t not necessarily equal high speed for snow, speed is also determined by the radius of the impeller which is slightly increased by impeller mods...

Oh, torque converter do create heat as fluid is moved and pressurized by the vanes.. the only difference is that the friction happen between oil particles instead of clutch surface material...

Thx
Stephan


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More impeller speed if you have power to spare.. if not then it will actually be counter productive (as long as you are not over working the impeller itself.
Then impeller mod on some of the machines makes a significant difference in getting the snow out... On the Honda's.. there isn't as much benefit and a person may not have the need to try.. The MTD based models have huge gaps and seem to gain alot from the mod.
I didn't even try mine(MTD based) out without the mod.. It got the mod before it saw the snow..as I know we get slushy conditions here.
As far as why some of the cheaper machines have large gaps?
Will still work if the impeller housing is egg shaped.
Less apt to freeze in place at the bottom.
Save a little money on production costs.
They just don't care ..and expect most people won't anything about the gap anyway..Just my guess


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As someone much smarter than me (@drmerdp, see thread https://www.snowblowerforum.com/for...nda-snowblowers/148607-why-dont-other-brands-require-rejetting.html#post1660267) postulated, it's all about what happens at the boundary layer between the high velocity snow and the low velocity snow close to the wall of the impeller chamber.

If you've ever worked with aerodynamic shapes in a wind tunnel, you know what happens when boundary layers interact... This wind tunnel video graphically shows the boundary layer (in this case air) slowing down, which causes friction and disrupts the airflow, messing with what you're trying to accomplish in the wind tunnel. Their solution was to add high-velocity air flow below the boundary layer to re-accelerate the boundary layer; in snowblowers we are adding the "impeller kit" wipers that accelerate the boundary layer snow and eliminate the low-velocity snow from the chute flow, reducing and usually eliminating the tendency to stick and clog in the chute.

I am about to install one of @drmerdp's stainless steel & 3-ply belt impeller kits, and am confident that my currently near-perfect, non-clogging HSS1332 performance will only improve. While I have the chute off, I'm also planning to cut a few extra teeth on either side of the chute base to increase the rotation as @ThumperACC did: https://www.snowblowerforum.com/forum/honda-snowblowers/137913-hss928-chute-rotation-mod.html

 

In my mod, a small gap that varies was left to have little to no friction with the housing, and it is throwing like a beast.

I don't recall having a snow thrower shoot far away and high like that.

When I feel like working on it at -10c I will finish adding a small pad on the inside left of the impeller, should help a bit more lol.