# Belt length change



## Town (Jan 31, 2015)

I am planning on increasing the engine double pulley for the impeller from 2.75" to 3" or 3.25" on my Ariens Platinum 414cc SHO with 30" bucket. Does anyone have an idea of the required increase in belt length?


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## JLawrence08648 (Jan 15, 2017)

Wouldn't it add 1/4" or 1/2" depending on the pulley? I have found that in the end it will still need to be put on, see, try, remove, and try a different size by an experienced guessitimate. In belt sizes, 1/4" matters!


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## db130 (Feb 16, 2013)

There's some trial and error involved, yes.

But... with the assumption that a belt uses about half the circumference of a pulley... a 2.75" pulley has a circumference of 8.64"

A 3" pulley has a circumference of 9.42"
A 3.25" pulley -> 10.21"

so... half of 8.64 = 4.32
half of 9.42 = 4.71 -> about 4/10" inch, i think you could buy a half inch longer belt and have a tensioner pick up the rest of the slack
half of 10.21 = 5.10 -> about 8/10" inch, i think you could buy an inch longer belt and have a tensioner pick up the slack


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## leonz (Dec 12, 2014)

Town said:


> I am planning on increasing the engine double pulley for the impeller from 2.75" to 3" or 3.25" on my Ariens Platinum 414cc SHO with 30" bucket. Does anyone have an idea of the required increase in belt length?



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Before you do anything I would use the online calculators they have for electric motors and roller chain and V belt pulley sizing where you can input all the numbers and see what drops out.

If I remember my physics correctly when you increase pulley size the output speed is reduced when maintaining the same engine speed so the impeller will be slower. 

opcorn:


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## 1132le (Feb 23, 2017)

leonz said:


> ======================================================================
> 
> Before you do anything I would use the online calculators they have for electric motors and roller chain and V belt pulley sizing where you can input all the numbers and see what drops out.
> 
> ...


the impeller will be faster thats why town is doing it
others have as well
if mr town doesnt want to keep his old pulley and belts id like to be 1st inline to score them


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## cranman (Jan 23, 2016)

I'd go 1/2 in bigger on the 3" and 3/4 to an inch bigger on the 3.25


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## YSHSfan (Jun 25, 2014)

cranman said:


> I'd go 1/2 in bigger on the 3" and 3/4 to an inch bigger on the 3.25


+1 on it


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## Town (Jan 31, 2015)

Thank you all for your helpful responses. 

I measured my new spare belt (Ariens 07200703) using a string at 42" circumference. I cannot seem to find the belt length for that part from the internet. My original belt works fine and when I slacked off the adjustment there appears enough room for a 3" pulley. If I remember correctly I had to adjust the idler pulley to get correct belt tension when new, so the stock belt is a little long.

I have two pulley assemblies, the original platinum and a Pro. Both are 2.75" diameter and fit my engine using the Platinum bolt. The Pro allows for a longer crankshaft extension (up to 3/8" longer) to fit inside the pulley assembly and is overall an 1/8" longer than the Platinum. So I will get a machine shop to shorten the end abutting the engine wheel drive pulley by 1/8" and replace the incorporated 2.75" pulley with a 3" pulley and try that out. 

If the 3" pulley works out as I think with the stock belts then I will get the Platinum pulley increased to 3.25" and look for a longer belt.

Currently the impeller speed is a little over 1100 rpm and with the 3" pulley will increase to 1230 rpm and the 3.25" pulley will give 1330 rpm.

So now to find a machine shop in my area.


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## 1132le (Feb 23, 2017)

Town said:


> Thank you all for your helpful responses.
> 
> I measured my new spare belt (Ariens 07200703) using a string at 42" circumference. I cannot seem to find the belt length for that part from the internet. My original belt works fine and when I slacked off the adjustment there appears enough room for a 3" pulley. If I remember correctly I had to adjust the idler pulley to get correct belt tension when new, so the stock belt is a little long.
> 
> ...


I have done alot of research on your belt part number mr town as thats the belt i will be getting if upgrade to sho top pulley
no place could i find the length on the net 
I found it on rock auto says 41.125 od
https://www.rockauto.com/en/moreinfo.php?pk=4970133&jsn=3

My blower has the 2.5 stock you are 2.75
2.5 impeller rpm 1010 
2.75 impeller rpm 1083
Think you are a lil high at 1230 think you will pick up around70 to 75 for 3 inch 140 to 150 for 3.25
3.25 would be the way to go imo
The length of the top pulleys are not the same you show a washer with your sheave mine does notyou say the pro is not the same as yours interesting
cant see that the crank is longer 414 should be 414
you would think being a larger pulley woudnt matter


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## Town (Jan 31, 2015)

1132le said:


> I have done alot of research on your belt part number mr town as thats the belt i will be getting if upgrade to sho top pulley
> no place could i find the length on the net
> I found it on rock auto says 41.125 od
> https://www.rockauto.com/en/moreinfo.php?pk=4970133&jsn=3
> ...


Thanks for your input.

Hard to believe that I made a mistake of an inch in measuring the outside circumference of the stock belt. Not sure how I can verify my discrepancy.

The 1083 rpm with the 2.75" pulley is at 3,600 rpm but Ariens allow a 100 rpm variance + or - so I am running 3,700 rpm which is about 1130 rpm by calculation and with my infrared laser rpm meter. Each 1/4" increase from 2.75" at 3,700 rpm (with a 9" impeller pulley) gives slightly over 100 rpm increase. So 1233 and 1336 respectively with the 3" and 3.25" pulleys by calculation method. Not being a mathematician I rely on an app for that. The problem is that the effective pulley diameter is not its outside measurement but the belt path which is considered to be about 1/2 the belt depth so a 1/8" or so less. So that is why the Platinum is rated 1083 compared to the calculated 1100 rpm at 3600 rpm. As the belt wears it drops a little in the groove so speed drops marginally. My setup is measured at a little over 1100 rpm for the impeller actual speed, but at higher engine speed. My issue is that the Pro spec is over 1112 rpm with the same size components as the Platinum, which cannot be the case.

The B&S 420 engine uses a longer crank extension than the LCT 414 engine. There is no washer between the LCT engine impeller pulley assembly and the engine wheel drive pulley. The Pro engine impeller pulley has a deeper 1" opening with an included keyway that fits over the crank on the B&S 420 engine. So the Platinum pulley will not work on the B&S engine but the Pro pulley will work on the Platinum. To get the best pulley alignment the Pro pulley needs to be shortened by 1/8".

Hope this explains my numbers better.


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## Town (Jan 31, 2015)

Measuring the new belt with a string many times gives a consistent 42" using a retractable tape measure and a fibreglass flexible (seamstress type) tape measure to apply the string length. Measuring the belt with a fibreglass flexible tape measure directly gives 41.5" consistently. 

To measure the belt I formed the belt into a somewhat rounded shape (and used a wrench to maintain that shape) to provide consistent pressure for the string/tape to press against the outer surface of the belt. Wrapped the string around the belt and marked the string at the length with very light pressure and transferred the length to a tape measure at 42" long. For the flexible tape I wrapped the flexible tape around the belt and at the overlap point it measured 41.5". Since the flexible tape is very thin there would be less of a loss to the thickness of the string exaggerating the belt length, so perhaps the flexible tape is more accurate? Perhaps the belts are 41.5" long.

Is there a better way to measure the length of a belt since I am still off from the length researched by 1132le at 41.125" circumference? I was not able to find a belt length for the Ariens 07200703 pair of auger belts directly.


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## 1132le (Feb 23, 2017)

Town said:


> Measuring the new belt with a string many times gives a consistent 42" using a retractable tape measure and a fibreglass flexible (seamstress type) tape measure to apply the string length. Measuring the belt with a fibreglass flexible tape measure directly gives 41.5" consistently.
> 
> To measure the belt I formed the belt into a somewhat rounded shape (and used a wrench to maintain that shape) to provide consistent pressure for the string/tape to press against the outer surface of the belt. Wrapped the string around the belt and marked the string at the length with very light pressure and transferred the length to a tape measure at 42" long. For the flexible tape I wrapped the flexible tape around the belt and at the overlap point it measured 41.5". Since the flexible tape is very thin there would be less of a loss to the thickness of the string exaggerating the belt length, so perhaps the flexible tape is more accurate? Perhaps the belts are 41.5" long.
> 
> Is there a better way to measure the length of a belt since I am still off from the length researched by 1132le at 41.125" circumference? I was not able to find a belt length for the Ariens 07200703 pair of auger belts directly.


thats a used belt right? might have stretched to the 41.5
I cant find the length of my belt using the part number anywhere on the net
As my top pulley is a 1/4 inch less then yours should be about 1/2 inch shorter buti cant find the od any place


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## Town (Jan 31, 2015)

1132le said:


> thats a used belt right? might have stretched to the 41.5
> I cant find the length of my belt using the part number anywhere on the net
> As my top pulley is a 1/4 inch less then yours should be about 1/2 inch shorter buti cant find the od any place


No, I am trying to measure a new belt. I have a new pair from my dealer as spare. I don't want to tear into my machine yet since it needs to be operational for a while yet; a foot of snow is forecast for the weekend.

Ariens parts list has the size of the Auger belt on the 926501 (source for my 14/6 ordered impeller) as 38". Cannot find anything from Ariens in the 42" size range I might need for the 3.25" pulley. Checking further afield there does not seem to be many belts in the 42" range and even less sold in pairs. The pair I found are 42.5" and cost CAD$80 plus shipping so not an attractive proposition for 2 sets.

From what I have seen in my setup the old belts on my machine will easily accommodate a 3" pulley with enough belt slack when the adjustment is backed off. Don't know about a 3.25" pulley.


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## JLawrence08648 (Jan 15, 2017)

Have you gone to Amazon and typed in the size you want, width 1/2" x 42", I found several, D&D Power Drive makes an excellent and accurate size belt, $5.12 with free shipping.


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## 1132le (Feb 23, 2017)

town check out this link you can put in stock part numbers some list the same belts a a lil diff od
my part number or yours dont show up to give you length i had to dig for what seemed like 2 weeks 2 find your length still cant find mine
that 38 inch belt was the same as my oh358sa 13 hp i think you are way off stock anything now with the lct crank height and a larger pulley

Main Belts Sizes Reference

Here is and ariens 42 inch on flebag

https://www.ebay.com/p/OEM-Ariens-Gravely-V-belt-4l-raw-Edge-07213200/1837577342

have and autoparts store measure your belt with there belt tool


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## cranman (Jan 23, 2016)

I have a long belt that is cut and I wrap around the pulleys, mark it with chalk to measure how long...then go buy one that length....
Lawn tractor deck belts are LONG......


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## Town (Jan 31, 2015)

Many thanks for all your help.

My dealer measured my 07200703 belt at 41.5" using a belt length guide fixture. That is the same length that I measured with a flexible tape around the circumference. So a Bolens/MTD 1716570 (pair of 1/2" X 42.5") belts would work for the 3.25" pulley.

Machine shop could not increase pulley diameter to 3" or more. The owner suggested a place (Industrial Solutions in Ottawa) that sells pulleys, and to use a sleeve over crank extension and a double pulley fitted over the sleeve. So I will see about that solution.


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## Town (Jan 31, 2015)

There is no available pulley setup that I can find or a professional dealing in pulleys can find to match the offset Ariens dual pulley assembly.


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## YSHSfan (Jun 25, 2014)

There are a couple of machinists on the forum, maybe one of them is willing to come up with something.... We’ll see...


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## Town (Jan 31, 2015)

YSHSfan said:


> There are a couple of machinists on the forum, maybe one of them is willing to come up with something.... We’ll see...


Thanks for your support.

The closest I can come to a solution would be to machine off the current 2.75" pulleys and reduce the shaft diameter from 1.7" to 1.625" to accommodate two weld on pulleys of 3.5" outside diameter and 1.625" inside diameter. There may need to be a shoulder between the two pulleys and the rolled outer edges of the steel pulleys may be too wide. The resulting impeller speed will be 1,439 rpm which is much higher than targeted and will create a belt length increase of 1.2" from 41.5" to about 42.5" approx based upon db130 input providing I increase the tensioner slot to create more belt slack when clutch disengaged. I have the Pro pulley on my machine now so the Platinum pulley will be used to check out any design ideas.

There are a number of issues in increasing the engine auger pulley diameter from 2.75" to 3" or 3.25":

1. Duplicating the SHO pulley assembly through machining is very difficult due to the internal fixed keyway in the assembly for the crank drive;

2. Machining the dual pulley off the assembly leaves a max shaft dia of 1.7" where the smallest pulley that will fit is 3.5" outside diameter and 1.625" inside diameter;

3. Machining the dual pulley off the assembly to fit a pulley of 3" to 3.25" will require a very small shaft diameter and make the metal too thin (based upon expert input);

4. A shaft of 3.325" length for a 1" diameter crank with internal keyway does not currently exist according to the experts so you cannot attach a suitable double pulley of 3" to 3.25" outer diameter.

Here are some pics of the pulley:


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## YSHSfan (Jun 25, 2014)

If getting a larger pulley for the engine side is going to be difficult, can you get a smaller dual pulley for the impeller (maybe out of another SHO model).....? Just a thought.

That's kind of what I may be doing with one of my Hondas to increase impeller speed.


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## Shaw351 (Nov 15, 2016)

Soo many posts to read through.....

Look here to get individual pulleys..
Single for transmission 
Double for auger

You should be able to find what you need. I've done many custom setups without much trouble, if you end up with a 1/2 size belt legnth I'd recommend changing idler pulley size to get you to an off the shelf regular legnth belt. 

https://electricmotorwarehouse.com/two-groove-fixed-bore/


This is how I ended up doing my Franken Blower project.


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## Shaw351 (Nov 15, 2016)

Here's some pixx of my belt guide finger. 


















Please let me know if I can help you any further. I'm sure we can get you squared away with your project.


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## Town (Jan 31, 2015)

Shaw351 said:


> Soo many posts to read through.....
> 
> Look here to get individual pulleys..
> Single for transmission
> ...


Thank you for the pic and the pulley reference guide. Your crankshaft is very long, while mine is short at only 1 3/8" (beyond wheel drive pulley) so the 2AK30 pulley ( http://www.electricmotorwarehouse.com/content/pulley/cat26.pdf ) for the 1" shaft is 1/32" short of the end of the crank when the belts are lined up with the pulleys. So no drive possible. This is based upon the measurements of the 2AK30 pulley overall length (P+F) = 1 27/32" while the Ariens pulley is 1 28/32" from pulley end to end of crank. Then there is the drive portion of 1 3/8" of pulley on the crank for overall length of 3 1/4" (the Pro pulley is 1/8" longer). I don't know how much of the pulley needs to be on the crank for proper support, but I cannot make that up by moving the engine forward or the impeller housing back.

Perhaps a machine shop could cut the drive portion off the steel Ariens pulley and weld it to the cast iron pulley boss. The short boss pulleys have been the problem all along with the target setup.

Thanks for the helpful posts.


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## YSHSfan (Jun 25, 2014)

Town,

I'd suggest you PM Shaw351, I think he'll definitely be able to help you with the pulleys issue.


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## Shaw351 (Nov 15, 2016)

You can overhanging / extend beyond the end of the crankshaft a little bit without any issues. I've done it on several machines and never had any issues or premature belt wear / failure. 

Here is a pixx of a recent machine that I've modified and is still running beautiful. 

You can also see how I made an adapter plate for the idler pulley to move it to a position that allows a regular legnth belt, not a 1/2 size one.... like 39 1/2"


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## Shaw351 (Nov 15, 2016)

If you would rather try to change the lower auger pulley setup then you can buy a similar pulley like this one but a little bit bigger, this is too small for your application. Should be able to get it locally at an industrial supplier or bearing house. Just buy the correct QD bushing insert for your application, just measure your auger shaft diameter. Just a note to think of...... you might have to also rework the brake assembly when you change the bottom pulley. 










Here's a pixx of the pulley on my custom bucket as I was fabricating it.


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## Town (Jan 31, 2015)

Shaw351 said:


> You can overhanging / extend beyond the end of the crankshaft a little bit without any issues. I've done it on several machines and never had any issues or premature belt wear / failure.
> 
> Here is a pixx of a recent machine that I've modified and is still running beautiful.
> 
> You can also see how I made an adapter plate for the idler pulley to move it to a position that allows a regular legnth belt, not a 1/2 size one.... like 39 1/2"


Thanks for your information. I was not clear in my explanation earlier, the whole of the 2AK30 pulley would overhang the end of the crankshaft by 1/32", so there is no support or drive for the pulley at all.

Ariens pulley uses a 1 3/8" drive section (1 1/2" diameter) to the end of the crank and then hangs a 3/8" continuation of the drive and the 1 1/2" pulley section over the end of the crank. So there is 1 7/8" of the assembly extending beyond the crank.

It is an unusual setup. 

Thanks for your help.


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## Town (Jan 31, 2015)

Shaw351 said:


> If you would rather try to change the lower auger pulley setup then you can buy a similar pulley like this one but a little bit bigger, this is too small for your application. Should be able to get it locally at an industrial supplier or bearing house. Just buy the correct QD bushing insert for your application, just measure your auger shaft diameter. Just a note to think of...... you might have to also rework the brake assembly when you change the bottom pulley.
> Here's a pixx of the pulley on my custom bucket as I was fabricating it.


Thank you for the great information. Changing that lower auger pulley from 9" to 8" would allow a target impeller rpm of 1271 rpm which would be good, and even a 8.5" pulley would allow 1197 rpm which is also good. I would need to modify the pulley brake system to accommodate the additional 1/4" of reach (or less with the smaller pulley), and a shorter belt. YSHSfan also suggested this route.

Do you have a website for the lower auger pulley that you showed as the Dodge 455590 2A5.8 B6.2 - SDS QD sheave? I have not seen a suitable pulley in my research.

Thanks again for your help and options.


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## Shaw351 (Nov 15, 2016)

Closest I could find......

https://www.motionindustries.com/productDetail.jsp?sku=00699936


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## Town (Jan 31, 2015)

Shaw351 said:


> Closest I could find......
> 
> https://www.motionindustries.com/productDetail.jsp?sku=00699936


Thanks for your research into that pulley. I think the Ariens impeller shaft has a flat machined into the pulley end for a drive boss that is then bolted to the pulley. I will take it apart today and see exactly how it is constructed.

Thanks for your help.


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## Shaw351 (Nov 15, 2016)

Hey Town....

Thinking about your project, how about taking a 1-inch diameter round stock Drilling and tapping the center to the same thread pitch as the crankshaft threaded hole. Then make an extension adapter to the length you need , assemble it with red Loctite on the threads. Then when you have it tightened as much as you can you will carefully take a cutting wheel and make a slot for a full-length key to go between crankshaft and new adapter and pulley.
I think this should work without any issues and make your project easier. 
You could also take a 1-inch diameter round stock and drill a hole through the center, then have a keyway cut onto it, and then have a long Bolt through this new piece and bolt into your crankshaft. This would make it longer and be able to allow the pulley to slide on it. But machining would have to be perfect as it will be turning 3600 rpms. Just another idea to make the crankshaft longer.


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## Town (Jan 31, 2015)

Shaw351 said:


> Hey Town....
> 
> Thinking about your project, how about taking a 1-inch diameter round stock Drilling and tapping the center to the same thread pitch as the crankshaft threaded hole. Then make an extension adapter to the length you need , assemble it with red Loctite on the threads. Then when you have it tightened as much as you can you will carefully take a cutting wheel and make a slot for a full-length key to go between crankshaft and new adapter and pulley.
> I think this should work without any issues and make your project easier.
> You could also take a 1-inch diameter round stock and drill a hole through the center, then have a keyway cut onto it, and then have a long Bolt through this new piece and bolt into your crankshaft. This would make it longer and be able to allow the pulley to slide on it. But machining would have to be perfect as it will be turning 3600 rpms. Just another idea to make the crankshaft longer.


Thanks Shaw351 for that ingenious approach. I will take a look at doing that.

I took my machine apart today and was surprised to find the driven pulley for the auger is actually 8.5" and not 9" as I previously measured while the machine was together. Using pulley outside diameter that should give an impeller speed of 1197 rpm, but I only measure 1100 or so. It appears that you really need to use the pulley ratio diameter for a half inch belt which sits about 1/8" below the pulley diameter. So when I reduce the two pulleys to 2.5" and 8.25" the impeller speed reduces to 1120 rpm which is about what I measured.

So now my focus is on your above proposed solution of extending crank shaft length and attaching the 3.05" engine pulley to give a corrected impeller speed of 1255 rpm. I can probably use the stock belt with some adjustment to the idler pulley location.

Thanks very much for your ideas.


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## Town (Jan 31, 2015)

Here are some pics of the Platinum impeller driven pulley assembly:


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## Town (Jan 31, 2015)

Just an update on fitting a dual belt pulley to my SHO. I bought a 2AK32x1 pulley and had a machine shop lengthen it to fit the SHO. Installed it today and it runs well with stock belts. Engine rpm is 3,925 and with the 3.25 engine pulley drives the impeller at 1,447 rpm. No vibration either.

Post #50 in this thread gives some pics: https://www.snowblowerforum.com/for...-6-blades-fan-adding-pads-3-blades-fan-5.html


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