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450, 451 and 551 Snowblower Application Notes...

Posted: Sun Oct 25, 2015 8:33 pm
by Tom Scott
Over the years this has been a repeated topic of conversation. With winter on the way yet again, I decided to make a sticky out of this information so it is easy to reference. I cut and pasted from posts I made over the years, as I am a bit lazy...

It is important to get the correct blower for pto size of the tractor you are using. Early tractors (GT and SGTs) had a 4.6" outer diameter (OD) front pto pulley. Later tractors (Ser. No. 821,060 and after) had a 6" OD front pto pulley. This change (and serial number) occurred several years into the Cyclops series. Although this was a design improvement, it has created an attachment nightmare for the unaware.

The belt speed produced by the larger 6" pto is much greater, so Cub changed the ratio of the attachments that went with those tractors. In the case of the snowblowers, the early blower that is correct for the earlier series (1811, 1772, 1872, etc. and early Cyclops) would be a model number 450. The later tractors with the 6" pulley used a number 451 snow blower (later upgraded to a 551). The 450 and 451 are essentially identical except for the gear ratio of the main gearbox. Later 451's had yellow paint and a plastic chute, but that is not a surefire way to identify them.

The gears to change the ratios are NLA, and a 451 won't work with the small (4.6") pto as the blower turns so slow it will barely push the snow out of the chute in some conditions.

With the equipment swapping that happens over the years I wouldn't even trust the model number on the tags; the gearboxes could have been swapped out. It is best to check ratio of the main gearbox to determine what blower you have.

Mark the impeller (fan) so that it can be seen from the top of the chute. Mark large 7" the input pulley. Count how many times around the input pulley needs to go for one turn of the fan.

For the 450 it will be 1.87 turns of the input pulley to make one complete turn of the fan.
For the 451 it will be 2.58 turns of the input pulley to make one complete turn of the fan.

No need to be super exact; the ratios are not very close to each other...So, if you come up with something less than 2, then it is a 450. If it is over 2.5 turns, it is a 451.

Unless...you have a 551. The dead giveaway for the 551 is a taller housing that the auger does not fill, but sits in the bottom half. The 450 and 451 have a housing that the auger fits evenly in top and bottom, with no extra room above the auger. Check out the diagrams of them on a parts site, and it will be obvious.

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Sun Oct 25, 2015 8:56 pm
by Tom Scott
Continuing...

Now to address using a 450 on a large pto (6" OD) later Cyclops (or an earlier tractor that has been retrofitted with the large pto)...

This too is an incorrect application. You are over-speeding the 450 by about 30% with this combination (as opposed to the under-speed condition I described in the first post). You can probably find posts I have made in the past advising against this due to the increased wear and stress on the components.

That being said, the tractor I wanted to use for blower duty last year has a large pto and my 551 was still torn apart for paint. I decided to try the 450 with it to see if it would have less auger packing at the higher speed provided by the large pto. (I have found that 450/451 blowers are miserable at packing the augers in any snow you can make a snowball out of.) This was a real heavy snow and it threw the snow well, but I did break the belt halfway through the job. So in this case as well, it is probably best to still use the right blower for the tractors pto size.

In summary:
Older 4.6" pto tractor should use a 450 blower.
Newer 6.0" pto tractor can use a 451 or 551 blower.
:beer:

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Mon Oct 26, 2015 8:30 pm
by SWilliams
Nice post.
Might want to add that the above applies to supers as well. And that you need the drop plates and longer belt for the 450/451 on the SGT. The 551 fits both the GTs and the SGTs that the 451 fits, with no drop plates.

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Mon Oct 26, 2015 9:26 pm
by Tom Scott
Good points, Steve. Thanks!

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Thu Oct 29, 2015 3:27 am
by SWilliams
Here are a couple pictures that show color isn't a true indicator of the model of the blower.
Model& serial tag
451tag.jpg
451tag.jpg (19.11 KiB) Viewed 28572 times
Overall unit, original paint
451 white.jpg
451 white.jpg (34.84 KiB) Viewed 28572 times

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Sun Jan 03, 2016 11:53 am
by JoeK
any tips on leveling a blower? mine wants to lift the left side off the ground first

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Sun Jan 03, 2016 5:47 pm
by dag1450
I dont think there r any adjustments for that? Your cross lifting shaft could b "tweaked". Although if that was the case i could see it wanting to lift the rt side first. idk. How much difference is there Joey? Did u check your tire air pressure? I know when using a loader and front end attachments pressures make a big difference in level from left to rt. Can u tell im just scraping for something :lol: Dave

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Sun Jan 03, 2016 6:34 pm
by ReicheP
JoeK wrote:any tips on leveling a blower? mine wants to lift the left side off the ground first
My 450 does that too. As long as it's flat on the ground that's all that matters.

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Mon Jan 04, 2016 10:54 pm
by JoeK
i got my tire on the right side about 10 psi higher then left to help level it out, helped some but i dont dare lower any more out of the left

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Tue Jan 05, 2016 11:06 am
by SWilliams
About the only way to level them is to either twist the lift rod or alter the lift links. You might want to check the lower pivot on the blower. Many of them have bolts and washers spacing the blower away from the lower links. If those were missing on one side it could cause the blower to lift crooked. Just don't try to eliminate the "play" that allows the blower to follow the terrain.

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Fri May 05, 2017 8:22 pm
by l palma
I raised my hand and want to ask a question about the auger gear boxes that are on the 450 and 451, they show different gear tooth count on those also, would you have to change those also to make sure too much or little snow is being fed into the fan?

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Fri May 05, 2017 8:45 pm
by Tom Scott
Hi, Lew, nice to hear from you.

No, they are both geared the same, which makes sense...

All the gearing change was done with the main gearbox. The auger gearbox only changes the speed of the auger in relation to the fan. Since Cub's goal was to only correct the input speed for the new larger pto, the auger to fan relationship would stay the same.

They did make a change in the gearbox which only changed the housing, but the guts stayed the same. As further evidence of this, both the 450 and 451 call for the same replacement gearbox, part # 917-0871A, and both gears carry the same part number for both styles of gearboxes. I swapped a newer style box into a 450 and it is the same other than the appearance of the housing.
:beer:

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Fri Jan 19, 2018 12:30 pm
by nddragoon1
The info on the 551 and SGT's is great...but I'm missing one prime piece, what size belt to use?

I have the 551 snowthrower attached to a 2082 with the 6inch PTO pulley. The gear ratios seem correct as this setup really chucks the snow when its working properly. The problem is...I shred belts quickly (literally leave small pieces of the belt that I can see on the ground). It seemed to me that the belt was catching on the snowblower drive pulley cover. I made sure there were no sharp edges and ground down the small screws on the inside just to be sure. The tensioner pulley does seem to move more than I think it should, creating slack and then catching and kicking off as the belt leaves the tensioner, does its 90 degree twist and entering the drive pulley.

All of the pulleys are smooth. I talked to a gentleman yesterday who suggested I was using the wrong size belt. I've been using an 89" but I think that is if you have the 4" PTO. The circumference difference would suggest using an 86" belt. Thoughts?

The other thing that seems suspect is the belt runs pretty deep in the tensioner and idler pulleys. The top of the belt probably sits close to 1/2" below the outer diameter of the pulleys....potential issue?

As alway...any help is much appreciated.
Nate

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Sat Jan 20, 2018 12:24 am
by Tom Scott
The 551 is only intended to be used with the 6" pto pulley and does not change in mounting height between GT and SGT, therefore... there is only one belt specified for the 551, as per the parts listings: Cub part number 954-0341 which is a 5/8" x 89" belt. Nothing should be rubbing or interfering with the belt.

You do not want to use just any belt. It should be a for real "lawn & garden" belt. I would recommend either the factory Cub belt or a "Gates PoweRated". The Gates PoweRated number is 6989. I have had good service out of both the Cub and PoweRated belts. Other types of belts may not hold up when used in lawn & garden service.
Gates 6989 PoweRated.JPG
Gates 6989 PoweRated.JPG (630.7 KiB) Viewed 28305 times
Sorry for the sideways pic, just pretend Joe posted it! :lol:

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Sat Jan 20, 2018 9:44 am
by JMotuzick
Looks perfect from here !

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Tue Feb 06, 2018 7:41 am
by nddragoon1
Well, I picked up the OEM belt from a local dealer. First impressions were it is much more sturdy. I blew 10-12" of snow yesterday for over an hour with no issues. Thanks for the advice.


Spoke to soon....I didn't just shread the belt...I ripped it to pieces. I'm throwing my hands up...bringing to the shop.

Nate

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Mon Mar 05, 2018 4:58 pm
by SWilliams
Double check that the pulleys are good and that you have the correct tensioner spring. Then with the belt on look down from the top at the actual alignment of the belt. The tensioner arm likes to twist and throw the belt tracking off.

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Sun Mar 18, 2018 11:31 am
by nddragoon1
I think it is the idler and tensioner pulley. I think the belt is sitting way to deep and both pulleys which actually increase the horizontal distance between the idler and tensioner and the snowblower drive pulley. I believe this is resulting in not only the 90 degree twist in the belt between pulleys but also adding the belt to do so at an angle rather than vertically. This is causing the belt to "shave" on the side of the idler and pulley....diagnosis....I need new pulleys. Crappy part...they are expensive. Anyone know of a lower cost alternative to the OEMs?

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Tue Mar 20, 2018 10:43 am
by SWilliams
The belt is supposed to turn 90 degrees between the pulleys. The belt is also supposed to set deep in the idlers, that is to keep the belt on. Properly installed the belt should set in the clutch pulley, then each side should twist 90 degrees to set in the idler and tensioner pulleys then out of them with a twist so it sets on the blower pulley.

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Mon Dec 17, 2018 9:02 am
by nddragoon1
I am done with the belts. Followed all of the advice and prior to this snow season did the following:

Purchased a new idler and tension pulley (OEM), purchased a new tensioner spring (OEM). I also installed a new electric PTO this summer since mine fried when my stator died. So it also has an after market PTO and a new stator. For info...the PTO worked great with the lawnmower.

That all said when I got it all put back together and engaged the the PTO the belt was thrown within seconds. I put it back on and it threw in 30 seconds. I tried again and it stayed on for a minute than I turned the machine off. I tried it again the day after and I smoked the crap out of the belt...not sure it was getting hung up. Bottom line is I am done with the belt. If you ask me it is a poor design (asking the belt to twist 90 degrees 4 times while in a big U-shape is too much to ask of a belt).

I am going to change the design to a belt/shaft design. Here is the plan:
1. Weld a plate below the PTO pulley on the snowblower frame
2. Remove the Snowblower Drive pulley (the 9 incher) from the snowblower and mount it to the plate in the same plane with but below the PTO)
3. Connect the PTO and 9 incher with a belt (no twists, no turns)
4. Connect a telescoping shaft with two U-joints to the snowblower splined shaft where the drive pulley used to be.

Thoughts? Has anyone done this before?

As always....thanks!

Nate

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Mon Dec 17, 2018 3:21 pm
by JMotuzick
I dont know if anyone has modified a blower this way. The factory was with you and did just that with the 3000 series.... the frame/Mount is different though.

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Mon Dec 17, 2018 5:12 pm
by nddragoon1
Last thing before I modify. The 9inch drive pulley on the snowblower seems odd. When installed, the rim closest to the tractor has a folded over lip in the inner race, Where the belt rides, this appears to be manufactured that way (because the lip is so consistent). However this could explain a lot about this issues I am having. This appears to cause the belt to ride 'high' in the pulley which seems to be causing some of the belt contact with the pulley guard. Anyone know if that lip should be there or not? I ordered a new pulley....

Nate

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Mon Dec 17, 2018 9:13 pm
by dag1450
Hi... sorry to hear of your trouble. I think it might help to get some pictures out on the table. Pics of all possible problem areas. Send a pic of your belt wrapping cardboard box sleeve with part number. Your comment in the spring saying the belt was riding way to deep sounds like a 1/2" belt? Doing a little more homework sounds better than all the mods you are thinking about.

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Sat May 11, 2019 10:27 am
by nddragoon1
I finally figured it out. The drive pulley on the snowblower (9 incher) was deformed. What happened was over the years the drive pulley, when lowered, would make contact with the idler puller. It deformed the drive pulley with such consistency I thought it was manufactured that way. The V was folded over (tractor side of the V) which caused the belt to ride high, causing excessive slipping, belt heating and eventual failure. Once replaced everything worked swimmingly and I made it through the whole season on one belt. I feel a pretty silly for not replacing it first.

Thanks for all the help though.

Nate :?

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Mon May 13, 2019 4:09 am
by dag1450
Glad you got it figured out.

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Sun Nov 22, 2020 3:10 pm
by JMotuzick
Has any one found a aftermarket idler pulley for the 450/451/551 blowers? I just picked up a 450 and it’s mossing both. $$50 each seams a bit high!? I know stick with OEM and I might still buy them but it just seams high?

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Tue Nov 24, 2020 4:49 pm
by SWilliams
450 and 451 use a 6" idler #756-0507, 551 uses a 7" #756-3090.
The only thing special about the factory parts are the inserts they pressed into the bearing to allow the use of a bolt.

The Stens 280-870 6" idler is the twin to the factory 756-0507 part but you need the inserts from the old unit, those can be easily knocked out with a pin punch. As of 2/5/2021 I have them running on my 451. Bought them in a twin pack for less than the cost of a single unit from MTD.

The OEM units I have use an ISO 62203 2RS bearing that is a double shielded 400mm X 16mm X 17 mm bore deep groove bearing.
The new Stens uses a 6203 2RS bearing. Same bearing with a new number.

These are a US made replacement.
The part crosses to a few numbers to allow easier shopping.
Stens - #280-870
Toro / Exmark - #1-633166
Husqvarna / Crafstman / AYP - #102657
Sierra - #N-752017
Rotary - #9793
JThomas - #JT-271
Sunbelt - #B1EM53
NHC - #276-9104
SureFit - #504-00644

Now to find a twin to the one on the 551s...

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Wed Dec 01, 2021 6:36 pm
by nddragoon1
I have a 451 on my 2082, It works great and I want to sell it. I have no idea how to off load it and I'm looking for ideas. Also not sure what a reasonable asking price is ($400?), I replaced the plastic chute last year. Craigslist is nothing but spammers and I don't (won't) have facebook for the market place. Any suggestions would be much appreciated.

Cheers,
Nate

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Thu Dec 02, 2021 3:58 am
by SWilliams
Post it here in the for sale section with some pictures, especially the scrolls and working parts. Being it's off a Super it has the drop plates and the longer belt. It will fit on the regular garden tractors by swapping the belt and removing the drop plates though. $400.00 isn't a bad starting price for one in good shape. I've bought them from $100 up to $450 for one that was like new and that person started at $550.00 but was missing the lift arm and rod. If I didn't already have 4 blowers I'd be tempted myself.

Re: 450, 451 and 551 Snowblower Application Notes...

Posted: Thu Dec 30, 2021 8:13 am
by cubsformymoney
Recently picked up a 1641 with a non attached 450 snowblower. that looks like everything is there and i would like to install it...
I believe the front pto should be 6" to use this blower because of auger speed ...it is a late serial # but pto measures 5 1/4" Whats everyones thoughts please ...And this is my 1st post being brand new to this great looking site.