# Craftsman 4/20 walking away



## Weltermj (12 mo ago)

Hi all, 

I'm new around here, and I did search for help before posting, but I have reached the point I am hoping someone has a new idea for me.

I have a Craftsman 4/20, model 536.98100. It's vintage 1979, or thereabouts, still runs like a champ, and starts on the first pull. It throws snow well too.

The problem I have is in 1st or reverse gear, the machine will walk away, without the drive lever engaged. I've tried everything I can think of, new belt, worn belt, every adjustment of the belt keepers I can think of, the idler pulley is in its lowest tension position, and I have scrubbed all the rust off of the pulleys. 

The parts diagrams at Sears are terrible, and I can't seem to find a belt/keeper diagram to be sure I've got it right.

Is there a secret to this old beast I just don't know, or can anyone here give me a "well, duh..."


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## The Q (Dec 19, 2016)

Have you checked the drive wheel against the friction disk in the underbelly?


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## Oneacer (Jan 3, 2011)

Ditto on the checking the drive system ...... Service position, pull inspection cover


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## rwh963 (Nov 21, 2019)

i read it that you were fed up and walking away from this blower!


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## Weltermj (12 mo ago)

So, it was as I remembered, it's a gearbox with chains to both wheels, not a friction disk. I did find another belt keeper that vibrated loose.

Rwh963..lol...I am at my wits end, and if I can't get this sorted out I may have to. I'd really like to keep the snowblower from walking off the job when I turn my back though.

So now my question is, does anyone have a good diagram for how the belts route and how to set the 3 keepers?


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## ST1300 (Feb 17, 2017)

You need a belt keeper set at about 2/3rds the way down from the top level of the drive pulley just in enough to keep the belt straight. The drive belt will then create a natural arc around the top of the drive pulley, instead now it is riding in the top of the pulley just enough to drag.


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## Weltermj (12 mo ago)

Ok, "2/3 of the way down" makes sense, another old post referenced one "at about 6 o'clock". Now that I found the longer keeper, I can actually do that. 

I put the shorter keeper on the other side of the pulley, so the belt has some resistance to spinning. Pulling the motor over by hand, it seems like it will work better now. I'll try it tomorrow when I won't be waking the neighbors


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## Oneacer (Jan 3, 2011)

Fwiw ..... Those look like solid wheels with chains over them ..... That will vibrate bolts loose on that machine, as well as cause more wear on the bushings, etc. ..... Even chains on pneumatic tires cause excessive vibration.

Jmo


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## Weltermj (12 mo ago)

Oneacer, you're definitely not wrong there. The tire chains don't help either. 

The other keepers had lock washers, but I didn't find one with the keeper and bolt in the bottom. I'm going to start with lock washers, and if it keeps trying to shake itself apart I'll look into some new wheels.


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## Oneacer (Jan 3, 2011)

My Yardman 7100-2 series from years ago came with solid Chevron tires when my dad bought it new ..... I wore them out, then put pneumatic SnowHogs with new hubs and split rims, and wore them out, then put on XTrac a couple years ago .....


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

You can try a heavy flat washer and a star lock washer. if it does not work or if you dont have any handy just a little bit of the blue (removable) Loc Tite or similar. Those tapped holes are typically fine threads so they are harder to vibrate loose. Make sure you are catching plenty of thread as you are going into aluminum and it can be easy to strip. Good Luck.


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## RAM22 (12 mo ago)

Toro-8-2-4 said:


> Make sure you are catching plenty of thread as you are going into aluminum and it can be easy to strip.


General rule of thumb is you want minimum of threads engaged in the hole as the bolt diameter. In other words if you have a 3/8 diameter bolt (the threaded part of the bolt not the head) you want to have a minimum of 3/8 of an inch worth of threads in the hole when the bolt is tight. Also when putting steel bolts into aluminum IMO a dab of aluminum (silver) anti-seize is never a bad idea as they are dissimilar metals and i would especially recommend this if they could be exposed to saltwater.


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

RAM22 said:


> General rule of thumb is you want minimum of threads engaged in the hole as the bolt diameter. In other words if you have a 3/8 diameter bolt (the threaded part of the bolt not the head) you want to have a minimum of 3/8 of an inch worth of threads in the hole when the bolt is tight. Also when putting steel bolts into aluminum IMO a dab of aluminum (silver) anti-seize is never a bad idea as they are dissimilar metals and i would especially recommend this if they could be exposed to saltwater.


Yes, and thanks for bringing up up this detail. in Aluminum the rule of thumb is one diameter of thread engagement. In steel it is 1/2 of a diameter. Since this is an old machine we do not know what kind of condition the threads are today. Or the bolt condition for that matter. Going well beyond the minimum is a wise idea. It will only help and won't hurt. Buy a new bolt if that is a bit longer if you have to.


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## Weltermj (12 mo ago)

Thanks for the reminders, I've got good thread engagement on the bolts, at least 1 diameter plus a thread or two. 

I decided to wait on the locktite until after a proof of concept run to be sure I have the problem solved, and I'm sure that is where the keepers will stay.


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## Big Ed (Feb 10, 2013)

I don't think this will fix your problem, but does anyone else think this pulley is out of place?
Too far out?


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## Weltermj (12 mo ago)

I took a good look when I got home, and I see now what may be happening. There is 3/16-1/4" of forward/backward play on the auger drive shaft. 

If I engage the auger and pull the motor over without starting, it seems to like to be in the "back" position (see pic). I think I had the motor pulley adjusted forward, to line it up when the auger pulley.

I think my question is, how much play is too much play? There seems to be about 3/16 forward/ backward on the idler shaft too. That is pinned, and looks "as designed" to me.


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

Seems like a lot of front to back play. I can not diagnose the root cause from here but it may be wear in thrust washers in the auger gear box. Also thrust washer wear between the pulley and main beearing or impellar and main bearing. It is a pain to take it apart but you may be able to reduce the play by adding thrust washers in these locations. I have done something similar on an old Toro. But not as old as yours. It may not be easy but First see if you can determine what is causing that much play.


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## Weltermj (12 mo ago)

Toro-8-2-4 said:


> Seems like a lot of front to back play. I can not diagnose the root cause from here but it may be wear in thrust washers in the auger gear box. Also thrust washer wear between the pulley and main beearing or impellar and main bearing. It is a pain to take it apart but you may be able to reduce the play by adding thrust washers in these locations. I have done something similar on an old Toro. But not as old as yours. It may not be easy but First see if you can determine what is causing that much play.


Fat fingered just the quote...

Anyway, I got the impeller out, which was notna task I'd like to do again. there was no washer of any kind on the shaft behind it, with some wear on all the bolt heads. There does seem to be Forward/backward motion of the impeller shaft at the gearbox too. I can't tell from the parts diagrams whether I'm missing washers behind the impeller, but the only thrust washers listed are in the gearbox, and unobtainium.

I think at minimum I'm going to put enough thrust washer behind the impeller to keep the bolts from rubbing. I can do that easily enough from McMaster Carr. I don't think I want to mess with the gearbox unless I can know for sure I can replace it or rebuild it.


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

Taking the gear box apart may be a summer project when you are not under pressure to get it done fast and the weather is a bit more pleasant. You can get steel washers to use as thrust washers from most hardware stores. Often called machine bushings which come in several thicknesses.. On the other hand McMaster ships fast and you can get exactly the size you want. 

If the gear box has never been serviced, for now you may want to add some gear oil to the fill plug if it has one.. It it is a grease lube it is likely pretty dry by now. There is probaly a good amount of wear and metal particles in there. You want to save the worm gear if you can. If at some point you choose to open up the gear box, you may be able to back into and source bronze bearing and thrust washers etc. from a source like McMaster. Regardless of Craftsman not supporting it. I have done that before on an old Snapper I rebuilt.

Best of Luck!!!


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## Bob O (Oct 16, 2020)

I had a similar problem and found success if I loosened the tension on the idler pulley, so the drive belt has the least possible tension.


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## Weltermj (12 mo ago)

Bob O said:


> I had a similar problem and found success if I loosened the tension on the idler pulley, so the drive belt has the least possible tension.


I wish that had been it, but I tried putting the pulley in the least tension position. I think the fix for me was finding where to put the keeper I found in the bottom of the beast. 

I'm still sidetracked on a bad thrust washer, I'll keep you posted on how it's going.


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## Weltermj (12 mo ago)

So my fix is enough of these washers from McMaster Carr to take up the play, and a backing plate behind the bearing for them to ride against. The hole in the auger housing was larger than the OD of the thrust washers. 

Its throwing snow even better, and isn't trying to run away from me anymore. Thanks everyone for your input and help!


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## Oneacer (Jan 3, 2011)

Get your heater box back on there ...


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

Nice inexpensive and sensible fix.


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## Weltermj (12 mo ago)

Oneacer said:


> Get your heater box back on there ...












Done and Done. I only wanted a quick test to be sure I didn't need to pull them off again


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## Weltermj (12 mo ago)

Toro-8-2-4 said:


> Nice inexpensive and sensible fix.


I feel like I got lucky on this one. I checked the gearbox too, it's got plenty of white lithium grease in it, and didn't look too bad, so I left it alone for now


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