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Sears Clevis pin breaks


phann's Avatar
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02-10-08, 01:01 PM   #1  
Sears Clevis pin breaks

Hi, have a 3 year old Sears snowblower 11 horse power 30" mouth.
Was working fine till it would not go forward or backwards.
I pulled off the bottom plate and checked and all I could fine was the bolt or pin was broken off the drive shaft. I punched out the old one and tried a regular 1/4" bolt and nut. Worked for a few runs and bang, broke again. Tried a clevis pin and that broke off too? and again another bolt, same thing. Why is that happening? Sears coming in 2 weeks and I can't get car in the backyard as too much snow.
Help is appreciated, thanks

 
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02-10-08, 01:30 PM   #2  
Is your snowthrower designed for the clevis pin to be put through the axle on the outside of the wheel as to allow for "free-wheel".And another hole that the pin to goes through the wheel and the axle for pulling or what?? Post your model and serial #'s so we can look up what you've got,and see what your looking at.Someone here will be a lot more able to help you with #'s

 
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02-10-08, 02:20 PM   #3  
Reply..

Thanks for the fast response. The model # is C950-52431-0.

When I took the cover off, inside where the friction plate is located, seen a hole in the axle and drive sprocket that appeared to have a bolt missing supporting why the wheels do not move. I punched out the broken piece and when I replaced with another bolt, worked?
Seem to explain why forward, backwards did not work. However, the replacements keep breaking almost right away...hmmm any ideas.
Thanks

 
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02-10-08, 03:09 PM   #4  
Hmmm,

For some reason the model number you posted didn't come up on Sears parts look-up page.

With no screw or anything in this hole, Does the wheels spin freely with the unit off the ground ?

Most all roll pins are hardened spring steel, I'm sure the clevis pin and screws you are trying are not. I would suggest going to your local hardware store and get another roll pin to install and try again.

Good Luck

 
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02-10-08, 04:06 PM   #5  
turns ok..

When you turn the wheels, shaft not locked onto drive sprocket. A bolt or Clevis pin is reqiured between the two or the shaft turns, not the wheels.
I did try hardened bolts, clevis pin and both break within a short use..is there that much stress.
The hole only supports 1/4" and any idea what kind of steel bolt is to be used. Hardware stores carry all kinds but this must be some extra strength or is something wrong causing the bolts to snap regardless is right bolt is used.

Best can tell you is that this blower is a Craftsman Dual Stage Snow Blower with that model #.

 
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02-10-08, 04:10 PM   #6  
Wheel..

Forgot that ?
Yes the wheels turn when you left off ground..but you can stop them by your feet as no torque to them.
They are getting a bit of traction from the akle.

Hope that helps.

 
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02-10-08, 05:15 PM   #7  
There was a recall on a particular brand for this exact problem, not long ago. I have looked but cannot find find the exact machines. I will bet yours is covered.

 
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02-10-08, 05:19 PM   #8  
Is this the drive system you have ? Is reference # 653 the bolt that keeps breaking ?


 
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02-10-08, 05:24 PM   #9  
Recall

The recall last year was for the Carburator that was replaced.
Have not herd from Sears now of any other issues.
I have a waranty till end of this year. Just trying to get this running as the repair fellow is not coming for another 2 weeks, you believe this and weather forcast is more snow..car already parked on the lawn...too much snow to get in the back.
Thanks again...

 
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02-10-08, 05:29 PM   #10  
#655?

Hi, judging from the pic, #655 looks more right...The pin, bolt or clevis pin or what name it has goes in the sprocket closer to the wall. Only one side has that support, the other wheel does not have that sprocket ...

 
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02-10-08, 06:48 PM   #11  
#655 is the axle bushing, #653 is a 1/4" bolt that goes through the sprocket and axle shaft to keep the sprocket from free spinning on the shaft.

 
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02-10-08, 07:23 PM   #12  
Does sprocket #652 Wobble on the shaft ? Thereby rubing against the pin or bolt,cutting it in two.Or does the axle wobble in bushing #655?

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02-11-08, 06:00 AM   #13  
On your machine one of the wheels has a bolt through it and the other has a pin. There are 2holes in the axle on the end with the pin, one so the pins goes through axle only and one where pin goes through axle and wheel. Make sure the pin is through the wheel and axle.

 
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02-11-08, 11:46 AM   #14  
Posted By: 31YTech Is this the drive system you have ? Is reference # 653 the bolt that keeps breaking ?

OK let me jump in here please. My Craftsman also broke the bolt #653. Put in a softer bolt, grade 5, for the time being. I see the markings on the origional bolt head have six marks, with the marks at the 3o'clock and 9o'clock postions being double marks. Would that be the equivalent of a grade 8 (six marks) or is this some other special grade bolt? Thanks.

 
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02-11-08, 12:23 PM   #15  
soulfish, All you have to do is type "bolt grade markings" in your browser, The one's below are the only I know of for standard type fasteners. The extra two marks could be manufacturer I.D. marks ?



Grade 2

Low or medium carbon steel



Grade 5

Medium Carbon Steel, Quenched and Tempered



Grade 8

Medium Carbon Alloy Steel, Quenched and Tempered

 
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02-11-08, 01:34 PM   #16  
I hear you. I was reading that any additional marks are usually Manufacturer ID. Think I'll just drop in an 8 and hope it snaps when it's supposed to.

 
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02-11-08, 02:31 PM   #17  
Bolt is free from Chain

Hi all and thanks for trying to help here.
Answer still not solved but from the manuel pics, appears that a nut and bolt go through the drive sprocket and shaft.
Only one bolt supports the drive. What bugs me is that the bolts snap too easy. At least you think a regular bolt would last for one driveway clean up.
Is there a special bolt to use? or is something possible wrong as too much torque snapping the bolt off.
This bolt goes through the sprocket and shaft, thats it. Does not rub or even near any other parts.
Any idea.

 
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02-11-08, 02:56 PM   #18  
This is why I asked if the wheels spin freely with no bolt/pin etc. in the sprocket/axle assembly, The only drag on the axle/wheels is the axle bushings. I see no way for this axle to be pinned/dragging in these bushings tight enough to sheer a bolt.

Try a Grade 8 bolt with the six marks on the head as above and see if that solves the problem.

 
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02-11-08, 03:39 PM   #19  
yes

The wheels still turn freely without the bolt...a little drag as the chain still attached. You need to just turn to align the holes. I will try this type of bolt and see how it goes. Thanks again. Just strange that it snaps a clevis pin easy and 2 other regular bolts.

 
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02-11-08, 06:15 PM   #20  
please correct me if I am wrong

Aren't the harder bolts (grade 8) more brittle and shear easier? And the softer grade more likely to bend without breaking? That being the design for machine component protection?

 
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02-11-08, 06:22 PM   #21  
one thought

This is probably unlikely but, is the surface of the driveway uneven or cracked enough that scraper is catching on the ground and stopping the forward motion of the machine? That would be where shearing a bolt would protect your snowblower from breaking something more expensive. Is the scraper blade dragging the cement all the time? Might try adjusting it up if it is catching something. Or lowering the skid pads. Same effect.

 
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02-11-08, 06:36 PM   #22  
Posted By: soulfish Aren't the harder bolts (grade 8) more brittle and shear easier?
IF you will DO as I mentioned and put "bolt grade markings" in your browser then click on "Bolt Depot" it will show you a chart with ALL the facts about Grades and Tensile Strength.......

 
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02-11-08, 06:58 PM   #23  
It's a grade 8

The correct bolt is a grade 8 bolt however there should be no threads in the gear. It needs to be too long so that when you tighten the nut the bolt will still turn & there is no threads in the gear. If the nut is tightened so that the bolt won't turn or there are still threads in the gear it will break. The vibration will cause the nut to continue to tighten until it breaks the bolt. An impact with a solid object will break it also.

AJ

 
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