Snowblower troubles - Shearing a pin

[USHorse 41]

Have a 1990 blower (06-42ST06) on a 1987 310-8.  

 

The hairpin cotter pin keeps shearing off from the flag that connects the lift tube to the lift mechanism.  So, here are my thoughts as possible causes.
1.  The cotter pins, likely from Harbor Freight are of low quality.  2.  The flag that i am using (RS member made) has the lift assist spring where the spring attaches to the left side of the flag....meaning under my left foot when sitting on the tractor. I have another flag that has the point of attachment for the spring on the right side.  Did they make them different? 3.  The lift tube is welded directly to the blower by previous owner.  Maybe having no movement in this connection point is creating undo stress causing the pin to shear?  4.  The lift spring seems to drift on the cross member piece....maybe its binding causing stress.  What are everybodys thoughts.

 

BTW...the pin always breaks when i am at farthest away from the garage 

[peter lena 8,583]

I would say that welded end to the blower is causing the issue, I have a similar blower on my 312, and the lift tube has to " work  " or move to lift the blower. probably the side thrust on the flag mounting point is causing it to shear the pin. I have never sheared a pin , and use the slide in spring type pins. do you have picture of the welding point? if possible you might be able to save that mounting area, pete

[gwest_ca-(File Mod) 11,033]

This is what should be at the bottom. A lighter cotter pin will shear so perhaps welding was a bad solution.

 

Flat washer at the bottom on the snowthrower pin

920013 - 5/8" SAE flat washer replaced by 3256-27 (.62625" ID x 1.3125" OD or 21/32" ID x 1-5/16" OD)

932034 - 3/16" x 1" cotter pin replaced by 3272-21 (Later models use a 9335064 hair pin but not sure that is a good idea. May get pushed out.)

 

Garry

[USHorse 41]

Here is a picture.  The weld can't be seen very well but looks like PO added weld material at the end of the stub to act like a mushrumed nut.  Surprised it as held 2 seasons for me. 

[peter lena 8,583]

the angular difference is the issue, have you tried turning that lift rod over? You can easily do that , is does not  matter to the flag hook up. I am not familiar  with that hook up , mine has the blower mount hook , facing down. my lift rod has a slight curve facing up ,to the blower bottom hook, if you can't get those contact points level to each other , you will not improve this , pete

[peter lena 8,583]

just backtracked and found this , looks like your issue and answer, Pete

 

[USHorse 41]

1 hour ago, peter lena said:

the angular difference is the issue, have you tried turning that lift rod over? You can easily do that , is does not  matter to the flag hook up. I am not familiar  with that hook up , mine has the blower mount hook , facing down. my lift rod has a slight curve facing up ,to the blower bottom hook, if you can't get those contact points level to each other , you will not improve this , pete

I will take a look but the lift rod is welded to the hook so i can't turn anything.  

[squonk 41,028]

I use one of those hitch pins with the round snap clip from TSC. I had to thin the pin a little to fit the hole but it's much stouter that a hairpin.

[USHorse 41]

Thank you all for your input.  I removed blower from tractor to get a closer look.  Took a few close up pics.  I would say that the PO definitely welded the lift tube to the round metal stub as a fix.  The stub must have broken off.  Can i grind off the weld and have someone weld in some new round stock to the proper length?  Anyone know the lenght the stub should be?

[wallfish 16,985]

It seems that lift rod is being held too tight on the rod and creating down force on the other end, pulling down hard on the flag when it's lifted. Which in turn could be the issue with the flag pulling out and breaking pins.

 

[Red Bull Stripe 5]

I keep breaking pins that hold the lift rod to the blower. What is “supposed” to be there and what have you guys used that works better? Believe it or not, when I got it, the PO had a 10 penny nail bent to keep it from falling oit. I’ve tried various clevis pins or bolts and the nail works the best (I’m sure the shear strength is many x greater).

 

Any thoughts?

 

TIA

Edited December 10, 2018 by Red Bull Stripe

[gwest_ca-(File Mod) 11,033]

Check the hole and make sure it is not half full or rust.

Lift hook flat washer 920013 is 5/8" SAE

Lift hook cotter pin 932034 is 3/16" x 1"

 

I have found any pin that is smaller won't last.

 

Also make sure the tube is not installed upside down. Wheel Horse published an operator manual showing it installed upside down followed by a service bulletin correcting their mistake so I guess it can be done.

The picture is on the front of the manual. Click on the picture and again on the next page.

Garry

[Red Bull Stripe 5]

3 hours ago, gwest_ca said:

Check the hole and make sure it is not half full or rust.

Lift hook flat washer 920013 is 5/8" SAE

Lift hook cotter pin 932034 is 3/16" x 1"

 

I have found any pin that is smaller won't last.

 

Also make sure the tube is not installed upside down. Wheel Horse published an operator manual showing it installed upside down followed by a service bulletin correcting their mistake so I guess it can be done.

The picture is on the front of the manual. Click on the picture and again on the next page.

Thanks Garry - no rust in that hole, though it's wearing thin around the edges. I definitely have the lift rod oriented correctly with the steel plate down. I feel like the cotter pins just aren't strong enough - they don't have the shear strength which seems to be why others use 10d-16d nails. don't think I've had a washer on there previously which will help of course. What do you use - cotter pin or nail? Any photos you can post, by chance?

[gwest_ca-(File Mod) 11,033]

I use a 3/16" stainless steel cotter pin. I think the key is to make sure to use a 5/8" SAE flat washer that has a 21/32" center hole.

A 5/8" USS flat washer has a 11/16" center hole.

 

Garry

[Red Bull Stripe 5]

Great, thanks Garry, much appreciated. Will stop at the hardware store today and pick these up. 

[Red Bull Stripe 5]

does the 1/32" make that much of a difference with the washer, slopping around?

[peter lena 8,583]

yes that area has to have movement , obviously the original stud hook had that . along with lubricant to keep it smooth and moving easily. Hope you find the combination, pete

  

[Red Bull Stripe 5]

thanks Pete! meant to get to the hardware store yesterday but never did...will try for tonight!

 

[Red Bull Stripe 5]

ok guys, I picked up the washer and cotter pin yesterday.  They didn't have a 1", so I happily went with the 2" SS cotter pin instead. Installed it this morning and so far so good. Thanks for the assistance.