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Z121S Lawn Mover bolt for Blade broke off in the Final Drive

#1

T

tfowler9

Has anyone have this happen? Cutting my grass and heard a loud bang. Thought I might have hit a sprinkler head. Nope, the bolt snapped and the blade,,,luckily drove into the ground.
Not sure on how to fix. Try to drill out the bolt or replace the Final drive. In either case how do I prevent the final drive from spinning while I am trying to remove?

Thanks, any suggestions would be very welcome. Tom


#2

StarTech

StarTech

If you referring to bolt holding the blade on, Yes had a Hustler Zuper Z to shear one. When I found the remains I found that someone had replace the bolt with with a low frade one.
1728659543344.png
blade bolt is a M12-1.25 x 30mm and should be a grade 10.9 and not be a 8.8 or less.


#3

I

ILENGINE

You may be able to take a small punch and catch the edge of the broken bolt and with small taps spin the broken bolt out. Most of the time when a bolt breaks off pending corrosion or other factors you can about spin it out with your fingers.


#4

M

mikekir

Good luck. There are screw extractors that have a left hand twist to them. You drill a hole, and insert the extractor in a left hand direction. To find strong bolts, look at the head. The more marks on them, the stronger they are. The really good ones have a mark that makes a hexagon or such.


#5

StarTech

StarTech

To find strong bolts, look at the head. The more marks on them, the stronger they are. The really good ones have a mark that makes a hexagon or such.
Only SAE bolts have those marks, metric uses numbers. Higher the number stronger the bolt.


#6

H

hlw49

like ILENGINE said most of the time the bolt is not tight when they break off and turn out easily. You can try a left hand drill bit and if it hangs in the bolt it will spin it right out.


#7

T

tfowler9

Thanks guys for all ypuir replay! Hope you're right on the ease of extraction. Tom


#8

T

tfowler9

Thanks guys for all ypuir replay! Hope you're right on the ease of extraction. Tom
Was able to remove the broken bolt and yes it was easier than expected! Another question. One of the bolts on another blade was very tight getting out...unlike the other two. Maybe a slight miss thread when installing. I would like to clean it up with a tap. Anyone know the size tap I will need?

Tom


#9

StarTech

StarTech

Have no earthly idea what you need for a M12-1.25 blade bolt.


#10

Hammermechanicman

Hammermechanicman

Have no earthly idea what you need for a M12-1.25 blade bolt.
🤔 😂

The fun part is M12 comes in 3 flavors. 1.25 1.5 and 1.75 pitch threads. Not sure the need for 3 different thread pitches but i have taps and dies for all 3 now because everybody has to be different.


#11

StarTech

StarTech

And they actually make a M12-1.00. So all I needed here is the 1.25 and 1.50 pitches.
1729042418395.png


#12

T

tfowler9

And they actually make a M12-1.00. So all I needed here is the 1.25 and 1.50 pitches.
View attachment 69852
The bolt - just purchased is a M12 x 1.25 x 30 I have not done many of these. I am not trying to drill out and re tap. I would like to use the correct tap and hopefully clean up the threads. What is the correct tap needed? is it the M12 x 1.25? What is the 30? it looks like pretty fine treads. Tom


#13

StarTech

StarTech

I hate to ask this but just how dense are you? A M12-1.25 uses a M12-1.25 tap or die ( the screw itself would need a die and the hole it goes in takes a tap. Since this is a blind hole hole you need a bottoming tap to reach the bottom but you need a taper or plug tap to get started. Most stand length in this size nearly 40mm long and your screw is only 30mm long.

Two of these from my vendor is only $60 plus shipping.


#14

S

SeniorCitizen

In instances similar , a metric thread file covering 8 options is a handy tool .


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