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54" BAD BOY MZ Magnum (zero turn) Blade Replacement OEM Blades - Blades Slipping

#1

D

Dionne Thacker

First blade replacement. Went very smooth. Maybe too smooth.
Completed the installation, took the mower out for a test-drive, it was working great. About 5min the blades stopped turning.
Disengaged the blades with the cutoff switch, took it back into the garage, lifted it and checked the torque on blade bolts to ensure 110 ft lbs.
Torque was good.
  • Started mower
  • Engaged the blades (low speed)
  • Belt squeal and smell
  • Tightened front tension spring
  • Started & engaged the blades (low speed) no squeal
  • Test drove - engaged blades at full speed, squealing.
  • Gave up on it before I took a hammer to it.

What could cause the belt to loosen when I never touched it while replacing the blades and the last time I ran the mower (before the blade change) it was fine?

What step did I miss when changing the blades that might cause the belt to loosen?

BTW - I never even touched the belt at all. All the work was performed under the deck the entire time.


#2

L

lugbolt

maybe a part damaged when lifting the mower for service? Like bent deck shell , etc. Look it over closely....


#3

M

MParr

Why do you engage the blades at “low speed”?
It sounds as if the belt is glazed. Check all of your pulleys, idlers, and spindles. The belt may be on the wrong side of a keeper.


#4

B

Bertrrr

New blades maybe bigger strain on the belt , might need a new belt, if it's squealing and it's tight, Get a new one


#5

H

hlw49

I think you should buy a new mower then that would solve all your problems. LOL Just Kidding


#6

D

Dionne Thacker

MParr said:
Why do you engage the blades at “low speed”?
It sounds as if the belt is glazed. Check all of your pulleys, idlers, and spindles. The belt may be on the wrong side of a keeper.
Click to expand...
First time changing the blades and I wanted to make sure that if I had a failure with my install it would be at lower speed if that makes sense. Once I determined it was OK I cranked it up and mowed for about 5-7 min and then the blades just stopped working altogether in the middle of mowing.


#7

D

Dionne Thacker

hlw49 said:
I think you should buy a new mower then that would solve all your problems. LOL Just Kidding
Click to expand...
Less than 30hrs on this one but hey, I'll consider it.


#8

D

Dionne Thacker

Bertrrr said:
New blades maybe bigger strain on the belt , might need a new belt, if it's squealing and it's tight, Get a new one
Click to expand...
I suspected this might be the issue. I changed to blades originally because I hit a stump and literally one whole piece of a blade was missing on both sides of the blade (about 2" chunk)


#9

D

Dionne Thacker

lugbolt said:
maybe a part damaged when lifting the mower for service? Like bent deck shell , etc. Look it over closely....
Click to expand...
No chance. I lifted it using a specific jack meant to lift the unit and used only the front tires as a point of contact. I also used a 500lb impact to remove the bolts to ensure the blades didn't spin and then torqued the new blades to 110 ft lbs with a torque wrench after install. This is what is puzzling me so much. There was no incident at all with the remove and replace of the blades and the mower functioned perfectly all the way up to the last cut other than the blades being dull and needing replacement.

Crazy!


#10

D

Dionne Thacker

I tightened the belt a little yesterday but the squealing kept happening. It sounds like it's coming from the rear of the mower rather than above the deck. The manual indicates the spring tensioner should be .025 - .030 (or about the width of a credit card). I checked it and there wasn't enough space between the spring coils to get .025 minimum so I tightened and test drove again. Minimal change if any. The only thing I can think of at this point is either a new belt (less than 30hrs on this one) or tighten it again and see if it changes.

The bottom line is that I cannot for the life of me determine how the hell this happened in the first place. The blade replacement went perfect and I torqued it to manual spec with a torque wrench (110lbs). I lifted the mower with a MoJack lift by the front tires only. There is NO chance I damaged the unit during lift

Anyway. all of that to say, it's a fucken mystery folks! I would love to know what I actually could have done differently because I actually need to mow my two acres today!

Thank you to everyone who responded so far, it really helps the thinking process to get different perspectives, even the smartass one that suggested I buy a new mower. Haha


#11

D

Dionne Thacker

I think I just figured out a piece of the puzzle. The blade on one side was broken because of a stump encounter. I think I may have damaged the spindle as it feels like it might be scraping a little. Checking it out now.


#12

M

MParr

Dionne Thacker said:
I suspected this might be the issue. I changed to blades originally because I hit a stump and literally one whole piece of a blade was missing on both sides of the blade (about 2" chunk)
Click to expand...
There’s your problem.
I don’t know if that would be covered under warranty.
Besides, you should have contacted your Bad Boy dealer about the warranty.


#13

M

MParr

Dionne Thacker said:
I think I just figured out a piece of the puzzle. The blade on one side was broken because of a stump encounter. I think I may have damaged the spindle as it feels like it might be scraping a little. Checking it out now.
Click to expand...
There’s a good chance that you have more damage than that.


#14

H

hlw49

Did you check to see if you bent a spindle. Something had to give to break 2 inches off the end of the blades. Could have bent the deck. Is one of the blades hitting the deck? But that should make a noise. But a bent shaft or a busted bearing might not. From the smart ass that suggested you buy a new mower. All in fun. LOL


#15

D

Dionne Thacker

Update: With the mower lifted, I slowly spun the blades by hand. I can feel and hear a spot it's catching.
I suspect I may have damaged the bottom spindle bearing or possibly both spindle bearings.
I am ordering a new bearing loaded spindle and some extra bearings for my original spindle.
Also since I'll have the belt off I am going to replace the belt as well just in case.

Also I am buying some yard flags to mark off all of the stump locations.

All of this problem is my fault. I cut down some small trees recently and tried to cut them as close the the ground as I could get them with the chainsaw. My idea was that I would not hit them if I cut them low. That was dumb because all I did is hide them from view so I could damage my brand new mower! I will be picking up some yard flags to mark the location until I can get them all ground down.


#16

B

Bertrrr

If your belt is in good condition and tight , might take a closer look at your clutch , you never know
Also look at the spindles and make sure there's no binding on any of them.


#17

M

MParr

Yep, a tree stump can mess up a mower big time.


#18

D

Dionne Thacker

Bought new bearings and removed the spindle. Tested the spindle bearings to see if I could detect any grinding. None detected. Dry fit all of the parts back on the spindle while off the deck and spun the blade counterclockwise to simulate running the blade and see if I could detect any grinding or balance issues. None detected. Reinstalled the spindle and tested the mower blades, squealing gone and the blades ran fine at full speed.

Like I said when I started this voyage. There was nothing wrong with the mower when I ran it the last time. The only difference was new blades and I lost function of the blades after 5 min of mowing during the first test drive. This whole thing has been interesting.

Just completed the two acre mowing after placing bright orange yard flags on the stumps and painting them with fluorescent orange paint.

Thank you to all who responded.


#19

B

Bertrrr

It's all good now , glad you're going again


#20

P

Peva

MParr said:
Why do you engage the blades at “low speed”?
It sounds as if the belt is glazed. Check all of your pulleys, idlers, and spindles. The belt may be on the wrong side of a keeper.
Click to expand...
A side comment on engaging the blades at low engine speed:
I had a 42" 16 (or 18?) hp 2009 Western Auto Wizard mower (I forget which of the 2 mower manufacturers of those days it was made by) - bought it used and used it for many, many years on a couple of rough acres.

Anyway - I was having to replace the very long blade drive belt 2 or 3 times a season. I would always engage the blade with engine running at relatively low speed and then speed it up to full speed to start mowing simply because I figure that's less stress on everything - it's just my habit of thinking that way in general.

I noticed that my wife always put the engine at full speed before engaging the blades. I got to thinking that that high-load shock was possibly killing the belt - the way the belts were failing (short sections were separating) supported the theory.

So I mansplained my theory to my wife (can be dangerous, but I took the risk 😱) and asked her to drop the engine speed before engaging the blades. She'd forget every once in a while, and I'd remind her (😬). Telling y'all all this to say that the belt started lasting well over 3 years between changes once we got the slow speed blade engagement thing established. Saved money and maintenance time.


#21

M

MParr

Peva said:
A side comment on engaging the blades at low engine speed:
I had a 42" 16 (or 18?) hp 2009 Western Auto Wizard mower (I forget which of the 2 mower manufacturers of those days it was made by) - bought it used and used it for many, many years on a couple of rough acres.

Anyway - I was having to replace the very long blade drive belt 2 or 3 times a season. I would always engage the blade with engine running at relatively low speed and then speed it up to full speed to start mowing simply because I figure that's less stress on everything - it's just my habit of thinking that way in general.

I noticed that my wife always put the engine at full speed before engaging the blades. I got to thinking that that high-load shock was possibly killing the belt - the way the belts were failing (short sections were separating) supported the theory.

So I mansplained my theory to my wife (can be dangerous, but I took the risk 😱) and asked her to drop the engine speed before engaging the blades. She'd forget every once in a while, and I'd remind her (😬). Telling y'all all this to say that the belt started lasting well over 3 years between changes once we got the slow speed blade engagement thing established. Saved money and maintenance time.
Click to expand...
The most important thing is to read the mower’s operation manual.
A PTO clutch operation is different than the old manual blade engagement of the older lawn tractors.


#22

R

RevB

lugbolt said:
maybe a part damaged when lifting the mower for service? Like bent deck shell , etc. Look it over closely...
Click to expand...


#23

R

RevB

lugbolt said:
maybe a part damaged when lifting the mower for service? Like bent deck shell , etc. Look it over closely....
Click to expand...
Ever try to bend 1/4 steel.


#24

R

RevB

Dionne Thacker said:
First time changing the blades and I wanted to make sure that if I had a failure with my install it would be at lower speed if that makes sense. Once I determined it was OK I cranked it up and mowed for about 5-7 min and then the blades just stopped working altogether in the middle of mowing.
Click to expand...
What "stopped"? The entire drive system? Just the blades but the pulleys and belt kept going (damn near impossible)? Was the deck loaded up with rock hard grass? Were the blades the same length as old? Was the clutch still engaged when it "stopped"?


#25

R

RevB

Dionne Thacker said:
I tightened the belt a little yesterday but the squealing kept happening. It sounds like it's coming from the rear of the mower rather than above the deck. The manual indicates the spring tensioner should be .025 - .030 (or about the width of a credit card). I checked it and there wasn't enough space between the spring coils to get .025 minimum so I tightened and test drove again. Minimal change if any. The only thing I can think of at this point is either a new belt (less than 30hrs on this one) or tighten it again and see if it changes.

The bottom line is that I cannot for the life of me determine how the hell this happened in the first place. The blade replacement went perfect and I torqued it to manual spec with a torque wrench (110lbs). I lifted the mower with a MoJack lift by the front tires only. There is NO chance I damaged the unit during lift

Anyway. all of that to say, it's a fucken mystery folks! I would love to know what I actually could have done differently because I actually need to mow my two acres today!

Thank you to everyone who responded so far, it really helps the thinking process to get different perspectives, even the smartass one that suggested I buy a new mower. Haha
Click to expand...
Have you manually spun the blades.....that means by hand.....with the mower off and check to see if anything is being struck by a blade? With your stump incident I wouldn't be surprised if a tear in the blade enclosure ( much less stout than the actual deck) is now being caught by a possible longer blade. Get under it and look, spin the blades.


#26

M

MParr

RevB said:
Have you manually spun the blades.....that means by hand.....with the mower off and check to see if anything is being struck by a blade? With your stump incident I wouldn't be surprised if a tear in the blade enclosure ( much less stout than the actual deck) is now being caught by a possible longer blade. Get under it and look, spin the blades.
Click to expand...
Read the previous replies.


#27

P

Peva

MParr said:
The most important thing is to read the mower’s operation manual.
A PTO clutch operation is different than the old manual blade engagement of the older lawn tractors.
Click to expand...
Good point about PTO vs. older manual type blade engagement. I believe PTO clutch has a little slippage while engaging. 👍


#28

G

GrumpyCat

MParr said:
The most important thing is to read the mower’s operation manual.
A PTO clutch operation is different than the old manual blade engagement of the older lawn tractors.
Click to expand...
Country Clipper says:

Only engage the clutch with the throttle approximately 2/3 to full throttle and no load on the deck blades. Allow the blades to come up to speed and move the throttle lever to full throttle prior to cutting grass.


#29

R

RevB

One of the nicest things you can do for your mower......

www.gdimeters.com

Why Does Your Zero-Turn Need a SoftStart Clutch Controller? | GDI

Having smooth clutch engagement every time you turn on your PTO is nice. Less of a teeth-rattling jolt when you engage your blades would certainly make any operator happy, but that isn’t why your commercial mower needs a SoftStart controller. Learn
www.gdimeters.com www.gdimeters.com


#30

G

GrumpyCat

RevB said:
One of the nicest things you can do for your mower......

www.gdimeters.com

Why Does Your Zero-Turn Need a SoftStart Clutch Controller? | GDI

Having smooth clutch engagement every time you turn on your PTO is nice. Less of a teeth-rattling jolt when you engage your blades would certainly make any operator happy, but that isn’t why your commercial mower needs a SoftStart controller. Learn
www.gdimeters.com www.gdimeters.com
Click to expand...
My dealer has an assortment of belts hanging on the wall which were shredded by owners starting the blades at idle. As an example of, “don’t do this.”

I don’t understand how this “soft start” would not create more problems than it solves?


#31

R

RevB

GrumpyCat said:
My dealer has an assortment of belts hanging on the wall which were shredded by owners starting the blades at idle. As an example of, “don’t do this.”

I don’t understand how this “soft start” would not create more problems than it solves?
Click to expand...
That's the problem with not understanding physics.....it acts over milliseconds not instantaneously. The difference between letting the clutch out slowly or just dumping it. But I guess if all you've ever experienced is an automatic that makes no sense either.


#32

G

GrumpyCat

RevB said:
That's the problem with not understanding physics.....it acts over milliseconds not instantaneously. The difference between letting the clutch out slowly or just dumping it. But I guess if all you've ever experienced is an automatic that makes no sense either.
Click to expand...
Mechanical engineer driving manual transmission since 1975. Try me on the physics.

Fact: Idle speed activation of electric PTO shreds belts. Manufacturer says 2/3rd to full throttle when activating.

What the manufacturer says is not intuitive but real world experience supports their instruction. Yet you claim an aftermarket gadget makes it better? How? “Milliseconds” suggests slipping the expensive clutch rather than slightly less expensive belt. The manufacturer doesn’t seem to think this is necessary. Perhaps the blade drive is designed to absorb the shock of dumping the clutch? Motorcycles are designed to withstand dumping the clutch.


#33

B

BigBlueEdge

If the blades are the issue you could check by putting the old ones back on temporarily and seeing if the belt issue goes away. While off, you can weigh the blades to see if there is a significant difference.

This is a stretch, but could you have put the blades on backwards? Maybe turning the blades the wrong way causes more drag (blades have lift wings, no?) and that is straining the deck drive system. Wild ass idea, but I've heard weirder things happening.


#34

D

ddbtdd

Dionne Thacker said:
First blade replacement. Went very smooth. Maybe too smooth.
Completed the installation, took the mower out for a test-drive, it was working great. About 5min the blades stopped turning.
Disengaged the blades with the cutoff switch, took it back into the garage, lifted it and checked the torque on blade bolts to ensure 110 ft lbs.
Torque was good.
  • Started mower
  • Engaged the blades (low speed)
  • Belt squeal and smell
  • Tightened front tension spring
  • Started & engaged the blades (low speed) no squeal
  • Test drove - engaged blades at full speed, squealing.
  • Gave up on it before I took a hammer to it.

What could cause the belt to loosen when I never touched it while replacing the blades and the last time I ran the mower (before the blade change) it was fine?

What step did I miss when changing the blades that might cause the belt to loosen?

BTW - I never even touched the belt at all. All the work was performed under the deck the entire time.
Click to expand...


#35

D

ddbtdd

Dionne Thacker said:
First blade replacement. Went very smooth. Maybe too smooth.
Completed the installation, took the mower out for a test-drive, it was working great. About 5min the blades stopped turning.
Disengaged the blades with the cutoff switch, took it back into the garage, lifted it and checked the torque on blade bolts to ensure 110 ft lbs.
Torque was good.
  • Started mower
  • Engaged the blades (low speed)
  • Belt squeal and smell
  • Tightened front tension spring
  • Started & engaged the blades (low speed) no squeal
  • Test drove - engaged blades at full speed, squealing.
  • Gave up on it before I took a hammer to it.

What could cause the belt to loosen when I never touched it while replacing the blades and the last time I ran the mower (before the blade change) it was fine?

What step did I miss when changing the blades that might cause the belt to loosen?

BTW - I never even touched the belt at all. All the work was performed under the deck the entire time.
Click to expand...


#36

D

ddbtdd

Something has obviously disengaged. Check the routing of your belt.


#37

F

Freddie21

Kinda reaching here, but remove the belt pulleys and blades off the spindle shafts. Clean and inspect the splines on both ends of the shafts and the mating pulleys and belts Check all idlers for correct alignment to others and spins freely and quietly. Check belt tension at all deck heights. Check blade levelness by rotating blades till tips touch and compare their heights.


#38

J

JHPArizona

With the pto disengaged, the blades should freely turn by hand. If not, take belt off, and check each blade spins freely.


#39

R

RandyT

Dionne Thacker said:
No chance. I lifted it using a specific jack meant to lift the unit and used only the front tires as a point of contact. I also used a 500lb impact to remove the bolts to ensure the blades didn't spin and then torqued the new blades to 110 ft lbs with a torque wrench after install. This is what is puzzling me so much. There was no incident at all with the remove and replace of the blades and the mower functioned perfectly all the way up to the last cut other than the blades being dull and needing replacement.

Crazy!
Click to expand...
Do some basics. Take the belt off compare length to a new one. Some lesser brands will stretch. If that is not the case check the gap on the electric clutch with a gauge. Only 30 hours the seller should do it under warranty. After hitting a stump look at all pulleys closely by lifting sides up and down for play. Seen many things happen over the years, start withe simple and weakest points of the drive system and work forward.


#40

G

Gord Baker

Dionne Thacker said:
First blade replacement. Went very smooth. Maybe too smooth.
Completed the installation, took the mower out for a test-drive, it was working great. About 5min the blades stopped turning.
Disengaged the blades with the cutoff switch, took it back into the garage, lifted it and checked the torque on blade bolts to ensure 110 ft lbs.
Torque was good.
  • Started mower
  • Engaged the blades (low speed)
  • Belt squeal and smell
  • Tightened front tension spring
  • Started & engaged the blades (low speed) no squeal
  • Test drove - engaged blades at full speed, squealing.
  • Gave up on it before I took a hammer to it.

What could cause the belt to loosen when I never touched it while replacing the blades and the last time I ran the mower (before the blade change) it was fine?

What step did I miss when changing the blades that might cause the belt to loosen?

BTW - I never even touched the belt at all. All the work was performed under the deck the entire time.
Click to expand...
It is likely that you have 1 or More Spindle bearings seizing up.


#41

P

Peva

GrumpyCat said:
Mechanical engineer driving manual transmission since 1975. Try me on the physics.

Fact: Idle speed activation of electric PTO shreds belts. Manufacturer says 2/3rd to full throttle when activating.

What the manufacturer says is not intuitive but real world experience supports their instruction. Yet you claim an aftermarket gadget makes it better? How? “Milliseconds” suggests slipping the expensive clutch rather than slightly less expensive belt. The manufacturer doesn’t seem to think this is necessary. Perhaps the blade drive is designed to absorb the shock of dumping the clutch? Motorcycles are designed to withstand dumping the clutch.
Click to expand...
"Fact: Idle speed activation of electric PTO shreds belts. Manufacturer says 2/3rd to full throttle when activating."

While idle-speed shredding is counterintuitive, I don't doubt it. Likely some resonant frequency dynamics (as you said - within milliseconds) going on, which will vary with system design/dynamics - see one theory in next paragraph).

My original comment (post #20) was about a non-PTO blade engagement rider mower. I never would suggest blade engagement at engine idle (for one thing, that would stall some engines or at least it wouldn't recover very smoothly - perhaps that's what shreds some belts if it triggered the governor to suddenly go full throttle with PTO clutch/belt engagement friction having already achieved full static-friction engagement) with PTO or non-PTO system. With the old school rider that I had, what worked smoothly was engagement with engine at speed definitely above idle, but not near full speed - what I can safely call a "lower medium" speed. Idle engagement was jerky, and full engine speed engagement definitely destroyed the belts in short order.

As previously acknowledged, PTO/non-PTO - apples/oranges, and answer not necessarily the same for different examples of the same type.

Not arguing or disagreeing with anybody - just having a discussion. 🍻


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