Export thread

Hi,

I have a Cub Cadet FMZ50, which I'm doing maintenance on. I'm following the manual. I'd like to remove the blade for sharpening, but I can't remove the nuts that keeps the blade on.

I've tried using an extension to get more force, I've tried heating it and it's been soaked in rust disolver for 3 days. I've also tried an impact wrench. I doesn't move at all.

Do I need to cut the nuts off with an angel grinder? Any advice?

I'm also trying to learn about the machine, how do I tell if the ball bearings under the blades are damaged? I've uploaded a video here, where you can see the blades, but the forum policies won't allow me to post links before post number 5.

If you see under my Albums I think you may be able to copy paste the link to see the YouTube video of the blades and the ball bearings spinning ability.

Welcome to the forum.

So sounds like the nuts/bolts are rusty. Have you tried having someone assist you by holding the top spindle bolt so you can really give it your all? I really don't like using a block of wood to hold the blades. If it's that stuck you can end up bending or even snapping the blade or denting the deck with the block.

As far as the spindle bearings go, I remove the deck belt, grab the blade and spin it by hand slowly to make sure it spins freely and that there's no "crunchy" feel or sound. I also try to wiggle it back and forth to see if there is any play.

Personally I would only cut the nuts off as a last resort because you stand the chance of damaging the bolts in the process.

Maybe someone else will have some suggestions...I've never had a blade nut (bolts actually on all my machines) get so stuck that I couldn't get it off with a breaker bar with an extension pipe on the end.

HMMMmm wont come loose with an impact wrench, ?? NOT being a "smart***" BUT, are you loosening in the correct DIRECTION ..??

Thank you both for your help.

I've had two other guys try to remove them as well, and they are used to working with machines. They have never seen as stuck nuts as these. We also tried counter holding on the top spindle bolt. Thank you for the warning with the wood, I'll keep that in mind.

No matter what, they don't move at all.

I believe it's the correct direction. I've attached a picture from the manual. We also tried the other direction shortly with no luck.

Yeah, sometimes going the other way a little (tightening) can actually help...just getting it to move at all so you can slowly work it back and forth.

So just to be clear, looking at the photo and assuming the wrench is on with the top of the handle at 12 o'clock, you're turning back towards 11 and 10 o'clock, counter-clockwise right?

I guess I'd stick with the impact wrench at this point if it's that stuck...just rattle the hell out of it and hope it eventually breaks loose...less likely to break something (spindle or your knuckles) than putting hundreds of pounds of torque on a wrench.

You aren't using the deck wash system on that mower by any chance, are you? It's a great convenience but a really bad idea and I wish they would stop putting them on mowers...

P.S. - One more thought. Have you tried holding the top bolt and tapping the wrench that's on the nut with a hammer? Kind of a last resort but I've done that when working on vehicles before with rusty/crusty hardware.

Blade retainers are designed not to loosen while being used .
So the opposite happens, they self tighten.
Get a nut splitter and remove the nut.
I keep replacement bolts for all of my commercial customer's machines.
The ones who do weekly sharpenings are always fine but the ones who fit blades then run them till they are stumps nearly always need to have the right side bolt cut off.
Once the head is removed the bolt generally will wind out with my fingers.

The previous owners did not mention bolts when I took over the business so it is something I have learned .
Thus every mower that comes in has the blade nut / bolt removed & retorqued no matter what it has come in for.

Also do not lubricate the threads with grease or never sieze, it will only make it worse.

In the field I have a 6' length of rectangular hollow tube, a 3/4" socket set with a scissor jack to hold it on the head plus another 6' of steam tube to go on the end of the breaker bar.
Even then there are some I need to push with my legs.

In the workshop I have the biggest 1/2" air impact on the market and there are times it takes a whole day to get the fasteners off.
I tried a 1" impact wrench but it twists the spindles.

On the tractors ( real ones ) we have occasionally had to heat a nut red hot and move it red hot ( use a shifter or stilsons not your good spannars for this )

If its a nut no problem. Spread the nut with a chisel, this will loosen it. Then install new nuts after. I use this method often with very rusted nuts and it works good for me.

That nut normally has 80 to 100 lb/ft torque, and with rust, and grass in the bottom thread under the nut, I have seen times where a 600 lb/ft impact wouldn't touch them. I have had to heat them to the point of turning red sometimes to break them free. Sometimes tightening and then loosening will get them broken free.

ILENGINE said:

That nut normally has 80 to 100 lb/ft torque, and with rust, and grass in the bottom thread under the nut, I have seen times where a 600 lb/ft impact wouldn't touch them. I have had to heat them to the point of turning red sometimes to break them free. Sometimes tightening and then loosening will get them broken free.

Click to expand...

Following the "mine is bigger than yours" line.
The 1/2 " impact I use is rated as 1375 ft lbs ( the biggest I could find ) and even this struggles with a lot of blade bolts.

Bert, worked for a guy at a mower shops years ago, and one of the customers had a Ferris rider. The blade bolts went from the bottom all the way through the center with a nut on top of the pulley. We would put the nut on with our fingers, and it would take an inch impact rated at 1600 pounds to remove the nuts after just a few mowing jobs.

I can believe that,.
All blade fasteners go on with a tension wrench so I know they are on right, no exceptions.
And yet I am regularly hitting them with the air chisel to cut the head off a few months latter.
Started off with one of the air kits like you get from HF or Lowes then realised it was not going to cut the mustard so spent big on the biggest 1/2" I could buy.
Got a 1" as well but need to hook up the new compressor & 2000 l reciever to use it.
We use the 1" on the farm hooked up to a jack hammer compressor modified to run 200 psi and even that did not remove some nuts.
So off they come & bill the customer for a nice shiny new nut.

Some of the newer mowers are set up with a spline-type spindle and blade system so that the blades won't "auto tighter" with use or if you hit something.

Thank you all for your great suggestions.

I finally got them off. I took the mower deck to the mechanic, and he had a compressor the size of a small car, and an impact wrench the size of a dwarf. They finally came off.

JackShaw said:

Thank you all for your great suggestions.

I finally got them off. I took the mower deck to the mechanic, and he had a compressor the size of a small car, and an impact wrench the size of a dwarf. They finally came off.

Click to expand...

GOOD-THING,... cause we were gettin ready to call THE-HULK !! ..:laughing:..:laughing:

Couple thoughts after your success. Lubricating the nut/shaft and using the recommended torque results in up to a 25% over- tightening. If the nut is pointing downward almost all of the penetrant oil is dripping off and not getting to the thread area. If the deck is off and nut pointing upwards little pools of the penetrant are available to flow into the little openings you make as you either tap with a soft hammer or use a low setting on an air hammer. Although frustrating, a couple days of tapping and penetrant seem to work. :2cents: