Remove mower blades without spanner wrench

[semper5 43]

How the heck am I supposed to remove and replace my mower blades when I don't have a spanner wrench? Nor do I have an impact gun. Would it be ok to sharpen the blades from the underside and just leave them on the spindles?

 

I'm speaking from frustration at this point.

 

Thank you for your input.

[SylvanLakeWH 24,093]

I put a screw driver through a drilled hole in the deck. Place the blade against the screwdriver and then wrench away. The screwdriver holds the blade from spinning...Works like a charm...

[EricF 589]

I doubt you'd be able to get good enough access on them to follow the original grind with a file or handheld grinder with them still on the deck. It's worth determining the size of the nut and getting a proper socket or wrench.

 

The nuts on my 48" deck are 1 7/8"  1 1/8" -- the same size as the nut commonly used on a lot of trailer hitch balls. If you have a trailer hitch and ever put the ball on the receiver adapter yourself, check your toolbox -- you might have the correct size wrench laying around already!

 

The blade rotation causes the nuts to tighten up by themselves as they run. They'll be torqued down very tight, and if they haven't been removed in a while, they won't want to budge without some gentle "persuasion". My method is to take the deck off and flip it over, then spray some PB Blaster or other good penetrant + corrosion buster on and around the nuts and let it work for a few minutes. Put a block of wood between the end of the blade you're working on and some part of the deck so that the blade end jams against the wood when you try to loosen the nut. Try loosening the nut -- and tap the wrench with a hammer a few times while you put tension on it. Not like hammering a nail, just tap it a few times. The percussion drives the penetrant deeper and also breaks up some of the inevitable rust "lock". Then, try wrenching a little harder, but not too hard. If it doesn't budge yet, get a rubber mallet and give the wrench some moderate "thwacks" with the rubber mallet as you pull on the wrench -- it will start to move. "Nudge" the wrench along with the rubber mallet and the nut will let go in a few more nice-and-easy thwacks with the rubber mallet.

 

When you put the blades back on, use a little anti-seize on the spindle threads. Use the wood block again to stop the blade rotating when you tighten the nut. Get the nuts nice and tight, but don't worry too much about torque specs. They'll tighten down more when you run the mower, guaranteed.

 

Edit: Dangit, that is 1 1/8"... typing is a pain sometimes!

Edited May 27, 2017 by EricF

[pfrederi 17,129]

6 minutes ago, EricF said:

I doubt you'd be able to get good enough access on them to follow the original grind with a file or handheld grinder with them still on the deck. It's worth determining the size of the nut and getting a proper socket or wrench.

 

The nuts on my 48" deck are 1 7/8" -- the same size as the nut commonly used on a lot of trailer hitch balls. If you have a trailer hitch and ever put the ball on the receiver adapter yourself, check your toolbox -- you might have the correct size wrench laying around already!

 

The blade rotation causes the nuts to tighten up by themselves as they run. They'll be torqued down very tight, and if they haven't been removed in a while, they won't want to budge without some gentle "persuasion". My method is to take the deck off and flip it over, then spray some PB Blaster or other good penetrant + corrosion buster on and around the nuts and let it work for a few minutes. Put a block of wood between the end of the blade you're working on and some part of the deck so that the blade end jams against the wood when you try to loosen the nut. Try loosening the nut -- and tap the wrench with a hammer a few times while you put tension on it. Not like hammering a nail, just tap it a few times. The percussion drives the penetrant deeper and also breaks up some of the inevitable rust "lock". Then, try wrenching a little harder, but not too hard. If it doesn't budge yet, get a rubber mallet and give the wrench some moderate "thwacks" with the rubber mallet as you pull on the wrench -- it will start to move. "Nudge" the wrench along with the rubber mallet and the nut will let go in a few more nice-and-easy thwacks with the rubber mallet.

 

When you put the blades back on, use a little anti-seize on the spindle threads. Use the wood block again to stop the blade rotating when you tighten the nut. Get the nuts nice and tight, but don't worry too much about torque specs. They'll tighten down more when you run the mower, guaranteed.

I think you meant to type 1-1/8"

[pacer 3,159]

1 hour ago, EricF said:

nuts on my 48" deck are 1 7/8"

 

As Paul said, this must be a typo as they are - should be - 1 1/8"

 

A suggestion - go to Harbor Frt and they have a "spanner" (must be from Europe!) selection of, I think, 3 wrenches (generally referred to as "crescent' wrenches) for small money. The big one should do this job easily, and the wrenches come in handy for lots of different things.

[Aldon 4,826]

I modified a cheap wrench by grinding it thinner prior to procuring proper spanner wrench.

[doc724 924]

Depending on how new (or old) your deck is, a 1 1/8 open end wrench can be use on the underside of the blade to hold the spindle and another 1 1/8 wrench or socket on the nut.  You can rotate the blade so that the underside wrench contacts the deck shell and then whack the top wrench with a hammer.  It USUALLY works.  Although I gotta tell you, there were a couple of times when it was easier to remove the pulley from the top side of the deck and whack the spindle out through the bottom of the deck and then take it across the street to a neighbor with an  impact wrench.  I now finally own an impact wrench.  Don't know why I waited so long.

 

If you have a deck from the 70's when the spindles were machined from 2 1/4 hex stock, you can buy a crow foot wrench, stick a 6 inch socket extension in the end then a long pipe over the socket extension and then wedge that against the deck shell.

[GlenPettit 1,714]

Wheel Horse made a special wrench just for that, 11/8" with a thinner head to fit

under the blade to hold the spindle while a second wrench loosens the nut.

Here some for sale today on eBay under "Wheel Horse wrench":

 

[lynnmor 6,762]

4 minutes ago, GlenPettit said:

Wheel Horse made a special wrench just for that, 11/8" with a thinner head to fit

under the blade to hold the spindle while a second wrench loosens the nut.

Here some for sale today on eBay under "Wheel Horse wrench":

 

I have one of those wrenches, it is made out of peanut butter.  Useless for the intended purpose, it hangs on the wall as a collectors item.  Buy a wrench at a yard sale and grind to fit.

[Jerry77 1,218]

Not sure what you are going to use to sharpen the blades, but in any event, buy a cheapo balancer -without it your deck will probably do a disco dance...one like this:   http://www.ebay.com/itm/Oregon-Lawn-Mower-Blade-Balancer-42-100/231947215073?_trksid=p2045573.c100505.m3226&_trkparms=aid%3D555014%26algo%3DPL.DEFAULT%26ao%3D1%26asc%3D41375%26meid%3D9073296e01594acead9428a4b8f8e6f4%26pid%3D100505%26rk%3D1%26rkt%3D1%26   you can probably find it at a local store..

[pfrederi 17,129]

For the thin wrench old blades are very tough steel they, will not bend .  A hacksaw a file and some patience ...

[Racinbob 10,271]

I went ahead and bought a quality wrench and had the open end milled down. The box end is a Reese from our RV days. No more skinned knuckles for me. For the smaller nuts like on the double D blades a chunk of 4x4 holds the blade well.

[Lane Ranger 10,474]

When the  mower deck is off the tractor and turned upside down, I use a   4 x 4  wood block  about 8 inches long  to hold the blade stable when  removing and replacing blades. 

 

I do this on almost every model of deck.

 

Sharpen the blades and back on.

 

On the 42  inch decks  I use a torque wrench to replace the nuts on the spindle.

 

[Sarge 3,462]

If you do a lot of this stuff - consider getting an electric impact , they are far stronger than you'd expect and will rip those nuts off easily . Best solution for those without a decent compressor and you can find them at times on CL or one of the auction sites . Some of the newer cordless impact tools are also quite capable - my little 1/4" hex drive Bosch will knock 120ft/lbs of force onto a nut - have removed the lug nuts off the old Cruiser with it several times and use a torque wrench to put them back on properly . I have a full compressor setup here as well as a 650ft/lb 1/2" drive impact here - stuff will come loose or break one way or another .

 

Sarge

[JimmyJam 516]

I have used, as stated by others, a 4x4 block of wood between blades and lots of penetrating oil overnight or so.

[Duramax7man7 505]

I agree on the Toro wrenches. I thought that I would be able to bust the nuts loose on a 42" SD and all that I did was bent that wrench apart so that it wouldn't grip at all. "Peanut butter"- LOL- basically yeah! I have cut a piece of 5/16 steel to reinforce the backside of the wrench and will be welding it to the wrench in hopes of a stronger tool. I'll post my results.

[slammer302 2,154]

I have purchased a large makita electric impact takes blades off no problem. I hear the HF 1/2'' impacts are pretty good too. When i say electric impact i don't mean battery powered I mean the plugin ones.

[semper5 43]

I broke down, and purchased an impact driver from Harbor Freight. Worked like a charm. 

[Duramax7man7 505]

Here is the upgrade that I made to my "Wheel Horse Wrench"... 

 

The top is the section that kept getting torqued outwards. So I figured that would be the best place to weld this piece on especially considering that my more beefier wrenches this size had extra support in that area.