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Discussion Starter · #1 ·
I have a 10-year old Craftsman 18.5HP. 6-speed, 42"deck tractor. For several months the right side has not been cutting well (leaves grass higher than the left). We've checked all the usual things (deck is level, belt is almost new and tight, spindle is fine, blades are sharp and put on correctly, etc). I've tried fast engine/slow speed, slow engine/fast speed and every combination in between, but can not get a full cut across the deck. My repair guy is stumped. I'd like to cut my 3/4 acre with more than half a deck. Any ideas? ThanX! Rick
 

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Discussion Starter · #3 ·
I understand how the deck is built. When I say the deck is level, it is measureed at the blade tips to the ground. What I am saying is that we have tried all the "usual" things.
 

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I have a 42" deck on my mower, however, it's a little older. I have had a few deck problems and have had to rebuild the pulley assembly after the welds on the mounting plate broke. Here are a few things to check:

Mine is supposed to be level left to right, but not front to back. The front is slightly higher. Distances are measured from the bottom of the deck to level ground with correct tire pressures. My manual has a pretty good alignment procedure, but it should be done in the order written.

New blades make a big difference. Putting on a new pair this year made a big difference. I've also had to replace one of the mandrels which fractured after I hit a rock. It was like mowing with one blade. If blades slip because of a loose belt the cut will be affected. I had that problem too after I rebuilt the deck; the standard belt was too big. I had to try a few before finding the new correct size. The folks at TSC were great about letting me exchange belts.
 

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You don't say what kind of blades you have and whether you side discharge or mulch. The right blade can end up doing twice as much work as the left since the cuttings from the left go past the right blade on the way out. The buildup of cuttings on the right can push the grass down which then misses the blade. Some of the flimsy OEM blades can flex a lot under load and setup an oscillation that can easily be heard. I switched to Gator blades which are much stiffer and don't oscillate.

How does the cut look if you overlap so that the left blade has nothing to cut?
 

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Discussion Starter · #6 ·
Thanks flyrv9. This is not a deck leveling issue. It is not that the cut is slanting to one side or the other. The right side cut is level (almost appears uncut) and 1/2 - 1 inch+ taller than the left side. The belt was new in the spring and is still tight (since it is a single belt tensioned by the idler pullies, we would expect any belt issue would equally effect both blades), the mandrel/spindle seems tight and the blade rotates freely, and although the blades are not new, they have been sharpened twice this summer with no change in performance. As someone emailed me last night, it acts like the blade is on backwards -- which it clearly is not.
 

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...we would expect any belt issue would equally effect both blades...
Not so. As I mentioned before, the right blade does more work than the left since the cuttings from the left move to the right by design.

Are you removing all build-up under the deck?
 

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Discussion Starter · #8 ·
Thanks LLIGETFA. The blades are "bagger/mulch", with a slight lift on the back. The performance is the same whether I discharge, bag, or put on the mulch plug. The deck has a little buildup (not much really), but I will clean it again to see if it helps. If I mow only on the right side, it still does not cut properly. Welcome to my insanity!
 

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Swap the blades, left to right in case it's an imbalance issue. Does the mandrel bearings feel tight and smooth?
 

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This isnt going to help you but I have this exact same problem and feel your pain. I just got on this forum as a last attempt.

I have about 3/4 acre to mow as well and I basically have to only do one blades width at a time. I have replaced both spindles, both blades and the belt all at the same time and it made no difference. I also agree that it cant be the deck being unlevel.

PLEASE let me know if you get a solution and i will do the same for you.

Jeff
 

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I was given a mower due to the same problem, not saying yours, but when I checked rotation blades were installed upside down one side.
 

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Rick - can you remember back to the last time it cut ok and what may have happened between then and when you noticed the cut wasn't ok? If the deck raises and lowers ok and is adjusted properly; how about the tractor and frame? Is it bent and are tire pressures close to equal. If all that checks out, I'd remove the deck and spin the blades by hand and see how they track. You can also inspect the deck better if it's removed. A bent blade can also affect the cut. I remove my deck once a year for cleaning and blade sharpening. As the blades wear they do get shorter and the tips get rounded which will eventually affect the cut.
 

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Due to a washing machine problem, I was just reading a service manual. Per the manufacturer, The motor to transmission belt has an idler pulley. For agitator use the motor spins one direction, where the pulley is supposed to provide a lot of tension to the belt for the higher torque need of the agitator. For the spin cycle, it spins the other way and there is purposely less tension on the belt.
I write that because it makes me wonder if all belt routing is correct, or if you have a old spring on an idler pulley(buy a new spring I've read that is a possible washing machine problem?), so there is less tension for one of the blades. If a belt slips, a blade is slower, it will not create enough suction up and grass might be cut at an angle instead of straight?

Also, I sorta wonder if it does the same thing driving backwards.
 

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I may have figured it out. On the right side (the side the grass shoots out) there is something like a guard that is bolted on with 4 bolts. I noticed it when I was cleaning the build up from underneath the deck. It seems like a horrible design that pushes the grass down past the blade.

So I took it off and it eliminated the problem. I dont know if this will fix your problem but it seems to have fixed mine.
 

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Hopefully all will stay well for you. I think that plate helps protect the blade from rocks, stumps, roots.. My previous MTD 's guard bent badly enough that I had to take it off, but then I started bending blades when they hit stuff...
 
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