warped mower deck

   / warped mower deck #1  

mrcaptainbob

Platinum Member
Joined
Mar 21, 2002
Messages
593
Location
Jackson County, Michigan
Tractor
Bolens HT-20
I have a 54" 3 blade mower deck that I believe is warped. Just purchased the tractor and deck (used) last year. The lawn looked terrible when I tried it. Flipping the deck over I found that the blade tips have about a 1/2" space vertically! between them. I believe all three mounting surfaces are out of flat to each other. The blades are not bent. The bearings are in good shape. Any ideas on how to straighten/realign?
I'm considering cutting the three surfaces out and replacing with a plate know to be flat. Transferring the holes would be a simple thing , using the old piece as a pattern. This is a last resort. I'd rather find a better way.
 
   / warped mower deck #2  
Does the grass have a sawtooth effect like with blades that have a tilt to them, or is it stepped with the cuts parallel to the ground? If it's the latter, it could be something simple like the blades have a different offset, or one of the spindles ("quills") was replaced with one having a different dimension.............chim
 
   / warped mower deck #3  
Ive had some fun times with warped mower decks (I dont think we have an icon for sarcasm). The hardest part is working out what is out of line. Be prepared to be very patient and take lots of measurements before you start planning anything. Do you have a good flat floor you can try this on? A little adjustment in the wrong place can quickly make the situation much worse.

One question first though - are you absolutely sure that it is not the deck mounting system on your tractor that is out of line? Make sure that everything is true - including getting your tire pressures right - before you start anything. Also make sure you clean and lube any kind of deck balancing system or pivots that are there (some have spring loaded balancers).

Let us know what you find as each situation has its own remedy.

Best of luck with it.
 
   / warped mower deck #4  
I have a JD F725 54"( 3 blades) front mounted mower that has a section in the owners manuel on how to adjust the deck for side to side and front to back "levelness". JD sells a tool that reaches under the side of the deck and measures how far the tip of the blade is off the ground ( you do this on a flat floor after pumping all the tires to spec). On my deck, zinc chromate rods run for and aft, left and right, and are threaded into an adjustment sleeve with a jamb-nut on it. I twisted the rod off from corrosion since a hadn't made any adjustment in 11 years. You adjust so that the blade tip heigth is equal from the floor with the blades pointing 12 o'clock/ 6 o'clock and 9 o'clock/ 3 o'clock. The JD tool would be handy but you can do it without with a stand-up 2-3" ruler and flashlite and crawling around on all 4's. Keep the WD-40 handy and use the right sized wrench so as not to bugger-up the hex. This cured my sawtooth cut after a new part from a JD dealer ( the JD 735 has the same deck and the dealer borrowed a part off it). These front mounted decks take beating since they're out there hitting things.
 
   / warped mower deck
  • Thread Starter
#5  
There's not near the adjustments on this as you describe your's has, RCH. But CHM, you called it good when you said 'sawtooth'. It's not that the deck is out of whack with a level surface. I set that up in the garage. It's even lh/rh & fore/aft. Most definately a problem with individual blade angle.
I rotated each blade relative to the adjascent blade tip. There's no wobble on any of the blades. But there is a full 1/2" distance vertically between the tips. Which accounts for the sawtooth effect.
Old Wanker, you lit up a good idea for me with suggesting the flat floor. I can prop up the deck at a nice workable height and parallel to the floor. Then I can take eight measurements off each blade through their turns and see exactly which direction the 'lean' is. That will tell me the angle as well. That just leaves me with one more problem...(will it never end?)...how to actually straighten those parts of the deck the bearing housings are bolted to.
 
   / warped mower deck #6  
Have you had the three blades off and then stacked them together to check that all three are the same shape? I had the experience of hitting a stump, and bent one blade. It was detectable by stacking them together. Just a thought.
Also, I once helped straighten a deck that, I think, had a similar problem to yours, where the housing around the bearing hub was bent (run over, I believe). We straightened it by using well placed (most of them!) blows with a sledge hammer, while continually checking where the blades met each other, and how they circled the perimeter of the mower deck. This was done with the deck off the tractor.
 
   / warped mower deck #7  
beenthere had some good suggestions about the sledgehammer but you may want to use a piece of wood between the sledge and the deck to prevent localized denting. Another idea is to bolt some angle iron on to keep things straight. Its much more rigid than the flat sheet metal in the deck and may be enough to keep it true if you bolt a couple of pieces along the length. Of course - I dont know what obstructions you have on your deck that may prevent this but just an idea. Key is to start with the measurement and find out where the problem is first.

I think its down to trial and error now. Best of luck with it.
 
   / warped mower deck #8  
I wouldnt consider 1/2" as terrible on a 54" deck. I have something like that on mine, but it's 72". Are you checking to see if both tips of one blade give the same result, while keeping the other blade fixed? Just as important, and maybe moreso, is front to rear level.

Most of these large mowers have a more difficult time lifting the grass if you are cutting it long, which may give you somewhat of a haggard look. I guess you could beat one side of the deck up or down to try to improve the level, if you really are sure that is the problem. Good luck.
 
   / warped mower deck #9  
I have a Craftsman 19hp/42" cut with the same problem. And I know exactly how it happened. The box in the ground near the road where the phone lines come in was a couple inches above ground level. The front edge of my deck caught the box and before I could stop, it had the deck bent out of shape. I have tried and tried to staighten it out. I just cannot get the deck to bend back to level. Like yours, my blades are about a half inch apart vertically. Doesn't sound like much, but is sure shows up on the grass. I have about resigned myself to buying a new deck. $100+ /w3tcompact/icons/frown.gif
 
   / warped mower deck
  • Thread Starter
#10  
Beenthere...The blades I put on were brand new and did stack flat with each other. In fact I dismounted them and checked them again for true after the first cut. I suspect that in it's previous life someone drove over the deck to mount it. Since it's a midmount deck, it would be easier than sliding it sideways. I did check each blade tip by rotating it relative to the next blade tip. Each tip is exactly the same amount off. That's what leads me to suspect the deck housing rather than anything else is the problem. The sledge sounds like it would do the trick as long as I secure the rest of the deck. I'm still considering mounting an old brake rotor to a substantial 5 foot rod. And by transferring the bearing housing bolt pattern to the rotor and bolting the rotor to the deck housing I may be able to 'persuade' it back to 'flat'.
 
 
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