Noisy Deck & Blade Interference

GWendell

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The 61" deck (3461) on my 2005 722D mower has 2 issues.

1. Deck is very noisy. The spindles and idler pulley seem free of play. Spindles are quiet when individually spun in the deck by socket chucked on a drill.

2. The blades strike each other, making a banging sound. I grind the tips of the blades to provide clearance. After 20 hours or so, striking recurs and more grinding is necessary.
I do not see any indication of spindle mount looseness or movement or other signs of looseness. These blades were on the deck when purchased.

722D with 61" deck purchased used in 2017.
Hours: 910?? (190 on meter installed after purchase + 720 hours on broken meter + ?? hours uncounted)
 

StarTech

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First verify that the diagangle lengths of blades are 21". Next take a hold on the blade tips and see if you are able to move them up and down. There should be no side to side play in the bearings. According to IPL 6205-RST bearings are used in these spindles. You can use 6205-ZZ bearings with one of the metal shields removed. Some after market suppliers will sell you 6205-2RS bearings they are usable but they not the spindles were designed to use.

But double check ID of the bearings as there are 25.4mm and 25mm ones and the shaft may just be the 25mm shaft. If so then standard 6205-ZZ/2RS are correct bearings.
 
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GWendell

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Thanks for the advice. I found that the discharge spindle moves a bit and I will replace its bearings.

The blades are Grasshopper brand and are 21 inches. I removed the blades and found no washer inside the right (discharge) Deflector Cone, 2 in the center Deflector Cone, and 1 in the left Deflector Cone.

I installed new 21" blades with 1 washer inside each Deflector Cone after wire brushing all washers to assure tight fit.

I see now 2 issues beyond the spindle bearings.

Keeping the same numbering of my first message:

2. Blades strike each other: discharge and center blades strike. The center blade has 1/4" clearance to the other blade.

3. Blades are not vertically aligned. I measured vertical offset between adjacent blade tips with blade tips closest. Discharge blade is 5/16" above the middle blade which is 3/8" above the other blade (above means closer to the deck).
 

StarTech

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Kinda unusually to have different blade heights on most mowers but Husqvarna two blade decks tend to one side higher than other. Grasshopper is one mower that I haven't seen in my shop so I am not familiar with their deck setups. I trying to d/l the owners manual from Grasshopper but it might take a while.

If it is consistently discharge and center blades striking each then I would say the discharge side is the problem because if was the center it would most likely be striking to other blade too. Either it bearings or a blade that is center mounting hole is off center slightly of the blade is badly out balance. And I have seen new blades be this way too.

My old blade balancer usually showed me this but my latest balancer is so sensitive that even many of the new blades are showing out balance conditions. Of al the new blades I tested yesterday only one set was in balance.
 

bertsmobile1

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Like Star I am yet to lay a spanner on a hopper and not even sure if they are exported to OZ.
As it was a second hand mower , no reason to believe anything on the deck is correct .
Blades are just about always on a single plane other wise you will cut the lawn stepped to different heights
As the blades had different numbers of washers it would appear the previous owner was trying to sort this problem out
Usually when a blade touches under power but not when the belt is removed the problem is either the deck is bent, the bearings are bad or the housing itself has a crack around the mounting flange
From your description I would expect the see the holes in the deck for the centre spindle wallowed out so that spindle is now closer to the discharge spindle
Easy fix is to weld high tensile washers over the holes
 
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