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cracks in seat pan


skunkhome

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My old 3414 has stress cracks in the seat pan that have been unskillfully welded up but are continuing to crack around the welds. Besides loosing weight, what can I do to correct and insure that this is not an ongoing problem?


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I like seat pan stops that hold it vertical or just slightly tipped back when the pan is raised. When the pan is down it is supported on the front so my theory is the cracks are due to the cantilevered weight when it is open. Hence the seat stop to prevent it from leaning back when open.
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I had one like that. I welded pieces to the hinge that made the piece about 6 inches longer. I welded those pieces to the pan also. The longer pieces and the additional weld have held up good. Sounds like whoever welded it the first time was trying to weld with the power too low.
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quote:
Originally posted by Roy
I like seat pan stops that hold it vertical or just slightly tipped back when the pan is raised. When the pan is down it is supported on the front so my theory is the cracks are due to the cantilevered weight when it is open. Hence the seat stop to prevent it from leaning back when open.
I shoved a 3/8" carriage bolt in my stop the other day to make it stop just slightly past vertical because I hated how it leaned back at about 45 degrees.
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quote:
Originally posted by HubbardRA
I had one like that. I welded pieces to the hinge that made the piece about 6 inches longer. I welded those pieces to the pan also. The longer pieces and the additional weld have held up good. Sounds like whoever welded it the first time was trying to weld with the power too low.
Rod, I am not a welder so I don't know what went wrong but I know it is tricky to weld pieces of vastly different thicknesses.
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I have the same cracking issue in the same place on the seat pan on both shuttles and the recently got 7016. There needs to be a seat-pan-in-a-can miracle product (for us guys who can't weld). Used, clean, undented, uncracked seat pan tin is well worth the price, IMO.
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I have seen a lot like that. I recently bend one back into place and re-welded it then ground the top smooth again. Sorry I have not come up with a better fix than re welding. Roy, the problem as I see it is the hinges should have been welded all along the seat pan. When sitting in it there is a lot of stress on that little dab of weld where they crack. Especially if one leans off to the side when mowing, with the hinge not being wide enough it give a tricycle effect and leaning on the rear corner of the fenders stresses that weld.
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Good point Thom. The basis for my theory is that the pan is pulled up/back away from the weld. The B-1, 700, & 725's came from the factory with good seat stops. Their fenders and pans are lighter than the full seat pans but to my knowledge did not crack there. A seat stop might help and won't hurt so why not.
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Roy, They moved the hinge point back farther on these seat pans. Instead of being under the pan they are actually behind the pan and with no support between the front and the hinge point beside the stiffness of the pan. The seat pan around those little welds take a lot of that leveraged weight and more when one leans on the rear edges of the pan adding a twisting force. After 30 some years of this with the added vibration of the tractor it's no wonder these crack.
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I had pieces of flat stock welded from the hinge onto the flat part of the seat pan. The flat stock goes all the way to the curve of the hinge, and about 6" onto the flat part of the seat deck. Seems to have solved the problem for me...
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quote:
Originally posted by Roy
Good point Thom. The basis for my theory is that the pan is pulled up/back away from the weld. The B-1, 700, & 725's came from the factory with good seat stops. Their fenders and pans are lighter than the full seat pans but to my knowledge did not crack there. A seat stop might help and won't hurt so why not.
Roy, On the B-1 and B-10 there is a tubular assembly which goes from the hinge to a saddle support mounted midway on the side plates. That one piece tube assembly has no welds to break and distributes the load between the saddle supports and the hinges. The seat pan itself carries little or no load.
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quote:
Originally posted by Kent
I had pieces of flat stock welded from the hinge onto the flat part of the seat pan. The flat stock goes all the way to the curve of the hinge, and about 6" onto the flat part of the seat deck. Seems to have solved the problem for me...
Kent, that is kinda along the lines of what I was thinking of doing. I just don't think the seat pan as designed spreads the load enough.
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  • 2 months later...
If I remember correctly, the welds on my 7016 seat pan were just at the corners, so I made a continuous weld, and welded the cracks about 1/4" past their ends, and also flipped the pan over to weld the crack end on the other side, just to be sure. I also noticed the bolts forming the seat pan hinge are threaded to the hex, which I will replace at some point with shouldered bolts in that region, or a bushing made from 3/8' threaded barbed wood draw up nuts. Great name, huh? An idea I have is to use two seat stops, the u-shaped clip, to maybe eliminate some flex at the hinge. These pans have some wobble when raised. I'm concerned about binding. Anyone have one laying around? Just some things I noticed. Not really that bad for 30 years old.
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quote:
Originally posted by skunkhome
quote:
Originally posted by Roy
Good point Thom. The basis for my theory is that the pan is pulled up/back away from the weld. The B-1, 700, & 725's came from the factory with good seat stops. Their fenders and pans are lighter than the full seat pans but to my knowledge did not crack there. A seat stop might help and won't hurt so why not.
Roy, On the B-1 and B-10 there is a tubular assembly which goes from the hinge to a saddle support mounted midway on the side plates. That one piece tube assembly has no welds to break and distributes the load between the saddle supports and the hinges. The seat pan itself carries little or no load.
I had 2 B-10's, a B-12, and 700 which all have stess cracks where the tube is welded to the seat pan. I have many RBT's with the crack probelm and I have only had one repaired. I wish I had a pic handy, (I can't even post pics with this computer because of problems with internet explorer) but I think I did something similar to what Kent described. I had a piece of 1/4 x 1-1/2" flat bar and cut slots for the part of the hinge and it was welded in as a reinforcement. It has worked well.
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If I remember correctly, the welds on my 7016 seat pan were just at the corners, so I made a continuous weld, and welded the cracks about 1/4" past their ends, and also flipped the pan over to weld the crack end on the other side, just to be sure. I also noticed the bolts forming the seat pan hinge are threaded to the hex, which I will replace at some point with shouldered bolts in that region, or a bushing made from 3/8' threaded barbed wood draw up nuts. Great name, huh? An idea I have is to use two seat stops, the u-shaped clip, to maybe eliminate some flex at the hinge. These pans have some wobble when raised. I'm concerned about binding. Anyone have one laying around? Just some things I noticed. Not really that bad for 30 years old.
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