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Trying to get a 5240 up an running for the winter. I got around to attaching the 4 bolt quick hitch horn to the top of the casting. And found one back bolt hole is stripped. Any suggestions. Would running with 3 bolts be bad? It is for a snowplow. I was also considering a Helicoil or rethreading with a larger bolt size. I guess these get a lot of pressure and get worked hard with forces pushing against them.
 

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3 is OK on a temporary basis. I would make plans to get a helicoil kit.

"If 3 can't hold it on, 4 won't." is one way to look at it.

Yet another way to look at it would be "If 3 bolts would have been sufficient, BF Gravely would have used 3 bolts, not 4."
 

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I don't know how it is set up but, if you can use a bolt & nut, once it is tight weld the nut. Then all you have to do is take out the bolt.
 

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The bolts he is referring to are the ones that hold the horn receiver onto the main casting. The threaded holes are blind so a nut is not possible. If I recall correctly they are 3/8" NC grade 8 bolts that hold that horn receiver onto the QH. I recently drilled out a broken bolt on a QH. The threads in the casting are rather deep. Stacking two helicoils in the hole is how I would perform that repair.
 

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Trying to get a 5240 up an running for the winter. I got around to attaching the 4 bolt quick hitch horn to the top of the casting. And found one back bolt hole is stripped. Any suggestions. Would running with 3 bolts be bad? It is for a snowplow. I was also considering a Helicoil or rethreading with a larger bolt size. I guess these get a lot of pressure and get worked hard with forces pushing against them.
The advance casting units themselves are fairly (though a number of different types were used) and are relatively inexpensive compared to other used gravely parts. A plow unit is one attachment that probably generates a greater amount of shock to the advance casting/horn unit, because of the jarring pressure generated by sudden stops when the plow hits a pile of snow that will no longer move. You'd probably be fine for the season using the arrangement "as is" - given that the iron castings are significantly overbuilt - but I'd still recommend using some some degree of care until repair or replacement is made.
 

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Discussion Starter #7
Thanks...will try a Helicoil as recommended. The 2 front holes actual go through the casting front while the back 2 bottom out inside the casting about 7/8" deep. I found helicoils that are 3/4 inches which should fill most of the threads. Seems like this is a weak point in this particular set up. With a 48inch blade, I could imagine the force exerted on the horn attachment. Has anyone had one sheer off? Is this why later models do not have this attachment and have a horn that slides into a round opening? Would this casting fit the older style I have if I can find one to avoid this issue going forward?
 

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The 4 bolt horn is a weak point which is why Gravely went to a one piece QH casting.

Yes, I bought one tractor that had a horn bolt sheared off. It was used with a 50" mower deck only which means the PO likely ran into a wall with the bolts loose. What will shear a grade 8 bolt is the shock generated when the bolts get loose. I have the 4 bolt style QH on one tractor and will continue to use it unless it proves to be a chronic problem. If that occurs it will get relegated to 30" mower duty.

The horn itself will fit all styles of QH.

The QH will fit all the older tractors. It might fit the Pro tractors too. I can't remember.
 

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If the threads are truly stripped then there is no material left to tap.
 

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Why don't you do the logical thing and run it as-is, in the meantime searching Ebay for a replacement 4-bolt quick hitch (minus horn) with 4 good threaded holes. I actually have several of these I'd be happy to sell for $50 each. You might have an easier time finding one with another horn already attached. I don't really like that style of QH and on your 5240, there's no reason to keep it. The newer style singularly cast piece will work just fine. It is somewhat incompatible with older electric-start tractors (it has to be forced on as it bumps the bottom of the battery box,) but your 5240 doesn't have a battery box so it's a non-issue.
 

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Mark and AJ are on the money. I would use it all season with three grade eight bolts and would have no problems. If you can break a grade eight you are doing good. This ain't a SR-71 at 80,000 plus feet. Fly it!! C.V. Common sense needs to used here.
 

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A snow plow does exert a fair amount of stress on the QH horn bolts. It is likely as much stress as can be placed on it. Get going good and snag a corner of the plow on something and the amount of force placed at that point is multiplied.

Buy a replacement QH, keep it on the shelf and see how long the one with 3 bolts lasts. Nothing worse than to be 1/2 way done plowing and then have a failure and no parts to fix it.
 
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