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BGB Bolts -- Grade 5 or 8?


Kent

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I installed the used BGB today in my HB-216. When I went to replace the broken bolt, I found that it was a Grade 5. I would have thought that it might be a Grade 8, but they were clearly stamped with a 5. I went to the local farm supply to see if I could find Grade 8 bolts in the right sizes. I found some for the bottom two holes, but not the longer ones used in the top, since they must also go through the mount for the hydraulic lift... So I used Grade 5 there. Are these bolts supposed to be Grade 5 or 8? Anyone know for sure? If I need to put Grade 8 in the top two, I want to do it now, before I start reassembling the rest of the tractor....
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Kent, I think I recall reading somewhere that the drive shaft bolts are Grade 8 and all others are Grade 5. I tried to find it again to make sure, but can't......
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Kent, remember that long post we had about last spring about bolt grades? Just went and cleaned off the ones outta the 725, they have no grade marking on them. Not much help too ya, least I have 4 clean bolts..MPH
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Kent, I looked thru Simplicity service manual, TP-503A, and nothing in the BGB section eluded a grade 8 bolt. In the parts book for the 7010-6 they show 7/16-14 X 1- 1/2 but give no torque value. Their statement in the parts book is torque to standard hdwe spec no. 173209 unless otherwise noted. Any being that it is not noted, my guess is grade 5. But then they also note in service manual that torquing is important and to look at bolt head to make sure you apply the right torque.
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Got me wondering too, so I had to go look at mine. Mine too has no markings at all. Should I change them to grade 5 before I get this tractor all the way together?
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Kent, You could order OEM bolts and see what you receive. Or, if you’d like I can check the bolts on my BGBs. Regardless of what was used as OEM on the FTDs, the “glitches” and “anomalies” of the FDTs were probably addressed and corrected on the RBTs. Just like the weak "V" frames were improved with the "Y" frames. That's called progress through R&D. Let me know :D:D:D:D:D:D:D:D}:)
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Kent, according to my handy dandy pocket reference... Grade five: 120,000 psi, medium carbon heat treated steel max torque 54 ft.lbs. Grade eight: 150,000 psi, medium carbon alloy steel max torque 78 ft.lbs Torque values are dry, lubed threads reduce by about 28% Steve
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I would go with the Grade 5. They will stretch a little more and maintain the preload torque better. Remember that they are screwing into cast iron, and the grade 8 torque is high enough to possibly break the BGB. A rule of thumb: Never use a high strength bolt if you can't torque it to the proper specs.
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Thanks for the input, guys. Having just broken one of those bottom bolts, I just wanted to make sure that I do it to factory specs before I put it back together -- whatever that is, since tearing it down to that point is certainly no fun. Nor do I want to destroy another BGB.... I didn't think of the difference in dry or "wet" threads on the torque values, though. I used LocTite Blue and torqued them to 50 ft lbs, per the Simplicity torque chart for Grade 5 bolts that Maynard linked here: http://www.simpletractors.com/club2/topic.asp?TOPIC_ID=11329 I didn't want to have a different torque setting on the bottom (Grade 8 bolts) versus the top (Grade 5) bolts, so I torqued them all to the Grade 5 spec. Like I said, the local Agway didn't have 2-1/4" Grade 8 bolts, only 2" and 2-1/2".... So, it sounds like I need to change the bottom ones back to Grade 5. Leave it to me to go around in circles, since I now have to take the top ones out again due to the hydraulic lift mount....
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Kent, a hacksaw, reciprocating saw, jig saw, bench grinder, etc. will make a 2 1/4" bolt out of the 2 1/2" bolts all day long. It's trying to make 'em out of those 2 inchers that's a little tough....... lol
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I thought of that Kirk, but they're shoulder bolts, instead of full-thread, and the shoulders were a bit longer on the 2-1/2" ones. I certainly didn't want to get into using a die to thread the shoulder down more... Well at least the time spent reinstalling the pulley, PTO, etc., wasn't wasted -- I don't have to backtrack that far....
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It's kind of ironic, Kent. I used longer bolts on the support plate and cut them down just so I would have the longer shoulder going through the plates and frame. The shorter bolts didn't have enough of a shoulder for me....... You should be able to just change the bolts out without taking anything else apart. When I took the lift out of the 2210 I just unbolted the ram bracket and installed the shorter bolts.
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Kirk, I was afraid the longer shoulder would "bottom out" somewhere... When you're standing in the hardware aisle trying to decide, where you can't take it to the tractor and measure or eyeball it, it's a "coin toss" kind of decision.... I'll check and see -- from memory I'm not sure I can readily get to the bottom bolts with the hydraulic ram bracket and driveshaft/coupling disk/BGB yoke all together. It's certainly tight quarters down in there...
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Well, I'm back to where I left it last night, this time with 4 Grade 5 bolts... Thanks for the info guys! Now I can start repairing the sheetmetal damage from the runaway, and put it back together. I didn't have much time tonight, since I had to clean up another 3" or so of snow that came last night/today. Now they're saying we'll get a break tomorrow morning but more light snow/flurries by tomorrow afternoon.... I'm beginning to relate to that diary of a snow shoveler....
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When it comes conveniently on weekends and prevents me from working on the never-ending "honey-do" list, it's quality tractor time.... When it has to be done early in the morning when you're half-asleep and the other half frozen, or at 8:00 at night after a long day... then it's hard to appreciate the quality... :)
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  • 2 weeks later...
Been thinking about this for a while after this topic started. The bolts on my BGB are not marked at all and I believe Marty said his were not either. So if you were to upgrade the bolts to a grade 5 or 8 wouldn't this actually put more stress on the BGB and not the bolts? In fact, doing what happened to daddycats BGB and breaking out the bolt holes. I think I would rather break a bolt than break my BGB. Just a thought. What are your thoughts on this one? Kris
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I believe this has been posted before. I find it to be an interesting and informative site. http://www.boltscience.com/index.htm
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