sammiefish Posted July 26, 2019 Posted July 26, 2019 (edited) I just installed a loader bracket that employs the 7/16-20 grade 8 bolts that attach the front and rear portions of the tractor on an Allis 314H. Does anyone have an idea of the torque spec for these guys? These are yellow zinc coated. The standard for plated of 58 ft lbs seems light to me. Edited July 26, 2019 by sammiefish Add and spell
PhanDad Posted July 26, 2019 Posted July 26, 2019 The chart from the back of many Simplicity tractor parts IPLs: So 80 ft-lbs per the chart.
sammiefish Posted July 26, 2019 Author Posted July 26, 2019 I was going off this chart. Not sure why the difference.
PhanDad Posted July 26, 2019 Posted July 26, 2019 The Fastenal chart has more variables (not always a good thing). For a K=20, 78 ft-lbs, close to the Simplicity chart. I know the ME's I worked with were always mumbling about thread conditions when talking torque and when they really got fancy, they talked "bolt stretch". The Simplicity chart has a +/- 20% tolerance - but I'm thinking that's the spec on the bolt, not the torque.
kwt Posted July 29, 2019 Posted July 29, 2019 Are you talking about the bolts going into the bevel gear box? I'm pretty sure that they came with grade 5 bolts. I've replaced some with grade 8 just because I think there is a lot of stress there and have seen some breakage in that area.
MrSteele Posted July 29, 2019 Posted July 29, 2019 Replacing a grade 5 bolt with a grade 8 is not always a good thing. The grade 8 is more brittle than a grade 5 and may break easier than a grade 5 when subjected to a moment or twisting stress. The grade 5 will absorb more of that loading than a grade 8. Whatever you don't attempt, never replace a shear bolt with a higher strength bolt than what it was designed for, just because you get tired of replacing shear bolts. Find the real problem of why and change that, instead of changing bolt strength 2
kwt Posted July 31, 2019 Posted July 31, 2019 I don't want to totally disagree with you Mr. Steel because I agree with the part about replacing a shear bolt. I will tell you that I regularly work mere feet from a 600lb hammer held together with grade 8 bolts with no guard between me and it. I would never replace them with grade 5 or lower. http://rtstools.com/are-grade-8-bolts-more-brittle-then-grade-5-8-8-vs-10-9-metric/ http://www.boltscience.com/pages/info.htm 1
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