Chinese Tractor Owners Association

Post edited 11:38 pm – January 29, 2012 by Len10

Starting where I left off before the SNAFU:

"Another reason for reinforcing the FEL subframe are two cutouts on the rectangular tube of the subframe. One is shown in the included picture. The other is on the inner side of the same tube toward the rear. As you can see from the picture, it is very roughly cut. It came directly from the factory this way. Does anyone know what they could be for?"

I finally cut most of the parts for the subframe. Thanks Rich for the tip about the Longevity plasma cutter.  Due to my inexperience with plasma cutting, I spent a lot of time with my angle grinder.  I'll post pictures as soon as the parts are welded together. 

In the mean time, does anyone have a good source for hex bolts?  Due to the modifications I made the u bolts that attach the ROP are not long enough.  I want to replace them with hex bolts (1/2-13 x 11 inches and 1/2-13 x 8 inches, grade 8, yellow zinc). Similar metric sizes would be OK too.  The only source I can find that sells zinc plated bolts that long charges $15-20 per bolt. I found many suppliers that charge about $2 per bolt, but they are not yellow zinc plated (although they are grade 8).

When I'm ready to post pictures should I continue with this thread even though it's in the wrong category (the original thread became corrupted)?

Post edited 9:37 pm – May 1, 2012 by Len10

I think most bolt suppliers use the term "yellow zinc" to refer to zinc plating followed by a chromate conversion coating. My understanding is zinc plated bolts always have a chromate conversion coating since zinc plating alone would corrode quickly when exposed to moisture. A zinc coating that appears "silver colored" is referred to as "clear zinc" or "blue zinc" and is less corrosion resistant than yellow zinc.  I would be happy with a clear zinc plated bolt since I won't be using my tractor anywhere salt water. 

I don't think cadmium plated fasteners are readily available anymore because of the toxicity of cadmium.  Even the type of chromate conversion coating used has changed because of the toxicity of hexavalent chromate.  The newer chromates are less toxic, but also less corrosion resistant.  At least that is my rudimentary understanding.

Post edited 8:57 pm – May 2, 2012 by Len10

My understanding is that grade 8 bolts should not be hot-dipped  galvanized secondary to the risk of hydrogen embrittlement.  I'm not sure how critical the use of grade 8 bolts is, but I want to over engineer the sub frame. I have no experience in structural engineering, so I'm basically flying by the seat of my pants.

Post edited 10:10 pm – May 3, 2012 by Len10

Here is a good  explanation for which high strength bolts can be hot-dip galvanized. According to the table at the bottom, grade 8 bolt can't be galvanized. 

Bob, you're absolutely right, I should have used the term "over-build." Equipment manufacturers engineer their products so they know or should know what size and grade of bolts are appropriate to use. Since I don't have that knowlege I would rather spend a little more a bolt that has 25% higher tensile strength.