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Eliminate fan belt tensioner air cylinder
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Thanks for pointing that out, Mike. I initially wanted to use all stainless steel parts, but shifted to all zinc-plated parts due to cost. I had some concern about potential corrosion when the guy at McMaster-Carr suggested the stainless steel substitution for the back-ordered turnbuckle rod, but I thought that was more of a long-term concern. I did some reading last night about galling and galvanic corrosion. I’m starting to suspect that the issue I had with the threads may actually have been galling. The stainless steel rod and zinc-plated female coupler certainly locked together, taking maximum effort to separate them with severely-damaged threads. Really, it took almost all my strength with a 12″ long wrench and a bench vise. It doesn’t make sense to me now that bad tolerances on the threads would have caused that when I used very little effort when threading them together.
I found a shorter jack screw/turnbuckle rod that will still work. The eBay listing doesn’t mention it, but I think it’s a yellow zinc coating. I found other sites that seem to have the same part with a better description. I’ll just need to cut a longer piece of threaded rod to make up for the lost length. As a benefit, this piece has 3/4″ hex flats, so the 1/2″ wrench won’t be necessary anymore.
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Yes, Never ever use stainless on stainless. I learned that many years ago, and regardless of what it says on the bottle, no anti seize works.
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Just to clarify, the turnbuckle rod with LH and RH male threads is the only stainless steel part. Everything else is zinc-plated steel. With this new part on the way, there will be no stainless steel in the assembly.
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I think you will be good to go with that. Get out the shaker can and live life to the fullest!
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Okay, I reassembled the tensioner using the new turnbuckle rod. The rod I originally wanted to use was threaded 2″ on each end. This new rod is only threaded 1 1/2″ on each end. That effectively reduces my range of adjustment by 1″. I was concerned about that, but I have since determined that I really only need an adjustment range of about 1 1/8″ to go from very taught belts to loose enough to easily change them.
The adjustment range is calculated by taking the length of the threads (1 1/2″ + 1 1/2″) and then subtracting the thickness of the jam nuts (5/16″ +5/16″) and the length of threaded rod you always want to remain engaged in the mated parts. I was shooting for at least 1/2″ engagement of the threads when the tensioner was fully extended. I ended up leaving a bit more (5/8″) engaged on each end. That feels very solid with the 1/2″-20 threads.
1 1/2″ + 1 1/2″ – 5/16″ – 5/16″ – 5/8″ – 5/8″ = 1 1/8″ range
All parts are now zinc-plated steel, with the turnbuckle rod being yellow zinc. I did throw a different cotter pin in at the yoke end, and cadmium plated is all I had on hand. I think that’ll be okay, but it’s easy enough to swap out.
I timed myself replacing all three fan belts at a relaxed pace. It took three and a half minutes. I’m calling this one a success!
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Nice job Chad. Looks better than the first go round.
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Chad, that looks a whole lot simpler than what you started with. Glad you pushed that project over the finish line.
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