How to Identify When It’s Time to Upgrade Your Concaves
Are you tired of the mid-season combine concave shuffle eating away your time, patience, and profit?
Many farmers find themselves constantly struggling with green pods and material other than grain (MOG) in the tank, despite making numerous adjustments. Whether you're dealing with worn round bar concaves or experiencing leveling issues with John Deere concaves, the solution isn't always as straightforward as you might think. In fact, many combine concaves require more effective threshing up front before those green pods fall through.
We've been there too. The frustration of changing settings repeatedly with minimal improvement, the challenge of switching between crops, and the nagging feeling that you're losing yield despite your best efforts. However, knowing exactly when to upgrade rather than adjust can make all the difference to your harvest efficiency.
In this article, we'll walk you through the clear signs that indicate it's time to upgrade your concaves rather than continuing to fight an uphill battle with your current setup.
Recognizing Field Performance Issues
The first indicators that your combine concaves need attention often appear in your harvest performance. Let's examine the most common field issues that signal it's time to evaluate your concave system.
Cracked soybeans in the grain tank
When you spot cracked or split soybeans in your grain tank, your combine concaves may be the culprit. This typically happens when beans drop to 10% moisture or lower. Additionally, worn grain tank auger flighting can significantly damage beans, especially when the tank is filled completely. For optimal results with food-grade soybeans, never fill the tank above the auger level.
Unthreshed pods showing up in tailings
Unthreshed pods in your tailings indicate ineffective threshing at the concave. If you notice this issue, try closing the concave 1-2 notches at a time until the problem resolves. Nevertheless, there's a delicate balance with concave clearance—too tight causes splits, too loose leaves unthreshed pods. Installing concave cover plates in the first 12 inches can also improve threshing power for green soybean pods.
Excessive rotor loss during harvest
Rotor loss often results from improper concave settings or rotor speed. Contrary to traditional thinking that slow rotor speeds give the best grain quality, starting rotor speed at 400 RPM actually lowers rotor loss without increasing grain damage while also boosting separator capacity. For soybeans, the optimal settings generally include:
• Rotor speed: 250-350 RPM
• Concave: 6-12 (depending on crop volume)
• Chaffer: 14-20
• Sieve: 4-8
Inconsistent crop flow through the feeder house
Poor material flow through the feeder house creates uneven feeding into the threshing system, resulting in inconsistent threshing. This manifests as crop piling up at the front of the feeder house, almost as if it's not being grabbed properly. During harvest, monitor for material throwing back over the spiral or crop being picked up by the reel and thrown onto the ground. Such issues often indicate that your current concave setup isn't processing material efficiently.
By identifying these performance issues early, you can determine whether simple adjustments will suffice or if upgrading your combine concaves is the necessary next step.
Mechanical Signs Your Concaves Are Worn
Beyond field performance issues, physical inspection of your combine concaves reveals telltale signs that replacement—not adjustment—is your best path forward.
Visible wear or damage on round bar concaves
Round bar concaves show distinctive wear patterns when they've reached the end of their useful life. As concaves age, the edges become dull and rounded, dramatically reducing friction on your crop during threshing. This rounded profile creates a reflective surface that bounces grain back into the rotor instead of allowing it to pass through. Furthermore, worn concaves often develop a bow in the middle—even a 2mm bow indicates uneven threshing across the width.
Difficulty maintaining proper concave clearance
Once concave bars wear down significantly, maintaining proper clearance becomes nearly impossible. The centers may wear down approximately 1/8" compared to the edges, creating inconsistent threshing across the concave width. Subsequently, you'll notice yourself constantly adjusting settings without improvement. Remember that running a concave too wide or too tight substantially affects harvesting efficiency.
Frequent plugging or poor material separation
Plugged concaves prevent threshed grain from falling through, forcing more grain to travel rearward along the rotor. This overloads your separator capacity and creates rotor loss. Correspondingly, grain falling farther back along the rotor puts extra stress on your combine's cleaning system. Though plugging occurs more commonly in high-moisture crops, it shouldn't be tolerated as a normal operating condition.
Concave leveling issues in John Deere combines
John Deere combines require proper concave leveling for optimal performance. On walker machines, the clearance at the rear concave should be precisely 5/16" between the highest part of the rasp bar and the concave bar. Meanwhile, the front concave should be level to within 3/32" to remain within specifications. When these measurements can't be maintained despite adjustment attempts, it often indicates underlying problems with concave condition or adjustment components that necessitate replacement rather than continued adjustment.
When Adjustments Aren’t Enough
Sometimes even the most meticulous combine operator reaches a point where additional tweaks simply don't deliver results. There comes a moment when you must recognize that your harvest efficiency issues require more than just another adjustment.
Using cover plates and inserts with limited success
Cover plates and inserts initially serve as excellent tools for enhancing threshing performance. Yet, as your combine concaves age, these temporary fixes often mask deeper issues. Upon installing these accessories, you might notice only minor improvements that quickly diminish as harvest continues. This declining performance curve typically indicates that the underlying concave structure has deteriorated beyond what accessories can compensate for.
Constantly changing settings with no improvement
If you find yourself continually adjusting your settings throughout the day without seeing consistent results, your concaves have likely reached their functional limit. Round bar concaves that require adjustment every few acres signal that the fundamental threshing surface has lost its effectiveness. Moreover, when your settings work briefly then suddenly stop performing, this inconsistency points toward worn components rather than incorrect adjustments.
Crop-specific tuning becoming time-consuming
Traditionally, switching between crops requires some fine-tuning. Nonetheless, once this process evolves from routine adjustment to a full-day ordeal, your combine concaves are likely the culprit. Perhaps the most telling sign appears when previously successful settings from last season no longer work for the same crop. Soon after, you'll notice the time spent adjusting begins to outweigh actual harvesting time—a clear indicator that replacement offers better value than continued tweaking.
Fan and sieve settings no longer improving sample quality
The final confirmation often comes when cleaning system adjustments fail to improve your grain sample. Since your John Deere concaves affect material distribution to the cleaning shoe, worn concaves create inconsistent material flow that even perfect fan and sieve settings cannot overcome. Ultimately, this cascading effect means regardless of how you adjust your cleaning system, the grain tank sample remains disappointing—containing either excessive foreign material or damaged grain.
At this point, additional adjustments become counterproductive—you're simply compensating for worn equipment rather than optimizing performance.
Choosing the Right Time to Upgrade
Timing your combine concave upgrade appropriately maximizes your investment and minimizes harvest disruptions. Strategic planning ensures you're not caught with inadequate equipment during critical harvest windows.
Before switching crops mid-season
Essentially, the days before transitioning between crops represent ideal upgrade opportunities. Farmers lose valuable harvest time when changing traditional combine concaves between different crops. All-crop concave systems eliminate this headache entirely, allowing seamless transitions from wheat to corn without swapping equipment. Consider that every minute saved during the harvest season translates to more acres covered and higher yields.
After multiple seasons of heavy use
Over time, even well-maintained concaves reach their performance limits. When your concaves show a bow exceeding 1-2mm, or edges have lost their sharpness, replacement becomes more cost-effective than continuous adjustments. After several seasons, worn concaves cause uneven threshing across the width, dramatically affecting yield retention.
When upgrading to newer combine models
As technology advances, precision upgrades allow you to fit your combine with the latest innovations. Factory-designed features can extend the life and capabilities of your current combine while solving real harvest challenges. Plus, integrated systems like remote concave covers eliminate manual adjustments, increasing operational efficiency without purchasing entirely new equipment.
If you're losing yield despite best practices
Ultimately, financial calculations make the decision clear. With higher crop prices, retaining even slightly more grain creates substantial returns. For example, reducing rotor loss from the OEM-accepted 1.5% to just 0.25% can pay for new concaves in under 500 acres! This makes upgrading before harvest particularly valuable during years with favorable market conditions.
Conclusion
Recognizing the right time to upgrade your combine concaves rather than continuing with endless adjustments can truly transform your harvesting efficiency. Throughout this article, we've examined clear indicators that signal when replacement becomes necessary. Most importantly, physical signs like worn round bars, bowing in the middle, and leveling difficulties tell you when concaves have reached their useful life.
Field performance issues likewise serve as warning signals. Cracked soybeans, unthreshed pods, excessive rotor loss, and inconsistent crop flow all point toward potential concave problems. Additionally, spending more time adjusting than actually harvesting certainly indicates your equipment needs upgrading rather than another round of tweaks.
The financial impact of delaying necessary upgrades cannot be overstated. Reduced yields, damaged grain, and wasted harvest time directly affect your bottom line. Therefore, strategic timing of your upgrade—before switching crops, after multiple seasons of heavy use, or when yield losses become apparent—maximizes your return on investment.
We understand the hesitation to replace equipment that still "works," albeit poorly. However, the math speaks for itself. Modern concave systems often pay for themselves within a single harvest season through improved grain retention and reduced downtime.
Your combine's concave system forms the heart of your harvesting operation. Although adjustments serve well for addressing minor issues, recognizing when upgrades become necessary saves countless hours of frustration and protects your yield. Stop playing the concave shuffle—watch for these warning signs and make the upgrade decision based on evidence rather than habit.
