Choosing the right combine concave system can significantly boost your harvesting efficiency. We've seen this firsthand with farmers like Temple Rhodes, who increased his output from 3,900 to a consistent 4,700 bushels per hour simply by upgrading his concaves.
The proper combine concave setting makes all the difference between average and exceptional performance in the field. When we investigated the latest innovations, we discovered systems like Thunderstruck Ag's Razors Edge, which features variable bar spacing that narrows at the front and widens toward the rear—a design previously untried in the industry. Additionally, these concaves are specifically engineered for each rotary combine model, accounting for different rotor performances across brands.
What impressed us most during our research was the extensive testing. For instance, the Razors Edge concaves underwent trials on 25 farms across North America, from Alberta to Washington, in various crops and conditions. In this article, we'll examine 7 top-rated combine concave systems, sharing real farmer experiences and performance results to help you make the best choice for your operation.
The innovative bar design in Estes XPR2 Concaves represents a major leap forward in combine harvesting technology. Unlike conventional systems that force farmers to choose between round bar or small wire configurations, these concaves merge the best attributes of both worlds into one versatile solution.
Field tests reveal remarkable efficiency gains with the XPR2 system. Every standard rotor combine typically loses between 3-5 bushels per acre with factory concaves. At current prices, this translates to substantial financial losses across larger operations. The XPR2's progressively open design prevents this waste by threshing grain sooner and directing it to the augers more efficiently.
The performance numbers are impressive—harvesting speeds increase by 2-3 MPH with the XPR2 installed, allowing farmers to cover more acreage in less time. Moreover, the system delivers up to 7000+ bushels per hour in S790 combines, representing a 200% capacity increase compared to OEM concaves in the same machine.
In side-by-side comparisons between combines using XPR2 concaves versus those with OEM equipment, Estes documented significant performance differences. The modifications resulted in machines operating at 180% of the OEM machines' capacity while maintaining excellent grain quality. These results weren't achieved through complex reconfigurations but simply by changing the concave system.
Perhaps most notably, farmers experience an average 30% horsepower boost just by adding the XPR2 concaves. This unexpected benefit means operators can potentially avoid upgrading to a larger combine class, generating substantial equipment cost savings.
Real-world performance often tells a different story than manufacturer claims. Nevertheless, farmer testimonials strongly support the effectiveness of the XPR2 system.
One farmer, Chad Henderson, reported meaningful productivity increases after installing XPR concaves: "We picked up on average anywhere from at least two to three tenths to up to a mile an hour according to the variety". Beyond speed, he emphasized the improved grain sample quality and reduced need for constant machine adjustments.
What particularly stands out in farmer feedback is how the XPR2 concaves simplify the harvesting process. Henderson noted: "It kinda closes that window gap for me where it wouldn't be as much moving of the machine during the day as the moisture changed". This ease of operation becomes especially valuable when managing multiple combines with different operators.
Another consistent theme from users involves the "all-crop" capability. The practical benefit of not needing to switch concaves between wheat and corn harvesting saves considerable time and effort. As Henderson puts it: "What I like about it is I can undo that cover right there, pull it out, and I'm ready to go to corn. I'm ready to go to soybeans".
The XPR2 concave system works with a broad range of modern combine models. For John Deere, compatibility spans both current and previous generations, including:
· S-Series models: S790, S780, S770, S760, S690, S680, S670, S660, S650, S550
· STS models: 9870, 9860, 9770, 9760, 9750, 9670, 9660, 9650
For Case IH operators, the system accommodates numerous models:
· X-Series models: 9240, 8240, 7240
· 30-Series models: 8230, 7230, 9230
· 20-Series models: 9120, 8120, 7120
· Older models: 8010, 7010, 7140, 6140, 5140, 7130, 6130, 5130, 7088, 6088, 5088, 2588, 2577, 2388, 2377, 2188, 1688, 1680
This wide compatibility ensures most operators with modern rotary combines can benefit from the technology without requiring specialized models or extensive modifications.
The engineering behind the XPR2 specifically addresses the traditional concave dilemma. As the manufacturer explains: "You can't thresh high-moisture corn with small wires, they will plug... You can't thresh hard-threshing wheat or other cereal grains with round bar concaves". The XPR2 resolves this by combining qualities from both designs—providing the threshing capability of small wires with the capacity of round bars.
Installation requires no extensive modifications, making this upgrade accessible to most farmers. The seamless integration allows for quick implementation without the need for additional equipment or complex adjustments.
In essence, the XPR2 concave system delivers a rare combination—better performance across multiple metrics while simultaneously simplifying operation. For farmers seeking to maximize both efficiency and grain quality without purchasing a new combine, these concaves warrant serious consideration.
Originally patented in 2012, the RPR Concave System brings a distinctive approach to grain threshing with its signature 90-degree notched bar design. This technology, developed by CM Welding's Donnie Estes, has gained recognition for its unique approach to managing crop flow through the combine.
The hallmark of the RPR Concave System is the patented "Pacman" round bar with its 90-degree notch, specifically engineered to restrict crop flow and force material to rub against material. This design creates a fundamentally different threshing action compared to conventional systems.
The system's progressive bar spacing is a key technical feature. At the right side of the combine where crops enter, the spacing measures 7/8" between bars, gradually widening to 1-1/8" at the left side. This progression serves a critical purpose—enabling more effective crop separation in the threshing area.
Furthermore, this design addresses a common harvesting challenge: overloaded separators. By facilitating better grain escape through the concaves, the progressive spacing prevents separator overload—the primary cause of rotor loss. Testing has shown this design increases flow by 68% compared to stock round bars with standard 5/8" bars and openings.
The system includes adjustable cover plates that serve an important function:
· Hold material in longer to encourage grain-on-grain threshing
· Typically used in all crops except corn
· Allow for quick transitions between crop types
In fact, switching from corn to harder threshing crops like soybeans requires only opening the machine and installing the cover plates. This versatility makes field transitions significantly more efficient.
Farmer experiences with RPR Concaves highlight both strengths and limitations. Many operators report substantial improvements in operating efficiency and capacity. As one user mentioned, after switching to RPR concaves in their Case 7240 flagship combine, they've successfully harvested corn, beans, and wheat for multiple seasons without issues.
Subsequently, another farmer using an S670 noted their neighbor had positive first-year results, leading them to investigate the system. The user sentiment suggests particular value for S-series John Deere combines, with one operator stating: "it's hard to imagine that anyone could own an S series deere without the RPR concaves".
Real-world benefits cited by users include:
· Cleaner grain samples with reduced damage (fewer cracks and splits)
· Increased horsepower and harvest capacity
· Better overall performance across multiple crop types
However, some limitations have been identified. The RPR system sometimes underperforms in small, hard-to-thresh grains like wheat, occasionally resulting in unthreshed heads in the tank. Additionally, the 90-degree bar can be overly aggressive in high-moisture corn, where soft cobs may be sheared by the "knife-like edge" of the bar.
The RPR Concave System is positioned as a budget-friendly option, particularly for operations under 1,000 acres that primarily harvest corn and soybeans. Currently, a complete RPR Concave System is priced at USD 430.00, making it considerably more affordable than alternative systems that can range from USD 3,600 to USD 4,400.
Ultimately, this pricing strategy targets smaller operations looking for performance improvements without the investment required for higher-end systems. The affordability comes with practical benefits—the system weighs approximately 230 lbs and fits multiple combine models across brands.
For farmers seeking factory-backed options, Kondex Revolution concaves (a related but different product line) are available exclusively through John Deere dealers, either as factory-installed options on new combines or as dealer-installed service upgrades. These concaves come with the advantage of John Deere's warranty coverage, offering an additional layer of purchase protection not typically available with aftermarket solutions.
The Thrash Master Concave System stands out for its strategic approach to threshing surface design. With engineering that prioritizes increased surface area without sacrificing grain quality, this system offers substantial capacity improvements for operators struggling with throughput limitations.
Thrash Master's patent-pending design delivers measurable performance advantages over factory concaves. The system provides 30% more threshing surface area than standard factory concaves, creating significantly more opportunity for grain separation early in the threshing process. This expanded surface area translates directly into improved efficiency—farmers consistently report harvest speed increases of 5-10% after installation.
What truly distinguishes the Thrash Master system is how it achieves these speed improvements without compromising grain quality. In fact, the system reduces cracked and damaged grain by more than 10% compared to factory concaves. This balance of speed and quality appears in multiple farmer testimonials.
One South Texas farmer running a Case IH 8120 reported remarkable results after trying two competing aftermarket concave systems before settling on Thrash Master:
"We stuck them in and will not be taking them out. The rotor design got more of the crop out in the early stages of the concaves bringing down rotor loss significantly... Grain quality also improved to almost zero percent broken grain".
Another farmer primarily focused on corn harvest noted, "We installed the Thrash Master Concave System into our combine and were able to increase our speed in our corn. We did this while decreasing our fan speeds, lowering fuel costs per acre, decreasing our cracked grain, nearly eliminating rotor loss, and meanwhile putting a cleaner sample in the grain tank".
First and foremost, these yield improvements stem from the system's design—increasing the threshing surface area without sacrificing grain escape paths, thereby improving flow by a full 20 degrees. This enhanced flow characteristic proves particularly valuable in challenging conditions like wet rice harvesting, where rotor loss reduction has been documented.
A distinctive feature of the Thrash Master system is its patented latch mechanism that enables quick adjustments when switching between crop types. This toolless installation design for cover plates addresses one of the most common frustrations in multi-crop operations—downtime during transitions.
To optimize performance, Thrash Master provides comprehensive setting charts based on crop type. These pre-setting recommendations serve as starting points that farmers can further refine based on specific field conditions.
As a result of the system's versatility, one set of concaves can effectively handle all crops—from corn and soybeans to small grains and rice. For smaller or difficult-to-thresh grains, the company offers specialized cover plates that create what they describe as a "forced cushion thrash".
Beyond that, testimonials suggest operators should be prepared to decrease fan speeds when using the Thrash Master system. As one farmer noted, this adjustment not only improves grain quality but also contributes to lower fuel costs per acre.
Thrash Master concaves feature case-hardened bars, contributing to their long-term durability. Although specific lifespan data for Thrash Master isn't provided in the documentation, the robust construction appears to deliver consistent performance across multiple harvest seasons.
The system's durability is affirmed through real-world testing on high-capacity machines. In one documented case, a Case IH 8240 equipped with Thrash Master concaves achieved throughput of 6000 bushels per hour, while an S670 John Deere reached up to 5000 bushels per hour of wet corn. These high-capacity operations place tremendous stress on threshing components, suggesting the system can withstand demanding conditions.
Consequently, the engineering focus on maintaining proper spacing across the width of the concave contributes to both performance and longevity. Farmers report the Thrash Master's more uniform spacing creates better chaffer load balancing compared to other aftermarket options.
Complete sets include three concaves with case-hardened bars for John Deere models, while Case IH applications receive two right-hand and two left-hand concaves—all designed for specific combine models to ensure proper fit and function over time.
Sunnybrook Welding's innovative box-style concave design has earned attention for its practical field performance and durability. Their half-width frame design prioritizes both maintenance ease and threshing efficiency, addressing common frustrations with OEM concaves.
Field results remain the ultimate test for any concave system. Throughout 2011, Sunnybrook conducted extensive testing by installing their box-style concaves in farmer-owned STS combines, providing each operator with four different box types.
Shawn Abel from Calmar, Alberta, reported significant improvements after installing Sunnybrook concaves in his 9750. "The Sunnybrook tolerances are way tighter, so you don't get that play. We get better cleaning through the Sunnybrook," Abel explained. In wheat, he configured his system with 45-degree max thresh on the first concave, fine round bar concaves in the middle, and John Deere fine wire at the back, noting fewer white caps than with factory equipment.
For canola harvesting, Abel used smooth box frames at the front, round bar frames in the center, and the original John Deere wire concave at the back. This configuration eliminated previous chaff buildup issues: "We had no chaff buildup over the shoe like we had previously. It kept the chaff more up in the rotor. We gained harvest ability because there was no overloading on the shoe".
The Acadia Colony near Oyen, Alberta provided another compelling test case. Mike Entz, who operates seven combines, installed four Sunnybrook maximum thresh concaves at the front with two standard Sunnybrook concaves at the back of their 9860 STS. Despite having other specialized inserts available, Entz maintained this setup across multiple crops: "I had the other boxes he (Gerald Foster) gave me for canola and other things, but I don't goof around when something is working for me".
In side-by-side field comparisons with three other machines running 36-foot headers, Entz achieved superior results: "Some of them ran the extra narrow (wire spacing) from Precision Farming, but I still got a better sample". Remarkably, he operated with concave clearance settings never below 12, running more open than other combines yet delivering cleaner grain.
Sunnybrook manufactures concave systems for all current and late-model John Deere rotary combines. For the new John Deere X9, they offer 12 heavy-duty frames—substantially more robust than OEM designs—each containing five replaceable box inserts.
For S & STS Series models, the system features six precision-tailored concave frames, each holding seven box inserts. These inserts offer three key advantages:
· Reversibility for extended lifespan
· Individual replaceability when damaged
· Improved threshing via angled helical bars
Even older T670 (T Series) combines from the 9600 through 9650 wide-body conventional series can utilize Sunnybrook's upgraded components.
A complete Sunnybrook concave with replaceable wear edges sells for approximately USD 1600. This includes a new concave manufactured from new steel, with fly-cut bars and equipped with a set of boronized wear edges.
The All Crop concave set for John Deere S & STS series combines is priced at USD 4055.00, whereas in Canadian currency, the same system costs CAD 5995.00. Considering the testimonials regarding durability and performance, many farmers find this investment justifiable given the potential harvest efficiency gains.
A standout feature is the modular repair capability. When Abel encountered a rock, it damaged only two individual boxes: "We put a rock through and it only knocked out two boxes. But they didn't get all bent up. We were able to use them again. It takes me less than a half hour to change the concaves or make repairs in there. Probably less than half the time compared to a John Deere concave".
Engineered with a focus on structural integrity, Loewen combine concave systems have earned a reputation for durability and performance across diverse harvesting conditions. Their heavy-duty construction philosophy addresses common failure points seen in OEM components.
Large-scale operators have documented substantial efficiency improvements after switching to Loewen concaves. Barrington Harvesting of Alex, Oklahoma tested Loewen Helicals in half their fleet, installing them in 6 of their 12 STS machines. They reported being able to "start sooner in the morning and run later at night due to the fact they were able to run wider concave settings" with "less power required".
An Australian farmer running a Loewen-equipped STS combine shared striking results when harvesting rice yielding over 12 tons per hectare. Initially skeptical, he noted: "After installing all the Loewen gear... rotor thrashing speed was reduced from 850+ to around 720 in wheat". Beyond threshing efficiency, his most surprising discovery was "the greatly reduced HP requirement & as a consequence, reduced fuel consumption".
This power efficiency appears consistently across testimonials. The Australian farmer measured actual performance using a turbo boost gage, documenting that "Pre fitting of the Loewen gear, boost pressure was often up to 25 psi - sometimes 30 psi under absolute maximum load. Post Loewen fitting, boost pressure is under 20 psi".
Loewen offers specialized concave designs optimized for different crops. For corn and soybeans, their Wide Wire Concaves prove most effective, featuring optimized spacing "to allow more space for larger material to be threshed and for the larger grain to make its way down through the concave without plugging". These concaves handle corn effectively at moisture levels below 25%.
For particularly challenging conditions, Loewen's Round Bar Concaves excel with corn, regardless of moisture levels. Unlike other designs, these concaves "feature round cross bars and is void of wires" making them "a great fit to harvest field corn (even at levels above 25% moisture), soybeans, popcorn, and food corn".
Many operators praise the reduced crop damage. As one testimonial highlights: "Another factor that is quite remarkable is the straw that comes out the back of the machine is nearly as good as when it went in the front. There is very little munching & roping of straw".
Undoubtedly, Loewen's design philosophy prioritizes structural strength. Their concaves feature "heavy duty wires, cross bars, and side plates", addressing common wear points in combine operations. This construction philosophy stems from years of "examining the weaknesses and damage points of combine parts".
The Helical Bar Concaves earn particular praise for longevity, with their angled cross bars providing "more aggressive threshing as material strikes the cross bars at a right angle" while preventing "whiteheads and unthreshed grain". This design practically eliminates a major maintenance concern - unthreshed material recirculating through the combine.
From a mechanical perspective, Loewen concaves' durability stems from their heavier construction. As one user succinctly stated: "They are built much heavier so that they won't bend and twist under any conditions. You want something heavy that will not flex thereby giving you a good consistent thresh".
For operators balancing maintenance concerns with performance needs, Loewen concaves deliver a compelling combination of structural integrity and optimized crop handling across varying harvest conditions.
Precision Farm Parts has developed a distinctive half-sized concave system that addresses common threshing challenges through clever engineering. Their design philosophy focuses on eliminating filler plates—a traditional approach that often compromises grain quality and harvest efficiency.
The heavy-duty concave design makes traditionally difficult-to-thresh grain varieties substantially easier to process without requiring filler plates. This engineering approach yields multiple benefits—primarily reduced grain damage, decreased dockage percentages, and lower rotor loss.
What sets these concaves apart technically is their wider cross bars combined with precise wire spacing. This configuration allows for wider concave-to-rotor clearances in hard-to-thresh grain varieties. In practical terms, this means less horsepower requirement and reduced fuel consumption during operation.
Many farmers find the half-sized design particularly advantageous. For instance, one operator running John Deere equipment uses four Precision Farm Parts extra narrow concaves (half the width of standard JD concaves) followed by a modified JD small wire concave. This configuration enables maintaining higher concave clearances—typically 22-24 units rather than dropping below 20—while still achieving excellent threshing results.
User experiences consistently highlight improved grain samples. One farmer reported dockage levels of merely 0.6% at the elevator after implementing this concave setup. Essentially, this represented significant improvement over previous configurations.
Above all, operators appreciate the elimination of white caps when used with these specialized concaves that don't need filler plates. The design has proven especially effective for operators handling multiple crops.
Individual concave pricing varies by model, with units for specific applications like Gleaner S-series priced at $1,118 for a set of three, certain AGCO-Gleaner corn concaves at $688, and New Holland concave extensions at $420.
The company offers customer support through their North Dakota headquarters, with sales consultants available at 701-459-2271 to provide application-specific pricing. Uniquely, Precision Farm Parts backs their products with a 300-acre unconditional money-back guarantee, reflecting confidence in their performance across various harvest conditions.
Farmers partnering with XtremeAg have field-tested RPR Concaves extensively, documenting substantial productivity gains across multiple crop types. Their real-world testing provides valuable insights into how these systems perform under genuine harvest conditions.
XtremeAg team member Temple Rhodes documented remarkable throughput improvements after transitioning to RPR concaves. With his 16-row corn head on a John Deere 680, Temple previously achieved maximum outputs of 3,500 to 3,900 bushels per hour using a competitor's concave system. Following the RPR installation, his harvesting capacity consistently reached 4,500 to 4,700 bushels hourly. This represents approximately a 20% increase in productivity without any other modifications to his equipment.
"This is a John Deere 680. Ain't nothing souped up about it, anything like that, but these concaves definitely super it up a little bit," Temple noted regarding the performance boost.
The XtremeAg team tested RPR concaves across multiple John Deere combine models to validate performance consistency. Chad Henderson operated three machines simultaneously—a John Deere 680, 690, and 780. Through systematic comparison, he initially equipped only one machine with RPR concaves, then expanded implementation based on performance results.
In later testing, Henderson equipped the 690 with first-generation XPR concaves while installing the newer XPR2 concaves in the 780, keeping OEM concaves in the 680. This controlled testing approach allowed for direct comparison across machine generations with different concave technologies.
Chad Henderson's detailed field observations highlight operational improvements beyond mere throughput gains. In wheat harvesting, he noted speed increases of "two to three tenths to up to a mile an hour according to the variety". Equally important, he observed significant benefits in operational simplicity.
"It closed that window gap for me where it wouldn't be as much moving of the machine during the day as the moisture changed," Henderson explained. This reduction in constant adjustment requirements proves particularly valuable when managing multiple combines with different operators.
Furthermore, Henderson emphasized grain quality improvements: "The grain sample was just amazing". The simplified transition between crops became another highlight—removing a single cover plate prepares the combine for switching between corn and soybeans, eliminating the need for complete concave changes.
Concave System Key Design Features Performance Benefits Crop Compatibility Notable User Feedback Price Range Estes XPR3 Progressively open design, combines round bar and small wire attributes 2-3 MPH speed increase, up to 7000+ bushels/hour in S790, 30% HP boost All crops - wheat, corn, soybeans Reduced need for adjustments, improved grain sample quality Not mentioned RPR by Kondex 90-degree notched "Pacman" bar design, progressive spacing (7/8" to 1-1/8") 68% increased flow vs stock bars, improved grain separation Corn, soybeans, some limitations with wheat Clean grain samples, reduced damage, increased HP USD 430.00 Thrash Master 30% more threshing surface area, patented latch mechanism 5-10% harvest speed increase, 10% reduction in damaged grain All crops - corn, soybeans, small grains, rice Decreased fan speeds, lower fuel costs, cleaner grain samples Not mentioned Sunnybrook Box-style design, half-width frame, replaceable box inserts Better cleaning, reduced chaff buildup Multiple crops including wheat, canola Tighter tolerances, easier maintenance, quick repairs USD 4055.00 Loewen Heavy-duty construction, Helical bar design Reduced power requirements, lower fuel consumption Corn (up to 25% moisture), soybeans, food corn Ability to run wider concave settings, reduced HP requirement Not mentioned Precision Farm Parts Half-sized design, wider cross bars, no filler plates Reduced grain damage, lower dockage percentages Hard-to-thresh grain varieties 0.6% dockage levels, elimination of white caps USD 688-1,118 RPR by XtremeAg Based on RPR technology 20% increase in productivity (3,900 to 4,700 bushels/hour) Corn, wheat, soybeans Improved grain sample quality, simplified crop transitions Not mentioned Conclusion
After examining these seven top-rated combine concave systems, we can clearly see how the right choice dramatically impacts harvesting efficiency. Each system offers unique advantages—from Estes XPR2's versatile design that boosts speeds by 2-3 MPH to Loewen's heavy-duty construction that significantly reduces power requirements. Farmers consistently report remarkable improvements regardless of which system they choose, though their specific benefits vary based on crop types and harvest conditions.
Performance differences between these systems primarily center around throughput capacity, grain quality, and operational simplicity. Thrash Master concaves deliver 10% less damaged grain while RPR by XtremeAg demonstrates consistent 4,500-4,700 bushel-per-hour performance. Meanwhile, Sunnybrook's modular design allows rapid repairs when damage occurs.
Price points range considerably among these options. RPR by Kondex offers an entry-level solution at USD 430, making it accessible for smaller operations, whereas comprehensive systems like Sunnybrook's All Crop set costs around USD 4,055. This price disparity reflects differences in construction methods, durability expectations, and design complexity.
Your specific operation requirements should guide your selection. Large operations harvesting multiple crop types might benefit most from versatile systems like Estes XPR2 or Thrash Master. Farmers struggling with difficult-to-thresh varieties might find Precision Farm Parts' specialized designs most valuable, while those prioritizing durability could find Loewen's heavy-duty construction worth the investment.
The evidence from real farmers proves these aftermarket concave systems deliver meaningful improvements over OEM equipment. Their testimonials demonstrate how seemingly minor equipment modifications can transform harvest efficiency, grain quality, and operational costs. Before your next harvest season begins, evaluating which of these systems best addresses your specific challenges could yield substantial returns on investment through increased throughput, reduced fuel consumption, and improved grain quality.