The Flex-Hone for Motorcycle Transmissions

The Harley-Davidson Shovelhead is an air-cooled, V-twin motorcycle engine with rocker box “covers” that resemble inverted heads on coal shovels. Built from 1966 to 1984, the Shovel delivered 10% more horsepower than the Panhead engine, making Shovelhead bikes the motorcycle of choice for many police departments. Although the Evolution engine ultimately arrested Shovelhead sales, many third-party manufacturers still produce Shovel-like designs.

The Flex-Hone® and the Art of Motorcycle Maintenance

Today, bikers and motorcycle mechanics such as Hawg Rider rebuild original Shovelhead engines and tune newer motorcycle crate engines. At Hawg Riders All HD Tech Forum, “a place where everyone with a love of Harley is welcome”, the long-time chopper mechanic described how he “spent an entire day teaching a young guy” how to refurbish a leaking transmission for his Shovelhead bike. Along the way, Hawg documented this motorcycle maintenance project in pictures – including a shot of a Flex-Hone.®   

Shovelhead Transmission Rebuild

Although the tranny’s gears were in a “good shape”, the Shovelhead Harley needed a new crankshaft, bearings, bushings, seals, and kicker parts. After repairing and reinstalling the countershaft gear cluster, Hawg installed the transmission main seal and tackled the sprocket. The biker then turned his sights to the kicker parts, starting with the spring and moving onto the sliding ratchet gear. Next came the kicker gear, keyed to shaft and secured with a nut and lock-washer.

Using the Flex-Hone® with Kicker Cover Bushings

“I replaced his kicker cover bushings” Hawg explained, “since these are not some super ‘critical’ engine or internal part.” Using a hand drill and a Flex-Hone® fromBrush Research Manufacturing (BRM), the Harley mechanic fit the bushings to the shaft “nice and simple”, and reported that everything “works fine”.  He then installed the kicker shaft and cover to complete the transmission rebuild, which cost less than $150 in parts.

From rebuilding motorcycle engines to  honing motorcycle brake rotors, bikers and bike-builders are using the Flex-Hone® with classic motorcycles. What’s your Flex-Hone® story?  

Flexible Honing for Motorcycle Brake Rotors

Flexible Honing for Motorcycle Brake Rotors

The Flex-Hone® for Rotors from Brush Research Manufacturing (BRM) provides the ideal cross-hatch surface finish for new and re-turned motorcycle brake rotors. Without this uniform pattern of peaks and valleys, burrs on front disc rotors can cause brake noise, rotor warping, and excessive wear. By removing fragments of ripped, torn, or folded metal, flexible honing for rotors eliminates surface irregularities and produces a high-quality plateau finish for a better ride.

Brake Rotors, Brake Pads, and Brake Noise
Motorcycle brakes are known to make noise during bed-in, when new disc pads begin to match the geometry of brake rotors. Some squeaking and squealing is normal at first, but worn rotors will cause even high-quality brake pads to continue to “chatter”. By smoothing the brake-rotor surface profile and reducing surface finish roughness (Ra), the Flex-Hone® for Rotors lowers the harmonic vibrations that cause these annoying, high-pitched squeaks and squeals.

Front Disc Rotor Warp or Pad Buildup?
When a user named madmortimer sought advice at Ducati Forums, the Australian owner of a 2002 748 was convinced he needed to replace his motorbike’s dual disc front brakes. After learning that new brake rotors could cost close to $1000, the motorcyclist listened to slower-than-you, a fellow Ducati owner who recommended the “rotor hone routine”.  Although madmortimer suspected “front disc rotor warp”, slower-than-you suggested “pad buildup” as the cause of “pulsing at lower speeds”.

Honing Ducati Motorcycle Brake Rotors
Instead of sending motorcycle brake rotors to a machine shop or replacing them outright, slower-than-you advised flexible honing and brake rotor cleaning. “If you have a drill press, it’s relatively easy,” he said of using the Flex-Hone® for Rotors. “You can manually rotate the table, but I motorized it to rotate at 30 rpm”. The photo above (top left) shows the Flex-Hone® for Rotors tool with its abrasive nylon globules. 

After the using Flex-Hone® for rotors to produce a non-directional plateau finish, slower-than-you cleaned the honed rotors – in a dishwasher! Although madmortimer opted for brake-and-clutch cleaner instead, the Ducati biker reported that all is well with his honed motorcycle brake rotors. “I’m still bedding them in,” he noted, “but the pulsing has ceased”.

Cylinder Deglazing– Piston Rings and Proper Lubrication

Cylinder wall deglazing is critical for the proper seating and sealing of new piston rings in car engines. Left unbroken, the “glaze” on highly-polished cylinder walls prevents piston rings from mating with the cylinder bore and providing an adequate seal. In used car engines, glazing is caused by the reciprocating movement of pistons, which polishes cylinder walls to a smooth finish. Glazed cylinder walls also cause friction and lubrication problems since engine oil won’t adhere properly to a mirror-smooth surface.       

Cylinder Wall Glaze Breakers for Engine Cylinders
RobertRO of CarDomain knew that he needed to deglaze the cylinder walls of his BMW M30B34 engine, but worried that he might “ruin everything” since he’d never honed an engine block before. Honing, a type of abrasive machining, breaks the glaze on engine cylinders and improves the geometric form of metal surfaces. Since rigid hones such produce uneven or unidirectional grooves that may prevent optimum lubrication, RobertRO choose the Flex-Hone® tool from Brush Research Manufacturing (BRM).    

Glaze Breaker Hones from Brush Research
Unlike conventional honing stones, BRM’s flexible honing tool produces a controlled surface condition and a cross-hatched pattern that’s extremely efficient at creating grooves for oil retention. BRM’s glaze breaker hone also “busts” the myth that cylinder honing is a risky business with the engine block on the car and the crankshaft installed. Abrasive honing waste can damage your car’s engine, but only if you let the dust cover the moving parts, and if you fail to clean the engine properly with warm, soapy water.

Engine Block Honing for a Plateaued Cylinder Wall Finish
Before honing the engine block in his BMW 5 series, RobertRO rotated and covered the crankshaft. Working on a “cylinder by cylinder basis”, the amateur engine mechanic then used the Flex-Hone® to produce the necessary plateaued cylinder wall finish.  Comprised of abrasive globules laminated onto the ends of flexible nylon filaments, the Flex-Hone® tool from Brush Research is self-aligning, self-centering, and self-compensating for wear. The Flex-Hone® is also easy-to-use, as RobertRO learned.

Once worried about whether or not he could hone engine cylinders, RobertRO now remembers his engine rebuild project with pride. “I was undecided,” he explains, “should I hone or not? Now, when I look back, I am positive it would have been a big mistake not doing it.” 

Engine Block Honing for Plateaued Cylinder Walls

Car engines with dual overhead camshafts (DOHC) provide more power and run at higher speeds. With four valves per cylinder, DOHC engines like the ones used in some Saturn automobiles allow more air to enter and more exhaust to leave. Higher-performance engines require proper maintenance, of course, and excessive heat from a lack of coolant can damage the engine block and cause the pistons to seize.

Such was the poor condition of a 1996 DOHC block that an engine builder from SaturnFansForums.com wanted to restore. Using a rigid honing stone, TomM96 spent “the better part of a week” with four damaged engine cylinders. Out-of-round and tapered, each cylinder was a different size. Honing them to “about the right size” wasn’t working, so TomM96 sought some advice from a local machine shop.

Plateaued Cylinders: Diamond Hones and Ball Hones
The solution, the machinist explained, was to use the right tool – “a special diamond hone” from Brush Research Manufacturing (BRM). OldNuc, another expert from SaturnFansForum.com, agreed. TomM96 needed to “bore out” each cylinder with a 100-grit flexible diamond hone, and then surface finish the cylinder walls with a 280/320 ball hone. “This is the process for creating plateaued cylinders”, OldNuc explained, adding that the BRM website provides “a detailed process description of how it is done”.

Flexible Honing: From Cylinder Boring to Wall Finishing

So TomM96 began reading our Technical Books about flexible honing. The first technical document he downloaded describes common practices in cylinder boring, honing and wall finishing. Known as the Gold Booklet, this resource also compares the surfaces of cylinder walls that have been finished with rigid hones (such as honing stones) vs. the Flex-Hone® tool from Brush Research Manufacturing.  

TomM96 also downloaded A Study of Cylinder-Wall Micro-Structure and The Necessity of a Plateaued Cylinder Wall Finish. The study of cylinder wall microstructure used a scanning electron microscope (SEM) to compare cylinder honing with the Flex-Hone® vs. rigid hones. The study of plateaued cylinder walls uses several test engines to demonstrate the “lower blow-by, increased compression, less ring and cylinder wall wear with the Flex-Hone® process.”

After visiting the BRM website and examining these technical references, TomM96 returned to SaturnFanForums.com and thanked OldNuc. “I am now a Believer in Flex/Ball hones!,” he explained.

The Flex-Hone® - Cylinder Honing for Engine Rebuilding

Engine builders have used the Flex-Hone® from Brush Research Manufacturing (BRM) to rebuild EG33 Vanagon engines for the Volkwagen bus and motorcycle engines for the Honda CB550. For any type and size of engine cylinder, BRM’s flexible honing tool is ideal for deglazing cylinder walls so that piston rings seat properly, friction is reduced, and proper lubrication is achieved. For car mechanics and automotive hobbyists, the Flex-Hone® provides the benefits of machine shop cleaning without the expensive costs. 

Cylinder Hones, Industrial Brushes, and Small-Block Engines
“Assembling a good engine,” explains Jeff Smith of Car Craft Magazine, “is less about high-dollar parts and more about taking the time” to do the job right. So when Smith found an old small-block engine in a junkyard, he spent several hundred dollars and some sweat equity on a project that was perfect for Car Craft readers. The “cheap, street, $650 small-block” that Smith built also demonstrated the value of the Flex-Hone® from Brush Research Manufacturing.

First, Smith used a numbered punch set to mark all of the rods and caps. Next, he partially disassembled the used engine and addressed several “potential problem areas”. Using a cylinder hone from BRM, he removed some “very mild” rust from the No. 3 cylinder. The engine builder also removed all of the plugs from the oil gallery and used a long tube brush to clean the area behind the cam bearings, which he did not replace to help contain costs.

Engine Hones and Cylinder Deglazing
With the small-block engine disassembled, Smith also deglazed the cylinder walls with a Flex-Hone® from Brush Research. Although engine builders sometimes call our trademarked product a “deglazing hone” or a “dingleball hone”, BRM encourages you to use the Flex-Hone® name. With its small abrasive globules, this unique glaze breaker is perfect for refinishing the surfaces of worn cylinder walls. Unlike other cylinder honing tools, the Flex-Hone also leaves an optimum cross-hatch angle for oil retention.
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NamPower Accessories for Abrasive Disc Brushes

NamPower™ accessories are specially-designed for NamPower™ abrasive disc brushes, professional-grade brushing tools that provide a total finishing solution. Precision-crafted and made of the highest-quality materials, NamPower™ accessories are reliable, cost-effective components that help provide optimal results from your NamPower™ products.
NamPower™ Brushing Tools
NamPower high-performance abrasive brushes from Brush Research Manufacturing (BRM) are designed for in-machine deburring, edge radiusing, and surface conditioning. Makers of the Diamond Flex-Hone® and pioneers of plateau finishing, BRM recommends NamPower™ brushing tools for applications such as appliance manufacturing, automotive parts, extrusion, and fine blanketing.  

Types of NamPower™ Accessories
There are two types of NamPower™ accessories for abrasive nylon disc brushes: brush holders and drive arbors. Both products are designed for use with automated finishing machinery, including CNC machining centers, transfer lines, and robotic cells. The Brush Research Manufacturing website provides an easy-to-use order form for your on-line purchases of these important accessories.

NamPower™ Brush Holders
NamPower™ brush holders are dependable, reusable tools that allow coolant to flow through from the brush center, resulting in better lubricant dispersion. Each brush holder is heat-treated and precision-ground with a physical vapor deposition (PVD) coating for improved corrosion resistance. There are two types of brush holders: standard collet and standard lock holder.

All NamPower brush holders are designed for both dot and turbine style abrasive disc brushes. Dot style industrial brushes are used in general-purpose edge deburring and surface finishing. These disc brushes are an economical choice for light deburring applications when short cycle times are important. Turbine style NamPower™ abrasive disc brushes are ideal for medium and heavy deburring applications.

NamPower™ Drive Arbors For Hex Drive Disc Brushes
NamPower drive arbors are available with a 1/4" or 3/8" diameter shaft for chucking directly into a drill motor. The 1/4" shaft is recommend for brush diameters up to 4", and the 3/8" shaft is recommended for brushes up to 5" diameter maximum.

More Information about NamPower™ Brushes
Deburring and Surface Finishing: NamPower™ Composite Hub Wheel Brushes
360° Surface Finishing: NamPower Abrasive Hex-Drive Tools

360° Surface Finishing: NamPower Abrasive Hex-Drive Tools

NamPower™ abrasive hex-drive tools from Brush Research Manufacturing (BRM) turn in both directions for 360° surface finishing. These versatile commercial brushes are easy to manipulate, and are designed for semi-automatic and fully automatic machinery such as numerical control (NC), computer numerical control (CNC), and robotic machine tools. In addition to general-purpose surface finishing applications, NamPower™ abrasive hex-drive tools are ideal for deburring and edge radiusing.

NamPower™ High-Performance Abrasive Brushes
As part of BRM’s NamPower™ family of industrial brushing tools, NamPower™ abrasive hex-drive tools are made of the highest-quality materials. Silicon Carbide (SC) abrasives at the ends of flexible nylon filaments remove torn, loose, and folded metal while conforming to part contours. Manufactured with a highest quality materials, NamPower™ hex-drive abrasive brushes provide greater rigidity and stability with less vibration. The result is a brushing tool with better performance and longer life.

Brushing Tools from Brush Research Manufacturing
Brush Research Manufacturing (BRM), makers of the Flex-Hone® tool and pioneers of plateau finishing, recommends NamPower™ abrasive hex-drive tools for in-line machining applications. When selecting these high-performance products, specify the diameter size in inches and choose 2”, 3”, 4”, or 5”.  For the 2” and 3” brushing tool, the maximum safe revolutions-per-minute (rpm) is 10,000. Both the 4” and 5” abrasive hex-drive tool have a maximum-safe-rpm of 6000.  The 2” diameter Hex Drive tool come with integrated 1/4" shaft.

Brush Tools for Deburring, Metal Finishing, and Edge Radiusing
NamPower™ abrasive hex-drive tools remove burrs, finish surfaces, and create a consistent radius. Using a low-temperature abrading process, these nylon abrasive brushing tools provide reliable results. When selecting NamPower™ hex-drive tools, specify the silicon carbide (SC) grit as 46, 60, 80, 120, or 180 for the 2” or 3” tool. For the 4” and 5” hex-drive abrasive brushes, choose from 60, 80, 120, or 180 SC grit.   

More Information about NamPower™ Brushes
NamPower™ Abrasive Disc Brushes
NamPower™ Composite Hub Wheel Brushes