BRM's Flexible Honing, Surface Finishing, and Deburring Blog Blog

BRM's Flexible Honing, Surface Finishing, and Deburring Blog

BRM's Flexible Honing, Surface Finishing, and Deburring Blog is the place for conversation and discussion about how to solve difficult finishing problems. For over 50 years, Brush Research Manufacturing (BRM) has helped customers use brushing technology to clean, rebuild, and resurface components ranging from engine cylinders to brake rotors to flywheels to firearms. BRM's Blog on CR4 provides real-world examples of how flex hones and wire brushes work. It also evaluates related technologies and invites questions from the community.

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Cylinder Honing for Honda D-Series Engines

Posted June 18, 2013 12:36 PM by Brush Research

The Honda D-series was a family of four-cylinder, in-line engines with displacement ranges between 1.2 and 1.7 liters. From 1984 to 2005, compact cars such as the Honda Civic featured fuel-efficient D-series blocks in SOHC and DOHC versions. Generally reliable but hardly powerful, these lightweight aluminum engines can be modified with high-compression pistons to increase power and improve performance.

Powerplants such as the 1.5-liter D-15 can also be torn down and rebuilt to extend the life of older automobiles such as the 1991 Honda Civic. Such was the case with The_Acid_Beaver, a hobbyist and Honda enthusiast who shared his engine restoration story with, an on-line community for automotive technicians and do-it-yourself (DIY) engine mechanics.

Rebuilding a Honda D-15 Engine

When the engine in his parents' Civic "died" from unknown causes, The_Acid_Beaver bought a used D-15 and rebuilt it. After hot tanking the head and mounting the block on an engine stand in his garage, the mechanic inspected the cylinders and pistons. The bores "aren't in the best shape," he reported, "as two of the cylinders were left open to the elements because the spark plugs were not left installed".

Pulling the pistons revealed additional issues with "rust and muck" in the bores. Wisely, the amateur engine builder then asked "many knowledgeable people" about whether to recondition the cylinders or scrap his junkyard find altogether. "Each and every one said that good honing will take care of the rust and anything else left in the bore," he explained.

Choosing and Using Engine Hones

For superior cylinder honing, the Honda mechanic chose the Flex-Hone tool from Brush Research Manufacturing (BRM). Built with a stiff metal stem and flexible nylon filaments, the BRM engine hone produces the optimum surface finish in any type or size cylinder. Self-centering and self-aligning to the bore, the Flex-Hone features abrasive globules that also make the tool self-compensating for wear.

Versatile and easy-to-handle, BRM's cylinder honing tool can be used with handheld electric drills like the 18-volt Milwaukee Power-Plus that The_Acid_Beaver borrowed from his father. Before honing the D-15 engine's four cylinders, however, the mechanic applied a generous amount of lubricant to the BRM brush tool. "It floats all the gunk away from the cylinder walls," he explained.

Honing the Cylinder Walls

With the ball hone spinning, the mechanic inserted the flexible honing tool into the first cylinder. As BRM's Flex-Hone Resource Guide explains, 700 RPM are recommended for the 3-inch brush tool that The_Acid_Beaver used. Through a low-temperature abrading process, flexible honing improves surface finish and produces an ideal cross-hatch pattern with oil-retaining grooves for optimum lubrication.

After honing each bore, The_Acid_Beaver washed the engine block with hot, soapy water and ensured that the cylinder walls were clean. Satisfied that his cleanup efforts passed "the white glove test," the mechanic lubricated the bores and completed the project. Although this amateur engine builder once "had some doubts" about cylinder honing, using the Flex-Hone tool made him a believer out of him.

Author's Note: This CR4 blog entry originally appeared in the BRM Flex-Hone Blog.


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