Overview
Designed as a drop-in aftermarket replacement, this piston driver assembly restores reliable nail-driving power to worn or malfunctioning nailers. Over time, the OEM driver can develop wear marks and lose its seal, leading to shallow drives and double fires. This replacement part brings the tool back to original operating condition.
Key specifications
- Aftermarket piston driver assembly
- Direct OEM-equivalent replacement
- Includes 2 piece(s) per package
- Includes o-ring(s) for proper cylinder seal
- Precision-machined for consistent nail depth
Compatibility
This piston driver is designed to fit Hitachi nailers as specified in the compatibility listing above. Always cross-reference the full model and type number stamped on your tool’s nameplate before ordering.
Installation notes
Disconnect the nailer from the air compressor or remove the battery before beginning disassembly. Remove the cap, pull out the old piston driver, and clean the cylinder bore before inserting the new assembly. Lubricate the o-rings with pneumatic tool oil for a proper seal and smooth cycling.
Common questions
Q: Will this 885-918 aftermarket piston driver fit my Hitachi NR90AES1 framing nailer, and is it the same as part 885-519 or 887-491?
Yes, this piston driver is made to fit Hitachi NR90AE, NR90AES1, NR90AES1M, and NR90AE(S) strip framing nailers. It replaces OEM part numbers 885-918, 885-519, and 887-491, so if your tool uses one of those numbers, this is the correct match.
Q: Does this 2-piece 885-918 piston driver come ready to install, or do I need to reuse parts from my old driver?
This is a 2-piece aftermarket piston driver, so before installation you should compare it closely to your original assembly and confirm whether your nailer requires any retained seals, rings, or related hardware to be transferred over. It’s a good idea to inspect the cylinder and bumper at the same time, because a worn bumper or damaged cylinder can cause the new driver to fail early.
Q: My Hitachi NR90AE is jamming and not driving nails flush—could a worn 885-918 piston driver be the cause?
Yes, a bent, chipped, or mushroomed driver tip can cause feeding problems, jams, and shallow drives in the NR90AE series. While replacing the driver often fixes that issue, you should also check air pressure, nail collation, and the condition of the piston O-ring and lower bumper to make sure there isn’t another cause.
