YKWYKW Hydro Boost Seal Kit 1.6in Bore Rebuild for Chevy & Ford — Complete Seals & Washers

This repair kit contains the seals and small metal components needed to rebuild a 1.6" bore Hydro-Boost unit (part number 2771004 / 2771004x compatibility) commonly found on older Chevy and Ford models. It’s intended for technicians or experienced DIYers who want to refresh the internal seals and return a hydraulic booster to service without replacing the entire assembly. The kit fits many Bendix-style units and covers several GM and Ford applications including F-Series trucks, Silverado, Express, Bronco, and various SUVs.

Which vehicles and booster types will this kit work with?

This seal set is made for hydroboost units with a 1.6 inch bore and matches the GM 2771004x replacement specification. It fits many Bendix-style hydroboost assemblies used across Chevrolet and Ford product lines produced prior to certain year changes.

• Compatible with Chevy models: Silverado 1500/2500/3500, Express 1500, Astro, Blazer, Tahoe, Traverse, Impala, and G30/S10 variants.
• Compatible with Ford models: F-150, F-250, F-350, F-450, F-550 Super Duty, Bronco, Expedition, Excursion, Fusion, Mustang.
• Designed specifically for 1.6" bore Hydro-Boost units (not for staked rod applications).

How does the kit restore a leaking hydro boost unit?

The kit supplies new rubber seals and the necessary metal washer components so you can disassemble the booster, remove aged seals, and install fresh parts to stop fluid bypass and restore proper hydraulic pressure. Replacing worn seals reduces leaks and restores pedal feel without the cost of a full unit replacement.

• Includes all internal rubber seals required for a full 1.6" bore rebuild.
• Contains the metal star washer (K-777464) for early hydroboosters where required.
• Eliminates the need to source individual O-rings or backup rings during a rebuild.

What should I know about installation and compatibility limits?

Installation is straightforward for someone familiar with hydraulic boosters and brake system safety protocols, but it requires proper disassembly, cleanliness, and careful reassembly. The kit does not support units with staked rods and hydroboosters with a 1.8" bore will require different star washer reuse or part variations.

• Requires basic mechanical tools and knowledge of brake/hydroboost systems.
• Not compatible with staked-rod style boosters or 1.8" bore units without modification.
• Cleaning components and inspecting the bore for scoring is recommended before installing new seals.

What parts come in the package and what condition are they?

The package ships as a single repair kit containing new rubber seals and the small metal hardware pieces necessary to rebuild the booster internals. All items are new and intended to replace the worn internal components that commonly cause leakage and loss of hydraulic assist.

• One complete seal repair kit (rubber seals and metal components) per package.
• Includes replacement for the Metal Star Washer where applicable and other small parts for early units.
• Supplied parts meet the specifications for 2771004 / 2771004x rebuilds on compatible units.

Who is this for: This YKWYKW Hydro Boost Seal Leak Repair Kit is for professional mechanics and knowledgeable DIYers who want a cost-effective way to repair leaking hydroboost assemblies on older Chevy and Ford trucks and SUVs equipped with a 1.6" bore unit. If you’re restoring pedal assist, trying to avoid full-unit replacement, and comfortable performing hydraulic component service, this kit provides the parts you need to complete a thorough internal rebuild.