AP Exhaust Pipe Stretcher Kit 1-5/8"–4-1/4" Metallic — 7 Collets, 28mm Impact Drive

The AP Astro Pneumatic 78835 Exhaust Pipe Stretcher Kit is a heavy-duty, impact-driven expander set that stretches and seals exhaust tubing from 1-5/8" up to 4-1/4" using replaceable collets and a 28mm drive.

Built for professional mechanics and serious DIYers, this metallic exhaust pipe stretcher kit pairs rugged steel expanders with a series of precision collets to reshape and seal pipe ends for repair or installation. The design focuses on durability and straightforward operation: a 28mm bolt head accepts high-torque impact tools, while each collet is two inches long to provide stable, even expansion. Follow basic preparation like greasing threads and using a recommended high-torque impact wrench for consistent results.

How does the kit expand different exhaust pipe diameters?

The kit includes a set of stepped steel collets that fit inside the pipe and a hardened expander that is driven by a 28mm bolt head. Turning or impacting the bolt forces the collet outward, reshaping the pipe evenly along the contact length.

• Expands pipe sizes from 1-5/8" (1.625") to 4-1/4" (4.25")
• Seven precision collets covering incremental diameter ranges
• Collets are 2" long for steady, consistent expansion
• 28mm drive accepts impact wrenches for reliable force application

What tools and prep are recommended for best performance?

Apply the included grease to threads before operating to reduce wear and ensure smooth movement. An impact wrench rated around 800 ft-lbs or higher is recommended to complete most jobs quickly and evenly.

• Grease threads before use to protect threads and improve operation
• Use an impact wrench (≈800 ft-lbs or greater) for consistent expansion
• Tighten in short pulses and check fit to avoid over-expanding thin metal
• Wear eye protection and work gloves while operating impact tools

What comes in the 78835 kit and how are the collets arranged?

The AP 78835 kit ships with one steel expander and seven collets that cover overlapping diameter ranges so you can progressively shape pipe ends. Each collet is sized to expand a small band of diameters, letting you match the exact fit you need for seals or slip-fit connections.

• One steel expander body compatible with the 28mm drive
• Collets included: 1-5/8"–2", 2"–2-1/2", 2-3/8"–2-3/4", 2-3/4"–3-1/8", 3-1/8"–3-1/2", 3-1/2"–3-7/8", 3-7/8"–4-1/4"
• Each collet measures 2" in length for stable contact area
• Compact kit simplifies storage and job-site use

How do I avoid damaging pipes while using the expander?

Work incrementally, selecting a collet that closely matches the target diameter and expanding in controlled steps. Inspect the metal thickness before starting; thin-gauge pipes may require more careful, lighter impacts to prevent splitting.

• Start with the nearest smaller collet and work up if needed
• Use short impact bursts to control expansion rate
• Stop and check fit frequently to prevent over-stretching
• If pipe is thin, consider clamping or supporting the area during work

Who is this for: The AP Astro Pneumatic 78835 is aimed at professional exhaust technicians, auto repair shops, and experienced home mechanics who need a durable, repeatable tool for fitting and sealing exhaust tubing. It’s especially useful when replacing sections, creating slip-on joints, or restoring slightly misshapen pipe ends; owners should be comfortable using impact tools and following standard safety practices.