» » Surseat Flare Lapping Tool

Surseat Flare Lapping Tool

5 out of 5 based on 4 customer ratings
(4 customer reviews)


  • Surseat P-51 is for 3/16″ to 1/2″ brake and fuel lines with 37° or 45° flares.
  • Surseat P-45 is for 3/16″ & 1/4″ brake lines with a 45° flare.
  • Surseat P-37 is for 3/16 & 1/4″ brake lines with a 37° flare.

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Product Description

The Surseat flare lapping tool allows you to lap-in flared tubing to eliminate leaks in fuel and brake line joints. This innovative new tool removes irregularities in the flare and hones it to a perfect angle to enable the tube to seat with the fitting. The Surseat will not only perfect your newly-flared stainless steel, aluminum or copper lines, it can also repair the seal with the fitting of an existing brake or fuel line. It is based on the tried and true practice of lapping engine valves. A diamond dust coated lapping head with a precision 37° or 45° angle literally polishes the flare smooth to perfection. The Surseat is a valuable asset for car builders, automotive repair facilities, and hobbyists.

Surseat Flare Lapping Tool Details

Surseat P-51
  • The Surseat P-51 comes with collets for 3/16" to 1/2" tubing.
  • Includes threaded collets for 3/16" and 1/4" brake lines.
  • Interchangeable 37° and 45° lapping heads are installed onto the shaft with set screws.
  • The set screws and wrench are included in the kit.
  • Includes a custom case for safe storage.
Surseat P-45
  • The Surseat P-45 is used for 3/16" & 1/4"  steel brake lines with a 45° double flare.
  • Includes threaded collets to screw the fitting into.
  • The collet and tube are secured into the P-45 with a lock spring.
Surseat P-37
  • The Surseat P-37 is used for 3/16" & 1/4" stainless steel brake lines with a 37° flare.
  • Includes collets to clamp the tube.
  • The collet and tube are secured into the P-37 with a lock spring.


Using the Surseat P-51

1. Install the 37° or 45° lapping head to the shaft of the Surseat.

2. Clamp the tube with the appropriate collet size.

3. Install the collet and tube into the Surseat yoke.

4. Spray some light lubricant like WD-40 to the lapping head before use.

5. Rotate the lapping head back and forth in the flare until a clean seat is formed.



Using the Surseat P-45 & P-37

1. For the P-45, screw the fitting into the collet.

2. For the P-37, clamp the collet around the tube.

3. Install the collet by sliding the locking spring into the closed position.

4. Spray some light lubricant to the lapping head before use.

5. Rotate lapping head back and forth until a clean seat is formed.

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4 reviews for Surseat Flare Lapping Tool

  1. 5 out of 5


    This tool is extremely clever design and very simple to us. It takes the imperfections that inevitably come from a flaring tool and finishes them, ensuring a proper seal. In my case I had to re-bend many lines on my car for adding Disc brakes and a Wilwood proportioning valve this meant I had many flares that potentially could leak this Lapping tool just took away all my concerns about slow leaks.
    Good stuff guys keep up the good work.
    What is next in the development timeline?

    • :

      Thanks Rich! Next up is a tool that will refinish and repair the conical seal on male fittings.

  2. 5 out of 5


    Another winner and time saver from Koul Tools!

    Here at Nerd Rods we have to make brake and fuel lines for out custom chassis. Its time consuming work especially when you need to pressure test each line to make sure that end didn’t split or have some other imperfection from the press on the ferrule face. With this little guy we slap it on make a few quick passes and done! Its been 6 months since we got this tool and 6 months since we’ve had to re-flare a line. Just the materiel we’ve saved has been amazing much less the time in redoing or pressure testing each and every line.

    Thanks again Koul Tools!!! Keep up the killer work. We can’t wait for the your next too we can’t live without and didn’t even know we needed!

  3. 5 out of 5


    I have been double flaring brake lines for street rods for 30 years with great success. My latest project, a 32 Ford Roadster had 6 fittings that I could not get to seal. I kept trying to tighten the fittings, hoping the joint would seal. I don’t know if it’s the quality of brake lines or just me, but I couldn’t get the brake system to not weep. I remember seeing this tool at the Street Rods Nationals, and decided to order one, and see if it would solve my problems. I disassembled the entire brake system and lapped every flare with the Koul Tool P45. I reassembled the brake system and didn’t have a single issue. I will lap every fitting I make from now on just to make sure I get a proper seal on my brake fittings. The tool is easy to use and certainly performs.

  4. 5 out of 5


    I’ve used several of your tools before, and have found all of them to be real time savers!
    I had a master cylinder to brake line leak with my ’55 Chevy that your line lapper resolved. It seems that no matter how carefully I flare the tube, sometimes I still have a leak. It seems that the cause of this is roughness of the flare. Your lapping tool removes this making for a positive, leak free seal.

    Thanks again for saving me time, and trouble!

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Additional Information

Select Kit

Surseat P-51, Surseat P-45, Surseat P-37