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Whether it’s your first engine build, or number 100, there’s one thing that’s guaranteed to be high up on your list of least favorite things to do – installing the piston retention clips, or ‘circlips’, as they’re called in the industry. There are many different ways to accomplish the task of installing and retaining the piston pins, and every engine builder has developed their own way that works, but ask five different engine builders how to do it and you’ll likely get five (or even six or seven) different methods.
Non-tang (left) and tang-style (right) circlips.
Thankfully, the guys at Mahle Motorsports have taken the time to put together one of their tech videos detailing the correct way to install these minor, but incredibly important engine components.
Mahle’s Justin Dossett walks us through the process, from the required and recommended tools to simplify the process.
“The most efficient way varies from piston design to piston design,” he says. “While there’s no exact right way to do it, there are several wrong ways.”
The frustrating nature of circlip installation becomes apparent when he details some of the tools he’s seen used, from flat-blade screwdrivers to O-ring picks to even a disassembled binder clip.
There are also a variety of custom-made tools that have been developed in the Mahle machine shop, each of which could be duplicated in a typical machine shop or even home shop with the use of a small lathe.
The vast majority of Mahle’s piston packages use either a traditional round-wire lock, or a round-wire lock with an additional tang on one side to facilitate installation.
Non-tang (left) and tang-style (right) circlip notches. The non-tang clip can be used in either type of piston, but the tang-style needs the larger notch to lock in place. Even then, the tang needs to come in from the side of the piston crown - it's not interchangeable.
Dossett goes on to detail how each of the tools work, provide a few installation tips to simplify the process with each one, and generally attempt to make your next engine build a little bit simpler. He also covers removal techniques and, perhaps most importantly, recommends that one wear eye protection during this process, as the clips are under a fair amount of force during both the installation and removal process.
For more information on the complete line of Mahle Motorsports products, check out their website.
One of the tools in action.
