Piston Slap: Re-Focusing Your Priorities

Sajeev Mehta
by Sajeev Mehta
piston slap re focusing your priorities

Heathroi writes:

Remember the Focus with the wandering rear that I thought (ha!) might need lower profile tires?

Well as an update, it didn’t need tires at all. It needed new bushings all though the rear suspension. Which turned into a mammoth job of taking the rear suspension apart, cutting rusted bolts, frequent trips to the ford dealer for new control arms and lower A arms but back together in working order, like its new again.

Sajeev answers:

Good. I never understood how sidewall flex was a problem on a Focus. I mean, you’re not exactly driving Dolemites’ Cadillac in an SCCA event. It’s good to hear you found the real problem: high-speed wander is because of play in steering and/or suspension components, not from the relatively short sidewalls on a modern car.

Bonus! A Piston Slap Nugget of Wisdom:

The mixing of Pistonhead and Gearhead often makes for poor diagnoses. Many (including myself) are guilty of engineering the need to buy unnecessary parts. For example, I suspected an ignition misfire and used that reason to buy MSD coils. In fairness they were cheaper than OEM replacements, but I was still way off the mark: my funny vibration was a collapsed engine mount. Fail!

We must take stock of our mistakes and learn from their lessons. For starters, always seek out the most detailed explanation of the problem. Then follow time tested (or manufacturer-specific) diagnostics to isolate the problem.

If more repair shops followed this advice, we’d have many more satisfied customers within every brand. Not just the brands that complain about a “perception gap” while their operations circle the drain, either.

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4 of 12 comments
  • Rpn453 Rpn453 on May 01, 2009

    Check for play in the front and back suspension and steering systems whenever you rotate/change tires and you should be able to catch problems like this.

  • Shaker Shaker on May 02, 2009

    Sorry for the O.T. post, but what kind of car is the white one in the driveway in the photo?

  • Martin Schwoerer Martin Schwoerer on May 03, 2009

    shaker, I think it's a UK-built Ford Cortina MKII. From around 1968.

  • Shaker Shaker on May 04, 2009