1997 Mazda MX-5 Miata: Lash
October 13, 2011
Last night's horrid commute traffic highlighted that Project Miata exhibits not-insignificant driveline lash. When you're modulating the throttle lightly in first or second gear, it's possible to set up one of those hilarious undamped fore/aft lurch cycles.
Low-speed part-throttle driveability slipped a hair when the supercharger went in, underscoring the lash issue which is definitely more pronounced now than it was when we bought the car. Engine mounts are likely accountable for the lash. The factory mounts are small blocks of rubber bonded on either face to a metal backing. Over time the rubber dries out, gets crusty and breaks away from the backing.
The engine mounts are not the best design, really, and should be considered a regular service item if you drive your Miata with any kind of spirit. Not only does Project Miata get worked hard; it's also making more torque than stock, exposing the tired old mounts to more extreme loading. Project Miata is pushing 140k miles and is very likely on the original mounts.
Mazdaspeed Motorsports sells engine mounts made with rubber of somewhat stiffer durometer than the originals. Something to add to this car's to-do list.
--Jason Kavanagh, Engineering Editor