adapter to put "standard" gear shift knob on 2007 Mazda3
April 19, 2023 7:02 PM Subscribe
I bought this "universal" gear shift knob to use in my 2007 Mazda3. It's not universal. My calipers say the Mazda's outer screw thread diameter =~ 9.58 mm. I can't measure the new knob. Will this part or this part work with the new knob? (I do not want to buy a set of six adapters in hopes one fits.)
Autozone.com has a feature where if you set up a free account, you can specify your vehicle and then search only for compatible parts. It's a good way to avoid situations like this.
posted by DirtyOldTown at 6:52 AM on April 20, 2023
posted by DirtyOldTown at 6:52 AM on April 20, 2023
Metric thread sizes are determined by the nominal diameter of the bolt shaft in mm, so a M10 bolt is 10mm outer diameter. Your measurement of 9.58mm is non-standard for metric, but is very close to a 3/8" (9.525mm) bolt. You'd think that most fasteners on a Miata would be metric, but Mazda of that era is partly-Ford, so who knows.
I'd go to the hardware store and grab two different 3/8" nuts, they should be marked "3/8-16" and "3/8-24" for 16 and 24 threads per inch, "coarse" and "fine", respectively. While you're there, also grab a couple metric nuts, in "10mm-1.5" and "10mm-1.25" (threads spaced 1.5mm and 1.25mm apart, "coarse" and "fine", respectively). If no designation is given on a metric bolt or nut, coarse is generally assumed. Baggie these nuts separately if you need to, or write on them with a sharpie, so you know which is which. While you're at the hardware store, test-fit bolts to your shifter knob, and you'll have figured out what kind of adapter you'll need.
Gently try each nut on your shifter shaft. The nut should spin on freely without any resistance. If it goes on easily for a turn or two but then resists, stop. It's the wrong size, and you could damage the threads on your shaft by forcing it on.
posted by xedrik at 8:25 AM on April 20, 2023 [1 favorite]
I'd go to the hardware store and grab two different 3/8" nuts, they should be marked "3/8-16" and "3/8-24" for 16 and 24 threads per inch, "coarse" and "fine", respectively. While you're there, also grab a couple metric nuts, in "10mm-1.5" and "10mm-1.25" (threads spaced 1.5mm and 1.25mm apart, "coarse" and "fine", respectively). If no designation is given on a metric bolt or nut, coarse is generally assumed. Baggie these nuts separately if you need to, or write on them with a sharpie, so you know which is which. While you're at the hardware store, test-fit bolts to your shifter knob, and you'll have figured out what kind of adapter you'll need.
Gently try each nut on your shifter shaft. The nut should spin on freely without any resistance. If it goes on easily for a turn or two but then resists, stop. It's the wrong size, and you could damage the threads on your shaft by forcing it on.
posted by xedrik at 8:25 AM on April 20, 2023 [1 favorite]
This thread is closed to new comments.
Ditto with nuts and your gearstick.
posted by gible at 7:53 PM on April 19, 2023