Targa Miata
August 18, 2011 - Not all the work on the Targa car is big cool projects like skid plates.
It's also getting some maintenance. For one, I'm changing out the front hubs to make sure they're at full strength. The current hubs had a total of about 10,000 miles on them but a large proportion of that was with hot race rubber bolted on. And, just like the original build, I had to grind off 75% of the teeth on the ABS trigger wheel in order to drop the number of pulses per mile to a reasonable number. The ABS sensor is used to trigger my Coralba rally computer, and it can only deal with 16,000 pulses per mile or so. With the modified ABS wheels, I get about 9,900.
And then I found a problem. The replacement hubs have an ABS ring that's about 2 mm smaller in diameter than the stock part. This meant the air gap to the non-adjustable pickup was too big, and it wasn't triggering the rally computer. That's not good. Luckily, the rings are just pressed on so I pulled off the old stock one and put it on the new hub. If only I'd noticed that before I spent all that time grinding!
entry 914 - tags: hubs, wiring, computer
May 1, 2013 - So, what caused the accident?
The hub came apart, leaving only the brake rotor to hold the wheel on. Of course, that ripped apart almost instantly and the car snapped into a spin.
It turns out that this was a known problem with the V8Roadsters hubs, which led to a redesign several years ago. The new one is 1/2" thick instead of the 3/8" found in the older design. In the fallout from my broken axle last month and some problems found with new parts, I ended up borrowing the hubs from FM's shop car, Elvis. For some reason, Elvis never got the upgraded parts. I'm going to try to figure out how that fell through the cracks. We're also going to contact all of Flyin' Miata's V8 customers and ask them to check their rear hub thickness to make sure there aren't any more out there.
The good news is that we now have proof that the rear caliper brackets on the new FM brake setup are stronger than the rotors!
entry 1087 - tags: failure, hubs