The V8 Miata project

Let's hear it for rally cars.

Fri, 03 May 2013 17:46:18 -0400

Nearly five years ago, I added some small ramps to the bottom of the control arms to protect the lower AFCO adjuster. Last weekend, they did their job. In fact, all of the skid protection worked as designed. The plates just behind the front wheels took a beating, as did the engine skid plate. The differential protection really shows a lot of scarring, but the differential itself is untouched. Almost nothing touched the ground that wasn't designed to touch the ground. The car was built to fail well, and it did.

So, what caused the accident?

Wed, 01 May 2013 18:49:53 -0400

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.
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Crash video.

Wed, 01 May 2013 18:43:36 -0400

How quickly did the failure happen? Pretty much instantly. Why did it fail? See the next post. YouTube video

This is the least amount of damage you can do if you lose a wheel in Turn 9 at Laguna Seca.

Mon, 29 Apr 2013 10:46:47 -0400

The bumper is just out of place. The exhaust got pulled out of shape and took some of the brackets on the body with it so the trunk floor is probably messed up. The skid plate under the diff is deformed and I want to check the subframe carefully. The front wheel is dented and the rear is all scarred up. But it's almost all bolt-on parts. There's one small dent in front of the missing wheel but otherwise is looks like the tub is untouched. Amazing. I got very, very lucky.
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So, what caused the accident?

Mon, 29 Apr 2013 10:45:40 -0400

Well, we'll have to do some closer investigation when we get back to the shop. We'll be checking the history and specification of the parts. There are some theories, but until they can be checked out they're just speculation.

This is not something you want to see out the windshield.

Mon, 29 Apr 2013 10:35:29 -0400

That's my rear brake rotor. I came down the Corkscrew, hit 4th gear and turned into the fast turn 9. Just before I reached the apex, I heard a bang and the car snapped into a spin at somewhere around 80 mph. My first clue as to what had happened was seeing my right rear wheel rolling along the pavement as we rotated the first time, then we went into the dirt after the second spin. On the dirt, the car lifted a little bit like it was trying to roll, but stayed happy side up as we scrubbed off speed.
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Time for the big Laguna Seca event.

Mon, 29 Apr 2013 10:16:58 -0400

It was not easy getting here. It turns out that my new axles did not have proper heat treatment, so they failed almost immediately. I decided to upgrade to the stronger G2 setup partly because that's what was on the shelf at Flyin' Miata, and I ran into a series of problems with the new parts. Finally, after working most of the day before I left, I ended up with the used parts from Elvis on the car - rear uprights (including hubs), rear upper control arm and axles. Finally, after all that work, the car was ready for the trailer. Then the long tow began.
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Sun, 28 Apr 2013 04:49:55 -0400

Short test session.

Mon, 22 Apr 2013 14:15:51 -0400

The new tall wing mounts were wobblier than I liked. Pulling back hard on the wing also showed a bit of bowing in the lower section. I looked at a few ways to fix it and decided to try guy wires. Excellent result, it's stronger both laterally and longitudinally. The lower guy wire points are right where the greatest deformation was when I yanked on the wing, and the whole assembly is solid. The fact that the wing attaches to the uprights with a big plate helps as well.
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I've been working on the car a fair bit.

Fri, 12 Apr 2013 22:43:04 -0400

First, I refreshed the shocks by changing the fluid and putting in new seals. They didn't need it, but it's good preventative maintenance. I also fine-tuned the corner weights, did a nut and bolt under the car, changed the oil (7 quarts!) and reset the alignment after the disassembly for the axle change. There's also an obvious change - a new mount for the wing. It's about 5" taller. This location should give more downforce without an increase in drag (or less drag for a given amount of downforce). We'll see how it works out on the local track next weekend. No high speed work, but 75 mph in a sweeper does tell some tales.
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I found the cause of the axle failure.

Fri, 12 Apr 2013 22:36:31 -0400

The spring clip on the end of the shaft broke, allowing the shaft to pull most of the way out of the CV. The small number of splines remaining just weren't up to the task and ripped apart.
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Now that's a fun bunch of cars to see at a track day.

Mon, 01 Apr 2013 16:09:57 -0400

That Formula B car had a tendency to simply appear out of nowhere and then just vanish into the distance.
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Canards!

Mon, 01 Apr 2013 15:22:24 -0400

After fixing the alignment problem, I decided to stick my canards on and see how much difference they made. The answer is: lots. All of a sudden the car had lots of turn-in grip, diving into the corner instead of feeling a bit soft. VERY nice. The front/rear grip was better balanced - in slow corners, the car still pushed a bit but above about 50 mph it was great.
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Track day test!

Mon, 01 Apr 2013 14:53:55 -0400

I headed over the mountains to High Plains Raceway for an open lapping day. This was a chance to check out the aero at high speed and sharpen up my high-speed skills in preparation for a couple of days at Mazda Raceway Laguna Seca in a few weeks.
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That's a much better way to cover up the wheels.

Wed, 27 Mar 2013 22:13:55 -0400

It seems a bit goofy, but it works. Some computational fluid dynamics run by "plucas", a member of the Miataturbo forum, shows that this setup increases front end grip and cuts down on overall drag fairly impressively. The expected hp to maintain 100 mph drops from 44 to 34 hp, and the car goes from generating lift to generating downforce. Hard to argue with Science, and definitely worth trying out.
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One of the dirty areas of the car, aerodynamically speaking, is the front tires.

Wed, 27 Mar 2013 22:09:17 -0400

That exposed rubber, spinning at high speed, generates a lot of drag. So I thought I'd be clever and build some canards that would cover them up in front view.
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There's a track day coming up this weekend (weather permitting) so I've been doing a bit of work on the car.

Wed, 27 Mar 2013 22:07:05 -0400

It was pretty obvious at the last test that the wing was increasing grip at the rear more than my little splitter was doing at the front. So I picked up some more aluminum and extended it by about 1.5". Easy enough. I also swapped the rigid turnbuckles for cables, allowing the splitter to move up a bit if it scuffs the ground when I'm loading into the trailer.

Power!

Sun, 17 Mar 2013 22:59:14 -0400

When I first built the car, I was watching every ounce of weight. Manual windows saved me 1 lb per door and were simpler, so I decided to go with them. Now, I've got a bit more power - and with the extra door bar in the roll cage, we can't wind the windows up and down with the doors closed. This can be awkward when you're driving. During the Targa, Janel and I got used to popping the door open on the highway to adjust them, but there's been at least one episode on the track where I had to pit simply to wind down the window.
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Time for a bit of shock maintenance.

Sat, 16 Feb 2013 14:08:28 -0500

One of the cool things about AFCOs is that you can work on them at home. In this case, I'm changing out the shock oil. The big syringe is full of the old stuff - it used to be clear! This is the same oil that has seen a couple of seasons of track days plus the 2011 Targa Newfoundland, so it's been worked over pretty hard. This should bring the shock up to full health. Not bad for an hour's work. I'll tackle the other three shortly, maybe even make a how-to video.

A couple of unlikely cousins.

Thu, 17 Jan 2013 10:01:36 -0500

These two cars have a lot more in common than you think. They're both running similar engines (5.3 for the race car, 5.7 for the MG), T56 6-speed transmissions, AFCO suspension, FM radiators and fans, FM fuel plumbing, etc. The MG actually runs Miata brakes, steering and a number of other bits as well. Heck, they even weigh the same. Most importantly, they both perform well beyond their original manufacturer's intentions and put a big stupid grin on the driver's face.