| MIATA BUILD |
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 | |  | September 8, 2012 - Time to test the wing!
Other than add the wing and splitter, I hadn't touched any other settings on the car since the Summer Camp a month ago. This was to give me a reasonable before/after picture of the effects of the wing. The short version? My first timed session popped out a 1:01.344. My previous best time in the car was 1:03.388. Yes, that's almost exactly two seconds faster. Two seconds! It may also be the lap record for cars with doors, although I need to do some digging around to be sure. It's certainly the fastest Miata time. Now, conditions were pretty much perfect and everyone was going quickly, but that's still a pretty spectacular difference. Not long ago, that would have been the overall record for cars.
I could feel the difference in the balance of the car as well. Where I'd previously had a bit of oversteer down the fast sweeper, I now had a bit of understeer. According to the rally computer, my peak speed was also something like 6-7 kmh faster than I'd seen before. That peak speed occurs as you're balanced on the limit of grip on the fast sweeper, and is limited (in this car) by the amount of lateral acceleration you can produce. So it's a quick and easy way to get a feel for actual grip. On that fast lap, it translates to sustained cornering of 1.1g or so, with a peak of 1.3.
I then proceeded to spend some time experimenting with wing angles. The next two sessions I cranked the wing down to a fairly steep angle. My fastest time dropped to 1:01.5, but the peak speed went up by 1 kmh. The understeer on the straight got stronger, and it actually became a bit more difficult to drive the car as the balance was changing so much based on speed. I continued to play with various angles, but it became apparent that the rising temperatures were affecting everyone's grip level and times gradually went up as the day went on. Still, it wasn't until the very last (hot!) session of the day that my times finally slipped above my previous best. So that's a big, big thumbs up to the wing, even on our fairly slow track - the average speed on my fastest lap was just a hair over 50 mph. It's also obvious that I need to do more to balance the front out. A lower ride height would help there, but I was leaving everything other than wing angle alone in my experiments today. I'm going to put on the stiff track springs and drop the car down a bit to get ready for an upcoming trip to Willow Springs.
As you can see from the picture, I added some labels to the holes so I can easily keep notes. For those who are interested, I tried C4, A1, B2, C1 and A3 today. It wasn't all perfect, though. It feels as if I lost a coil. I'm still letting the car cool down, but based on a quick test of header tube temperatures, it's the same #1 that has failed twice before.
Brandon also had a good day in his bike-engined Locost. After I was faster than him on the first session, he put his fast pants on and turned a 1:00.355. I believe that's the overall lap record for cars on this track, and so close to the elusive one minute mark!
entry 1065 - tags: aero, testing, personal best | | |  | November 30, 2012 - There's been a bit of interest in copies of the wing mounts for the COT wing.
Brandon made a 3D model of them, and Mark at Paco Motorsports will see what it might cost. Drop me a line at keith@flyinmiata.com if you're interested.
entry 1066 - tags: aero, wing | | |  | January 9, 2013 - The Targa Miata is confined to the garage by snow at the moment, but I'm using the time to work on a number of aspects.
First, I'm installing the track suspension and doing some maintenance on the AFCOs. I'm also changing out the hood pins for Aerocatches so it's easier to open and close, and a pair of hydraulic rams have taken the place of the hood prop to improve access underhood.
I've also got some electrical parts to install. The big one? Two big burly relays to replace the factory one that cost us the lead at Targa last year. They'll be installed in parallel so I have some redundancy in case one goes out, and I might add some warning lights so I know if one has failed. I'm seriously considering the wiring on the car, it's showing the signs of the car's gradual evolution and it might be time for a complete rethink. There are also a few areas where I've been relying on Miata reliability to keep me out of trouble, perhaps more redundancy would be smarter. Twin fuel pumps and filters, maybe? Given the Newfoundland gas, that's not a terrible idea.
I've also got some power windows to install. Way back in the original build, I decided the manual windows were a good way to save one pound per door. But with the current cage configuration, we can't actually adjust them with the doors closed. Janel and I both became fairly blasé about popping the door open on the highway to wind the windows up and down, but it sure would be a lot easier to simply hit a switch. It would definitely attract less attention.
entry 1067 - tags: wiring, suspension, plans | | |  | January 14, 2013 - I spent part of the weekend setting up the car.
Cornerweighting, ride height and alignment. The ride height has changed considerably since the last time it was on the alignment rack, but the new hub stands from FM made this pretty easy to put right. It was pretty revealing how off the alignment was!
I didn't really want to give the stands back, maybe I can find a way to justify a set of my own someday. Springs are now 750 lb front and 450 lb rear, with a pretty low ride height. It should be quicker around our track now - can I duplicate my numbers from last time? Too bad I have to wait a few more months to find out.
entry 1068 - tags: setup, suspension | | |  | January 15, 2013 - I finally replaced the hood pins with Aerocatches.
Much nicer - it's easier to open and close the hood, more aerodynamic and easier to tell if they've been left open. This involved drilling and cutting my poor hood even more - it's been pretty heavily worked over by this point! I've also learned that white Aerocatches get dirty really quickly.
entry 1069 - tags: hood, aero | | |  | January 17, 2013 - A couple of unlikely cousins.
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.
entry 1070 - tags: other cars | | |  | February 16, 2013 - Time for a bit of shock maintenance.
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.
entry 1071 - tags: suspension | | |  | March 17, 2013 - Power!
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.
No longer! Now I've got power windows. I've simplified the wiring quite dramatically by putting the switch in the door, so there's only one wire going in. It's going to feel so luxurious to simply push a button and have the window go up. Aaaah.
entry 1072 | | |  | March 27, 2013 - There's a track day coming up this weekend (weather permitting) so I've been doing a bit of work on the car.
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.
entry 1073 - tags: aero | | |  | March 27, 2013 - One of the dirty areas of the car, aerodynamically speaking, is the front tires.
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.
Well, that didn't work out. Somehow I came up with a pretty cool design, but crouching down and looking at the car head-on showed that they only covered about half the tire. Oops. The canards evolved from the original design as I made them.
entry 1074 - tags: aero | | |  | March 27, 2013 - That's a much better way to cover up the wheels.
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.
I'm going to bring the canards along and give them a try to see if I can feel a difference.
entry 1075 - tags: aero | | |  | April 1, 2013 - Track day test!
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.
It was a nice day with a wide variety of cars in attendance. I was sharing the track with everything from Formula B cars (one step down from Formula Atlantic!) to a McLaren MP4-12c that was still on temporary tags. Cool.
During the first session, I was mostly feeling my way around. The car was understeering, particularly on long lefts. I pulled into the pits and checked tire pressures - oops. Heading back out with about an extra 4 psi, the car felt better but was still pushing more than I liked. I'm on a new spring set that wasn't quite balanced right. I decided to keep the sway bars where they were and see if I could sort it out with other aspects.
Otherwise, the car felt good. Very strong, hitting 4th gear on the back straight pushed me back into my seat and I was topping out at around 126 mph before braking for the end of the straight. A couple of fast Porsches gave me someone to chase and - more importantly - learn from.
On my second session, I was dodging through the quick left-right-light chicane of the "Prairie Corkscrew" and felt a bang through the steering and the wheel went off-center. That's a front alignment cam slipping. So I headed back into the pits to sort that out.
entry 1076 - tags: aero, testing | | |  | April 1, 2013 - Canards!
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.
There's one corner on this track that is a long, climbing right turn. I was taking it at full throttle in 4th, accelerating through the whole thing as the car just stuck and stuck and stuck and the track appeared over a crest at the top of the turn. So much fun, and the car showed great balance.
So, big thumbs up to the canards.
During the third session, I was starting to get a bit tired - it had been a hectic day already, with 30 minutes on and 30 minutes off the track, working on the car. Just as I started to think about cutting the session short, the McLaren caught up and I waved him by.
If you ever get the chance to follow an aggressively driven supercar on the track, I recommend it. We were well matched in the corners and I was hugely entertained by the antics of the rear spoiler and the car dancing at the limit. However, once we got on the back straight, the difference between a 400 hp Miata and a 616 hp supercar became quite apparent. The modified Porsche turbo that had been running with the McLaren also powered past me at this point, so I sat back to watch the two of them play. On every straight, they'd move off a bit more. But wow it was fun.
Unfortunately, as we can down through that chicane again, the engine revs suddenly spiked and I lost drive. I tried some other gears to no avail. I'd lost drive. There was no noise, so it wasn't a driveshaft. I was right by the pit entrance so I dove off the track with enough speed to coast through the hot pits, around the corner and back to the trailer.
Looking under the car, the outer CV boot on the driver's halfshaft and the inner CV boot on the passenger's halfshaft are ruptured and threw grease everywhere. So I'm assuming that one CV joint failed with the second one following immediately afterwards thanks to the diff transferring the entire power load over to it. I have a suspicion as to what the cause might be but I'll keep that to myself until I have a chance to confirm that this is exactly what failed. It was an unfortunate end to what was proving to be a very fun and productive day.
entry 1077 - tags: aero, halfshafts, damage, canards, testing | | |  | April 1, 2013 - Now that's a fun bunch of cars to see at a track day.
That Formula B car had a tendency to simply appear out of nowhere and then just vanish into the distance.
Along with the aero, I was testing some new rear brakes on the car. I'm going to have a look at the pads shortly, but they felt great with lots of bite.
entry 1078 - tags: trackday, brakes | | |  | April 12, 2013 - I found the cause of the axle failure.
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.
On the other side, one of the CV boots ripped and was slinging grease, but I haven't taken it apart to find out just what's going one. It wasn't ripped last time I was under the car and since it was slinging grease on to the exhaust, I would have been able to smell it if it had been happening for a while. I'm curious as to what I'll find in there.
No matter, I've got a new set of halfshafts in the car now. Not a cheap fix, but an easy one. I did check to make sure I wasn't exceeding the amount of allowable change in length of the shafts due to excessive travel, but it looks as if I'm dead on the correct amount.
entry 1079 - tags: failure, axles | | |  | April 12, 2013 - I've been working on the car a fair bit.
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.
I've realized that, with the big change in performance thanks to the engine, tires and aero, the car is becoming needier. I can't just beat on it the way I could when it had the old four cylinder, everything's under much higher stresses and needs more maintenance and more frequent checks. That's why I spent the whole day under the car checking over everything. It's also burning up consumables faster. Nothing like a Corvette, but my tires and brakes don't last the way they used to - never mind the fuel!
It's got two days of hard use at Laguna Seca coming up in a few weeks, and I have to make sure it can run hard the entire time. It failed last year through no fault of my own, but I don't want to give it any excuses!
entry 1080 - tags: aero, suspension | | |  | April 22, 2013 - Short test session.
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.
On Saturday, I took the car out to Grand Junction Motor Speedway to test it out. And I only got in one session. The track was cold and the car was pushing around, but more importantly I could hear a thumping from the rear when accelerating out of left turns. It appears the new axles might have a bad CV joint, I'll dig into it later today. I have to get it fixed by tomorrow night!
entry 1081 - tags: testing, aero, axles | | |  | April 29, 2013 - Time for the big Laguna Seca event.
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.
Finally, we got to Laguna Seca. My first lap was uneventful, then an alignment cam slipped. Argh. Still, the car felt strong. I went out again and on my second lap, the clutch hydraulics failed. Argh.
Much prodding and poking at the clutch ensued. I got it back again briefly, then it went away. I thought it was a bad clutch master or slave. After working on it all day Saturday, I called Bill Cardell that night and he suggested there might be some debris in the hole between the clutch reservoir and the master. I worked on this the Sunday morning and had a clutch within half an hour! I took it out for some exploratory laps and it was coming and going. I seemed to have about three shifts in rapid succession, then it would go away - which made the front straight and the braking into turn 2 fairly interesting. A bit more bleeding and it came back 100%. Time to go drive.
This car is a beast. I'm certainly not the fastest driver on the track at an event like this, but the car is a great equalizer. With the big engine, I could pass just about anyone as we climbed the big hill up to the Corkscrew. The aero seemed to be working nicely, as the car remained well balanced in the high speed turns as well as the slow ones. I was having a fantastic time working my way through the pack.
Janel finally got a few laps in it after the disappointment of last year and the non-functional Saturday. Her biggest adjustment was to the braking points - the car builds up speed so quickly that you have to brake a lot earlier for the turns. She was starting to get more comfortable, though, and looking forward to her last couple of sessions.
entry 1082 - tags: testing, axles, failure | | |  | April 29, 2013 - This is not something you want to see out the windshield.
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.
A big thumbs up to the track designers - we finished our ride safe and sound without hitting anything but a small drainage ditch. Then it was just a matter of sitting in the car with our helmets on and watching the other cars come around the corner, seemingly aimed directly at us. Finally, all the traffic was cleared and the flatbed showed up.
entry 1083 - tags: crash, failure, laguna seca | | |  | April 29, 2013 - So, what caused the accident?
Looks as if the rear hub failed, leaving only the brake rotor to hold the wheel in place. Obviously, that's not what it's designed to do so it simply ripped apart. This was an upgraded but used rear hub - taken from Elvis, remember - but I'm going to be taking a very close look at the bearing and specifications to see if it's possible to build something stronger.
This also reinforces my belief that I need to step up my maintenance. Talking to Emilio at 949Racing about his enduro experience, I'm learning more about the difference between a track day car and a racer. Yes, I only use this car for track days but it's highly stressed and those track days stack up. I'll start flushing and cleaning all the hydraulics on a regular schedule instead of just the brakes. Wheel bearings are going to start getting treated like consumables. Although I'm not sure I would have identified this one as a problem, as I had it off the car on Wednesday and it felt fine. The hub's previous history was as a street car that has seen a few track days, but at a much lower stress level than the Targa Miata runs.
entry 1084 - tags: failure, hub | | |
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