Archive for May, 2012

Spring Nationals

Posted in Handling, Reliability, Wiring Harnesses on May 29, 2012 by David de Regt

Because of the alignment and truck issues, we, of course, had another frantic last minute prep session.  We spent Monday afternoon pulling the front UCAs off to bend them more, reinstalling them, and getting the car to an alignment shop with zero notice in time for them to work on it.  While some of that was in process, we had to pull the alternator off the truck and get a rebuilt alternator and install it.  That evening we finally got to clean up some last minute stuff on the car and packed up the rig to head to Lincoln.

2 days of towing later, we arrived to glorious 90 degrees and humid Lincoln, NE.  We spent Thursday doing practice starts to figure out how to launch the thing (which neither of us ever got any good at – my best 60ft was 2.01s.)  Everything was going well, so we retired to beer.

Friday (ProSolo day 1) morning, I got 3 runs then the car sputtered and died sitting in line to take my 4th run and wouldn’t restart.  We pushed it off to the 2nd driver line and let it sit for a minute.  We checked everything – nothing obvious was wrong, but a minute later we tried firing the car back up, and it happily did.  My dad then got 2 runs in before it died in the same way for him and we retired to impound.

Very perplexed, we guessed it was a fueling issue, and I’d been worried about my fuel pump since the Packwood weekend of harness melting/shorting.  So, at lunch we changed the fuel pump to the new Deutchwerks pump.  I didn’t get a right side run (apparently I rolled out of my one right side run, grr), so my dad got to go first.  We sent him out without a hood for afternoon runs, on the off chance something was overheating, to get some more ventilation into the engine bay.  He got his 4 runs in, so we hoped it was fixed and put the hood on for my runs.  I got one run before it died again briefly after I departed for my second run.  We again retired to impound and had an evening to consider.

Fortunately, I had noticed, when it wigged out on me, that the tach was going nuts, implying that the ECU had lost cam/crank sync (or something far more heinous, possibly.)  I asked around the paddock and found two very nice competitors (Bill Schenker and Mike Heinitz) that had spare crank and cam angle sensors to loan me, and swapped them onto the car.

The next day, we decided the better part of valor was to run without the hood again (but we “replaced” the hood with a strip of tape, which is technically legal under SSM rules, stupid as that may be) and I went out for my runs.  The car had no issues, and I managed to save for 3rd place, and my dad also got his 4 runs in without issue.  When we tried to start the car up again after weighing it, it wouldn’t start, or even show any signs of ignition signal.  We towed it back to the paddock and poked around at it for a bit.

I found nothing wrong, but finally decided to try swapping the main relay out for a spare I had lying around, and the car sprung to life.  That relay had likely been damaged in the wiring debacle of the Packwood weekend, but it’s still a little distressing.  The car seemed fine after that, so we declared victory and went for celebratory BBQ and beer.

The NT went mostly without issue.  They yelled at us after the ProSolo, because apparently our exhaust was blowing 103dB consistently (limit of 100dB), so we had to attach a clamp on muffler for the tour.  I had a small power burble on day 1 in the middle of my third run, but it’s vaguely possible it was just fuel starvation.  We made it through — I got 3rd again, 1.4 off the win.  The only day two issue was when, on the way out to grid for our day 2 heat, my dad drove the truck over the hardtop I’ve been using to keep the car dry/sealed overnight, which is now forcing me to come up with some new solution…

On the drive home, so far, I’ve ordered brand new replacement relays from Mazda and also new crank and cam angle sensors.  I noticed the cam sensor and the main relay had both been superceded, and reading up on miata.net, it looks like my issues are pretty known issues, so I’m vaguely hopeful that I’ve discovered the cause(s) of my more major problems.

We also had a chance to play with the Hoosiers vs. Goodyears at the Prosolo, and we both agreed that the Goodyears make the car much more drivable, so for the forseable future, it looks like it’s going to be a Goodyear car.  They seem to be able to put down power much better, and also they don’t overheat nearly as badly as the Hoosiers do, both of which are good things for an SSM car, especially at a hot site like Lincoln.

I hopefully will have time coming up to work on some of the other projects for the car: a front brakes solution, possibly moving to a permanent carbon hard top, venting the hood for real, tuning the rear wing, canards, etc.  The really short summary, though, is that the car, for its first showing, when it was working, proved that a Miata can get it done in SSM (if I stopped driving like such an idiot.)  So, despite all the other stresses of the weekend, it was a resounding success.  I also had some more time to mess with the data system that I’m developing, and worked some of the usability kinks out, which was helpful at the events and should be even more useful as the year goes on…

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Second Packwood weekend and Spring Nationals Leadups

Posted in Delays, Handling, Suspension, Traction Control, Wiring Harnesses on May 29, 2012 by David de Regt

It’s been an incredibly hectic two weeks.  I spent a couple days tearing into more of the electrics and found that the fuel pump wire down the driver’s side of the rear harness had rubbed through to the chassis, which is probably what started everything.  I ran a new thicker gauge wire and re-loomed/moved some of the harness, so it should hopefully never rub through again, and the thicker wire will be less prone to heating.  I also ordered a Deutchwerks 300LPH pump due to my decreased confidence in the Walbro, intending to use it as a spare if the Walbro died.  Finally, I moved the fusebox out from under the side of the engine bay into a spot near the intake with some airflow, in case it just needed some ventilation as well.

The subframe that we were told existed wasn’t actually the right subframe, which we didn’t discover until after close of business Thursday night.  We got to wake up early Friday morning and call every parts shop in the area to find a new subframe.  The only one we could get before Monday wouldn’t be pulled until 5pm that night, 2 hours from home.  So, we picked it up, got back home around 7:30pm, and spent the entire night swapping the subframe and front control arms.  Shaikh finished up the shocks Thursday night and overnighted them so those arrived Friday morning, and when we finished with the subframe, we got to also assemble/swap the new shocks (mounting canisters, etc.)  Around 11:30pm we finally finished with all the work, then spent until almost 2am doing a ride height set and string alignment.  We realized the alignment wasn’t going terribly well, and we couldn’t get enough camber out of the front anyway, so we called it good enough for a shakedown and went to bed.

We decided that waking up in 3 hours and driving to Packwood for the morning session was out of the question, so we went down for the afternoon, which was a nice dry day, and had no major issues at all with the car.  The car was pretty loose, but still drivable, and we settled into liking a RaceLogic setting of 20% slip and 5.0mph wheel differential.  Sunday morning we woke up to a wet ground and ongoing rain, and we ran a very wet morning session, where we got to throw on the Hoosier Wets (225/50/15 H2Os on 15×9 6ULs) and play with the RaceLogic to figure out a wet setup, which worked out quite well.  We tried 5%, which seemed pretty good, but 10% was really the sweet spot, if you had quick enough hands.  The car is remarkably drivable in the wet, which is good to know.  On a very representative course, I was only 0.4 behind the Hyman GT-R car in full wet trim, which is closer than I would have hoped to get.  We had no issues with the car in the wet either, called it a day, and drove home.

On the tow home, the alternator on the truck let go, though, adding some more insult to the existing injury.  Nothing is ever easy…

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Ups and Downs

Posted in Delays, Subframes, Suspension on May 15, 2012 by David de Regt

It’s been an interesting month.  Soon after the last post, I decided that nothing was coming in soon enough and that I should just bring the car in to get painted.  I had Showcase Auto do it, and it came out great (for a racecar — painting carbon fiber body parts is never fantastic unless you put 20 pounds of paint and bondo on it, hence removing the point.)

I got the car back a week and a half ago, just in time to try to put all the new parts that arrived on it.  The Ciro Designs wing came in, and we fabbed up a splitter (currently in revision 1, there’ll be canards and paint later).  The control arms and delrin finally came in, and we spent days assembling the car and finally, this past weekend, had a chance to bring the car down to Packwood for what was supposed to be a 2 day event, getting a ton of runs on the car in preparation for the Lincoln mini-nationals in 2 weekends.

Unfortunately, that was not to be the case.  We took a couple runs in the car, which were pretty good, but quickly started getting some nasty rubbing making the sharp turn to get to the start line from grid.  We ignored it, planning to look into it at lunch.  A couple runs later, we started getting something acting like the car being out of gas in the middle of my dad’s run, and then shortly thereafter it gave out entirely and refused to run any more.  Some quick diagnosing led me to find that the ignition lead was shorted to an always-on battery line somewhere, and it wasn’t obvious where.  In addition, when you shorted the fuel pump on with the diagnostic connector, the circuit main relay under the dash started buzzing heavily, and was rapidly heating up (to the point that the wire insulation was melting).  So, after spending a while with it, we decided to bail and head home to diagnose with more tools and time.

Monday, my dad and I converged on the car and pulled the front wheel off, only to discover something really unfortunate.  The rubbing apparently was caused by the new front control arms pretzeling themselves under the stress of the Packwood bumps, or somethingorother.  I’m working with the EPMiata folks to try to figure out if we have a good answer, or if their arms are just not strong enough for SSM autocross duty.  However, that give us a bit of a major problem.  There’s one more weekend of events (19/20th) and then we have to hit the road Tuesday to get to the Lincoln events in time, which means we only have one more shot to test this stuff out, and it needs to be ready for this weekend.

As a result, just to have a prayer of making it to Lincoln, I’m enacting a fallback plan of using stock front UCAs.  AWR is overnighting me some delrin bushings for them, which come in Wednesday, and I’m putting the V8Roadster ball joints into them.  We’re going to bend them in a press a little bit to get the camber level we need, and run it as is for now to hopefully get some events under it before going with another custom solution of some sort.

I also pulled apart most of the electrics in the car today (pulled the dash, fuseboxes, and relay blocks) to try to figure out the problem.  The only issue I can find so far is that two of the wires in the main fusebox had melted together, which shorted the ignition (white/red) line to another fused always-on line (white/green).  I re-insulated them and separated them, and I will be moving the fusebox to somewhere with more airflow to keep it cool (the event this weekend was quite warm, and I think the splitter was keeping underhood temps higher than usual).  In addition, I should probably add some vents to the hood to let some of the air out, which will likely assist with front downforce as well.  I’m replacing the main circuit opening relay with another I had kicking around from a lower mileage car, and hoping for the best this weekend.

With any luck, I’ll have better news to relay soon.  Tomorrow I get a different used front subframe to swap mine out with (we had to drill the front UCA sleeve out to 5/8″ to use the EPMiata control arms) so I need to get another stock one to put the stock arms back onto, and the delrin bushings come in to reassemble everything.  The real DA shocks come in from Shaikh either late Thursday or early Friday, leaving me a few hours to get the car aligned for the weekend.  From there, hopefully our last minute changes here will keep it running long enough to abuse it all weekend, then head east to Lincoln a few days after that…

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