SlowTeg

Looks like a blast. I haven't been on track at VIR but hoping to make it down this year.

OptionXIII

And I'm looking to get to Summit Point or Dominion! I need more track stickers for my back window. I keep my eye on MotorsportReg looking for cheap seat time. I also need to find some local guys doing private party track reservations. Towards the end of my time in Michigan that was how I was getting most of my track time in.

My next event on the calendar is the Gridlife South Carolina Festival. I can't think of anything the car truly needs, but I have some projects ideas ready for it.

SlowTeg

Question for you about your skunk2 TB.. Have you had to mess with it at all recently sticking, greasing it, etc? I ask because I just went out to the car to check it since it started sticking at the end of my track day and took a closer look at it. The 1/2" nut loosened a bit (the one nut I didn't loctite of course) so I snugged it back down. Operating the rotor by hand now causes it to make this nice squeaking sound. I'm 90% sure it didn't do this before. Who knows if the loosened nut allowed a little bit extra side to side shaft play which caused some wear and is part of the reason it squeaks now. Trying to wobble the rotor it doesn't really have any play to it. Have you fully disassembled the TB to try and grease it? The squeaking tells me something isn't right on mine. I see some people have tried greasing the spring.. Next time it's off I will definitely have to mess with it..

Regarding a wing, I'd say just bite the bullet and do the 9LR big wing. I think I will likely go that route when the time comes as well. Do you drive your car a lot on the street?

Z_WAAAAAZ

Nice drivin' and recap! Super sick to see you would've been 3rd overall in TT5. Do you know anything about the setup the Miata with the 2:22 was running?

OptionXIII

No idea, I wish I had gone and looked at his car more closely. I did some digging and I'm guessing he's a been a regular there for a long time and has modified his car quite well to the rulebook to be 4 seconds faster than the rest of the field that's only separated by 3 seconds. And obviously he can drive!

What you see in this thread (and the condensed S2 TB thread I made) is everything I've done with it. Not sure which nut on it is 13mm/1/2" but I'm guessing the throttle shaft? I went a bit past the paint markings from the factory when I torqued it back down, but no loctite on that part. Other than my stalling issue on warm up, it's been fine. And that I won't even entirely blame on the TB, as I have this warmup misfire I can't figure out. Plus some of the feedback I got in that thread indicated that it could also be due to the IACV getting to be past it's prime.

As for how else I drive this car - it's my preferred daily. If it's not torn apart or absolutely pouring rain out, this is what I drive. For a while I was regularly driving 11 hours one way to visit my GF in North Carolina before I left Michigan. That's why I'm not exactly eager to get a big attention grabbing wing that won't come off without leaving a panel gap for everyone to see. Usually the only thing that changes between a Friday commute or date night and a Sunday HPDE is the tires. If there's a long time between events, the race seat will come out.

OptionXIII

The caveat to my last post is that dual duty cars aren't daily cars you track, they're track cars you try to drive to work as often as possible.

I had heard a shudder or vibration when I was braking in reverse and decided to take a look at my rear pads. I figured they just needed to be flipped.

On the drivers side of the car, I found the caliper pivot pin on the bracket to be completely loose. That was a sobering moment,. I regularly check the bracket bolt torque but hadn't looked at this since at least my last rear pad change.


I'm not sure what the threads are on this. M9x1.25? Neither my M8 or M10 dies would thread on. I cleaned it up with hand files, then cleaned the threads both bolt and bracket with brake clean before smothering them in red loctite and torqueing to 25 ft-lbs.


This definitely caused some uneven wear on the pads.


Woof.


The new Stoptech 309 Sport pads have a different backing plate shape. They must have changed the manufacturing plant, I have heard they are moving operations to Mexico and there may be a dry spell of parts, assuming they continue production. Hopefully these pads remain available.

Z_WAAAAAZ

I'll be stealing this quote lol. Spectacularly put.

Glad you caught that pin before the issue turned into something worse. Maybe the photo is just out of focus, but I'm surprised you were able to bring the threads back on that thing. From the pic, it looks like they were all but completely flattened.

SlowTeg

That's good to hear. Ya I torqued my nut down a bit more after drilling the hole you suggested but it still loosened up. Oh well. I'm going to start tinkering with the car again this week so we'll see what's up with the TB.

That makes sense. Ya I'm not a big fan of driving with a giant wing on the street either but I might make an exception for this car when the time comes. My car won't see many street miles though. On my Honda I can easily swap trunk lids with a big **** mounted to it but with the 9LR wing being essentially chassis mounted it doesn't look like there's an easy way to remove the 9LR wing in between track days.

OptionXIII

I made it out to Gridlife South Carolina for the second time in a row, and again, I was really only there on Sunday. Unfortunately they sold out of camping spots while I was making the last minute decision. Springtime means there's a lot to do around the house, too much for me to get a hotel to spend a day looking at cars. One year I'll make it out to the whole event!

I drove down there this morning in the Miata, with the RS4s already on the car, and a minimum of tools and spares. To summarize, I got a best lap of 1:56.3 which is right about in line with where I was last year IIRC. I'll take that as a good improvement for running on RS4s instead of RT660s. I got about 2 hours of track time total - the last session was an hour, and I could have gone longer. I had to stop for gas once, and with about 15 minutes left to go I decided I'd had enough fun for the day. I wasn't as consistent, and I could tell the tires were getting tired too.

I cursed myself a few weeks back by posting in @Z_WAAAAAZ build thread.

I had came into the weekend wanting to play it safe, but at some point in the third session I decided the risk was worth keeping my foot in it on corner exit just once or twice. CMP curbs are absolutely absurd and punish anyone who dares go wide, and I was a victim. Eventually I noticed my steering wheel was pointing straight ahead, when it had a slight left tilt beforehand. a look under the car after the session confirmed that the two camber bolts were not at all in the same position. I ran around the paddock looking for anyone with alignment equipment, and eventually found a guy with toe plates he was willing to loan me. I used the toe measurement as a substitute for camber, setting it back to the original setting. This took a few tries, then I cranked down on the camber bolt real hard and hoped for the best.

I'll be ordering the new Supermiata upgraded bolts here soon.

Anyways, here's a few pics from the day.


I was first to grid for the Advanced group, and soon regretted it. I'm pretty outgunned in this crowd.


I got some ice cream out of the cutest little Subaru Sambar.


Neat.


And this is why I could never actually do drifting as an event. That is a staggering number of destroyed tires, and several destroyed wheels.


I'd never seen these Rush SR cars before, but they look to be my perfect racecar. Simple, small, low cost commodity parts, and a sportbike soundtrack. Too bad the buy in is $40k!


Somebody absolutely wadded up this Sundae Cup Fit.


The coilover mounts on this car are nightmare fuel. Also, that air filter location!


That's not what a fuse box should look like.

I saw this guy pulling a car onto his trailer with his truck and knew it looked sketchy. Within ten seconds, the chain caught on his tire rack and tore it down.


I finished the day by hanging out with some Miata guys.

Gridlife is such a strange event. There's some insanely cool cars and great engineering. And then there's some real head scratchers.

Z_WAAAAAZ

Hey that dude with the orange miata is the guy who 3D printed like 100+ parts and all the aero for his car, right? I've been following him on instagram for a bit. That thing is super cool!

Looks like a good time, man. Running the same time on RS4s vs RT660s is a solid improvement for sure! Glad it was a good weekend aside from the alignment conundrum. I'm sorry for bringing the bad bolt juju to the track with you

OptionXIII

Yep, that's him! We talked for a bit to catch up as I'd spoken to him last year. He was having issues throwing belts off of his Rotrex supercharger back then. A few washers to shim the pulley in alignment was all it needed. It was super cool to see the 3d printed air dam, wing, and side skirts. I've been disappointed with how I can't find what I want in the aftermarket for a few items. For the past few weeks, I've also been thinking of upgrading my laptop and buying a 3d printer of my own. Seeing his car was definitely a kick in the pants to get that going and spend some of my bonus this year. I hope I see him again this year, it's always nice to chat with someone who wants to do things their own way.

The alignment bolt juju was my own doing, I didn't knock on wood! Plus, now that I'm doing more alignments myself and being on gripper rubber instead of 300+TW tires, this was inevitable. And honestly this is a great lesson. I've been meaning to expand my alignment gear setup, so a set of toe plates will be a good addition for quick work at the track.

I forgot to mention the biggest lesson learned of the weekend! I've always been pretty aggressive with my heel-toe downshifting. With the heavily front biased stock setup, getting those shifts in ASAP and keeping the engine close to redline was effectively moving the bias rearwards and getting me more overall braking ability. Plus it sounds great. But now that I've got the Afco setup that moved the mechanical bias to the rear, I was running into issues with unstable braking. I've been backing off on the rear brake bias with the proportioning valve, but going forward I'm going to try to do some driver mod and focus on breaking old habits.

SimBa

Great photos! Sounds like a fun weekend. Gridlife seems like an awesome event.

Do you think the break bias is a crutch for bad form? I would think you'd want to run slightly biased towards the front.
I could've misinterpreted what you said.

Z_WAAAAAZ

I remember reading more than once that if you have the option to adjust brake bias manually, it's best not to rely on downshifting for additional rear bias. Actually one of the books I'm reading right now drove the point home to downshift deep into the braking zone so that, additionally, you can focus on threshold braking before you have to heel-toe. I'll have to find the passage and post it up here.

I downshift too early somewhat frequently, although not consistently. Really depends on how in control I am before entering the corner, and has never had anything to do with trying to set my brake bias. Lots of things to do while driving a relatively-fast, manual transmission car with no driver aids

Props for working on breaking old habits! I tell myself that some of the reason my mountain bike career never took off was because I was too stubborn to take a step backwards and change up my technique/eliminate old habits lol.

OptionXIII

Well, I don't think that's the most flattering way to put it, but on the face of it I can't say you're wrong.

When I was working on my BBK, I did some quick and dirty math based solely on rotor OD and caliper piston diameter to get context for all the opinions out there on proper brake bias. Might as well share it now.



Mind you, I stand behind none of these figures, I am not a brake engineer. This is far from an exact figure at any point while you're braking - realistically you need to look at the system pressure you've created with the brake pedal, factor in the proportioning valve knee point and curve, and use the centroid of the pad instead of the outside edge of the rotor, pad temperature vs friction coefficient curve, etc.

But it does give context for what's going on. Since I started with a Sport package braking system, I have the most rearward biased brakes from the factory. Based on my experience so far, that is still too far forward biased for straight line braking on 200tw tires without any engine braking. Manufacturers set it further forward than ideal for the racetrack this because it's safer for an inexperienced driver in a panic situation.

My ideas on how that has affected me so far is that the excessive factory front bias let me develop my driving habits in a way that was very aggressive on downshifting. When I went to the Afco calipers, I actually reduced the effective front braking force for a given brake pedal pressure and moved the brake bias rearwards as a result. Now that the rear axle is much closer to the limits of traction just from the braking system alone, engine braking has a much larger effect on the car balance and I can exceed the limits of the rear tires when the two are combined. So, what helped me with stock brakes is now a bad habit with the BBK.

I typed all this out before I remembered a professional already spelled it out far better than I can.

Supermiata Brake FAQ | 949 Racing

Please share if you come across it! I love it when I discover on my own what professionals knew long ago. I mostly went down this line of thought after realizing I had no instability issues when I knew I overshot the braking point, and only focused on the brake pedal. Fixing this habit and experimenting with going back up on the brake bias will be a project for another day though.

That brings up a good point - I set up my car for a remote bias adjuster cable, but I've yet to get it actually working properly. Once I remount the prop valve at a different angle, and shorten the cable to remove some of the twists and turns it was taking, it should be more effective.

I also need to get a passenger race seat setup and start asking for instructor ride alongs. It's been years since someone more experienced than me was in the passenger seat.

Z_WAAAAAZ

Found ‘em! Maybe I need to reread the passage. I remember the point being driven home to downshift late into the braking zone, but forgot about the bit regarding getting your downshift done before entering the corner.

Your brake bias findings and resulting downshift technique make absolute sense, though. I seem to remember NA8’s have the most frontward bias, and after tracking my car for a while, I began to do the same thing with early downshifts, although I didn’t know why I was doing it at the time lol.

This book generally assumes the car being driven is a race car with an adjustable/dialed in brake bias, so a stock Miata may not be covered by said passage.

SimBa

Well TIL. I always assumed that adjusting brake bias via a valve had a major effect on the overall system. I guess I never thought about it too critically, but it makes sense that if you have massive brakes at one end and tiny ones on the other that there would be an imbalance.

Good reading material from both of you. Cats for everyone.

OptionXIII

Since I've decided this car is too reliable to go and make a mess of the engine, I finally decided to get a cold air intake. I was planning out the design and what parts to use when my buddy said I deserved a little treat and to just get a bolt on part.

So, I ordered the Cobalt CAI because it's the most complete one out there, and on sale.



I've only driven with it twice, but so far I love it. I don't care if it makes more power, I just want that intake HONK. It sounds great!



I also scored this hood for free off Marketplace. It was in an accident and apparently has a bend in it. All I could find was a small wave in one spot, and that the skin and frame have separated a little bit. I had to take the gas tank tin as well.

None of that really matters though, I'll cut this one up and add vents for a summer track day hood. I've never wrapped anything before, I might give it a shot on this.

SimBa

Score on the hood! Any idea what vents you're going to go with? Any thought to a DIY venting solution?

OptionXIII

I'm not sure yet. Most likely the R Theory units or something similar, but I would really prefer something a bit more aesthetically minded. I'd be willing to go to hood pins as well.

I need to get a better computer so I can start to learn to model off of 3d scans. Padlock is putting out some good stuff, and I have other things I'd like to create as well.

SimBa

I downloaded Polycam recently and was impressed with the scans I was able to get just from my phone. I tried it out for fun, but when I was at the store looking for some materials I actually pulled it out and looked around in my engine bay scan to reference. I think there are limitations on the free version, but its worth a shot if you're getting into that space.