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One thing that was clear during my track weekend was that the stock 1.6 VLSD was basically an open diff. It’s legal to put in a 4.3 Torsen from a later car but people in the know say that in 1.6L cars the Mazdaspeed LSD in the 1.6L carrier is about a second a lap faster on most tracks due to lower rotating mass and the clutch-type action of the LSD. It just so happened that another 1.6L racer had a fresh one for sale so I picked up this:
and put it here:
Rear end swaps are a PITA in Miatae due to the PPF but the stub axles of the 1.6 made it a little easier, they don’t even have to come out of the carrier- axles just bolt up. The original diff will live in the trailer as a backup. We all know that 1.6L differentials are weak, but the ring and pinion is the failure point and the actual Mazdaspeed LSD component is supposedly bulletproof.
While I had the car on the lift I changed the oil and replaced the trans fluid with some of the Ford Motorcraft unicorn tears. In my last car it really improved the shifting.
Last edited by Schroedinger; 03-08-2021 at 03:48 PM.
The bearings in the cheap front hub that I installed last spring were already shot, so I needed to replace the hub with the newly re-greased Centric Premium hub that I built. In other news, after my last race the car and I were 20 pounds overweight with an empty fuel tank, and since I'm not having much luck breaking up my love affair with beer and cheese I'll have to remove some weight from the car. I also fortuitously learned that the factory parking brake can cost up to 2hp because the auto-adjusting rear calipers create extra drag on the rotors, which is why SM's often have the parking brake deleted.
Thus, I decided to take on a pretty comprehensive hub/brake/weight loss project. I started by replacing the front hubs and rotors, and removing the brake shields.
Next I did the parking brake delete. This involves removing the handle and all the cables and brackets, as well as removing the self-adjusting mechanism from the inside of the rear calipers. Since I was taking the calipers apart, I got a seal kit from Mazda Motorsports and just rebuilt the calipers. I found these instructions to be very helpful. It was a messy job but not really a hard one. https://nasaspeed.news/tech/brakes/m...brake-removal/
The "hand grenade" is the offending device inside the piston that needed to be removed.
After I reassembled the calipers I flushed/refilled the entire braking system. Doing this project gave me a new perspective on bleeding brakes. In the past I always thought of it as just flushing out the lines, but opening the calipers makes you realize how much stagnant, cruddy brake fluid lives inside the cylinder. The fluid inside the caliper is also the fluid that is most likely to overheat. To replace all this during a brake bleed you need to flush a LOT of fluid through. In the future I will plan accordingly.
After I was done with the project there was a surprising amount of stuff on the garage floor.
Along with a few extra nuts and bolts that weren't in the bucket, I removed over 9 pounds from the car. I’ll also remove the passenger side harness which is 5-6 pounds, which should get me near enough to ideal weight. For the car anyway.
Last edited by Schroedinger; 03-15-2021 at 05:16 PM.
I went to Track Night In America at AMP last night to test and tune the car before my next race. Since the last time I had it on track I've added the Mazdaspeed LSD, reset the engine timing, replaced the wobbly front hub, deleted the parking brake and dropped about 20 pounds. In short, the car is very, very good! Having a real LSD (rather than the nonoperative VLSD) is a game changer- so much easier to put the power down out of corners. Speaking of power, it felt like the car had noticeably more of it. The timing barely changed so I'm guessing it's a combination of the parking brake delete and the wheel bearings. I also noticed that the car is more squirrely in the braking zones. The new front rotors needed to be bedded so it wasn't surprising in the first session, but by the last session hard braking still felt different than before, like I had more rear bias. I think it has something to do with the LSD. Nonetheless, I had adjusted to the difference pretty well by the end.
Per the usual TNIA **** show... a guy spun his Lotus Elise into a wall back-end first. The subsequent explosion of fiberglass body work was totally out of proportion with the size of the hit, the car shattered like a carton of eggs. I used to lust for an Elise, but after seeing that I'm pretty happy with my Miata. A brand new C8 also puked oil all over the track and seized its transmission, they couldn't even get the car loaded on the flatbed. When I see people with cars like these sitting dead in the paddock I often try to read their reactions and determine if they paid for the track day insurance or not.
I never bought track day insurance because last year I was in a stock miata with a harness bar. However, now with a lot more money invested into it I'll more than likely invest in it
I've heard about enough TNIA ****-shows that I won't be attending one. Ever.
Almost without exception the incidents I’ve seen there are in the Intermediate group. Advanced group drivers pretty much know what they’re doing, and novice group are usually brand new and pretty cautious. Intermediate seems to be full of guys in fast/expensive cars who have done a couple track days and start writing checks with their ego that their skills can’t cash. Generally speaking I’ve had a lot of fun in the Advanced sessions without incident.
The fluid inside the caliper is also the fluid that is most likely to overheat. To replace all this during a brake bleed you need to flush a LOT of fluid through.
Or stick in a new set of pads, which forces you to retract the piston and reduce the mixing volume within the piston.
Then flush. Still the same amount of bad stuff, but way less hard to flush it out, since the piston mixing chamber is a lot smaller.
That said, I usually use almost a full bottle each time I bleed after a track weekend, based on checking when the colour of the fluid coming out changes back to something reasonable.
So I fixed my weird rear brake bias issue by just replacing all the pads and rotors, DTC-60 up front and DTC-30 in back. Braking is superb now.
I did my 2nd real race last weekend at AMP. They have a summer racing series that runs once a month, only three run groups. Group 1 is anything that looks like an SM. Group 2 is Radicals. Group 3 is Historics. There were 20 “SM’s” and one SE30 in my group this time. I have the SM is quotes because the field was entirely NB SM’s, and I think most of them had the restrictor plates removed based on discussion overheard at the drivers meeting and the lap times that I was seeing. The rules on tech were pretty fast and loose, and there is really no way to know who was cheating.
The bad news: I got absolutely SMOKED, I was DFL in both races and was almost 5 seconds/lap off the leaders pace. I have no sense of racecraft whatsoever, and all of my little driving flaws are more apparent than ever. My car does me no favors in the power department compared to unrestricted NB’s so I have to be faster than other people in the corners.
The good news: I had an absolute blast. I didn't crash, I executed my first real pass, and my best laps were three full seconds faster than my previous PR's at that track. The guy that won the Historic group was in an EP prepared Miata that was 200 pounds lighter than mine with a brand new pro-built race motor, and his laps were 5+ seconds slower than me and my junkyard 1.6L. I would have done better in the 2nd race if not for a drive-through penalty for tracking out too wide. Met a bunch of cool guys, and can't wait to get out there and race again.
For entertainment purposes, here you can watch a 13 year old rookie come from last place in the grid, positively annihilate me in turn 1 after the start, then proceed to pass every other driver in the field and finish first. Nice kid, I bet he has a great future in the sport.
Last edited by Schroedinger; 05-11-2021 at 10:25 PM.
Like all possibly bad ideas, my latest started with good intentions.
A year and a half ago I bought a Cayman as a fun street car and track day toy, for when I didn't want to haul out the race car. It was great on track but very expensive to run (compared to Miatas anything is expensive I guess), and I felt bad beating up such a nice car. With the used car market as crazy as it is, I decided to sell the Cayman at a decent profit. It was a great car but it didn't align with my goals any more. Fare thee well Elvira... I miss her but honestly I'm glad I've moved on.
With fresh money in my pocket, I re-committed to becoming a better driver and racer. I want coaching and data/analytics, so I started to size up a full data acquisition system. Quickly learned that to go all the way it would cost $4-5k to put such a system in my current car. In the next few years this car will also need a fire suppression system and the Penske SM suspension. I quickly arrived at the conclusion that it made more sense to start to look for a fully prepped and competitive race car than to throw more money at the one I've got. This car is perfect for someone getting into racing, working on getting their license, doing vintage/endurance racing, etc. Time to move it along, the next owner will be really happy.
I started pricing out fully prepared, regionally/nationally competitive SM's and figured out the price range. As I considered this type of spend, a few things stuck in my mind:
- At six feet and 220 lbs, it takes some doing for me to fit comfortably in a caged Miata. It can be done but it's not easy.
- Miatas are street cars converted to race cars. They do the job well, but there are some inherent compromises with that and there's a whole world of purpose-built race cars out there to explore.
- "Spec" Miata is not a true Spec class, as as such it is cheaty as ****. After five+ years in the Miata game, I need a break from wrenching and I just don't have the patience to chase 0.25HP at a time any more.
So after much deliberation... I'm now a Spec Racer Ford (gen 3) racer. A championship-winning car came up for sale close to me at a price that worked, it has a brand new motor/transmission and all the goodies and spares that I could ever want/need. SRF is a true Spec series with sealed motors and transmissions, and it's a big race class where there should always be someone to race with as I get faster. Running costs are on par with SM. They have around 136hp and race at 1560lbs, and are supposed to be a blast to drive. Maiden voyage is this weekend, I'm pretty excited.
Not super surprised to see the logical progression here. Spec Miata is a great class but yea, if you want a truer spec class with good car counts in general, SRF is a great choice.
I’ve never driven a Gen III, but I’ve heard they are a dramatic improvement over the previous versions.
Have fun! I’m curious to hear your driving impressions.
Thanks. I have a test day on Friday and local historic race on Saturday, I'll definitely report back. By all accounts the Gen 3 is a big step up. The Gen3 transmission is the weak point and requires some babying, but this year they're implementing a SADEV sequential transmission that will become Gen 4 next year. It will require a pretty good chunk of change to upgrade but the result will be a very fast and bulletproof track car.
03-07-2021, 08:21 PM
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