What is corner balancing?
Corner balancing is the process of shifting weight around in the car and adjusting corner heights to obtain a desired 50/50 cross-weight percentage, ultimately making the car perform equally in left and right turns. The weight you shift in the car is usually the battery, but can also include ballast, the fuel cell, oil accumulators, and fire system tanks. You want to place these items in areas of the car that is lighter than the rest to off-set the weight from the driver and drive-train components. Ideally, these items should be kept within the wheelbase of the car, and not placed in the far corners of the trunk or engine bay to prevent a pendulum effect. After relocating everything possible the ride heights are adjusted to create a 50/50 cross-weight percentage.
When I installed the BC Racing coilovers I decided not to do the corner balancing right away. Instead, I started with the weight reduction and testing spring rates, this way I didn't need to get re-adjustments after every change. Once I had removed a lot of weight from the car and settled on the 5k springs, I set an appointment with Bret at Yawsport for corner balancing. I also asked him to do a thorough inspection of the car to verify everything was optimized. We made the 50min drive to his shop in Ramona CA to drop off the car, and anxiously awaited his updates...
The following day I get a message that the balance was pretty far off, (maybe 3% if I remember correctly) and he is unable to correct it any further due to lack of adjustment in the rear. I'm told I need to purchase ANOTHER set of Swift springs since I was sent the 7" instead of 6". When I installed the Swift springs last year I did notice that they took up almost all of my adjustment to set the ride height, but I'm a noob and didn't think anything more of it at the time.
I emailed BC and was told to call their tech support hotline, I tell them my situation and they begin to look up the part numbers to verify I was sent the correct springs. It turns out that they did send me the correct parts listed in their catalog, and because my springs were installed we couldn't do an exchange. I'm not sure if this is a isolated problem for me because my car is much lighter than stock, or if anyone else with a Yaris and these DR's have run into any issues like this.
I told Bret to do whatever was necessary to get the car balanced, he ordered and installed the new springs and had the car balanced by the following day.
I was a bit annoyed about having to buy a second set of the same springs, and Bret gave me the appropriate "I told you so" talk in regards to testing a new set of coilovers. He had warned me plenty of times, but I wanted to test something other Yaris owners could attain easily with good results. Well, that's how it goes I guess, all is well now and It didn't cost too much to do some valuable R&D. haha.
You can see in the photo above that we are now at a 50% cross weight with a driver ballast, and everyone mentioned it was going to be a huge improvement. Bret gave me a list of improvements I can do to the car, including getting that LSD as my main priority. We talked about the future of our local SCCA region and how we can make another round of spring rate changes next year when we know more about venues.
So what are the differences?
On the drive home the car felt amazing, it was like the front and rear suspension were working together now. Before, anytime I went over dips or large bumps it felt like the back of the car would rebound off the bump pretty hard. This is the reason I had to turn the dampers down to 5 clicks to drive it on the street, but now I was able to keep it at my race setting and not get beat to death. Interesting.
Our first race after the corner balancing was the 2018 Match Tour, and I noticed right away that the car felt loose. I was struggling to hold the car composed through the slaloms, but it was easily correctable so I kept rolling with it. It wasn't until my co-driver spun the car that we made some changes, we turned the rear damping down from 16 to 12 and that seemed to solve the problem. We will continue our tuning process at the next event and refer to the results to verify we going in the right direction. You can check out the Match Tour video below:
Coilovers are an amazing tool for tuning a car's suspension, but don't think for a second that you can just install them without ever messing with them again. If you're buying coilovers to slam a car and go hard-park at meets then that's fine, but to me, that seems like a waste of such a functional product. For those that want to race you need to properly install and set preload, test-n-tune the dampers, figure out spring rates, and corner balance the car. Everything you change will affect how the car behaves, so be prepared to repeat this process as your project advances. I highly recommend you get in touch with Bret and discuss your suspension goals, and listen to what he recommends the first time so you don't have to learn the hard way like me.
The SCCA Match Tour is essentially a National Tour style event with an index challenge on the following day. This event started for us on Friday, where Robert and I did some test-n-tune runs on the small practice course. I did 2 runs and Robert did 6 runs, ultimately putting down a faster time than me. We both thought the car felt good and moved on to check-in and tech inspection because we are in the Prepared category this meant we had to get weighed. The SCCA has "minimum weights" that the Prepared and Modified classes must meet based on engine displacement and aspiration. The limit for our car with a N/A 1.8L engine is ~1500lbs, so we hit the scales knowing we had a TON of room for error.
After handling the legalities, we headed out to walk the course together. I've walked many courses over the years, but this time was different. Robert has a way of stopping and analyzing the course in different areas, noting elevation changes and discussing alternative methods of attack. This is something I've never seen before, as I normally just walk the course to take mental notes of where to brake and turn lol. With Friday's activities completed, we packed up and went home.
Saturday morning we walked the course again, went to the drivers meeting, then observed the first heat take their runs. We had to work heat 2, which seemed to last forever due to timing issues. Heat 3 was finally up around 11 am, so we pulled the car into the grid and set up the GoPro. We were the second car in line so I had to get ready right away, I got strapped in while Robert verified tire pressures. On my first run, I was surprised how loose the car was at speed, somewhere in the middle of 3rd gear the rear of the car felt very light. This caught me off-guard at first but it seemed to be easily correctable, so I just rolled with it. Then once Robert spun the car at the finish, we agreed to turn the rear damping down from 16 to 12. This seemed to help and we finished our runs for the morning, me with all dirty runs and Robert having one clean time. The event shut down for the lunch break and we took some time to reflect on our situation.
During our afternoon heat, we decided we had nothing to lose and just tried tossing the car around the course and not holding back. It was a bit warmer now and the car was still loose, so Robert did some tire pressure tuning to real it back in. We did the best we could to log clean, fast runs for the afternoon...but we were still way off the pace. I'm not sure if the corner balancing shifted how the car behaves or if my tires are starting to fall off...but the car behaved vastly different. Comparing my times from the previous event, either I was one second slower than usual or Ian in the BMW was one second faster.
I also took a look at the overall PAX results, and I placed 124th. That's only about 20 spots slower than my usual pace at the local events, so maybe we didn't do too bad. Of course, we could have gone faster, but I think having to relearn and retune the suspension set us back in our efforts to drive the car at our absolute best. That's a testament to how much the balance was off previously, and verifies everyone's statement about how different it was going to be. Also, there is the fact that we don't run Hoosiers or any boost, yes we have a light car but that alone is not enough for Prepared class. I just can't justify the cost of those upgrades right now, I like having a reliable "do anything" car more than anything else.
Huge thanks to Robert Stangarone for driving with us, I learned some new course walk techniques and had an absolute blast chasing the XP field with him haha. This guy is a real asset to the racing community, very knowledgeable and always willing to share what he knows or help others in any way. I highly recommend co-driving with Robert, we could all benefit from gleaning some of his qualities. Thanks, man!
In my time as a technician I've encountered some strange issues, from defective new parts to ECM software bugs. Most of the time theres something obvious telling you there is a problem, like a check-engine light or noises. But on rare occasion, you get a customer that is very aware, and a car that only malfunctions ever so slightly in a brief operating window. This brings us to my very first Tech-Tip, how to capture ghost fault data.
In the picture above you can get an idea of how modern engines operate, there are many sensors providing feedback to the ECM(Engine Control Module) to maintain optimum performance. Most sensors themselves are also monitored to ensure accuracy, they are required to respond a certain way within a predetermined time frame. I'm sure you can guess what happens if a sensor responds too slowly or incorrectly, you get a fault code and a check-engine light. So what about those issues you feel but never get any red flags from the ECM?
Capturing and Analyzing Data
One of the most important tools I use everyday is an OBD scanner. The most accurate way to analyzing data is by logging in graph view, otherwise you would never see the large variations in sensor output that are so close together. Look at the RED line in this picture, that is the A/F sensor signal and you can see it's going a bit bonkers next to the vertical FLAG line. Now look at the BLUE line, that is the REAR O2 sensor and it seems to be reacting to the same influence upsetting the A/F sensor. At this point it's safe to say something is causing a erratic lean condition, so now you should be testing your fuel pressure (ours was 52psi, good). Next I tested the alcohol content of the fuel, and it was exactly 10%, good. Knowing our fuel system is in good shape, I went back and monitored manifold vacuum, -9.6psi at idle, -10.2 at 2500rpm, and -12.0 on decell-all good here. Now I need to check a few other graphs...
Here we have the BLACK line showing the MAF sensor and the GREEN line showing the THROTTLE. The MAF signal looks very smooth and follows the pattern of the throttle, showing the increased airflow then returning to idle flow. At this point I did a smoke test on the intake manifold and the exhaust manifold, revealing no leaks. I did another drive cycle monitoring the VVT, EGR, and EVAP, and these systems seemed to be affected by the surging but still very much operational. I called the dealer help-line and informed them of all of this data, and they were confused as well.
1-A/F sensor-no change
2-EGR valve-no change
3-Evap purge solenoid-no change
4-PCV valve-no change
5-Accelerator pedal-no change
At this point I just decided to grab a loaner car and start swapping sensors, since talking to tech-line and ordering parts was taking ages. I started with the MAF sensor, swapped in the part and went out for a drive. I didn't feel anything going around the block, so I went around again and nothing. I went around the city a few times and never felt the surging again, so I logged the data again and behold...the A/F sensor signal is clean!
So what can we learn from this so we catch it faster next time?
First I would say trust your instincts. I knew there was something affecting the A/F sensor and the car could have been fixed a lot sooner if I swapped in a known good MAF sensor first. I guess the MAF sensor can be faulty even if the signal looks good, witch is strange. I did everything possible, reached out to my peers, then started hypothesizing. Kinda sounds like life right? Take a look at the photos below showing the difference between the production part and the new part. When I fist saw the difference I assumed it was some type of update to improve flow, but I was wrong.
Round 3 was a real blast. We had a blazing fast course to challenge our survival instincts and Solo Storm to show us some data. Huge thanks to Warren L. for designing a course that had us running in 4th gear for the first time, resulting in a 50 second course around the whole west lot! We ran the car in the exact configuration from last time, but that was not the best idea. What I've noticed is that the additional clicks on the rear dampers we love for the SE lot, resulted in a very loose car on the West lot. So there's a pro-tip for you, don't expect one damper setting to work on every course(duh).
Another thing I learned is that SoloStorm is awesome! You can have the two drivers fastest laps play over each other, showing exactly where one line is faster than the other. I was faster in the first part of the course and Patrick was faster in the second half. We analyzed the data between runs and knew exactly where to make changes. Patrick had the lead at first with a 50.5 then I took the lead on my 3rd run with a 50.3. We looked at the data and hit the course for our final runs, sadly though we both kept sliding too wide at section 8 losing vital exit speed for the fast finish. So I was stoked that I finally beat Patrick, but a few days later the results were posted and apparently I hit 3 cones on my fastest run(really?!). My video doesn't show it and unfortunately video alone is not enough proof for the SCCA. So I lose again, but at least its not by much this time haha!
2017 (C50) vs 2018 (C60)
So now we've had 3 events to get acclimated again and to gauge how the C60 and weight reduction has changed the car. Lets look at the PAX results from this time last year after 3 events, but keep in mind I had a Cusco LSD(5 speed) and fresh Hankook R-compound tires:
105th....not great but who cares right. Ok now lets look at the 3rd event of 2018:
100th...and this run was a half second slower than my fastest, supposed 3-coned run. Without their mistake my Pax would have been 98th, 7 spots faster than last year.
With this information I believe its safe to say that the C60 is in fact faster, even without an LSD. I'm aware 3 events isn't enough to judge a whole season by, but its at least a good preview. We will all get faster as the season progresses and then we can get a better idea of how the car has improved with the C60.
Our next event is the 2018 Tire Rack SCCA San Diego Match Tour on April 6-8, and we have another talented co-driver signed up... Robert Stangarone. I've talked to Cusco and attempted to order an LSD, but there are no parts available for the C60 right now and it will be on backorder until late April. Instead of just being on stand-by, I dropped the car off at Yawsport for a full inspection and corner balancing to ensure the car is at its absolute best. There aren't many people I trust to work on my car aside from Bret. If you take a look at his history you'll understand right away.
Take a look at our video from Round #3 below:
Before purchasing this set of Winmax brakes, the only other aftermarket pad I have tried was the Hawk HPS. I did a couple years of autocross and 2 track days on them, along with a ton of daily driving. They were fine I guess, they did their job but didn't have a noticeable difference from the OE pads. I had worn the Hawks down to 3mm right about when everyone was raving about the Winmax W3's. So I contacted a Winmax representative and let them recommend a full set for my application. They decided on the W4 pads for the front and the WRS-1 shoes for the rear.
The install for the front pads is pretty standard; use a new or resurfaced rotor, clean and lubricate the pad carrier and sliders, install the pads properly, compress caliper piston and install, then torque fasteners. I already have the stainless steel braided brake lines and flush in new DOT3 fluid annually, the car is very light so no need for the DOT4 or higher. I have another write-up HERE for installing the rear shoes if you're interested. Once your done handling the hardware its time to go out and do the bedding procedure below:
The first thing you will notice about these W4's is the bite. The W4 is designed specifically for circuit racing and has performed flawlessly for me the past 2 years, and there is still 6mm of pad left! They are by nature a more aggressive compound, so expect to see some dust, hear some noise, and only be able to use the rotors once. These pads will wear down the rotor surface creating a lip on the edge and make some squealing noises when driving on the street. Everyone that has driven my car is blown away by the braking performance, and cant believe I'm still using OE size rotors and rear drums. The Winmax brakes have showed you don't always need a BBK, but just a really good pad set. My car recently ran back-to-back sessions at Willow Springs Raceway with 2 drivers, and not one issue arose from the brakes...or anything else really. You can see the video HERE.
If you study the chart above you'll see the circuit W4 can withstand just a bit more heat than the W3, but still have a similar profile to a "sport" style pad. You can also see here that there are many other tiers you can choose from to suit your needs. I've had nothing but powerful and reliable performance from this Winmax brake system, and I fully recommend these products to everyone. Contact a dealer in your area to order a set for yourself! Check out the video below to see exactly how the pads looked after a full autocross season and a track day.