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Lap of the Extended Jefferson Circuit in the Rain
Continuing the theme of recent posts this soggy summer, here’s a wet lap of the Summit Point Extended Jefferson Circuit. The most challenging part was the new turn 4 which is the transition from the old circuit to the new(ish) extension. There isn’t enough grip to get enough weight transfer to turn-in, so you end up turning in early and just managing your way through the apex. You also had to be careful about getting back on the power at the top of the hill between turns 6 and 7. If you had any steering input still in when you got back on the power, the car would sort of slide off the top of the track to the outside. Some of the data inserts are a little funky, like one corner shows corner speed of zero. Still loads of fun though. Here’s the lap:
Summit Point in the Rain
Track season is just starting to get into full swing so I thought I’d share a lap of Summit Point in the rain. Newly repaved for 2018, the surface as fairly good grip and no more of the inconsistencies from water on seam sealer. The surface is less crowned than before. Water run-off is mostly good, but there are some areas where small streams of water cut across the full width of the track, especially in the exits of turn 2 and 9, both heavy acceleration zones.
Corner Weight & Cross Weight
One of the additional benefits of an adjustable suspension, besides being able to dial-in ride-height and rebound, is the ability to corner weight the car. “Corner weight” refers to the static weight at each of the four wheels. 50-50 front to rear weight distribution is ideal to maximize handling on most road cars, but a distant pipe-dream for MINI owners. “Cross-weight” compares the lateral total (Rear Left + Front Right) to the total weight. If that percentage is over 50%, that’s called “wedge” in NASCAR terms. (Reverse wedge if under 50%). Corner-weight can be changed by adding ballast if necessary to make a weight minimum, or making, adjustments to spring perches and sway-bar pre-tension in an attempt to equalize the weight at each wheel. But more importantly, what matters for handling is near 50% cross-weight in a FWD car.
Take my car as an example: I have an R53 with a rollbar, AC delete, race seats, and a gutted interior. With driver and a full tank of gas, my car weighs 2,685 pounds. 61.8% of that weight is in the front; 38.2% is in the rear. That is slightly better than stock which had a weight of 2,853 (with driver) and 62.7/37.3 weight distribution.
The first time we attempted to corner-weight my car, I only had an adjustable suspension to work with. I didn’t have adjustable drop-links on the swaybars. That resulted in a cross-weight of 52.4%. That isn’t terrible, but still helped to contribute to under-steer in left turns due to wedge. We installed Alta adjustable drop-links on both swaybars, and without adding any ballast, tried again. The results are below:
Each corner is within 5 lbs. of the target weight. Cross-weight is 50%. The car now seems very neutral in left or right corners, which for MINI means equal understeer in both directions, as opposed to excessive understeer when turning left. Result.
Read more about cross-weight at GRM. If you want someone to do the math for you, see this corner balance calculator.
Wheel Studs
Last weekend brought the final track event for NCC BMW CCA this year at Summit Point. Although I had a great time as usual, the weekend wasn’t completely worry free. If you run wheel studs instead of bolts, you may not be aware that you need to replace them every couple of years. I know this, but I tried to delay for the winter, but the gods of oxidation thought otherwise, teaching me a few important lessons.
Lesson 1: Don’t cheat time. If you know a part should be replaced based on time and not wear, don’t push your luck.
Lesson 2: Just because something tightens to torque, doesn’t mean it isn’t about to snap. I broke two bolts. Both tightened to torque when cold, even though both had already rotted half-way through.
Lesson 3: Buy a bolt extractor before you need one.
Lesson 4: Assenmacher makes a really cool stud removal tool which will make your life so much easier. (Assenmacher, that’s funny…)
Here’s a lap when everything went right.
OBDII Data Link Review
If you have read through this blog, you know we’re huge fans of using data and video to improve driving performance. In this post, we’ll look at options to get OBDII data from your car to your phone. If you are planning to use Harry’s Laptimer, we also suggest you start your shopping journey there. Harry is a great guy and he keeps the recommended accessory page updated (separate pages for iOS and Android.) Let’s take a look at three products that represent the spectrum of options available.
At the low end are what I’ll categorize as the “plug and pray” devices. You plug them in and prey that they work because they’re really cheap. You can find them on Amazon or ebay, often under $20 and you get what you pay for. They may work to allow you to clear some codes, but generally they are not going to maintain a secure connection long enough or fast enough to get the flow of data you’re looking for. If you found one that refreshes at a 4hrz or faster rate, then consider yourself lucky. If you’re on a tight budget, the up-side is you could buy about four of these before you spend more than the next device on our list. Our general recommendation is to stay (no, run) away from these and support the companies making an investment in this space.
Next up are the WiFi connected devices. Several good devices fit into this category and our favorite is currently the OBD Link MX by ScanTool. In fact, I wish I could carry these in our store, but haven’t found a distributor yet so search on Amazon for a deal. The data link is fast. The connection is reliable (though all of these devices take several attempts to form a connection.) It comes highly recommended by Harry and it supports a wide range of protocols. Wifi does have some disadvantages compared to Bluetooth such as complication of forming the connection (unnecessarily complex 
password that’s printed on the device so write it down before you plug it in) and the fact that you can only form one wifi connection at a time. You also need to disable the “ask to join networks feature” once you have a connection, or you phone may lock-up trying to connect to the paddock infrastructure hotspot as you circulate on the track. I used it for my last track weekend, plugged it in on Friday, made the connection, then forgot about it all weekend and it worked like a charm. They also make a Bluetooth version which I haven’t tried. There are more expensive recommendations on Harry’s page, but for my money, this is the sweet-spot in the market right now.
PLX Devices recently started selling the KIWI3, the latest iteration of their popular KIWI line of adapters. On paper, it offers some 
attractive features: high data transfer rates, easy connectivity through Bluetooth 4.1 (low energy), and good power management. The form-factor is the best of the three tested, and we like the low profile. We just couldn’t get it to work initially. We tested 10 devices with iPhone 5S, iPhone 6s, and Galaxy 5. We got one to connect sometimes to the iPhones. (There is a firmware update available for Android 6 users but not iPhone yet.) The price is about $20 more than the OBD Link MX. If the firmware update gets published for iPhone it may be worth it. They also announced an updated version of their old device called the KIWI2+. It has the technical specs of the old cabled device (photo right), but offered without the cable and in the new case of the KIWI3. Not sure about price and availability though. When we went to their website to grab a link it wasn’t there, so stay tuned. If you’re an Android user, it 
might be a slightly less expensive alternative for you to consider. [We would like to hear from you if you’ve been able to get the Kiwi3 working with iPhone.]
