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.
Bumper Scratch Repair
If you’ve read any prior posts on this blog, you know I’m a huge fan of Dr. Colorchip. For small paint chips and scratches, the good doctor cannot be beat. But when the chips and scratches get bigger, the repair isn’t usually as simple. So I thought I’d try out some other products on the market to see if they work as advertised. Today I’m trying the ScratchWizard system.
First some background. I bought a 2013 BMW X5 in the fall of 2017. Although it came equipped with Park Distance Control sensors and cameras (back and side), the previous owner (aka Mr. Magoo) managed to scrape some paint off of all four corners. I bought a bumper repair kit from the ScratchWizard last November, and it took until May before the weather was nice enough for me to use it.
I followed the video instructions more or less, starting with two problem areas. First was this huge chip and scratch on the top edge of the bumper cover.
And secondly, a large scrape along the fold. One good thing about the color of this vehicle is that it hides scrapes really well, and I didn’t initially see this scrape until I started to work on the other one.
I didn’t want to use filler on plastic so I tried my best to repair the areas just by sanding before using the primer. The key I’ve discovered is to go big.
Take advantage of the natural panel seams and plan ahead where you want to blend into the original paint. If you mask off a small area, you’ll get hard lines and the repair will be more obvious.
Follow the instructions allowing 10 minutes between coats, and 30 minutes between primer and color, as well as color and clear. Each step involves a light initial coat, followed by two medium-heavy coats. You want good coverage, but you don’t want the paint to sag. Metallic paint is usually tough to match, but this came out pretty well.
I’m really happy with the result. Once the paint has hardened for another month, I’ll level the clearcoat with Meguiars 105. Result.
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.
BMW Sets World Record for 8 Hour Drifting
BMW recently reclaimed the Guinness World Record for the longest drift, drifting 232.5 miles over 8 hours in the new BMW M5.
I was recently attending a seminar at BMW NA HQ and they have the vehicles on display in the lobby.
I found a few of the details interesting. At about 1:50 in into the video, you’ll see the two cars come together. Even though they were traveling at about the same velocity and just a few inches apart, it still made a decent dent.
I also appreciated the four cup holder on the passenger seat, which makes sense if you’re going to be in the car for 8 hours, you want to stay hydrated. But it makes you wonder if the driver Johan Schwartz also had the stadium pal. I also like the way the pump controls were integrated into the center console.
The driver called for refueling using the bluetooth connection to his phone. He had to reestablish the pairing of his phone and the car a few times over the 8 hour period. If you’ve ever used the BMW iDrive controller, you know that in itself deserves a Guinness record. (I can’t get that to work while I’m in my driveway, let alone mid-drift.)
The fuel line and return pass through the side rear window into the fuel cell in the trunk. As stated in the video, their biggest concern was fire so there was a fire suppression system in the trunk and special vents were added so the trunk would vent to the outside.
