Home » 2014 (Page 2)
Yearly Archives: 2014
Track Analysis: Summit Point, Jefferson Circuit Extension
Last weekend I had the chance to drive and instruct on the extended Jefferson Circuit at Summit Point. Below is my analysis of the changes and a description of my line around the track. This works for me in a FWD MINI on summer street tires. Your results may vary. No wagering. (In-car video by ReplayXD.)
The extension (turns 4 – 10) adds about a half a mile to the old track and doubles the number of corners. I think most old-timers would have preferred if they had just renumbered the new section as corners 4a to 4g instead of renumbering all of the corners, but we’ll use the new numbering scheme. The old track could be run in both directions. The new layout only works in a counter-clockwise direction (though you can still use the old course in the other direction.)
Google Earth hasn’t yet uploaded a new image of the circuit so the plot shows the path through open fields, but it is actually paved, just not well (more on that in a minute.) How to read this chart: Turn numbers are in circles. The color on the path of the car shows acceleration (green) or deceleration (red). Note that deceleration might just be lifting as in between 2 and 3 or the apex of 4 or 8. Green speed readings on the track show max speed before deceleration and red shows apex speed. The bars in each corner show relative lateral G load. Green bars are .4 to .8 Gs. Yellow bars are .8 to 1.1 Gs. Notice the lateral load where the new track rejoins the old track and in the middle of the back straight. There the car is going straight and the lateral load is from the unevenness of the surface. You see some of that on the front straight from 14 to 1 as you drive across the crown to set up for turn 1. Red arrows show apex visuals. If you already know the old Jeff, then jump down to Turn 4.
When you enter the track from pit-out, stay to the right all of the way to the apex of turn 1, otherwise, when at speed cross-over from right to left on the front straight and look down the track to the flagger’s bucket. RWD cars set up to the left for turn-in. The road is crowned so FWD will want to be more in the middle of the left half of the track or you’ll never get over the crown to the apex.
The apex is very late and almost at the end of the curbing. You can ride the middle part of the curbing, but stay off of the end as it will unsettle the car. Stay to the right upon exit and let the car settle before turning-in to turn 2.
Turn 2 and 3 should flow. If you’re early for 2, you’ll also be early for 3 so wait to turn in and make 2 a very late apex. Lift or tap the brakes to turn-in to 3.
Turn 3 is one of the few corners where you can ride up on the curbs without unsettling the car. Apex is very late and carry as much speed as you can. Don’t worry about track position on track-out as the entry to the next corner is rough and you’ll probably have to lift anyway to get back to the apex.
Turn 4 is also a late apex. Ride the rumble strips and try to straighten 4 and 5 as much as possible.
The exit to turn 5 is the roughest spot on the track. Point the car straight after the apex and brake in a straight line. Wait for the second bump before turning-in to turn 6.
Set the car about a car-width from the curbing and late-apex turn 6 at the top of the hill. Open the wheel and let the car track out to set up for turn 7.
Turn 7 is the most difficult corner on the track. You must be patient, especially when your tires are cold. It is a decreasing radius corner. Look for the path of the patch. Set your entry squarely in the middle of the patch and then pinch-off the apex. Trail-braking helps. If you don’t sufficiently load the front-end, expect to under-steer through the apex and off the other side of the track. Track out to mid-track.
Treat turns 8 and 9 as one double-apex corner. Do not track too far out in the middle as the pavement drop off is pretty severe.
Ride the curbing on curves 8, 9, and 10.
Late apex 10 but get on the power early to increase the length of the straight. The point where the new track joins the old is quite bumpy so stay away from the track edge.
Stay 3 feed from the edge in the braking zone to 11 to avoid more bumps. Turn 11 will really hook up when done right. Release the brakes as soon as the car starts to turn-in and power through the exit using the full track width. Cross over from right to left to set up 12.
Staying as far left as possible, turn in for 12 as soon as 12 and 13 line up and straight-line 12.
Stay off of the curbing on 12 as it will really unsettle the car. Downshift and brake for 13 in a straight line. Some people are able to carry enough speed to brake once through 13 to set up turn 14. In the FWD MINI I have to release the brakes in 13 to get the car to rotate and can actually accelerate a little up the hill before turning-in for 14.
RWD set up 14 by going as deep as possible for the entry. FWD don’t go too deep or you won’t be able to cross the crown to get back to the apex of 14.
The apex of 14 is very late. Stay off of the curbing. If you are tracking out to the edge of the track before the pit-in lane, then your apex was early. Cross over from right to left and do it all again.
Larger photos here.
Random Orbital and Machine Polish
We started carrying Griot’s Garage products in the stop this month and as part of the dealer agreement, we have to be familiar with the full line of products. So dang, now we have to stay in the garage until everything is polished. I now completely understand why one of their kits is called “weekend garage therapy” – I’m a believer.
Start with the book young Jedi: Once you admit you don’t know what you’re doing, read the Detailer’s Handbook cover-to-cover and you can start the journey of learning. Turns out I’ve been polishing, waxing, and buffing wrong all of these years, likely doing more damage than good. Fortunately the Porsche has a really thick layer of clear coat and quality paint.
It’s hard to try to photograph before and after pictures of scratches in paint, but I think this one spot is a good example. This was a scratch on the driver’s side just past the driver’s door. Probably came from a parking lot. There was no ding or chip, but this mark would not come out even with a clay bar.
But just by following the right steps: wash, claybar, machine polish, and wax – it disappeared. I haven’t completed the whole side of the car yet, so right now there’s this one two-foot section that has a very deep shine surrounded by a rather dull, much larger field of blue. Ah something to do for the long weekend coming up!
MINI Brake Pad Change DIY
Armed with my trusty Bentley manual and the internet, I decided to learn how to change my own brake pads. The dealer charges somewhere north of $400 for pads and labor so I thought I set out to get a higher grade pad and to do it for less money.
To start with — the pads. I decided to go with the Hawk HP Plus pads. I had read several good reviews that claim they offer increased stopping power, lower temperatures, and less dust. And they would hold up to occasional track use. There are several good pad changing guides on the internet; I suggest you read several along with the Bentley manual before you begin. The process is really quite simple (once you get past the fact that if you screw up, you aren’t stopping….) Consider upgrading to higher temperature brake fluid if you will track the car often. Disclaimer: This guide provides an overview and is not a substitute for common sense. Use at your own risk.
1. Chock your wheels and loosen the lug bolts and get the car up on jack stands on a flat, level spot with plenty of room to move around the car.
2. Remove the wheels and inspect the inside of the rims for any damage; inspect the rotor for damage and measure the thickness of the rotor (measure a number of spaces and take the average.)
3. Loosen the cap on the brake reservoir. (If you recently topped it off, remove some fluid with a turkey baster so it doesn’t overflow when you compress the caliper pistons.)
4. Remove the wire retaining clip by prying up at the bottom with a screw driver; remove the two caps and 7mm hex bolts that hold the caliper to the carrier.
5. Wiggle the caliper free of the rotor (remember to release the parking brake in the back). Don’t let the caliper dangle — support it with a box or use coat-hanger to hang it.)
6. Remove the outside pad (it may have stayed on the rotor)
7. Remove the inside pad by pulling it toward you.
8. Remove the wear sensor wire (left front, right rear). If you haven’t worn down to the sensor, no need to replace it. Just be careful when you pull it out so you don’t break it.
9. Compress the piston (a special tool helps, see below.) The front ones just compress, the rears compress and turn. Inspect the rubber boot for damage (See this post for rebuilding the calipers).
10. Clean the calipers and the piston with a wire brush. Do not damage the dust boot.
11. Grease the piston leading edge; the caliper opposite the piston, and any place where the metal of the pad will come in contact with metal of the caliper with Plastilube to prevent squealing. (Top tip: If you’re going to track your car, grease the edges where the pads ride in the carrier, but do not grease the piston or backing plates. The grease increases heat transmission. Not greasing the backing plates does significantly increase brake noise, however.)
12. Put the new inside pad into the piston opening (be sure not to touch the surface of the pad with your fingers or with any Plastilube) and attach the sensor wire.
13. Put the new outside pad into the carrier.
14. Slide the carrier housing onto the rotor and re-tighten the two 7mm hex bolts, then replace the caps
15. Replace the wire retaining clip (insert top in slot and pull down with pliers into the lower hole.)
16. Replace the wheel and tighten the lug bolts (80 lbs. or so).
17. Repeat 1-16 for the other 3 wheels.
18. Lower the car off of the jack stands (remember that you reset the emergency brake so it won’t stop the car from rolling, use a block.)
19. Torque wheels to recommended torque setting. (My car is 87 lbs.)
20. Before you remove the chock block, start the car and step on the brakes repeatedly. They will go to the floor. Repeat and you should feel the car adjust and the brakes return to normal feel.
21. Check the emergency brake, it should now grip.
22. Check brake fluid level and top off if necessary.
23. Go for a short test drive. REMEMBER THAT YOU HAVE NEW BRAKE PADS. (See “Bed-In Procedure” below.)
24. Drink beer when you get home (optional).
Helpful hints:
1. It’s a messy job. Brake pads do not contain asbestos any longer, but you should still avoid breathing brake dust. Do not use compressed air. Consider wearing gloves.
2. You can get a piston compression tool for about $40. I used this one.
3. Consider following this procedure to bed-in your pads. (Not that I’m suggesting you violate any posted speed limits….)
4. If you brake wear sensor light was lit or you see that the sensor wire was damaged, you should replace the sensor wire.
5. Check your new pads for the slot for the sensor wire before you begin. If you do not use the wire, just tie it back with zip ties, but remember that you will need to check your pads for wear.
6. If you have topped off your brake fluid recently, remember to remove some before you press the pistons back into the calipers and place a rag around the reservoir to catch any spills if you push any out. Remember to top off when done.
7. And whatever you do, don’t be this guy….
What was the cost? I suppose it depends on how you add it up. The jack was a sunk cost and the jack stands were borrowed from my neighbor. The caliper tool was $40. Plastilube was $8. New pads $248. Turkey baster used to remove brake fluid was $2. New brake fluid was $17. Total $315. It took me about 3 hours to do the work. The first wheel took over an hour; the second about 45 minutes; the third about 30 minutes; and the fourth about 20 minutes. I think I could do four wheels now in under 90 minutes.
Dragging Rear MINI Caliper Mystery Finally Solved
I think I finally solved a nagging problem I’ve been having with my right rear brake caliper. The right rear brake always ran hotter than the left. In normal city driving, it wasn’t a big problem, but at the track, that meant I would cook the brake pads at the end of a long session. It was all the more confusing because I was at Summit Point main and that’s the unloaded side. I replaced the brake caliper thinking the piston wasn’t retracting and that didn’t help. I disconnected the emergency brake cable thinking it was somehow binding under suspension compression and that wasn’t it either. Pressure was good and the brake line was unobstructed. It was perplexing.
While changing brake pads last weekend, I noticed the brass bushings had seized. Not only that, but they had seized in two different positions, as if under a very strong twisting force. Then I realized, the one thing I hadn’t ever checked was the brake carrier. At first I thought maybe one of the posts was cross-threaded, but sure enough the carrier itself was bent.
It’s bent. Dang. The direction of deflection made it difficult for the caliper to move once brake force was released. This would cause the inside to remain in contact with the rotor causing increased heat and wear. I installed a new carrier and no more heating problem. The piston retracts, and the inside pad moves away from the rotor again.
So the question now is why did it bend? It was binding because the brass bushings allowed no room for play, but did the bushings somehow cause the bending or was it just a manufacturing defect? For now I’m running OEM rubber bushings, but will keep an eye out for future temperature spikes when I head back to the track this coming weekend.
