Saturday, September 12, 2015

HPDE at Putnam Park Road Course (followup)

I had time today to tear into the Corvette and look at some of the issues I had last weekend.

First on the agenda was to clean up the car, it had rubber marks all over it along with rubber behind the wheel wells. I put the car up on jack stands and removed the wheels because I needed to look at the front end and brakes anyway and its easier to wash the wheel barrels when they are removed.

When I removed the tires, I noticed the buildup of rubber on them. This could have been the cause of the push, its also a lot of buildup still on them after driving the car all week putting almost 200 miles on it since the track.

There was also still a ton of brake dust inside the wheel barrels, I wash these weekly on or off the car.

Looking a bit further I found the passenger side forward sway bar bushing had migrated out of the mount making the forward sway bar ineffective causing the push. The mount bolts were torqued properly and I cannot find any history on the net of this ever happening so the only conclusion I can make is I installed it incorrectly possibly not getting it set in the groves of the subframe and bracket.

You can see the bushing still on the bar in the lower center of the picture.

As for the spongy brakes I was able to figure a lot of that out before I left the track. Apparently bleeding my brakes a month before the track day was a bad thing to do, I should have bled them the day before. I wont go into a ton of details but basically brake fluid is very hygroscopic, the water it absorbs when heated turns to steam, steam compresses and you get spongy brakes.

The problem compounds itself because the brakes are weaker you use them longer and they get hotter.

Beyond even this is the brand of brake fluid, the better fluids cost more and the advantage of them is they raise the boiling point of the fluid some by more than 100 degrees.  Nearly everyone I spoke with was running Castrol SRF making it seemingly simple to just switch to using that. The problem is Casterol SRF is $60.00 for a 1 liter bottle, meaning it would cost $120.00 to flush and fill before a track event. Some of these guys are flushing their systems once a month and at a minimum before every track day they attend. I read some positive information on another fluid, Motul RBF 600 which has a slightly lower boiling point but costs only $15.00 a bottle, I will try it first.

Lessons Learned:
Track Days are fun!

Track Days are expensive!
  • $325.00 Registration Fee
  • $220.00 Insurance
  • $050.00 Fuel (approximate)
  • $350.00 wear on brake pads and rotors (approximate)
  • $500.00 wear on tires (approximate)
Right at $1500.00 considering incidentals 

Flush the brakes and use good fluid

Take off center caps

Driving position
The entire day I felt like I was fighting the car, I generally drive with the seat fairly close but I had the seat back reclined too much. With it in a more upright position it put my arms at a more favorable angle and would have made it much less tiring.

As much as Id lke to do it again I don't know if I will due to the cost, there is probably some things I could do to cut out some of it but registration fees, fuel, wear and tear are pretty fixed. I may try some autocross, its cheaper, easier on the vehicle and less chance of wrecks and damage. 

Monday, September 7, 2015

HPDE at Putnam Park Road Course

A few months ago I stopped by my neighbors house and he invited me to join him for an HPDE (High Performance Driving Experience) at Putnam Park Road Course. Its something I had thought about trying but didn't really know where to start.

He regularly attends with 10 / 10ths Motorsports driving a modified, street legal 2007 Z06 with approximately 550 rwhp. Running in the advance group he is a skilled driver and very quick.

10 / 10ths had a HPDE scheduled at Putnam Park Road Course Aug 2nd, I had never been there before so Tania and I drove out to look around. The track and facilities are basically a country club for gear heads. The grounds and the garages are immaculate, there is a concession stand with good cheap food and a small set of stands to watch from. It also has a nice administrative building with classrooms and a members only clubhouse. During their lunch break we were allowed to take tour laps on the track (60mph max speed), that sealed the deal for me.

Over the last few weeks I had been preparing for the day, modifications to the car, researching safety equipment and insurance options. Fireproof driving gloves being recommended I bought a set of Impact Racing gloves last week and Saturday was debating purchasing one day insurance. The difference between driving on public roads and at an HPDE is you are responsible for damage to your car (regardless of someone else causing it) and any damage you do to the track, facilities, guardrails etc.

Sunday morning my neighbor stopped by at 5am and we headed to the track just over 30 miles from our homes. Stopping a few miles from the track to fill our tanks, we arrived at the gates just before the 6am opening. I parked on the main pit lane, unloaded the car and set up my canopy, the next couple hours consisted of a drivers meeting, classroom training, and instructor assignments. I contacted an insurance company recommended by 10 / 10ths and secured one day of insurance.

We were running the basic 1.766 mile Long Course (marked in red).

My first 30 minute session consisted of learning corner entries, where to accelerate, where to brake and getting comfortable on the track. Towards the end of the session I was growing in confidence until I closed a bit too quickly on a ZL1 Camaro entering turn 7 and went off track to avoid hitting him. This required me to enter pit lane while the track Marshall looked at the car for damage and gave me a short pep talk about staying on the track. The session ended with a reality check on my driving abilities and the realization of how long it had been since I had done this type of driving.

The second session of the day was by far my best, I had regained my confidence, was hitting my marks on the track and making consistent laps. Early in the session though my brakes felt spongy, this condition would plague me the rest of the day. When I returned to my pit area, I parked the car, chocked the wheels, opened the hood and grabbed something to drink. While we were sitting there I heard some strange noises from the Corvette. Walking around the car I found both front wheel center caps laying on the ground. The brakes had gotten so hot the heat that transferred to the wheels had melted the tabs on the center caps and they fell out of the wheels.

Session 2 video Tania took from inside the flagman tower.

Shot from the base of the flag tower:

A friend of mine stopped by and took pictures with his iPhone 4, the heat apparently was getting to it as well creating some interesting pictures.

Cool down after session 2.

My third and final session started very well, then the brakes started becoming spongy and the front of the car developed a push. My instructor thought my tires were the culprit, a low fuel light ended the conversation and we left the track.

Because the day went so smoothly they had a fourth session scheduled. I was physically exhausted after 119 laps, 90+ degree temperatures and had a gallon of gas left, so I chose to call it a day.

I learned a lot yesterday, I have some unexpected things to look at on the car, the brakes, sudden push in the front end and it looks like I just drove it 2k miles cross country. I had a total blast and cant wait to do it again.