Sunday, March 11, 2012

Top 10 Things to Bring to the Track: 7. The Fluids

Engine oil, brake fluid, coolant, differential fluid, transmission fluid, and water.

Car fluids easily make the Top 10 List of Things to Bring to the Track. To a car, they are just as important as water is to the human body. Neither will survive long without fluids. Insufficient fluids will seriously impair vital functions. Putting a car through the stress of a track event significantly increases the demands on the fluids it consumes. Bringing spares to top off fluids or flush them completely becomes very important.

Engine oil
At a performance driving event, you will spend most of the time in the right side of the tach, especially close to redline where the vast majority of cars make their max horsepower. An engine spinning at 6, 7, 8k RPMs will burn some oil, especially turbo cars and older cars with high mileage on the engine. It's not unusual for my '01 BMW 325i with 170,000 miles on it to use 1 1/2 quarts of oil over a 3-day weekend. So I bring two spare quarts when I take it to the track for "exercise". 

Brake Fluid
If you are running with a reputable car club that takes safety seriously (not all of them do!), you will be asked to tech your car and fill out a tech form before the event. By far the most important question on the tech form will be when you last changed your brake fluid. You probably know that once the rotors get too hot, the brake pads start transferring heat into the calipers. This in turn can overheat the brake fluid, which enters the caliper to hydraulically compress the pads against the rotor, to a point where it starts to boil. As this happens, bubbles start to form in the brake fluid. Air is compressible, and fluid isn’t; so you can sink your left foot all the way down without being able to slow down when there are bubbles in the brake lines. Brake fluid is hygroscopic, meaning it absorbs moisture over time. The higher the percentage of moisture in the brake fluid, the lower the boiling point. This is why changing the brake fluid is one of the most important things you can do to  get your car ready for track driving. Some clubs now even use a tool to measure the percentage of moisture in the brake fluid during track event tech inspections. Even if you changed the fluid recently and it was properly done, you may still need spare fluid for top-off. This is because the brake fluid level drops in the master cylinder as the brake pads thin down.

As you well know, coolant is the fluid that absorbs heat from the engine and dissipates it through the radiator. You will need coolant for top-off in case its level falls below the minimum indicated. I trust that you know not that check the coolant level when the engine is hot and the coolant is under high pressure. Just saying...

Differential Fluid
The differential has a lot of moving parts and the diff fluid can leak slowly. You'd be wise to peak underneath the car once a day at the track for signs of leaks around the differential. There isn't an easy way to check the level - you'd really have to stick your finger in the diff's fill hole and estimate the level. If there is a diff fluid leak and it feels that the level is low, top it off.

Transmission Fluid
Same goes for the tranny fluid.


With all this car talk, don't forget the fluid for the most important car performance contributor: the driver. I can easily go through a gallon of water during a hot Summer track day. You should be sipping water all day, at regular intervals, and drink before you feel thirsty. You know that if you do that, you will be going to the restrooms more often than a typical day in the office and that's OK. Also, no-one else may tell you this obvious fact so I'll have to say it here: when you go to the restrooms, make sure your pee is clear. If it's yellow, you are not drinking enough water. If it's orange... hmm you're in serious trouble. If it's blue or green, you are probably mutating (OK, this last part has not been scientifically proved yet.)

My Favorite Fluid!
And my favorite fluid: a cold beer or two at the end of the track day. But I trust that you are well familiar with that fluid and don't need to read about it. So if you are still reading this, please stop right now and treat yourself to a cold beer!

Gate sign at Roebling Road during the 2005 One Lap of America tour

Top 10 Things to Bring to the Track:
  7. The Fluids
  8. Code Reader
  9. Big Tarp
10. Pyrometer