Monday, September 25, 2017

mini at the track - part 8

Driving on the track tax the car much more than one would ever driving on public road, as I found out from personal experience. It is extremely important to perform detail pre and post track day mechanical inspections. The heat, mechanical stresses, shocks, and vibration put the parts to their extreme limits. The most dangerous is fasteners loosen from shocks and vibration. There are many things I took for granted until I discover their vulnerabilities when pushed to the limits.

I always check the torque of the wheel lugs before and after a track event. They have been fine until after this most recent track event. I wanted to check them at the track but I didn't bring the torque wrench with me. In my post-track day inspection, I was very surprised to find a few of the front wheel lugs has lost their torque. I had brake much later and harder at the end of the straights from speed in excess of 100 MPG down to circa 40s.

The other thing that I discovered is how hot the floor of the boot is after a track session. I found out the high density Styrofoam tool kit container in the batter box has melted from the heat of the floor.

the small tool kit tucked next to the batter in the battery box

the styrofoam container was melted by the heat from the muffler and tailpipe under the boot floor

MINI engineers has placed heat shields to protect the boot floor as well as the battery box

the last 1.5 foot of the tailpipes are the only spot that are not protected by heat shield

Also in the last track day the muffler pipe joint worked loose leading to sagging tail pipe which rested on the battery heat shield. I realigned the muffler/tailpipes and tighten the muffler pipe clamp before the track day. Less than half way through the the event the joint is loose again, and I wonder if the U-shape steel clamp had grew red hot and stretched, or just the two nuts has worked loose. It is impossible to tell after the fact. This time I added two nuts to act as lock nuts.

I added two nuts to lock the two nuts.

here shows heat shields by the muffler

this shield for the battery box looks to be more of a splash gaurd rather than a heat shield, and I think it traps heat and leads to hotter battery box

I noticed a few drop of liquid on the driveway. It turned out is engine oil. I was alarmed. My immediately thought is may be the compression fitting for the mechanical oil pressure gauge had worked loose from extreme vibration and rocking of the engine.

a few drops of engine oil

I notice that the connector for the factory oil pressure switch is charred - obviously from the radiant heat emitted by the exhaust feeder pipes. I have no doubt after mostly sustained wide open throttle driving on the track the header pipes must be glowing red hot.

the charred connector for the factory oil pressure switch

I believe the reason the connector is charred is due to my installation of a oil pressure gauge pickup fitting. In order to add the oil pressure gauge pickup I had to install a T-adapter fitting, which pushed the oil pressure switch and its connector farther away from the engine by about 1.5 inch. Just this subtle change of the location vastly increases the exposure to the irradiated heat from the feeder pipes.

The other thing that alarmed me is the cause of the engine oil leak. It is not from the compression fitting for the oil pressure gauge. It is from the pipe thread of the T-adapter that screws onto the oil filter housing. Because of the tight confine of the location, the T-adapter must be installed with the extra tap facing 11 o'clock I did not tighten the adapter as tight as I would like for the fear of breaking the aluminum oil filter housing. I relied on the teflon tape to take up the looseness of the threads.

The heat and vibration stress from the track as well as the engine oil acting as excellent lubricant on the teflon and metal mating surfaces caused the fitting to become so loose that I could turn it with my fingers. My initial thought that may be the teflon tape has been dissolved by the engine oil turned out not to be the case.

with the advise of my ME friend I drove to Napa Autoparts to buy a $15 tube of special automotive thread sealant; it turned out I do not like the product over generic household teflon tape

here is a better view of the charred connector of the oil pressure switch

The problem with the T-adapter is, to install it with adequate torque I will have to tighten it one half turn in order to orientate the compressing fitting for the oil pressure gauge at 11 o'clock. I am very wary in doing so I might fracture the aluminum oil filter housing.

alarmed by the charred connector I removed the T-adapter and put the oil pressure switch back into the factory configuration

I covered up the for-now defunct oil pressure pickup compressing fitting and zip-tied it securely until I can decide what to do.

The next thing is to inspect all the tires and rotate them. I always read the tire wear after a track event.

left front (left) and left rear (right) side by side so I can see the outer shoulder wear

the center thread of these tires took a beating and a slant is worn on it, while the outer shoulder wear is not excessive

here is a better view of the slanted center thread

these tires were brand new 2 1/4 track days ago

the right rear (left) and the right front (right)

On thing that I like in reading the tires is the right side tires wears are very close to the left side counterparts. Portland International Raceway is a clockwise track so the left side tires should wear significantly more than the right side.

I performed a X-pattern rotation  on the tires to even out the wears. These tires are asymmetrical but bidirectional.

Mini's rear suspension has the colours of German flag - black, red, yellow

The next task of business is to inspect all the brakes.

the front racing brake pads has lost about 1/4 of the friction material in just one track event

while inspecting the brake pads I noticed that I neglected to put the grommet that secure the brake hydraulic line into the steel cradle after I installed the racing pads before the track day; this is a serious oversight

the pads for both rear brakes are considerably worn from having to keep up with the front brakes, and that I braked harder and later during this track day

Mini consumed about 1 3/4 tank of petrol for about 145 miles of intensive driving

I topped up with Costco cheap (price wise) fuel so I can more accurately calculate the MPG at the track. My rough calculation of the fuel that I put in in three occasions worked out to about 20.5 gallons consumed based on 161 miles results in 7.85 MPG on the track!

For my concerned readers, I should add that as soon as I saw the few drops of oil left on the driveway I look under the engine too and confirmed some wetness. I immediately check the oil level, and it was only down 1/4 quart if at all on the dipstick. So Mini is absolutely fine.

As I wrote above that I was reluctant to tighten the T-adapter fitting for the oil pressure gauge pickup for the fear of breaking the aluminium alloy oil filter housing. I went and look for a good closeup photo of it for a better look how strong it is. I found one from back in May when I did the drivetrain modifications.

the threaded boss of the oil pressure switch seems to be strong enough to take a half more turn without causing any harm

This is the reason I can never throw anything away. I found the piece of remnant of the nylon oil pressure line that came with the Autometer oil mechanical pressure gauge that I installed. It is no cheap tubing like most automotive gauges that are made in China. It has marking of "airlite s&l nylaflow pressure tubing" with the manufacturing date stamp. Google it and I found the very detailed and complete product specifications.

The tubing is type T which has a melting point of 500F. However the suggest application temp is only 150F. I infer it is this low to take into consideration of plastic creep under the maximum rated pressure.

weather outlook is good when the Milltek arrives

BP-10 pads

other pads for Wilwood 12.19" BBK calipers

R53 Mini's gearing ratios

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