20 Oct 06: After the hygienic stop at SportClips, it is time for another Trans Am pit stop, this time at Lewisville Muffler.
Two concerns: the mufflers installed earlier this year are occasionally scrapping the road, as first seen at Kwik Kar and
a leak in the rear engine seal, also seen at Kwik Kar.
The mufflers ride only four inches above the ground, so it doesn't take much to "bottom out." There is no other place
to put dual mufflers. The stock single muffler configuration robs about 40 hp from the engine, due to excessive
back pressure, according to Jason, the owner of Lewisville Muffler. The use of a wider, thinner muffler pair
is costly, both in terms of money and performance.
Turns out this car has air shocks, and I didn't even know it! Jason found the fill port in the trunk and pressurized the shocks to 60 psi. He checked the pressure multiple times over a period of time in search of leaks, and the the pressure eventually stabilized at 50 psi. Part of this drop is due to the shock stablizing; part of the drop is caused by the pressure check itself. The added air raised the back end of the Trans Am by one inch to provide five inches of clearance for the mufflers. The distance from the ground to the botton lip of the rear wheel well is 28.5 inches, as measured through the center of the wheel emblem. I will be checking this dimension daily, noting any changes. Jason commented that switching to a 70 series tire would raise the back end about 3/4 inch.
He recommends just running the tires I already have on the TA.
We also noted that the spare tire seen in this pic is marked "GR70-15" so it is at least 20 years old and is not suitable for actual use as a spare tire. I need to find a space saver spare, like the one that came with my first Trans Am in 1976.
The 2nd item to address is the source and severity of the leak seen here. There is a mixture of oil and transmission fluid on the transmission cover, the oil pan and the catalytic converters.
No head gasket leaks were noted. No leaks from the transmission lower cover were noted either. It is postulated that the leak originates from the rear engine seal. The fluid and oil mixture exits via the drain hole and is sprayed along the underside of the car. Jason estimates that the cost to fix this leak is $500, and recommends doing nothing about it. The leak is very slow and is not of any significance.
Next thing is to spray a protective film over the mufflers, particularily the areas showing impact with the pavement. This is done in the interest of rust and corrosion prevention. The spray color approximates the color of the mufflers and pipes.
Then a degreaser is used to clean up the spray from the rear seal leak, and high pressure air is used to complete the job.
Time to get back on the road again. I'd like to thank Jason for his expert care of my TA, and for his patience and tutorials.
If you ever need exhaust work performed on your vehicle, I highly recommend Lewisville Muffler.
Next, come with me to see my friends Juston and Terry.
