With the price of gasoline creeping higher and higher at every commodity trader's whim, some owners may find it increasingly difficult to fill up their classic car, or take it on that weekend getaway simply because of the poor fuel economy. Shane Struthers of Tarpon Springs, Florida, experienced this firsthand when the majority of his vacation money went toward filling up the tank in his '73 Mach 1 Mustang.
It turns out that the thirsty 302/C4 drivetrain combination isn't the most frugal of gas sippers when it's buzzing at 3,000 rpm while going down the highway at 70 mph. Do this for, oh say 1,000-plus miles like Shane did while on the Hot Rod Power Tour and you can imagine the sucking sound the debit card makes at the pump as it drains your bank account.
To remedy this situation, Struthers contacted the folks at Monster Transmission in Brooksville, Florida, to see what they could do to ease the excessive highway rpm. The solution came in the form of one of the company's AOD swap kits.
The Monster AOD is fortified with Alto clutch packs and friction plates, as well as Kolene steel plates to provide a gearbox capable of 450 hp. We documented the buildup of a similar AOD in our Feb. '11 issue, which you can obtain through our back issue department or check it out on our website. In this article, we've documented the installation of the AOD in Struther's fastback. The result, as predicted, knocked the cruise rpm down considerably, so the next time Struthers wants to make the long haul, he'll have a little more green leftover for the fun stuff.
Shane Struthers, and his father Gene, built this Mach 1 from the ground up over a year's time. At just 17 years of age, Shane has plenty of time to enjoy his Mustang in the future. Having followed the Hot Rod Power Tour in 2011, Shane dropped more than $1,000 on high-priced gasoline to make the trip. With the three-speed automatic, the Mach 1 was turning 3,000 rpm at 70 mph, and sucking the tank dry. Now with the added overdrive from Monster, Shane tells us that the Mach is now a highway cruiser turning just 1,750 rpm at 75 mph. That'll keep those butterflies closed a bit more and likely improve fuel mileage considerably.
1 The first step in our AOD...
1 The first step in our AOD conversion is to remove the driveshaft. Have a drain pan or bucket handy for trans fluid that may leak from the tailshaft.
2 The starter is next, and...
2 The starter is next, and depending on your header/manifold setup, may cause the use of some four-letter words and/or possibly the removal of the header. Ours dropped out fairly easily, but we like to give you the heads up anytime you may encounter difficulties. Depending on your header selection, fitment of the AOD between the collectors may prove problematic.
3 The shift lever was disconnected...
3 The shift lever was disconnected next, and the neutral safety/reverse light switch is removed as it will be converted to a different harness connector.
4 The transmission cooler...
4 The transmission cooler lines are disconnected--there's a good chance that you'll need to reroute these once the AOD slides into place.
5 The lines to the C4's vacuum...
5 The lines to the C4's vacuum modulator are disconnected and removed. You'll need to plug their source in the engine compartment, as the AOD does not require these.
6 The torque converter bolts...
6 The torque converter bolts are removed next.
7 It's time to remove the...
7 It's time to remove the bellhousing bolts, and while you're doing that, you can remove the dipstick tube. The C4 bolts are shorter than the AOD's due to a difference in case thickness, so you'll need to source new fasteners that are 1/2-inch longer.
8 After dropping the crossmember,...
8 After dropping the crossmember, the old automatic box comes right out.
9 This stud on the shifter...
9 This stud on the shifter lever is removed, as the new Lokar cable that Monster utilizes bolts directly to the lever.
10 Prior to installing the...
10 Prior to installing the AOD, you'll want to clean out the trans cooler lines and the cooler itself. Monster uses Kooler Kleen, a product designed just for this task.
11 Here, the neutral safety/reverse...
11 Here, the neutral safety/reverse light switch has been replaced with the later-model plug that will connect directly to the AOD.
12 All the key players in...
12 All the key players in the AOD swap are here (the trans cooler cleaner and trans fluid are not included in the kit). Monster can tailor the torque converter to your application, which can be beneficial should you have a higher duration camshaft or just want a bit more stall speed for a harder launch.
13 The flexplate is bolted...
13 The flexplate is bolted up just after the installation of the block plate. Remember to use thread locker on the bolts and torque to spec.
14 Be sure to top off the...
14 Be sure to top off the converter before installing it into the transmission. Monster prefers to use Schaeffer's All-Trans Supreme synthetic lubricant in the AOD.
15 The included transmission...
15 The included transmission crossmember is a beefy tubular piece. Depending on the model year and exhaust system, it may be easier to loosely install the crossmember and then slip the trans mount into place.
16 Depending on the model...
16 Depending on the model year, rear axle, and current driveshaft, you may have to modify the driveshaft to fit the longer AOD. We were lucky in that ours required no such modification, but there are a number of driveshaft shops that can cut, weld, and precision-balance your shaft should you need to shorten it.
17 Rather than utilize the...
17 Rather than utilize the old rubber transmission lines, Monster bent up a new pair of metal extensions that bolted directly to the transmission. Be careful not to kink the lines if you go this route, as you can damage the transmission by choking off or backing up the fluid.
18 The TV or throttle valve...
18 The TV or throttle valve cable is next, and key to the AOD's proper function. It replaces the kick-down lever from the old transmission, and will need to be fine-tuned to adjust the transmission line pressure to provide accurate shifts based on pedal position. Monster does this at its facility on its in-ground dynamometer to ensure that your vehicle shifts properly before going out the door.
19 The speedometer driven gear is updated to accommodate the different gear ratio of the AOD and keep the speedometer reading accurately.