If you drive your car hard, broken parts are inevitable. If you go to the track regularly or drive your car in anger, you will eventually find the weak link in your combination. Downtime and the expense of replacing hardware thoroughly sucks, so we always recommend installing the best, and strongest components that you can afford.
Last month, we buttoned up some odds and ends on our Three-Valve Fox project and headed to the track. With the engine firing on all cylinders, we laid down a mid-12-second quarter-mile time, while not cleanly negotiating all of the gears in the high-mileage T45 transmission. The end result was a best e.t. of 12.63 at 108 mph, a broken T45, and a majorly disappointing ending to our track outing.
After limping home, the transmission debate started. Some said go auto; some said stay with a stick. All had valid reasons, which made the decision a tough one. In the end, we opted to rebuild the T45.
The first step in our trans...
The first step in our trans swap was to remove the broken T45. Although we are just guessing, we think a bent shift fork is all that’s needed to make this a useable transmission again.
We began looking for rebuild kits that would allow our T45 to handle a significant amount of power. We contacted American Powertrain, which offered its Patriot T45Plus, designed to handle 500hp and 430 lb-ft of torque. But when we spoke to Gray Fredrick of American Powertrain, he had another idea.
"Tremec acquired parts of Borg-Warner in the late '90s," explains Fredrick. "It kept the T45 in production for the Mustang until 2000. In 2001, Tremec supplied Ford with a the TR3650 as a direct replacement for the T45."
When it came down to it, there is no logical reason to built a T45 when the 3650 is readily available and is simply a better transmission. Factor in that Tremec still makes parts for the 3650 and the decision was an easy one. Once we decided to go with a rebuilt TR3650, the next step was to find a core. A call to MPS Auto Salvage in Statham, Georgia, netted us a solid one from a New Edge GT.
1. The base of the rebuilt...
1. The base of the rebuilt TR3650 is hardened internals from American Powertrain.
Once at American Powertrain's facility, the gearbox was completely stripped and inspected. Any damaged or worn parts were replaced, and the trans was reassembled with new parts that allow it to handle massive amounts of power.
For our build, we're upgrading to one of American Powertrain's Patriot 3650Plus Extreme units, rated to handle 700 hp and 600 lb-ft of torque. The build includes new bearings and seals; carbon fiber synchros; hardened dual fork pins; new small parts kit; 1⁄2-inch and 3⁄4-inch Gorilla shift forks; solid billet keys; and a dual base-welded, Cryo-hardened, 26-spline input shaft. We also installed an American Powertrain's Science Friction Street Slayer clutch and White Lightning shifter.
To finish the drivetrain upgrade, we contacted Axle Exchange in Fairfield, New Jersey, for a driveshaft that would handle abuse at the track along with the street miles we intend on putting on our Three-Valve Fox. It supplied us with a 4-inch, aluminum shaft with upgraded yolks in the correct length for our odd build. After giving Axle Exchange all of the measurements, we were supplied with a shaft that fit perfectly.
2. The gears, input shaf...
2. The gears, input shaft...
2a. ...sliders....
2b. ...and output shaft are...
2b. ...and output shaft are Cryo-hardened for strength.
With everything back together and some light miles to break-in the clutch, we headed to Bradenton Motorsports Park for some quarter-mile action. Before the trans swap, our Three-Valve Fox laid down a 12.63 at 108 mph, with us missing Third before the T45 let go. As we pulled the car into the burnout box for the first time, we were hoping to drop a couple of tenths by simply getting through all the gears. We were rewarded with a 12.17 at 112 mph on the first pass!
Seeing a low 12-second run without really launching or driving hard gave us faith that an 11-second pass wasn't out of reach. Unfortunately, it wasn't meant to be. After launching, it made some horrible noises and we were forced to park our Pony.
Once it's back in the shop and we tear it apart, we'll make it stronger and try to break (pun intended) into the 11s.
3. The upgrade to the Patriot...
3. The upgrade to the Patriot 3650Plus Extreme gives you bronze shift fork pads.
4. With the 3650 ready to...
4. With the 3650 ready to go in the car, we installed the shifter outside of the car. We started with a healthy bead of silicone.
5. Next, we dropped the American...
5. Next, we dropped the American Powertrain White Lightning shifter mechanism on top and bolted it down. This shifter has two adjustable centering springs that find Third gear for you. You can also adjust the spring to make it easier to put the trans into Reverse. We left the shift handle off till later for extra clearance during installation.
6. Side by side, it’s easy...
6. Side by side, it’s easy to see the difference between the two transmissions. The 3650 (near) has a much beefier case with more webbing for added strength.
7. The T45 uses a 10-spline...
7. The T45 uses a 10-spline input shaft, which is a weak link in higher horsepower applications.
8. Although we aren’t rotating...
8. Although we aren’t rotating the Earth, our Three-Valve engine makes good power naturally aspirated, and may see some boost in the future. To prepare for big power, American Powertrain’s built our trans with a stronger 26-spline input shaft.
9. We were also supplied...
9. We were also supplied with American Powertrain’s Science Friction Street Slayer ceramic clutch. It’s rated to handle up to 845 lb-ft of torque, while offering comfortable pedal pressure and tons of holding power.
10. After torquing the clutch...
10. After torquing the clutch to the flywheel, we were ready to install the 3650. Being that this is a direct replacement for the T45, there were no modifications needed. Simply swap the boxes and get on the road. All of the connections are the same, so is the driveshaft and transmission crossmember.
11. Next one the list was...
11. Next one the list was our new driveshaft from Axle Exchange. We called the New Jersey-based company, gave them the needed measurements, and in a couple of days we had a custom driveshaft made specifically for our combination. The 4-inch shaft is a tight fit with the torque arm, but after lowering the rearend housing, it slid right into place.
12. Before moving the car...
12. Before moving the car under its own power for the first time, we filled the 3650 with fresh ATF from Amsoil.
13. Inside the car, we finished...
13. Inside the car, we finished off the install by installing the shift handle adapter supplied by American Powertrain. The adapter allows you to put the shift handle in a variety of positions, allowing you to find the most comfortable driving position.
14. With our new transmission,...
14. With our new transmission, a few other things needed to be upgraded to make everything come together. One of these things was the speedometer.
15. Auto Meter sent us an...
15. Auto Meter sent us an electric speedo to replace our mechancal version.
16. Our old gauge cluster...
16. Our old gauge cluster housed a mechanical speedometer, which used a cable to manipulate the needle in the gauge. Our 3650 uses an electronic sensor. Auto Meter sent us a Pro-Comp Ultra Lite speedometer to match the rest of the gauges in our cluster. The Ford Racing Control Pack has a lead for an electronic speedo, so hooking up the gauge was as simple as finding the lead under the steering column, and plugging the harness into the new trans.
17. With the gauge cluster...
17. With the gauge cluster back together, the new gauge looks right at home with the rest of its silver-faced relatives.
18. After some light street driving to break-in the clutch, we headed to Bradenton Motorsports Park. The new trans worked great and we were rewarded with a 12.17-second pass at 112 mph on our first attempt. Unfortunately, when you fix one weak link, another can rear its ugly head. On the next few runs, something in the rearend gave out, and we were forced to park the car for the night. Once we get it fixed we are hoping for some 11-second timeslips!