Installing a 5-Speed into a 1971-73 Mustang/Cougar

By Modern Driveline • August 06, 2019 Posted in Builds, Ford Featured Cars, Tech Info, Transmissions

It’s a gorgeous summer day in suburban Boise, Idaho where we’re installing a TREMEC T5 five-speed transmission in the “Rebuilding Generations” ’71 Mustang convertible along with a Modern Driveline cable clutch upgrade for smooth clutching and shifting.
The TREMEC T5 from Modern Driveline, which has been in continuous production since the early 1980s, maintains its great reputation as a lightweight, easy to shift, durable five-speed overdrive transmission.

At Modern Driveline, we’re well known for great classic Mustang and Cougar five-speed swap packages where all you need is the desire, energy, and a weekend to get the job done. You can go from straight drive automatic or stick to efficient overdrive in the time it would take you to mow and trim the yard over a weekend. If you get hung up with a technical problem we’re here to help you through it with close, personalized tech support from enthusiasts who understand your challenges because we’ve been there ourselves. We own and drive the great performance cars you’re passionate about.

It’s a gorgeous summer day in suburban Boise, Idaho where we’re installing a TREMEC T5 five-speed transmission in the “Rebuilding Generations” ’71 Mustang convertible along with a Modern Driveline cable clutch upgrade for smooth clutching and shifting. The TREMEC T5 from Modern Driveline, which has been in continuous production since the early 1980s, maintains its great reputation as a lightweight, easy to shift, durable five-speed overdrive transmission. The real beauty of the T5 is size and weight. It fits the classics and it also fits the late-model Fox body and SN-95 Mustangs.

Let’s get started.

Modern Driveline T5 Quick Tech

Introduced in the early 1980’s the T-5 has evolved to become an extremely versatile 5-speed that fits nearly every application imaginable. In its more than three decade history of great overdrive performance, the TREMEC T5 has been installed as original equipment in a variety of vehicles, from pick-up trucks and SUV’s to the fun to drive 1979-95 5.0L High Output Mustang. Today, the T5 still enjoys service as an original equipment unit in many applications around the world while remaining popular in the performance aftermarket. Dollar-for-dollar, pound-for-pound, the T5 is the smoothest-shifting, and most reliable five-speed manual transmission in the world.

Easily accepting up to 300 lb-ft of torque capacity, the TREMEC T5 is not only durable, but offers easy operation and a very efficient overdrive making any vintage or late-model Ford great fun to drive with fuel to spare when the drive is over.

T5 Performance Facts

Just 75 pounds dry
300 ft/lb Torque Capacity
Buttery smooth shift quality
Most popular light duty five-speed in the world
Main/Countershaft Distance – 77 mm
Overdrive in fifth gear for fuel economy and less wear
Aluminum die cast housings for reduced weight
Tapered roller bearings on main and countershafts reduce noise and improve durability
Needle bearing under 1st through 4th gears improve high speed performance and reduce shift effort
Advanced synchronizer technology
Powdered steel core blocker rings
Engineered friction materials for improved durability
Double cone design for lower shift effort
Patented strut-type design for improved durability
Sliding idler reverse for simple, reliable design
Internal, single-rail shift system
Reverse brake option allows immediate shift into reverse without clashing
Multiple shift lever locations
Adaptable to 4-wheel drive applications

Car Transmission Specifications

TREMEC Part Number	Weight (lbs)	Torque Cap. (lbs-ft)	1st	2nd	3rd	4th	5th	Rev
1352-000-208	75	175-230	3.35	1.99	1.33	1.00	0.68	3.15
1352-000-238	75	175-230	3.35	1.93	1.29	1.00	0.72	3.15
1352-000-239	75	175-231	3.35	1.99	1.32	1.00	0.68	3.15
1352-000-245	75	175-233	3.75	2.19	1.41	1.00	0.72	3.53
1352-000-247	75	175-230	3.75	2.19	1.41	1.00	0.72	3.53
1352-000-248	75	175-231	2.95	1.94	1.34	1.00	0.8	2.76
1352-000-249	75	300	2.95	1.94	1.34	1.00	0.63	2.76
1352-000-251	75	300	2.95	1.94	1.34	1.00	0.63	2.76
1352-000-254	75	175-230	3.35	1.99	1.33	1.00	0.83	3.15
1352-000-259	75	175-230	3.75	2.19	1.41	1.00	0.72	3.53
1352-000-260	75	175-230	3.35	1.99	1.33	1.00	0.68	3.15
TTET1239	75	175-230	2.95	1.94	1.34	1.00	0.8	2.76
TTET1544	75	220	3.35	1.99	1.33	1.00	0.68	3.15
TTET1798	75	220	3.35	1.99	1.33	1.00	0.68	3.15

Light Truck Specifications:

TREMEC Part Number	Weight (lbs)	Torque Cap. (lbs-ft)	1st	2nd	3rd	4th	5th	Rev
1352-000-077	75	175-230	4.03	2.37	1.49	1.00	0.76	3.76
1352-000-191	75	175-230	4.03	2.37	1.49	1.00	0.72	3.76
1352-000-216	75	175-231	4.03	2.37	1.49	1.00	0.86	3.76
1352-000-229	75	175-232	3.35	1.99	1.33	1.00	0.72	3.15
1352-000-234	75	175-230	3.76	2.18	1.42	1.00	0.72	3.76
1352-000-243	75	175-232	3.97	2.34	1.46	1.00	0.85	3.71
1352-000-250	75	175-231	3.76	3.18	1.42	1.00	0.81	3.76
1352-000-255	75	185	3.97	2.34	1.46	1.00	0.85	3.71
1352-000-256	75	225	3.97	2.34	1.46	1.00	0.85	3.71
1352-000-257	75	210	4.03	2.37	1.49	1.00	0.86	3.76
1352-000-258	75	175-230	3.76	2.18	1.42	1.00	0.81	3.76
1352-000-261	75	185	3.97	2.34	1.46	1.00	0.85	3.7
1352-000-262	75	225	3.97	2.34	1.46	1.00	0.85	3.7
TNET0563	75	175-230	4.03	2.37	1.49	1.00	0.86	3.76
TTET1333	75	185	3.97	2.34	1.46	1.00	0.85	3.71
TTET1750	75	225	3.97	2.34	1.46	1.00	0.85	3.7
TTET1751	75	225	3.97	2.34	1.46	1.00	0.85	3.7
TTET1752	75	225	3.97	2.34	1.46	1.00	0.85	3.7
TTET1853	75	190	4.03	2.37	1.49	1.00	0.86	3.76

Fig. 1: The Rebuilding Generations ’71 Mustang convertible is a My Deals LLC and Calvary Chapel of Eagle, Idaho adult/youth group project bringing young and old together in a genuine spirit of learning and growing from building a classic car together. Modern Driveline’s Bruce Couture hosted and sponsored this Rebuilding Generations five-speed swap where powertrain fundamentals were explained to young and old alike. We are proud to have been associated with an effort to bring the young and the elder experienced together in such a positive way.

Fig. 2: Modern Driveline’s performance-proven five-speed manual overdrive transmission from TREMEC has been an industry mainstay for more than three decades in a huge variety of applications around the world. If you’re doing a simple five-speed upgrade and your engine’s maximum torque range is below 300 ft/lbs, the T5 is an affordable choice that will serve you well for years to come. What’s more, Modern Driveline offers parts, service, and great personalized technical support.

Fig. 3 Here’s the complete Modern Driveline five-speed swap package ready to go for the Rebuilding Generations ‘71 Mustang project including a new TREMEC T5 transmission, engine separator plate, Superior clutch, flywheel, crossmember and mount, hardware, shifter, new Modern Driveline bellhousing, and Amsoil DEXRON III transmission fluid.

Fig. 4 Bruce Couture of Modern Driveline stresses the need for Teflon thread sealer on all small-block Ford V-8 flywheel to crankshaft bolt threads because these bolt holes go directly into the crankcase. He adds not using a suitable sealer will cause oil leakage into the bellhousing. He also points out the need to install new bolts due to stretch and fatigue issues. Never reuse old bolts.

Fig. 5 Flywheel bolts are installed and torqued in one-third values to 75-85 ft/lbs in crisscross fashion for uniform seating.

Fig. 6 Modern Driveline strongly suggests checking bellhousing alignment with a magnetic dial indicator. Even with a factory original engine, bellhousing misalignment can still happen causing clutch malfunction and driveline binding. Once an engine is rebuilt and line honed, this issue is even more critical because it changes crankshaft centering as it relates to the flywheel, clutch, and transmission. Ideally, you will have zero to no more than 0.005-inch alignment issues (0.010-inch total 360 degrees or double 0.005-inch). Rotate the crankshaft 360 degrees or one full revolution and watch the dial indicator. Alignment should not be any more than zero to 0.005-inch total out in any direction. A misaligned bellhousing can be corrected by checking alignment dowels for debris or using offset dowels available from Modern Driveline.

Fig. 7 Our new Superior diaphragm performance clutch from Modern Driveline is cleaned with a high-evaporative solvent like brake cleaner and a tack cloth. Flywheel surfaces get the same treatment to prevent clutch friction contamination.

Fig 8/9 Clutch disc and pressure plate are positioned using the installation tool provided in the kit. You can use the provided clutch alignment tool or a discarded transmission input shaft. Bolts are treated to a thread locker and torqued to 12-20 ft/lbs in crisscross fashion. Always use Grade 8 fasteners and lock washers.

Fig. 10 Cable style clutch fork and release bearing are installed in the Modern Driveline cast aluminum bellhousing because we’re doing a Modern Driveline cable clutch conversion. Release bearing is constant duty cycle meaning it rides the clutch fingers and spins all the time. For proper clutch operation, there needs to be cable tension all the time to get a smooth release.

Fig. 11 Bruce Couture (right) explains T5 function and proper installation to the Rebuilding Generations group while securing the new TREMEC for installation. Because the T5 is compact and lightweight, it is easily installed with a vehicle on jackstands in your garage. It is lighter than a cast iron Ford Top Loader or Borg-Warner T-10, which makes for easy installation.

Fig. 12 Bruce guides the Modern Driveline TREMEC T5 into position using a transmission jack showing Rebuilding Generations how to get the input shaft lined up with the new Superior clutch disc. This is where the bellhousing alignment check demonstrated earlier pays off because installation is a snap.

Fig. 13 Modern Driveline transmission crossmember for 1971-73 Mustang and Cougar is installed along with transmission mount.

Fig. 14 Modern Driveline/TREMEC T5 transmission is equipped with a back-up light switch, which is connected to the factory back-up light wiring leads. This is an easy modification to make.

Fig. 15 Completed Modern Driveline five-speed conversion looks terrific and is ready for operation. Modern Driveline has custom driveshafts in steel or aluminum to complete this installation.

Fig. 16 The Modern Driveline T5’s shifter location is perfectly centered in the 1971-73 Mustang/Cougar transmission tunnel. All you need now is the shifter handle and boot. What’s more, you may opt for a stock handle and boot for a stealthy appearance.

Enthusiasts Who Are Also Engineers

This is why you do business with Modern Driveline. We are not a large company with huge product development teams with bean counters and Wall Street investors looking over our shoulders. We are automotive enthusiasts bent on getting our products right before they’re ever sold to the public. We are also very determined to deliver great technical support after the sale. As a Modern Driveline customer, you will never be our guinea pig. We find problems before they get to you and solve them before they ever become a headache for you.

We don’t just find the fault — we find the fix at the prototype phase before products ever reach the mass production phase. And if you ever encounter a problem with any of our products, we invite your contact so we may solve it before it ever becomes a frustration for you. If there is a problem after the sale, we are here to provide lifetime technical support for any Modern Driveline product you buy.

If you’re looking for more information or a quote for your project send us your details and we’ll get back to you with a quote. Or call…

208-453-9800

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