T-5 Guidelines – Manual Transmission Upgrades for Older Cars and Trucks
by Tom Langdon
All pre-1955 cars and trucks have gearing that is not optimized and inappropriate for today’s roads and especially for cruising on the interstates. The Borg Warner T-5 manual transmission as used in the 1983-1987 S-10 trucks has become a favorite choice for resolving these issues. There are over 200 versions in this family as used in S-10 trucks, Camaros, Firebirds, Mustangs, Ford Rangers, Toyotas and Jeep Cherokees. These transmissions have many variations – bolt pattern, shifter location, speedometer drive, input spline and length, gear ratio, strength, and non-world class vs world class. Some parts interchangeability and adapter availability make this transmission the most popular and affordable transmission upgrade for older vehicles.
For bench seat pre-1955 Cars and Trucks you will need the S-10 truck version.
Assuming you want to retain your original cable drive speedometer, you will need the 1983-1987 truck version ONLY!
There are two bolt patterns: Chevy, which fits most Chevy applications and Ford, which also fits some Mopar applications.
These transmissions were torque rated for engines from 150 Cu. In. to over 300 Cu. In. Non-abusive driving allows some latitude in your choices, but using a transmission from a 150 Cu. In. four cylinder in a 300 Cu. In. engine will result in early gear failure. As a general guideline the 1st gear ratio is an indication of relative strength: 4.03: 1 (4 cyl) being the weakest and 2.95:1 (V8) being the strongest. As the design was upgraded to ‘World Class’ these torque ratings were increased somewhat.
Also, as the ratios varied, (from 4.03 to 2.95) the pleaseability and performance characteristics improved. (“Closer” ratios)
General guidelines would recommend about 12:1 1st gear overall driveline ratio (1st gear x axle ratio) for a good ‘take off’ gearing for a 235 Cu. In. engine. Below 10:1 will require clutch slipping and in excess of 15:1 will be an aggravation similar to a ‘granny gear’.
Final drive should be between 3.0 and 2.50. If overdrive is .73 and your axle is 3.73, your final drive will be 3.73 X .73 = 2.72 (perfect!)!
A clutch disc with splines compatible with the transmission you choose will be required. If your pressure plate is in good condition, you can use it.
Refer to the T-5 website for more info and customer installation information. Http://www.5speeds.com/t5
revised 2/6/14 del