FAQ’S

Common Questions About Transmission Tech

We address the most common inquiries from our customers.

No, the 700R4 and 2004R only need voltage to control the torque converter clutch solenoid, all the shifts are performed hydraulically.

We wire our transmissions up internally so all you need to do is attach a 12 volt source to the supplied pigtail and the trans will do the rest.

The term “Lock-Up” refers to a clutch inside the torque converter that , when applied, locks the internal components of the converter together to achieve zero slippage in the converter.

These type converters are found almost exclusively in overdrive transmissions but were also incorporated into some 3speed automatics with electronic control.

The greatest source of heat in an automatic transmission is the torque converter. This is because there is a constant source of friction within a converter and as we know, friction creates heat.

Even the most efficient low stall torque converter will never stop slipping so you will always have that source of heat generation in a non locking converter. When you add stall speed to a converter you are raising the RPM that the converter must attain before it transmits full engine power back to the transmission.

While this is great for performance, it creates an even greater heat and efficiency problem. To make matters worse, in an overdrive transmission, even with steep gears, the engine rpm’s at cruise may be substantially less than the stall speed of the converter, a recipe for disaster.

By applying a Converter Clutch you eliminate this slippage and heat source, allowing you to have the benefits of a performance oriented stall speed, plus economy, efficiency and lower operating temperature.

Stall speed is when your torque converter transfers engine power to the transmission. Think of it like two fans, one spins with the engine, the other with the transmission. At stall speed, they’re moving nearly together.

Key Types:
Brake Stall: RPM when throttle is applied while braking (hard to measure)
Flash Stall: RPM spike during full-throttle launch (what racers tune for)

What Affects It:
Engine torque
Vehicle weight
Converter design (fin angle, oil flow)

Why It Matters: Proper stall speed matches your engine’s power band for optimal acceleration without sacrificing driveability.

COMPUSHIFT® is a revolutionary, state of the art product designed by HGM Automotive Electronics Inc. The COMPUSHIFT Transmission Control System (TCS) operates automatic shifting and converter clutch lock up for the 4L80E, 4L60E, AODE and 4R70W transmissions. 

COMPUSHIFT® is fully programmable and user friendly. Adding an electronically controlled transmission into a street rod, truck, RV or vehicle was never so easy.

First a bit of history, the Throttle Valve or TV system for transmission pressure control has been around since GM introduced the Hydramatic transmission before World War II nearly 70 years ago.

These early systems used a collection of rods and clevises to connect the accelerator linkage to the transmission and required skill, and patience to adjust as well as some special tools. GM continued to use this type of system as did both Ford and Chrysler until the 1970’s when a cable system was adopted.

The more “modern” variants of this system have been in place since the 1976 introduction of the TH-200 transmission. Mercifully, GM did away with the complex linkage and provided us with a simple cable system which stayed in use till 1993 when the General phased out tv controls all together for fully computerized transmissions.

Basically, the TV system provides the transmission with pressure increase proportionate to throttle opening. Why is this important you ask? Well, when you are cruising around slowly or gently accelerating you want the transmission to shift smoothly and keep the engine at a practical and efficient rpm.

But, when you want to accelerate quickly you want the transmission to keep the engine in a higher rpm range where it makes more power. Under this scenario the transmission needs increased pressure to apply the bands and clutches and keep them from slipping under the demands of increased power and acceleration.

A modern TV system uses a cable which runs from the accelerator linkage to an internal transmission linkage that depresses a plunger in the valve body to regulate tv pressure so that transmission line pressure matches acceleration demand.

All GM TV cables require the same basic adjustment: 1 1/8″ of pull from idle to wide-open throttle (WOT), with the cable fully tight at WOT without restricting throttle travel.

This ensures proper line pressure, shift points, and kickdown. While factory Chevy carbs (like Quadrajets) have ideal linkage, aftermarket carbs often need adapter brackets, which we manufacture for precise adjustment.

Even with unconventional setups, the key is maintaining straight cable routing and the correct 1 1/8″ travel. Our Weatherford-designed solutions work with stock or Lokar cables, including discreet installations for stock-appearing restorations.

Below, we have tried to answer the most common questions visitors may have. If you find that your question is not answered on this page, please E-mail us at questions@phoenixtrans.com or call us during [7:00 to 5:00 Monday-Friday CST] at 817-599-7680.

Transmission Gear Ratios

1st2nd3rd4th
TH-3502.521.521.00–
TH-4002.481.481.00–
TH-2004R2.741.571.000.67
4L80E2.481.481.000.75
TH-700R43.061.621.000.7
4160E3.061.621.000.7
AOD2.41.461.000.67
5182.451.451.000.69

Popular Automotive Math Formulas and Conversions

RPM = mph X gear ratio X 336 divided by tire diameter.

To convert from:

Miles to Kilometers, Multiply by 1.609344
Liters to Cubic Inches, Multiply by 61.023744
Inches to Millimeters, Multiply by 54.4
millimeters to Inches, Multiply by .0393701

OPENING TIME

Monday7AM – 5PM CST
Tuesday7AM – 5PM CST
Wednesday7AM – 5PM CST
Thursday7AM – 5PM CST
Friday7AM – 5PM CST
SaturdayCLOSED
SundayCLOSED
Closed for lunch 11:30AM – 12:30PM