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 Most Frequently Asked Transmission & Torque Converter Questions

    1. Should I use an external transmission cooler in conjunction with the oil cooler supplied in the radiator?

    2. What is the correct size cooler for my application?

    3. Where should I mount a transmission cooler?

    4. What type of clearance should I have between the torque converter and flexplate before pulling the converter forward and bolting it to flexplate?

    5. Is there an ideal way to measure the converter and transmission outside the car to make sure you should have the proper clearance between the converter and the flex plate before installation?

    6. Should I replace the front seal and bushing in my transmission before installing the new TCI® converter I just purchased?

    7. Should the brake lines for the TCI® "Roll Stop" be installed in the firewall side or the wheel cylinder side of the proportioning block on later model vehicles?

    8. What does the term "Lock-Up" mean?

    9. What about the Lock-Up feature in the overdrive units that TCI® offers? Doesn't my vehicle need an onboard computer (ECM) to work these newer transmissions?

    10. What is the difference in the terms "Flash Stall" and "Foot-Brake Stall"?

    11. What does the vacuum modulator do?

    12. Is there a right way or a wrong way to hook up my vacuum modulator?

    13. Are there any adjustments that can be made to the modulator?

Should I use an external transmission cooler in conjunction with the oil cooler supplied in the radiator?

Answer: Unless operating in an environment where the outside temperature is below 0°F, you should cap off the radiator cooler line openings and run your cooler lines directly to a new cooler mounted in front of the radiator. This allows the transmission to have its own cooling system and doesn't allow the engine water temperature to heat the fluid.

 

What is the correct size cooler for my application?

Answer: Unlike a lot of items you buy for your vehicle, bigger is predominately better when it comes to transmission coolers. The answer would be as big as you can get or to run multiple coolers in series, again staying away from the factory radiator cooler lines.

 

Where should I mount a transmission cooler?

Answer: TCI® highly recommends mounting your external transmission oil cooler in front of the radiator. This allows for adequate airflow. If this is not possible then you should mount it in a location where the cooler can receive airflow. In extremely tight quarters, you may also mount the cooler and build an air dam that would allow the cooler to have air pass through it.

 

What type of clearance should I have between the torque converter and flexplate before pulling the converter forward and bolting it to flexplate?

Answer: You should have 1/8" (.125") to 3/16" (.1875") between the torque converter and flexplate before pulling the converter forward and bolting it to flexplate.

 

Is there an ideal way to measure the converter and transmission outside the car to make sure you should have the proper clearance between the converter and the flex plate before installation?

Answer: Yes, you can use a straight edge, laying it across the face of the bell housing. (Engine side) Then with the converter installed in transmission, take a ruler and measure the distance from the straight edge down to the mounting pad of the converter. The measurement should be as follows:

GM 4L60E 1 1/8" from Bellhousing to Pads
GM 4L80E 1 1/8" from Bellhousing to Pads
GM TH350 1 1/8" from Bellhousing to Pads
GM TH400 1 3/16" from Bellhousing to Pads
GM Powerglide 1 1/8" from Bellhousing to Pads
Ford C6 1 1/8" from Bellhousing to Pads
Ford C4 1 1/8" from Bellhousing to Pads
Ford AOD/AODE 1 1/8" from Bellhousing to Pads
Chrysler Torqueflite 727 1 1/4" from Bellhousing to Ring Gears (Not Pads)

  Note: Distance may vary +/- .050"

 

Should I replace the front seal and bushing in my transmission before installing the new TCI® converter I just purchased?

Answer: Yes. You should inspect the old converter you are removing for damage to the converter hub that rides in the pump of the transmission. If you find any wear on the hub at all, you should replace both seal and bushing. If you find no wear at all, you may be fine with just a seal replacement. You should at least do one (seal) if not both. (seal & bushing)

 

Should the brake lines for the TCI® "Roll Stop" be installed in the firewall side or the wheel cylinder side of the proportioning block on later model vehicles?

Answer: Brake lines for the TCI® "Roll Stop" should be installed on the wheel cylinder side of the proportioning block.

 

What does the term "Lock-Up" mean?

Answer: This term refers to a converter that contains an internal lock-up piston or device, either friction or mechanical. Transmissions such as TH350C, 2004R, 4L60 (700R4), 4L60E, 4L80E, AOD, AODE/4R70W and others, use these methods of eliminating slippage for an increase in fuel economy. Older transmissions such as the TH400, TH350, C6, C4 and others did not incorporate these methods of lock-up. The only way to increase fuel efficiency in these types of converters is to change clearances, redirect fin angles and usually lower the actual stall speed.

 

What about the Lock-Up feature in the overdrive units that TCI® offers? Doesn't my vehicle need an onboard computer (ECM) to work these newer transmissions?

Answer: No. The Ford AOD & GM 2004R/700R4 transmissions themselves are controlled by the internal governor and the TV (Throttle Valve) system. The lock-up mechanism in the Ford AOD transmission is entirely mechanical. The advantage to the AOD is that it operates automatically without any outside controls. This makes for an easy swap for an older Ford automatic behind non-ECM controlled small block engines. The only disadvantage is that there is no way to turn off the lock-up system.

The GM transmissions are connected to the ECM to run the torque converter clutch (TCC). TCI® has developed a universal lock-up system (Part #376600) that allows the TCC to be controlled automatically using a valve body pressure switch and an engine vacuum switch. 700R4 and 2004R transmissions equipped with this system can be used in any vehicle, whether it has an ECM or not. The system also allows manual control to override the automatic functions so that the TCC can be turned on in second and third gear or shut off altogether.

 

What is the difference in the terms "Flash Stall" and "Foot-Brake Stall"?

Answer: Of the two measurements of stall, 'Flash Stall' is the most accurate. Foot-Brake stall is dependant upon too many variables. (i.e. type of braking system, disc or drum brakes, how well adjusted the brake system is, ring and pinion ratios effect foot-brake stall more dramatically, idle characteristics of engine, cam installation for low end torque as needed by automatic transmission.)

Flash Stall can be determined a couple of different ways:

  • With the vehicle sitting still and idling in low gear, apply full throttle. As the vehicle begins its motion forward, notice the RPM hand on the tachometer. That is your Flash Stall. (Engine should be very responsive from idle. If not, camshaft timing and/or carburetor adjustments may need to be made in order for engine to be crisp from idle.)

  • With the vehicle in forward motion in high or drive gear and at its lowest mph where it will not kick back to a lower gear, apply full throttle while noticing rpm hand of tachometer. (This measurement of flash stall is best achieved with a full manual transmission.)

 

What does the vacuum modulator do?

Answer: The vacuum modulator is a canister that contains a diaphragm and a calibrated spring. The diaphragm senses changes in engine vacuum due to throttle position/load changes and transfers the diaphragm motion to the modulator valve in the transmission. The calibrated spring opposes the diaphragm movement. This provides the means for the transmission to adjust internal pressures based upon torque demand by the engine.

 

Is there a right way or a wrong way to hook up my vacuum modulator?

Answer: Since the transmission is so dependent upon the modulator to function properly, a good vacuum signal must be transferred from the intake manifold down to the modulator. The best way to insure this is to utilize hard steel line to carry the vacuum signal with approximately three inches (maximum) of rubber hose on each end for the connections. This setup will prevent the hose from cracking or burning in areas that are close to the exhaust system and will also reduce the chances of the hose collapsing onto itself. Most modulators require a minimum of 15 inches of Hg (Mercury) at idle to function properly.

 

Are there any adjustments that can be made to the modulator?

Answer: Stock factory modulators are pre-set and most are sealed. TCI® StreetFighter® modulator-type transmissions are all equipped with adjustable modulators. By turning the adjusting screw (found in the vacuum nipple) counterclockwise, you will lower the spring pre-load. This will cause earlier shifts. By turning the adjusting screw clockwise and raising the spring pre-load, the shift points will go up. The range of adjustability is only a few mph either way.

 

Please do not hesitate to call TCI® at (662) 224-8972 or E-mail us if you have any additional questions.