Is a Competition Transmission Needed
There is probably a competition transmission shop in almost every town in the country. That can build a bulletproof transmission for American made vehicles. Whether it is a late model Mustang or a 60’s Chevelle, there are lots of aftermarket components. And many years of technology available for the transmission rebuilder to utilize.
The same cannot be said for the 4EAT automatic transmissions found in Subaru vehicles. In factory form, these transmissions demonstrate several problem areas. That can cause failure in as little as 20,000 miles with a stock engine. And even sooner in modified applications.
Poor shift quality, anemic factory components, and above all. Improperly configured torque converters plague the automatic transmission equipped vehicle. This is in conjunction with the automatic’s propensity to burn out the high clutch pack (third gear). The 2-4 clutches (second and fourth gear) with even moderate increases in engine output.
Import And Sport Compact Automatics To Their Fullest Potential
Realizing the need to take import and sport compact automatics to their fullest potential. IPT Competition Transmission – a New Jersey-based company. C
First up on the hit parade of internal modifications is the need to address the issue of valve body calibration. The valve body mods are really the foundation of any performance trans rebuild. An automatic transmission utilizes a network of valves, servos, solenoids, orifices, accumulators. And passages that control and route hydraulic pressure to the appropriate places to apply the clutches and bands.
Without going into elaborate detail which would fall outside the scope of this article, Suffice it to say that modifying the valve body effectively changes the rate of clutch applies. Also increases the clamping force with which these components have to work with. This is why shift kits and modified valve bodies produce that firm. P
Critical Support Bushings With Competition Transmission Need To Be Replaced
Next, all critical support bushings need to be replaced. To
Many of the other parts also such as the pinion shaft. The front differential ring gear, and the planetary gearset undergo various metallurgical processes such as heat treating, Meta-Lax stress relieving, and cryogenic treatment (freezing them in liquid nitrogen at -300 degrees Fahrenheit to ‘reset’ the part’s structure on the molecular level).
Lastly, all of the required seals and gaskets are changed to materials that are better able to cope with the heat and stress. That is common in high powered applications. Performance clutches and steel reaction plates are installed. Their clearances set too much more exacting specifications than those that are used by the factory. Most importantly, IPT utilizes a proprietary six disk high clutch pack and a five disk 2-4 clutch pack which increases the second, third, and fourth gear. Torque capacity by over 25% versus the factory set up. This is the key to getting a high powered vehicle make a 1-2, 2-3, and 3-4 shift. Instead of just bouncing off the rev limiter.
As for the modifications outside of the gearbox. The next thing of importance is, of course, the torque converter. In an automatic-equipped vehicle. O
Properly Designed Competition Transmission Converter Will Allow a Vehicle To Launch Under More Power
In addition to being made with many strength improvements over the factory piece. A performance converter enables a vehicle to better take advantage of the RPM range at which maximum power is made. In simple terms, a properly designed converter will allow a vehicle to launch under more power. By increasing the rpm at which the launch takes place. In essence, a torque converter is an infinitely variable transmission in and of itself. A
Even in otherwise stock turbocharged Subaru vehicles. ET reductions of over one full second are not at all uncommon with the addition of a properly configured converter.
Competition transmission, torque converter, and valve body upgrades are not only for American made vehicles anymore. Increased performance, durability and more efficient shifting are now available. For the vehicles of almost every manufacturer. Thanks in part to the few companies that are willing to do the research and development work required for this rapidly growing segment of the automotive aftermarket.