Precision Industries Vigilante Torque Converter Install and Test - Converting For Lower E.T.S - Pontiac Tech

We all like to go faster, but the path to lower e.t.'s isn't always through engine upgrades. There's performance to be found in the remainder of the drivetrain as well. Adding a higher-rpm stall torque converter to the 4L60-E or 4L65-E automatic transmission behind your GTO's LS1 or LS2 powerplant will improve acceleration, providing that the stall speed is properly matched to the engine output and torque characteristics. Another advantage is the stealth nature of a converter upgrade. No one will know about it except for you. In fact, it will be very difficult to detect-even by the dealer-which is a major plus if your GTO is still under warranty. This can't be said for more obvious underhood mods.

The torque converter, which is a hydrodynamic fluid coupling device, links the engine and transmission and acts as a torque multiplier during the stall and acceleration phases. Providing your GTO with the optimum stall speed will result in the best performance.

As the fluid is pumped through the converter, there are energy losses, however, leading to a coupling efficiency that in the past could never achieve 100 percent. With the advent of the lock-up torque converter, the industry was forever changed. Lock-up converters by nature add a clutch that physically links the pump and turbine, effectively changing the converter into a purely mechanical coupling upon lock-up.

This is a benefit to those installing a higher-stall speed converter when using the overdrive transmission because at highway speed with overdrive, cruise rpm will be lower than stall rpm. There would normally be slippage, which increases heat and reduces reliability, however, the lock-up feature has eliminated the slippage so now you can run a higher-stall speed converter to improve torque multiplication (performance) off the line and still cruise in overdrive at low rpm without worry.

Choosing a converter upgrade is generally determined by matching the converter stall speed to the engine's powerband, vehicle weight and rear gear, among other factors. According to Terry Hendrick, of Precision Industries, "Stall speed is determined by the engine's peak torque and is the rpm at which the converter will hold the engine speed and not allow further increase. Since many times when you rev the engine against the brakes the torque will overcome braking power and the car will start to push through them before stall speed is reached, hobbyists commonly use flash speed to discuss converters; that is the engine rpm at which the car begins to move forward when the gas pedal is depressed on launch.

"The real trick is to produce a torque converter that's strong enough to handle increased stall speed and still lock up efficiently. For owners of late-model F-bodies and GTOs, the factory torque converters stall between 1,500-1,800 rpm, depending on power. In general, for the majority of street applications, our Vigilante series of lock-up converters with a stall speed of between 2,800-3,200 are recommended."

Precision Industries developed the Vigilante line of converters from a clean sheet of paper and they contain state-of-the-art features including a specially designed and heat-treated 4130 alloy machined impeller hub, along with a heat-treated 4142 alloy turbine hub.

Precision Industries was the first aftermarket torque converter manufacturer to design, develop and manufacture multi-disc torque converters. In addition to carrying an industry-leading written unconditional two-year warranty, each converter is eligible for one free stall adjustment within two years of the date of purchase.

Unique features include a...        read full caption Unique features include a one-piece billet mounting cover and a billet clutch surface that provides an enlarged clutch contact area, and specially designed damper and clutch linings.	The Precision Industries Vigilante...        read full caption The Precision Industries Vigilante series of torque converters for the LS1- and LS2-equipped GTOs are 9.5- to 10.5-inch lock-up style units that can be ordered with stalls between 2,400 and 6,500 rpm. After consulting with RPM and Vigilante, a 9.5-inch, 3,200-rpm stall converter (PN LS2-3200, $765) was sourced.	Installation of the converter...        read full caption Installation of the converter begins by disconnecting the negative battery terminal and placing the trans in neutral. After getting the car in the air, the front skid plate was pulled off by removing the four 13mm bolts retaining it.
The two 13mm bolts that attach...        read full caption The two 13mm bolts that attach the catalytic converters to the headpipe on each side were removed, followed by the two 13mm bolts that join each pipe to the factory after-cat exhaust at the junction of the muffler and dual exhaust pipes. The two separate exhaust sections were then removed and stored for reinstallation later.		Electrical connectors were...        read full caption Electrical connectors were disconnected for each of the two front and rear O2 sensors because the exhaust system needed to be taken out to provide enough clearance to remove the transmission.
An 18mm socket-and-wrench...        read full caption An 18mm socket-and-wrench combination was used to remove the three nuts and bolts to separate the driveshaft-mounting flange from the rear pinion yoke flange. The front driveshaft yoke was left in the transmission to prevent fluid from escaping out of the rear seal.	The shift linkage was rem...        read full caption The shift linkage was removed.	Next, the four 16mm bolts...        read full caption Next, the four 16mm bolts holding the transmission crossmember were extricated.
At the front of the transmission...        read full caption At the front of the transmission on the passenger side, the two engine starter bolts were liberated with a 13mm socket. Gently allowing the starter to rest on the steering rack, the single 10mm bolt that holds the transmission dustcover was then taken out.	At the back driver-side of...        read full caption At the back driver-side of the bellhousing, the inspection cover was snapped off and a prybar was employed to rotate the flywheel until each of the three torque converter bolts was visible through the transmission dustcover. Then they were removed with an 18mm socket wrench.	Since the plan was to upgrade...        read full caption Since the plan was to upgrade the transmission with Amsoil synthetic ATF, the pan was dropped by backing out the 16 13mm bolts with an impact wrench. In addition to reducing the weight of the transmission assembly when removed, it's a good idea to do a trans service at this point, anyway.