[14] With the front adapter...
[14] With the front adapter elevated, the cryo- and REM-treated input shaft with its pressed-in tapered bearing is lowered into place.
American Powertrain’s cryogenic treatment consists of slowly reducing the temperature of the parts to -300 degrees F using liquid nitrogen, and then holding that temperature for 12 hours. This process relieves stresses and minute fissures in the part by refining the structure of the metal, resulting in a more uniform material. Strength and wear resistance are improved.
The rate at which the temperature of the part returns to normal also contributes to its attributes. According to American Powertrain, the quicker the part is returned to normal temperature after the process is completed, the better.
[15] After Greg taps the bearing...
[15] After Greg taps the bearing onto the front of the mainshaft using a properly sized traditional socket, the mainshaft is mated to the backside of the input shaft on the adapter.
REM treatment follows cryo and is a process that fills the minute imperfections that occur naturally in the gear’s surface. By filling and polishing these minuscule valleys and inconsistencies, fluid pressure requirement and friction are reduced across the gear face, and durability and corrosion resistance are enhanced. According to Gray, this translates into reduced temperatures, noise, and parasitic loss—which is good.
With the package chosen, we disassembled our broken transmission and sent the parts to American Powertrain to have them treated and put back together with parts included in the Level 2 package. Greg Lovell at Anti Venom handled the disassembly and reassembly.
[16] Next the countershaft was installed after its tapered bearing was pressed on (shown behind the bottle). Maintaining optimal lubrication of the parts—especially the bearings—during the assembly process is crucial. Greg uses Pennzoil ATF.
[17] The shift rails were...
[17] The shift rails were installed next. These will house the shift forks that we sent out to American Powertain for the treatment process. This is where a professional installer comes in handy to line things up correctly. Everything will be installed in neutral to keep the Third/Fourth shift rail from engaging.
While Anti Venom is mostly known for its high-end builds and performance installs, Greg has been rebuilding transmissions since he was a teenager and most of those high-horse cars that roll off out of his garage feature a trans he rebuilt. Even with the great “how-to’s” out there, it’s always best to seek out professional expertise when dealing with an expensive manual transmission.
Please keep in mind that this is not a step-by-step trans teardown and rebuild story, as space would simply not allow it. Instead, we cover most of the highlights of the process and discuss the upgrades.
[18] Greg slides on the new...
[18] Greg slides on the new bronze fork pads. From the factory, these pads are made of a nylon that tends to wear and distort under the stress of performance driving. Once they have worn out, it can make it extremely difficult to shift—as was the case with our GTO. As the first point of contact after a shift is made, this simple upgrade can increase transmission longevity and improve shifting feel.
[19] This is what 80,000 miles...
[19] This is what 80,000 miles of performance driving can do to the stock fork pads. These units were all showing signs of intense wear, and certainly contributed to the shifting issues we were experiencing.
[20] Here we see what the...
[20] Here we see what the transmission looks like after installing the mainshaft, countershaft, and First/Second and Third/Fourth shift forks.
Level 2 M12 T56 transmission
495 lb-ft constant-load torque rating
Price: $995
The Level 2 kit includes:
Bronze fork pads for 1st, 2nd, 3rd, 4th, 5th, 6th, and Reverse
Billet synchronizer keys and spring kit for 3rd/4th synchronizer assembly
Cryo treatment of 1st-4th gears, shift forks, and sliders
Call tag to pickup parts from customer (within continental U.S.) to have cryo-treatment performed
The following parts will need to be removed and boxed for American Powertrain to Call Tag for this upgrade:
1st/2nd/3rd/4th gears and their input shaft
Countershaft (lower gear in gearbox, also known as cluster)
Sliders, not hubs, for 1st-2nd and 3rd-4th
Shift forks (no rails) for 1st-2nd and 3rd-4th
[21] Next, Greg lines up the...
[21] Next, Greg lines up the parts for the Fifth/Sixth driven gear and Reverse gear to be installed. First the case has to be installed, so he cleans the gasket mating surface.
[22] This closeup of the shift-fork...
[22] This closeup of the shift-fork rail assembly gives you an idea of its complexity, which can be overwhelming for a first timer. Greg tells us that everything will only be happy going together one way, so it may take some trial and error before moving onto the next step. A generous bead of high-temperature silicone is applied to the perimeter of the front adapter on the raised surface where it will come in contact with the case.
[23] Greg slowly lowers the...
[23] Greg slowly lowers the case onto the front adapter. This can be tricky, as the parts resting in place underneath will want to move around with the slightest touch. After a few attempts, he is finally able to align it correctly to the dowels and keep the front assembly together. He then tightens the case-to-adaptor bolts in a crisscross pattern to 26 ft-lb.
[24] Finally, the Fifth/Sixth...
[24] Finally, the Fifth/Sixth gear driven is lowered onto the main shaft with Sixth gear aligned. This is followed by the reverse shift fork, which is held in place with a snap ring, and the reverse speed gear assembly.
[25] Carefully, the transmission...
[25] Carefully, the transmission extension housing is lowered into place and guided in with the alignment dowels. This houses the countershaft extension bearing, as well as the reverse idler shaft, gears, and bracket. The bracket bolts are treated to Loctite and torqued to 18 ft-lb. The extension housing bolts receive 26 ft-lb and the same silicone process as the front adapter. (There are many other steps and procedures to dismantling and rebuilding the T56—too numerous to cover in a single story.)
[26] Here’s the completed...
[26] Here’s the completed trans, ready for reinstallation. The process of removing the transmission from our car took a couple hours on a lift. Greg had it apart in less than an hour with our parts bagged and tagged to be sent out for treatment. The turnaround time from American Powertrain is usually one to two weeks, depending on the package.
[27] As per Gray’s suggestion,...
[27] As per Gray’s suggestion, instead of tracking down another expensive OEM bellhousing, we took the opportunity to upgrade to this sharp SFI-approved QuickTime bellhousing that is offered with some of American Powertrain’s kits. Unfortunately, our large 1.875-primary headers created some clearance issues with the slightly wider bellhousing. This required Greg to remove some material on the driver side, which negated its SFI rating.
[28] This is the ACT Street...
[28] This is the ACT Street Disc (PN GM9-HDSS)—an entry-level clutch, which offers a holding capacity rating of 745 lb-ft while offering smooth actuation. The kit comes with a heavy-duty pressure plate, a sprung hub organic disc, and a 26-spline alignment tool. It retails for around $488.
[29] We combined the clutch...
[29] We combined the clutch kit with the SFI-approved Prolite Xact Flywheel (PN 600585; $350), which has a terrifically low weight of 14.7 pounds. The combo has proven after-track use and extended street driving to maintain its user-friendliness and easy operation with crisp throttle response. We also installed a new hydraulic slave cylinder (PN SACHS PN SH6414; $87) that actuates the clutch and pilot bearing (ACDelco PN CT1078; $14) from Rock Auto. It took Greg a little over two hours to reassemble the trans, and another couple hours to put it back into the GTO. With its upgraded parts and Pennzoil Synchromesh Manual Transmission Fluid in it, the trans shifts buttery smooth and there is a positive feel to each gear selection. It’s the perfect build for our demands and makes the car more enjoyable to drive every day.