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T56 Transmission Build - Transmission Critical - Tech

We Team Up With D&D Performance To Build A Bulletproof T56 And Prep Our Camaro For Its New Drivetrain

Justin Cesler Mar 5, 2010

For those of you not in the loop, we are nearing the final build stages of our "STi Killer" Camaro, which is almost ready for its maiden voyage across the parking lot. What started as a decrepit roller, has already been through paint and body, a complete interior restoration, a couple of key safety upgrades, and has seen its new GM Performance Parts LS6 crate motor get prepped for our abuse. This month, we have turned our attention to the transmission, which, like everything else in this project, started from a broken core. Unfortunately, finding a T56 for a decent price, even an almost useless core, proved to be a difficult task. After weeks of searching and what felt like ten thousand phone calls of begging, we were able to finally locate one from our friend Ron Mowen at Vengeance Racing. A couple hundred dollars later we had a core on a pallet and shipped directly to D&D Performance in Wixom, Michigan, so that they could work their magic. If you're not familiar with D&D, they are one of the premier transmission builders in the country and one of the best sources for anything T56. After talking to Don Walsh of D&D about our goals, we decided to build a "Viper Spec T56," which would bolt back directly in place of our old unit.

gmhtp_01_o T56_transmission_build Engine 2/21

According to Don, "the LS1 T56 is rated at 450 lb-ft by Tremec but has the exact same gearset as the Viper. We rate our 'Viper Spec T56' at 800 lb-ft and we have not had a single mechanical failure in the over 2,000 units we've built and sold. Although the LS1 Camaro T56 has the same gearset as the Viper, it does require some upgrades for maximum performance. The stock output shaft is a 27-spline, which will fail under high load and/or good traction conditions. D&D modifies the 30-spline Viper output shaft to fit the Camaro package. We also modify the Camaro Extension Housing to accept the larger Viper slip yoke. D&D offers this package including a special tone wheel for $499. We also offer the Viper 30-spline slip yoke for $89. Chrysler found that the aluminum 3-4 shift fork would fail under hard shifting during the 1995 24-hour Le Mans race. They upgraded race and production units in 1996. GM did not feel it was necessary on the Camaro units, so the aluminum fork was still in production with the 2002 Camaro. We recommend replacing it with the steel unit (PN BS6) on all rebuilds. Another potential failure [in all T56s] is the 3-4 synchro inserts. They are a stamped steel part in production and are susceptible to sudden failure. With the design input of Steve Holman, one of the original designers of the T56, D&D brought to market a super alloy heat-treated billet part that uses the stock synchro springs. At $99 for a set of three (PN BS47), they are not cheap but they are unbreakable and they won't wear out. The production fork pads are molded plastic and work very well in normal usage. For high-performance and road racing usage, we recommend upgrading the plastic fork pads to our aluminized bronze pads (1-2 and 3-4, PN BS14B; 5-6 and R, PN BS19B). The synchro blocker rings on all T56s were upgraded to a carbon-fiber material around '99. We always check them on teardown and if they are of the old paper design or have excessive wear, we offer a complete Synchro Rebuild Kit (PN BS45)."

With our transmission torn apart and under the knife, we made a couple of phone calls to Centerforce Clutches and Summit Racing, hoping to round up the last of our transmission parts. After checking out all of our options, we chose to go with a Centerforce Light Metal clutch (LMC) and flywheel (PN LM017010), which would offer enough holding power for our future goals (hint, hint) while minimizing rotating weight and inertia. The LMC series is built from a billet aluminum pressure plate, which uses a dual-segmented carbon composite disc for maximum torque capacity. The coolest part, however, is Centerforce's patented ball bearing diaphragm and centrifugal weight system, which means we will have a smooth, comfortable pedal feel, a ton of holding capacity, and no headaches. From Summit Racing, we ordered a new McLeod adjustable master cylinder (PN MCL-139001) as well as a new GM Performance Parts slave cylinder (PN NAL-15046288). The McLeod adjustable master cylinder offers a larger bore than the stock unit, which will definitely improve our high-rpm shifts. More importantly, the McLeod master cylinder can be easily adjusted, allowing us to get the clutch engagement point exactly where we need it. With those parts in hand, we began prepping our GMPP LS6 for install. Follow along to see how everything went.

gmhtp_03_o T56_transmission_build Core 3/21


Summit Racing
Akron, OH
D&D Performance
Wixom, MI
Midway Industries
Prescott, AR 86301



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