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Chevy T56 Transmission - Missed-Shift Mayem
We Visit Rockland Standard Gear To See How They Beef Up A T56 Transmission.
Jun 18, 2009
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Rockland Standard Gear
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Chevy T56 Transmission - Missed-Shift Mayem
While Rockland Standard Gear (RSG) uses only new parts, that doesn’t mean they don’t modify some of them. This T56 tailshaft housing was machined to fit the larger main shaft used in this build.
Here you can see all of the trans components. This is a good example of why building a transmission should be left to the professionals. One incorrectly installed part could cause the whole deal to grenade when blasting through the gears.
The 32-spline shaft on the left is a hell of a lot bigger than the stock 27-spline unit on the right. They are made from the same material, but there’s considerably more of it in the new shaft from RSG.
"Viper spec" is a common term thrown around when it comes to T56s, so don’t confuse it with RSG’s Son of Tranzilla since they aren’t the same thing! Here you can see the Viper-spec single-carbon blocker rings on the left and the Tranzilla double carbon rings on right. RSG only does "Viper spec" on the stock-style transmissions they build. Viper spec is nowhere near as good as the multi-ring Tranzilla parts.
Second gear goes on next. On regular T56s, only double carbon goes here, but on Corvette and Transzilla, there are three carbon surfaces on gears one and two. The 1-2 synchronizer, which is the thicker steel piece, goes on and gets tapped with a hammer's butt end, then it's put in a press to get it on the entire way with its bearing. Here’s the completed main shaft assembly with first gear installed.
Main shaft assembly is done in a vise. Third gear goes on first, followed by an array of blocker rings. The pocket bearing goes on top, then the shaft is flipped over in the vise where the main shaft is assembled.
Prep work is a major reason for RSG’s success at building the most reliable transmissions around. The first thing to check is preload of the cluster. The fifth and sixth auxiliary shafts goes in to check preload. Rockland’s Transmission guru, George Kreppein Jr., sets shims in the tailshaft housing before setting it in place. To check endplay, the "endplay plug" is removed at the front of the main case and a rod is inserted with a dial indicator resting on it. George looks for 0.002 to 0.004-inch endplay on the auxiliary shaft and 0.000 to 0.002-inch on the cluster shaft, also referred to as the main shaft.
Next, fifth and sixth gears get built. In the first image you can see the double blocker cone versus the larger single cone. All new parts are used in this section including the blockers. First, fifth goes on with a hydraulic press, then sixth is put in place and secured.
The reverse idler gear goes into the tailshaft housing and is secured in place. Then the rear output roller bearing race is tapped into the tailshaft housing. The casings, like all the other parts , are new — not used or reconditioned.
The main shaft is set on the front adapter plate, after which the main case is placed atop. This way they can check the main shaft preload. Once the main case is on, George twisted the shaft to ensure correct freedom of movement
The output shaft bushing is tapped and then pressed into the back of the tailshaft housing from the outside. Of course, this is bigger than stock to accommodate the new 32-spline output shaft.
B. Tranzilla uses a one-piece countershaft versus a stock two-piece. This used stock piece (foreground) was actually showing some wear at the junction; with a lot of power, they eventually fail and take the rest of the transmission with it.
A. Check out the Tranzilla second gear versus stock. Tranzilla, shown on right, has much thicker gear teeth. The stock gears are helical cut, whereas Tranzilla gears are 22-degree helix. Also, no modifications are necessary to accommodate these in the stock case because the 22-degree -cut gears actually generate less thrust. Stock gears also generate more heat because of the cut, which are designed for quiet operation. RSG sees much lower trans temps in Tranzilla, so it’s a double win.
Stock T56 trannies have an aluminum shift fork like the one shown on the right, but RSG upgrades to the steel version on the left. This greatly increases the overall strength of the T56.
Here you can see bronze versus nylon shift fork pads. The nylon ones are new, while the bronze ones are used. You can see the obvious wear from just one race weekend on the bronze pads. Other builders charge customers more money for bronze as an “upgrade,” when in reality, the stock nylon items are better. So that's what RSG uses.
Now it’s time for final assembly. All the shafts are placed into the front adapter plate and the main case is slipped atop them and secured in place. The newer-style casting surrounds the five-six shaft for extra support. This is a great upgrade over older cases which offer far less.
First through fourth are in the main case, while fifth, sixth, and reverse hang out back. Here they are installed in the case.
After a few final checks to make sure everything is properly torqued down and spinning freely, this Rockland Standard Gear Son of Tranzilla T56 transmission is ready to be shipped.
After applying a thin bead of silicone sealant, the modified tailshaft housing is put in place.
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