Bolts the Tremec T56 six-speed to the LS1 block in 1998-2002 Camaro Z28 and Firebird, replacing a housing cracked at the bolt bosses.
A cracked bellhousing on a 1998-2002 Camaro Z28 or Firebird Trans Am, or a T56 that keeps eating release bearings and pilot bearings, usually traces back to this casting. This is the aluminum clutch housing that bolts the Tremec T56 six-speed to the LS1 block in the fourth-generation F-body and the 2004-2006 Pontiac GTO. It replaces GM 12453263 and 92142856, also cataloged as 1386-212-005, and weighs about 10.8 pounds.
On these cars the bellhousing is a separate aluminum piece between the engine block and the T56 case. It encloses the flywheel and clutch, carries the starter, and surrounds the hydraulic release bearing that rides on the transmission's input shaft retainer. Its most important job is invisible: two dowels on the block locate the housing, and the register bore on the back of the housing locates the transmission. Together they decide whether the input shaft spins on the same centerline as the crankshaft. If that bore is off center, every clutch component works against a misalignment.
None of these produce a trouble code. A manual gearbox failure like this is diagnosed with eyes, a straightedge and a dial indicator. For a sense of what clutch-side repairs usually cost against the transmission itself, see our breakdown of automatic versus manual transmission repair cost.
With the transmission out, inspect the casting under good light around every bolt boss, the starter mount and the dowel holes. Then check alignment rather than guessing. Bowler's T56 dial indicator plate instructions describe bolting the housing to the block, rotating the crank and reading the register bore. Their quick reference lists 0.010 in. total indicated runout for a standard street build and 0.005 in. for high-rpm performance use, and the offset dowel needed is half of the total reading. A dial indicator and magnetic base set is all you need to do the check yourself. If a cracked or badly misaligned original cannot be brought back into spec, replace it.
Listed fitment is the LS-engine T56 cars: 1998-2002 Chevrolet Camaro Z28 and Z28 SS, coupe and convertible; 1998-2002 Pontiac Firebird Formula and Trans Am, coupe and convertible; and 2004-2006 Pontiac GTO. It is not for the 1993-1997 LT1 F-body, which used a different engine, and it is not an automatic transmission part. Match your original housing's part number before ordering, or send us your year and VIN. For other parts in this family, browse our T56 listings such as the T56 short throw shifter for 1993-2002 Camaro and Firebird.
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It replaces GM 12453263 and 92142856, and is also cataloged as 1386-212-005.
No. Listed fitment is the LS-powered 1998-2002 Camaro and Firebird and the 2004-2006 GTO. The earlier LT1 cars are not covered.
Yes. Block dowels and machining tolerances stack up, so check the register bore runout on every install. Common targets are 0.010 in. total reading for street use and 0.005 in. for high-rpm performance use.
Shock loads from hard launches and clutch dumps, loose or missing bolts, and a housing that has been shifting on worn dowels. Cracks usually start at the lower bolt bosses or around the starter pocket.
Inspect the hydraulic release bearing, replace the pilot bearing, and check the flywheel and clutch. Repeated release bearing failures are a sign the old housing was out of alignment.
