Quarter-inch billet spacer that pushes the bellhousing back so the torque converter clears the flexplate on LS and LT swaps into 4L80E, 4L60E, TH350 and TH400 cases.
If you are bolting a 4L80E, 4L60E, TH400 or TH350 behind an LS or LT engine and the torque converter will not pull forward to meet the flexplate, you have a depth problem, and forcing it closed is how front pumps get destroyed. This quarter-inch billet aluminum spacer plate goes between the engine block and the bellhousing, moving the whole transmission back 0.250 in. so the converter sits where the pump was designed to see it. It is one piece, machined from hardened aerospace-grade billet, part number 551820-250, and made in Wichita, Kansas.
Every automatic expects a fixed distance between the block face and the point where the converter snout pilots into the crank. When the crank flange sits deeper than the transmission expects, which is common on LS and LT engines, short-crank truck engines and mixed-generation swaps, the converter bottoms out in the crank pilot before its pads reach the flexplate. Bolt it up anyway and the converter hub is pushed into the pump gears. The pump then wears itself out, often within a few hundred miles. Adding a quarter inch between block and bellhousing restores that lost depth without touching the crank, the flexplate or the case. On a 4L80E, with its large converter and heavy-duty pump, getting this wrong means a full teardown, so it is worth measuring before the first start.
With the converter fully seated in the pump (you should feel it drop in over the input shaft, stator splines and pump drive), mate the transmission to the engine and try to slide the converter forward to the flexplate. You want 1/8 to 1/4 in. of free play between the converter pads and the flexplate before you install the bolts. No play, or a converter that already touches the plate, means it is sitting too deep and the spacer is the fix. Too much play after you add the spacer means the flexplate is wrong, not the plate. Read the crank flange notes on our 6-bolt 4L80E flexplate listing, and see the LS to TH350 and 700R4 adapter kit if your problem is converter pilot engagement at the crank rather than bellhousing depth.
The plate uses the standard Chevy small-block bellhousing bolt pattern and the factory dowel locations, so nothing is drilled or clearanced. Engine side, it fits Gen I through Gen V Chevy engines: small-block, big-block, LS1, LT1, 4.8, 5.3, 6.0 and 6.2. Transmission side, it works with any case carrying the SBC pattern: Powerglide, TH350, TH400, 700R4, 4L60E, 4L65E, 4L70E, 4L80E, 6L80E, 6L90E, 8L80E and the T56 manual. It is a swap and build part, not a replacement for anything a factory truck shipped with, so measure your own combination. Browse matching swap and service parts on our 4L60E parts page.
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Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
No. You need it only when the converter has no forward free play to the flexplate after the transmission is bolted up. Measure first: 1/8 to 1/4 in. of play is the target.
Yes. The plate uses the Chevy small-block bellhousing pattern, which the 4L80E shares, and fits Gen III and Gen IV engines including the 4.8, 5.3 and 6.0.
Bellhousing bolts 1/4 in. longer than stock and dowel pins that reach through the plate. Also check your driveshaft length and slip yoke engagement, because the transmission moves back.
No. A crank spacer or sleeve fixes converter pilot engagement at the crank. This plate moves the whole bellhousing back. Diagnose which problem you have before buying, and do not run both without measuring.
Yes, it fits the T56, and some short-crank LS builds stack two plates when converting from an automatic crank to a manual setup.
