OEM-spec 6-bolt flexplate for the 4L80E torque converter pattern, the part you need on an LS or Vortec swap onto a 4L80E or a 4L60E-to-4L80E upgrade.
Upgrading a Silverado, Sierra, Tahoe or Suburban from a 4L60E to a 4L80E, or dropping an LS or Vortec engine in front of a 4L80E, and the old flexplate will not line up with the converter? Or hearing a rattle at startup and a vibration under load from the bellhousing? This is the ATP Z-270 flexplate, made to the 6-bolt torque converter pattern the 4L80E uses. It is alloy steel, balanced to factory spec, with a welded ring gear for the starter.
The flexplate bolts to the back of the crankshaft and carries the torque converter, and its outer ring gear is what the starter drive engages. It has to match two patterns at once: the crank flange on the engine side and the converter lugs on the transmission side. The 4L80E was developed from the TH400 and uses a larger converter than a 4L60E; Novak lists it at 310 mm, and ICT Billet groups 4L80E converters with the 11.5-inch bolt circle, many with six bolts instead of three. That is why a 4L60E flexplate, drilled for a three-lug converter on a smaller circle, will not work after the upgrade. The 4L80E is also 26-1/4 inches long and rated for about 440 lb-ft of input torque, which is why it is the common answer for trucks that keep burning up a 4L60E.
A cracked plate cannot be welded or straightened. Replace it, and replace the converter bolts with it.
Pull the bellhousing inspection cover and turn the engine by hand while you look at the plate with a light. Check for cracks, missing or loose converter bolts and damaged ring gear teeth. If you are planning the swap, count the converter lugs on the 4L80E converter you will run and measure the bolt circle. If the reason for the upgrade is a failing 4L60E, our 4L60E common problems guide explains the 3-4 clutch and sun shell failures that push owners to the bigger transmission.
This plate is listed for GM trucks and cars running a 4L80E behind 4.8L, 5.3L, 5.7L, 6.0L and 6.2L V8s, and for 4L60E-to-4L80E and LS or Vortec swap builds. The crank side matters as much as the converter side. ICT Billet notes that most Gen 3 and Gen 4 LS engines use a 6-bolt dished crank flange, while the 1999-2000 6.0L uses a flat flange with a longer crankshaft. A Gen I style small block such as the older 5.7L uses a different crank pattern again, so compare your old plate, or send us your engine, year and VIN and we will confirm. See the full 4L80E parts collection for the rest of the swap.
Staying with the 4L60E instead? The heavy-duty reaction sun shell and a 2004-up master rebuild kit address the most common reasons the smaller unit fails.
| Brand | ATP Automotive |
| Part number | Z-270 |
| Bolt pattern | 6-bolt torque converter pattern (4L80E) |
| Material | Alloy steel |
| Fits | 4L80E-equipped GM trucks/cars with 4.8L, 5.3L, 5.7L, 6.0L, 6.2L small block or LS-family V8 (confirm exact year/engine fitment before ordering) |
| Also used for | 4L60E-to-4L80E swaps and LS/Vortec engine swaps onto a 4L80E |
| Warranty | 1-year manufacturer warranty |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
No. The 4L80E converter uses a larger bolt circle and six lugs, while the 4L60E converter uses three on a smaller circle. After a 4L60E-to-4L80E swap you need a flexplate drilled for the 4L80E pattern like this one.
Check before ordering. Those early 6.0L engines use a flat crank flange with a longer crankshaft, unlike the dished flange on most later LS engines. Send us your year and VIN and we will confirm the fit.
Do not assume it does. Older small blocks and LS engines have different crank flange patterns, so one flexplate cannot fit both. Compare the crank bolt holes on your old plate to the product photos.
Usually a light rattle or clatter from the bellhousing at idle, at startup or right when the engine shuts off. A cracked plate can also cause a vibration that follows engine speed.
Yes. Use new converter bolts whenever the flexplate is replaced, and make sure the converter is fully seated in the pump before you tighten them.
