Grade 10.9 flange bolts that fasten an LS or LT engine to a GM 4L60E, 4L80E, or T56 bellhousing, replacing the strip-prone factory Torx-plus hardware.
Bell housing bolts are the hardware that goes missing on every LS swap. The junkyard engine shows up without them, the donor transmission came out of a different truck, or the old bolts are rusted and rounded from years under a Silverado. This kit is eight Grade 10.9 hex flange bolts for fastening a GM 4L60E, 4L65E, 4L70E or 4L80E bellhousing to a Gen III, Gen IV or Gen V LS or LT block, and it is listed for the T56 manual as well. It is cross-referenced to the 551652 bell housing bolt set.
The bolts clamp the transmission case to the back of the engine block, and the two dowel pins in the block locate it. Together they hold the transmission input shaft and pump on the same centerline as the crankshaft. That alignment is what keeps the torque converter hub running true in the pump bushing. If a bolt is missing or loose, the case can shift slightly on the dowels under load, and the converter starts pushing on the pump every revolution. Over time that shows up as a front seal leak, a worn pump bushing, or pump gear damage. On a swap, a bolt with too much thread or the wrong length can also bottom out in the block before it clamps the case.
A hex flange head spreads the load across the case ear without a separate washer, and the zinc coating helps a bolt that sits right behind a hot exhaust survive the next teardown.
Count the bolts you have against the holes in the case and block, and check that both dowel pins are present and undamaged. Look for stretched threads or rounded heads on the old ones. If the transmission already leaks or slips after a swap, find out why before you button it up again. The 4L60E common problems guide explains how pump and converter damage shows up, and the 4L60E Camaro shift problems guide covers the symptoms on the LS-powered F-body cars.
The listing covers the GM 4L60E, 4L65E, 4L70E and 4L80E automatics, and the T56 manual, to LS and LT Gen III, Gen IV and Gen V engines. That covers most late-model truck and car combinations and the common swaps of those transmissions into older vehicles. It does not cover small-block Chevy engines, and a few installs use a different bolt at a location shared with a bracket, a dipstick tube or a ground strap. Hold a bolt up to each hole before final assembly. If you are not sure, send us the engine, transmission and year, or the VIN. More parts for these transmissions are on our 4L60E parts page.
Rebuilding the transmission before it goes in? A 4L60E holding fixture keeps the case steady on the bench, and the 4L60E master overhaul kit covers the seals and frictions.
| Fits | GM 4L60E, 4L65E, 4L70E, 4L80E to LS/LT Gen III/IV/V engines and T56 |
| Count | 8 bolts per kit |
| Grade | 10.9 carbon steel |
| Finish | Zinc-coated, hex flange head (no washer needed) |
| Cross-reference | 551652 bell housing bolt set |
| Ships | From the USA |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Yes. The listing covers the 4L80E as well as the 4L60E, 4L65E and 4L70E to Gen III, Gen IV and Gen V LS and LT engines, and the T56 manual.
GM's Supermatic installation guide for the 4L65E and 4L70E lists transmission to engine bolts at 37 ft-lb (50 N-m). Use your vehicle's service manual figure if it differs.
This set is listed for LS and LT engines. A traditional small-block Chevy uses different bellhousing hardware, so match your bolts before ordering.
The kit has eight. Count the holes in your case and block, because some locations also hold a bracket, dipstick tube or ground strap and may need a longer stud or bolt.
No. A gap usually means the converter is not fully seated in the pump or the dowels are not lined up. Pulling it in with the bolts can break the pump. Fix the cause, then install the bolts.
