Going In-Depth With Lakewood's New Aluminum 11-Inch Clutch Bellhousing

Engine and transmission swapping just got another boost with this new bellhousing from Lakewood. For years, Lakewood was the go-to company for scattershields and high performance bellhousings. While QuickTime is now the best choice for new steel SFI scattershields, there’s been that missing link for street guys needing a high quality 11-inch aluminum bellhousing to mount a traditional four or new-age five-speed manual transmission.

Not everybody needs an SFI-spec bellhousing, so for years Chevy guys have scoured the junkyards and swap meets searching for the classic “621” factory 11-inch aluminum bellhousing. Those pieces have become so rare and demand is so great that this void cried out to be filled.

This new Lakewood housing is now out, but they didn’t just pull a mold off an old Chevy bellhousing and leave it at that. If you look closely, this new casting offers subtle advantages that you won’t find on an early bellhousing. Right off, it feels heavier because these are made with slightly more wall thickness and use a higher quality aluminum. Sharp-eyed readers will immediately notice the flange includes the mounting locations for the Gen III and IV LS pattern with the bolt hole at 12 o’clock as well as for the Gen V LS with its slightly skewed top bolt position.

According to Lakewood’s Ross McCombs, there are also Ford and Mopar bellhousings for popular applications and many more are in the pipeline.

It’s worth noting that this bellhousing will bolt directly to any small- or big-block Chevy as well as all the aforementioned variants of the LS family. This means you could use this bellhousing to bolt a new Tremec TKX five-speed to the back of a brand new LT1 or LT4 engine if you so desired.

This new casting offers the same depth as the original 11-inch bellhousings from the ‘60s, but there are some details that are definitely worth probing. The most important one deals with LS engine swaps where we recently learned something that can save you tons of grief.

We discovered that if the oil pan has been removed or replaced that when reinstalled it may be positioned too far rearward, which will kick the bottom of the bellhousing rearward. This will cause all sorts of bellhousing alignment problems resulting in poor shift quality. Make sure that the oil pan does not intersect with the lower portion of bell by using a feeler gauge. We sanded the oil pan in this application to create sufficient clearance.

When bolting any manual transmission bellhousing to the back of an LS engine, pay close attention to the interface between the bottom half of the bellhousing to the oil pan. Factory LS engines position the bellhousing flange to line up with the oil pan’s rear-facing flange and there’s even a couple of bolt holes there to attach an automatic transmission bellhousing to the pan for structural support.

However, if your engine has been the fitted with an aftermarket cast aluminum pan like the Holley engine swap pan, it’s possible that the pan’s rear vertical exterior wall can extend past the bellhousing mounting flange’s vertical plane. This will kick the lower portion of the bellhousing outward which will directly affect its concentricity.

We discovered this while dialing in this bellhousing on a Gen III LS engine. Once we realized we had a problem, we merely ran a metal file across the lower portion of the Holley oil pan until we had 0.010-inch of clearance between the pan and the bellhousing to eliminate that issue. Another way to eliminate this would be to loosen all the front and rear cover and oil pan bolts and reposition the oil pan slightly forward. We didn’t do this on our engine because it was already RTV sealed and we didn’t want to create an oil leak.

We discovered that if the oil pan has been removed or replaced that when reinstalled it may be positioned too far rearward, which will kick the bottom of the bellhousing rearward. This will cause all sorts of bellhousing alignment problems resulting in poor shift quality. Make sure that the oil pan does not intersect with the lower portion of bell by using a feeler gauge. We sanded the oil pan in this application to create sufficient clearance.

Continuing with LS engine swap info, there are also some specific requirements for using this bellhousing with an older Muncie and Super T-10 four-speeds and the Tremec TKO or the new TKX five-speeds. If you bolt any of these transmissions to the bellhousing, the input shaft pilot will protrude roughly ¼-inch from the bellhousing flange. This will require the use of either a medium or large diameter pilot bearing. This fits in the large diameter portion of the LS crankshaft that’s closest to the transmission.

When using these transmissions, do not use the small diameter pilot bearing as it will be positioned too far forward in the crank to support the pilot shaft of the transmission. This is a common mistake that will cause all kinds of shifting problems and could also damage the transmission.

Of course, it should go without mention that you should always check the bellhousing’s concentricity with your particular engine. While factory machining accuracy is far better with modern LS engines, the same cannot be said for older Chevy engines that have been heat cycled a few million times. Our experience with checking the same bellhousing on several different small-block Chevy engines is that the bellhousing checked differently each time. This means that the cylinder block locating pins were not consistently in the same place.

One point worth making is that some aftermarket reproduction bellhousings may not be quite as accurate as others. We recently ran one in a testing fixture to discover that it was 0.030-inch off center. We put this new Lakewood bellhousing to the test on that same test fixture and discovered it measured right at 0.001-inch from perfectly centered. This means that when testing one of these bellhousings on your engine, the error is likely to be with the location of the dowel pins rather than with the bellhousing.

Should it be necessary to realign the bellhousing, offset dowel pins are available from Lakewood. We will follow this story with a separate tech piece for this website on how to dial in any bellhousing the right way should you need to perform that task. The operation is not difficult but does require a dial indicator and a little bit of effort.

Even with a simple device like Lakewood’s new aluminum bellhousing, there are details that need to be addressed. But once you know your way around this piece of hardware, it offers an accurate connection between the crankshaft and that manual trans.

Of course, it should go without mention that you should always check the bellhousing’s concentricity with your particular engine. While factory machining accuracy is far better with modern LS engines, the same cannot be said for older Chevy engines that have been heat cycled a few million times. Our experience with checking the same bellhousing on several different small-block Chevy engines is that the bellhousing checked differently each time. This means that the cylinder block locating pins were not consistently in the same place.

One point worth making is that some aftermarket reproduction bellhousings may not be quite as accurate as others. We recently ran one in a testing fixture to discover that it was 0.030-inch off center. We put this new Lakewood bellhousing to the test on that same test fixture and discovered it measured right at 0.001-inch from perfectly centered. This means that when testing one of these bellhousings on your engine, the error is likely to be with the location of the dowel pins rather than with the bellhousing.

Should it be necessary to realign the bellhousing, offset dowel pins are available from Lakewood. We will follow this story with a separate tech piece for this website on how to dial in any bellhousing the right way should you need to perform that task. The operation is not difficult but does require a dial indicator and a little bit of effort.

Even with a simple device like Lakewood’s new aluminum bellhousing, there are details that need to be addressed. But once you know your way around this piece of hardware, it offers an accurate connection between the crankshaft and that manual trans.