How to bolt a Toyota V6 engine to a 30-year-old MR2 transmission

Thank you, Toyota. Thanks for making such a modular set of drivetrain bits that a transmission from decades ago is adaptable to an engine design still in use today. That certainly saved us a lot of hassle when it came to assembling the components needed to fit a 2GR-FE V6 into our 1991 MR2.

While not a total bolt-together project, the three-decade-old E153 transmission is surprisingly adaptable to the more modern 2GR-FE engine, with the mating only requiring some minor mods and parts shopping.

First, you’ll need a flywheel. This is because the junkyard 2GR you bought almost certainly comes with a flexplate, having been coupled to an automatic transmission (unless you found the one Lotus Evora in a junkyard in the U.S.)

Fortunately, there are options. Frankenstein Motorworks builds a custom, lightweight steel piece, and it’s easy to click that order box since you’ll be getting much of your 2GR swap bits from there anyway.

Or you can do what we did and go with the aluminum version from Fidanza, which specs out for the V6 versions of the early '90s-to-early 2000s V6-powered Camrys, Solaras and Lexus ES250s.

This $329 flywheel features Fidanza’s unique replaceable friction surface. That means, should you ever burn the surface of the flywheel, salvaging it won’t require a trip to a machine shop for resurfacing–and the subsequent clutch shimming that usually goes along with this operation–or an expensive flywheel replacement. Simply bolt on a new friction surface, clean it up and go.

The ACT clutch we'd just installed on our MR2 literally two days before the fire bolted right up, and we used ARP hardware throughout to keep our rotating assemblies safely in place.

On the engine side, you’ll need to do a small amount of cutting and grinding as well as install some threads in one hole that will likely be blind on your replacement V6. But once these operations are completed, the new engine and old transmission merge together almost as though they were made for each other.

Early (pre-1993) E153 transmissions will end up with four bolts holding the assembly together, while later E153s have six bolts attaching engine to transmission due to a slightly different design of the lower bellhousing. In either case, no failures have been reported due to a lack of clamping force between the two components.

Here’s a closer look at our operations. For an exhaustively detailed rundown, Frankenstein Motorworks’ Mark LaBranche has a great video that we kept running on a loop while we were completing this part of the operation. It’s available at Frankenstein’s website.

These bolt bosses on the right side of the engine need to be flattened, and the hole near the upper dowel pin needs to have M12-1.25 threads. There’s a chance this hole may already be threaded from the factory, but in most cases, you’ll want to use a thread insert.

This is what the bolt humps should look like when you’re done grinding.

On the left side of the engine, you’ll need to relieve a pocket for the clutch actuation cylinder to clear. The outer wall of this piece of block structural webbing can be mostly cut away. We used a cutoff wheel to take out the big chunk of block, then finished up with a finger sander.

Prepping the upper hole to receive a thread insert is much easier if you have a proper tap adapter for a ratchet handle. Get some and you’ll never again use the dumb handles that came with your tap kit.

This hole is fairly deep, so with the thread insert in place, only the bottom 12mm or so of the hole is threaded. This can make it tricky to get the bolt started if the transmission and engine aren’t completely mated. Keep that in mind when you’re assembling the pair.

Back to the lower-right side of the block, the areas highlighted in red need to be removed. That threaded hole is still in use in this application, so make sure it still has plenty of material around it.

On the lower-left side of the block, no such quarter needs to be given. This hole can be cut off and ground flush with the rest of the block.

Here you can see the cleanup completed on the right side of the block, and we’re ready to bolt our Fidanza flywheel in place.

A full complement of fresh ARP hardware was used to attach the clutch and flywheel. Even if you don’t use ARP fasteners for this application (but really, why wouldn’t you?), always use new fasteners to attach flywheels and clutches. Torque is critical in these applications.

Properly torqued in three passes, our Fidanza flywheel was ready to prep for mating.

Fidanza recommends an acetone-based solvent and cloth rag to clean off the protective friction surface coating. Of course, we selected an appropriate can from the CRC shelf. The coating melts off easily and requires only minor wiping to clear away and ready it for final installation.

Like the flywheel, we torqued the ACT clutch in three stages. Now everything was ready to become one.

Following some wiggling, success. After we made initial contact, joined the clutch and input shaft, and a placed a couple bolts, we were still slightly misaligned. This was mostly a result of the clutch not being perfectly centered. Jesse Spiker of Spiker Motorsports—our official project car helper guy and all-around mechanical expert–had the brilliant idea of just actuating the clutch release lever by hand, taking some of the clamp force off the clutch disc and letting the engine and transmission basically self-align. As soon as he worked the clutch lever with a pry bar, the dowel pins fell right into place between the engine and transmission.

The three shiny bolt heads you see are from the 12mm bolts holding together the engine and transmission on top. The two on the left are in pretexting holes. The one on the right is in the hole we added the thread insert to.

This 10mm bolt on the bottom goes in from the engine side. This is the one where we cautioned you to leave enough material around the threaded boss that needs some relieving. The flanged head of the bolt or a washer makes a great guide to grind to.

If you have an early E153, these will be your only bolts connecting the engine and transmission. On our later-model transmission, there were two more accessible bolt holes that took 12mm fasteners directly on the bottom of the case. Since they were easily accessible, we installed these bolts from below once the powertrain was in the car.

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