Tech Corner: Add Reliability to Your 24-Valve with a 6-Speed Manual Swap

Keep in mind that a 6-speed manual swap is a heavy job—and often best performed as part of a complete overhaul, since you’ll already be getting your hands into every part of your truck’s guts.

Let’s face it, the truck world is full of appealing features. Big, powerful engines. Killer suspension. Massive capabilities with potential to pull the world. However, nothing is quite as sexy as that third pedal. Though, even with an older RAM 2500, finding a Cummins-powered rig fitted with a stick is pretty hard to do. Even worse, finding one with low miles and minimal wear-and-tear can be downright impossible. And if you do manage to track one down, the price tag is often way more than you’re willing to fork out. But, have you ever considered tackling a 6-speed manual swap?

Why Should You Consider a 6-Speed Manual Swap?

So, let’s not ignore the elephant in the room. Swapping from an automatic transmission to a manual is a large undertaking, regardless of the make and model. It could be a classic hot rod, diesel truck, or even a sport compact import—you’re in for a lot of work.

Which begs the question: why bother?

True, building an automatic transmission is an option, and so is buying one that’s already built up. And sure, these units can take a fair amount of abuse and will easily bolt right into place of the factory equipment. However, the stock automatic transmission in this generation of Cummins-powered RAM trucks are a pretty agreed-upon weak point of the platform. For daily driving and light use, you won’t have much to worry about. But if you plan on any sort of recreational use, the trans can act like a zip-tie in place of a chain link. Going even as little as 50-60 hp more than factory specs can spell trouble for many applications.

As far as budget goes, traditionally building up an automatic or buying a built automatic transmission isn’t that much more cost-effective than opting for a manual swap—especially when you’re talking about huge power numbers like you find with diesel applications. Now, where you source your parts from will impact price, but some ready-built auto transmissions run about the same as a complete conversion kit to swap to the manual. While the swap is going to take significantly more time and effort to properly install, these manual transmissions are crazy stout! There are always big fish stories, but many owners claim that with factory transmissions, they’re taking on well over 1,000 lb-ft of torque.

What Will You Need?

No sugar coating here: this is a big job, so preparation is critical to a job well done. On the bright side, while most work-intensive projects like this come with a host of surprise setbacks, the second-gen RAM 2500 packs some surprises that will actually make life easier. Having been equipped from the factory to accommodate the third pedal and master cylinder for the clutch pedal assembly doesn’t sound like much, but it’s enough to save a few headaches.

Parts

So, what will you need to perform this 6-speed manual swap? While no two jobs are ever quite the same, for this undertaking, you’ll need a 6-speed manual transmission, bellhousing, flywheel, clutch and clutch system, along with the pedal and brake pedal, a crossmember for the application, and shift lever.

Keep in mind. There are two popular swaps done to these applications: the G56 6-speed and NV5600 6-speed. If you have the G56, you don’t need an adapter plate to fit the transmission to the engine, but you will with the NV5600.

Tools

Aside from the parts, gear oil, and hydraulic fluid, you need tools. Considering how high these trucks sit, its going to be easier to drop the transmission from the bottom of the truck and install the engine to the trans outside of the truck. That being said, you’ll still need an array of tools.

A wide selection of hand wrenches and sockets are just the start. A transmission jack and clutch alignment tool, as well as means to cut the floor pans will definitely be needed. Additionally, air tools, floor jack extensions, and u-joint attachments will make life easier, as well.

6-Speed Manual Swap

First things first, is to get the driveshafts off, both front and rear. Unbolting the torque converter can be a pain in the rear-end, but it’s really the most annoying part of the process. Support the transmission with the transmission jack, and unbolt the crossmember. Once undone, lower the transmission. With the transmission lowered, you can undo the engine-to-trans bolts, wiring, starter, and then lower the transmission out of place.

Unfortunately, installing a manual in the reverse order is not so straightforward. Remember, most of those old parts are no longer compatible with the new equipment.

First, you’ll be removing the flexplate and replacing it with a flywheel. From there, you need to install the clutch system. On these models, a hydraulic clutch will be used. This means you need to mount the master cylinder to the firewall along with the hydraulic throwout bearing and the plumbing to operate the system.

Once the clutch and throwout bearing are rigged up, you can move onto the transmission. However, with a manual, you will want to mock the transmission up, mark where you need to cut the floor for the shifter and remove it. After you cut the floor, then move to the actual install of the unit by bolting it to the engine and the crossmember.

It’s incredibly important to not forget the wiring.

Even on older-model RAMs, computers will need to be flashed or swapped to prevent the engine light from appearing on the dash. You’ll also need to create harnesses for the neutral safety and reverse lights when swapping from an automatic to a stick. It’s pretty basic stuff but cannot be overlooked.

As I mentioned above, the pedal assembly swap is made easier by the fact that the truck is factory-ready to accommodate the third pedal. However, some people still say that this is the most annoying step in the process for the simple fact that space is so limited. The existing brake pedal will need to be removed and replaced with the pedal that can exist with the clutch pedal. Claustrophobia is going to be a factor, so stay focused and don’t be tempted to rush.

Driveshaft and Transfer Case Issues

Setting the transmission in the truck is the most physically demanding part of the swap. Once it’s in place, you’re pretty much over the hump of hard work—but you’re not entirely out of the woods yet. You still need to get yourself some proper driveshafts and transfer case.

The G56 is two inches longer than the automatic transmission in these trucks. This means, the rear driveshaft will need to be cut to be two inches shorter and the front driveshaft will need to be extended to be two inches longer, or both will need to be replaced. With the N5600, it’s about 5.5 inches.

As far as four-wheel drive goes, the transfer case splines will not match up, which is another issue to overcome. There are two things you can do: You can modify the transfer case so that the splines do match up or you can move to another transfer case entirely.

Making these accommodations for the driveshafts and transfer case are absolutely necessary and will be the difference between driving the truck or not. Of course, you will want to plan for these obstacles ahead of time to keep the process a smooth as possible.

Jumping into a 6-speed manual swap is not for the faint of heart. However, if you truly feel up to the challenge and have a good understanding of what you’re getting into—it’s an incredibly rewarding feeling when all’s said and done.