The Charger, Part 9: Shoving A Tremec TKX Where It Truly Belongs

The Charger, Part 9: Shoving A Tremec TKX Where It Truly Belongs

Every six months, it seems, it’s time to provide an update to you, the BangShift reader, on the status of my ’76 Dodge Charger. Let’s be honest: in the entire duration of my haunting of this corner of the Internet, this has been my most well thought-out project to date. The Dodge has made great strides towards reliability, usefulness, and capability. What was an easy flip that looked day-one stock when purchased now has the look of someone’s dream hot rod circa 1988, with the slot mags, the slightly-hiked-in-the-back stance, and just enough roughness to come across as honest. We’ve even upgraded safety items and performed bodywork on the Malaise-era B-body.

But this time around, we’re performing major surgery. Considering the last update focused on the installation of a complete gauge cluster, that’s saying something. But it’s true: the 727 TorqueFlite is gone and a Tremec TKX took its place, with help from our friends at American Powertrain.

Why Put A TKX Into A Mid-1970s Mopar?

“Warhammer”, the 1987 Dodge Diplomat AHB (2006?)

For those who have been around BangShift for years (or date further back to the days), and especially those who know my proclivities when it comes to odd Mopars, the dark blue Dodge Diplomat pictured above should look familiar. This is “Warhammer”, a 1987 AHB (police package) car that had been built with a heated 360 and an A833 four-speed. I bought the car from the original builder in 2005, had it painted, bought those chromed trailer wheels, and proceeded to drive that thing like I had been gifted something from a NASCAR garage. I’ve owned about eight or so FMJ-body vehicles in various tunes, but that Diplomat had violence and manners, thanks to the manual transmission. The car is long gone, but the idea of another row-your-own Mopar never left.

I’ve wanted to have another manual transmission-equipped car in the fleet, but that hasn’t worked out well. About the same time I owned the Diplomat, I had a four-speed 1980s shortbed Dodge truck that I had to sell off to a friend. After a seriously long drought, we bought a 2012 Chevrolet Cruze that had a six-speed as an economy car. Once we learned how much of a dumpster fire that thing was, I decided my next project vehicle would be a stick shift…and forgot that entire idea when the Charger popped onto my radar.

Luckily, after coming to my senses, some research showed that swapping the car could be a possibility. The 1971-74 B-body platform and 1970-74 E-body (Challenger/Cuda) body share many common traits, and there was a good chance that the “black metal” of the 1975-up B-body wasn’t much different than before, due to Chrysler’s financial troubles. After some discussions, I committed and started to put this idea into motion.

Before The Swap

The pedals were the first items to be swapped in. They bolted right into place with plenty of clearance.

Before I was going to shell out for a transmission, I wanted to make sure that this swap was going to go my way. I made two purchases: a steering column from a floor-shifted 1979 Chrysler 300, and manual transmission pedals for a 1970-74 E-body. The pedals were sent to American Powertrain to be studied to see how close they were to parts already sold, while I spent time restoring the column. In early December, American Powertrain sent back a pedal assembly that used a Malwood hydraulic clutch pedal for a test-fit. Once the pedals were swapped in and were working, I bit the bullet and paid for a Ford-style TKX with a 2.87 first gear and a 0.68 overdriven fifth gear.

Out comes the faithful, if incontinent, A727 TorqueFlite. A good re-sealing at every possible leak point and this transmission is good to go.

The only thing happier than having the UPS guy showing up just before Christmas is unloading several large boxes from the truck, including one that leaves the driver asking what dead body you ordered due to the weight. In addition to the TKX, American Powertrain sent over just about everything possibly needed to finish off this swap, from the transmission crossmember and pilot bushing to the fluids needed and, naturally, the crowning touch for the finished product:

That’s right. The MF’ing Hurst Pistol Grip shifter.

Where Is My Grinder? Time To Cut A Hole!

With the 727 and related items out of the way, it was time to start planning out the swap properly. I wasn’t worried about making major holes in the floor…the TKX was originally designed to fit into a 1970 Chevelle with little to no modifications needed. After a couple of test fits and a few measurements, I had a pretty solid square of transmission tunnel that needed to go away for the shifter area and with it, a small section of inconsequential floor bracing above the transmission crossmember. I didn’t even have to bash in the seam at the firewall any!

Cardboard-Aided Design at its finest! The first measurements were taken underneath the car, and once the square was measured out the template was used to locate the two shifter locations offered.

As you can see in this image, the forward shifter location was a no-go from the start. Punching the dash on the 2-3 shift wasn’t going to cut it.

This was the first section removed from the floor: the square lines up with the Tremec’s shifter plate and the section of crossmember was in the way. There was some additional metal removed, but this is the largest section.

From above, you can see that the initial cut was restrained.

How Easy Is It To Manually-Swap A Cordoba Clone? Surprisingly Easy!

Once the cut was made, the next few steps were pretty typical: install the pilot bushing, bolt on the flywheel, install the clutch using the provided alignment tool. Simple and straightforward. It was during the installation of the Lakewood bellhousing that adapts the TKX to the small-block Chrysler that we found one thing we didn’t count on: the passenger-side exhaust interfered with fitment.

A quick trip to Mark Muffler in Bowling Green, Kentucky took care of our bellhousing/exhaust fitment issue.

Once the car was back from the exhaust shop, we entered the critical phases of installation: measuring bellhousing runout and the air gap for the hydraulic throwout bearing. Besides being critical for your warranty, both of these are critical towards your transmission’s happiness in day-to-day operations and overall lifespan. Here’s what you need to know (mainly because I listened to people who know more things than I do):

With measurements taken, I found that the bellhousing was exactly where it needed to be and that the hydraulic throw-out needed three shims. Perfect. I put everything together and aside from a slight bit of hole enlargement for the trans crossmember to bolt up properly to the underside of the Charger, everything installed together just fine.

In-between transmission work, I prepared the new column to go into the Charger. That included painting the visible parts in Claret Red (the darker red tone of the car’s paint job).

It also required a complete swap of components from the Charger’s original steering column. Everything from the lower steering shaft bearing to the entire wiring situation, all of that was swapped into the new column. And naturally, so was the ignition key tumbler. Works like a freaking charm.

The other final touch? The Tuff Wheel that used to belong in the SuperBeater Mirada. I sold this wheel when that car was stripped back in 2012, and the guy who bought it from me returned it to me at the Chrysler Nats at Carlisle last year! Craft Customs restored the wheel to what you see here. You can also see the adjustable “White Lightning” shifter kit that American Powertrain sent. Using a series of dog bones and Allen-key bolts, you can adjust your shifter to suit just about any application your heart desires. We ended up turning the shifter a little more towards the driver’s seat from this picture.

To mount the hydraulic reservoir for the clutch, the bracket that had been for the cruise control cable was removed, pounded flat on an anvil, and drilled for mounting holes before being mounted mirror-image onto the opposite side of the master cylinder. Cheap, easy, simple.

Once the transmission was bolted into place and I was content with the way everything sat, I took measurements per the instructions American Powertrain sent and placed the order for the new driveshaft, which arrived in short order in the most non-discreet package possible. Lord knows what my neighbors were thinking. All you have to do is follow the directions, know how to read a measuring tape, and understand what kind of U-joint connects to your rear axle. In my case, a 7260 (small Mopar) was ordered and once it was bolted in, it was time to drive.

Change One Thing, Change Two More…

Our first attempt at driving the Charger immediately ended when it became apparent that yours truly broke the bearing input shaft. That forced me to pull the transmission and replace the broken unit with a new retainer. But once we fixed that and finally got the car onto the roadway, it became apparent fast that pairing off a transmission with a 2.87 first gear and a 2.41 rear gear axle was a match made in Hell. Too tall a gear combination paired off with an engine that has just about no low end to speak of resulted in max effort to get the car moving without venturing into “hurting things” territory.

Oh, sure, the Charger would cruise at 70 MPH in fourth gear without breaking a sweat, but even at 75 MPH, the Charger didn’t have the oats to pull fifth gear. Oh, damn…guess that means new gears! And if I’m paying for new gears, I might as well add a limited-slip, right? It was a process (translated: the first set of gears nuked itself after eight miles, warranty repairs, and that the car was in the path of both tornadoes and flooding areas during the recent spat of psychotic weather that Kentucky and Tennessee went through) but the final result is that the car is home, the rear axle is back in the car, and we’re breaking in the gears over the next couple of weeks. A big kudos to Ron’s Machining Service LLC and Seth at Rears and Gears for their assistance with everything, I’ve never received customer service like that from either. Both are now immediate go-to sources for axle parts and work.

I’m sure that catches up the story. Between now and the next update is Hot Rod Power Tour…and the car is slated to go come hell or high water. Right now we have a sticking brake pedal (if not sticking front brakes), valve cover gaskets, a tune-up, a floor patch to complete, the interior to completely install, new air shocks so we don’t eat another set of rear tires prematurely, a tune-up, and an inaccurate fuel gauge to fix. Don’t wish me luck. Wish me someone who has been speaking Mopar since the late 1960s who can handle this list in 45 minutes.

Photo: Ron Turransky

Need to catch up?

The Introduction

Part One: The First Assessment

Part Two: Trunk Paint, Instrument Cluster Work

Part Three: Deeper Instrument Panel Work and the EFI-Ready Fuel Tank

Part Four: The Heater Core Job We Should Have Been Worried About

Part Five: New Wheels, Wiring Fixes, Fuel Pump Troubleshooting, First Dragstrip Pass

Part Six: MSD Distributor, Coil, and Solid-State Relay, RetroBright Headlights, And More

Part Seven: Brake Repair, Winter Projects, Subframe Bushing Replacement, Firm Feel Upper A-Arms

The Charger’s 2023 Trip To The Carlisle Chrysler Nationals

Part Eight: Fixing The Gauges Once And For All With Classic Instruments

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