In the process of building several cars over the last 30 years, most recently the 48 Hour Camaro, I have had the opportunity to use many different engine and transmission combinations. MOST have turned out very well. I’ve had great success with the 700R4, especially with a manual valve body and a Gear Vendors overdrive unit in our 66 Chevelle on the autocross and road course. I’ve used a 4L60 and a 4L80 automatic in a couple of cars with similar success. Velocity had a ZF 6 speed which I loved!
When we started planning the 48 Hour Camaro the criteria was simplicity and ease of installation, along with durability and performance. This led us to try a plain old Muncie M21 4 speed with a Gearvendors overdrive unit. I must say I really enjoyed that combination on the street and on the track. The ability to toggle between direct and overdrive by pushing a button on the shifter knob was almost an unfair advantage on the autocross and road course, and the 22% overdrive made highway use a breeze. The shifting precision was certainly above adequate and it went into the car with no modifications whatsoever.
Unfortunately, the Muncie just wasn’t up to the use [abuse?] that I gave it on the road course. I kept shucking the teeth off third gear. After the third unit I went to a Tex Racing T101a that I had laying around for another project. This was a great racing transmission… clutchless shifting up and down, light, efficient… but with the straight cut gears it made more noise in the car than any mechanical device I’ve ever seen. People would watch the car run and wonder what the hell was wrong with it! It’s other sin was that there was no adapter available for the Gearvendors overdrive unit, so highway driving was a high RPM chore. I ended up chipping a tooth on second gear at the Texas Goodguys event so I had yet another decision to make.
Why didn’t I simply go with a T56 Magnum in the first place, you ask? Well, there were several reasons. During the planning stages of the car I couldn’t seem to find a decent supplier for such a unit [I hadn’t met the guys from American Powertrain yet]. Also, I had a fairly poor experience with the TKO series Tremec units previously and wanted to explore other alternatives.
After I hurt the Tex unit in Texas I had to make something happen fairly quickly because I was scheduled to race at the Optima Ultimate Street Car Invitational right after SEMA. Over the summer I had come to know the guys at American Powertrain who have developed a VERY complete system for installing both the TKO and the T56 Magnum into these musclecars. We actually used their bellhousing/clutch/master cylinder/throwout bearing in the 48 Hour Camaro build to install the Muncie. Good people…great products.
Matt Graves, Grey Fredrick, and Robert Hall had been teasing me all summer about my transmission problems with the Camaro and said anytime I wanted to “come in from the rain” they could set me up with a nice T56 Magnum. While I was still in Texas, I texted Matt and said: “ Tex broke. Bring me a T56.” So they did.
Matt and Grey swore and be damned that the T56 would go in that Camaro without cutting the floorpan. If it weren’t for the fact that I was using half height body bushings, and that we had moved the engine back by about an inch…they would have been exactly right. Even with all of my previous customizations we just cut the top of the trans tunnel out and made a new one. It just wasn’t that big a deal. The T56 is not really much smaller than the TKO, but the top is shaped differently so it’s actually a much better fit in any given trans tunnel. The video that we made [linked] gives you an overview of some of the features and benefits of that transmission…I won’t repeat them here. I do, however, want to offer an evaluation of this transmission from a hotrodders perspective.
I had MANY reliable people tell me about the virtues of the T56…Brian Finch, Mark Steilow, Steven Rupp…these are guys who flog their cars regularly and have no agenda for or against this transmission.
Grey Fredrick from American Powertrain had to teach me how to shift. [you’ll see this in the video] At 50 years old with well over 30 years of hotrodding experience behind me, I found it a little hard to believe that I didn’t know everything there was to know about shifting a dumb old transmission. Here’s the lesson: An open mind will make your car faster.
The T56 is to be shifted with 2 fingers, not your whole fist. If you try to rape this thing it will seem sticky and notchy. It shifted fast…VERY fast, at any RPM I tried it at…IF you treat it like a partner instead of a servant. It’s not tricky at all, it’s more of a mindset. I love the ratio spread…it’s never hard to keep the engine in an appropriate RPM range. I love the tall 6th gear as well. On the way to Pahrump from Vegas for the Optima event we were running…well, never mind how fast we were running. The engine was at about 3100 RPM in 6th gear with a 26” tall tire and a 3.50 gear. You figure it out. The point is that ANY reasonable [or unreasonable] highway speed is much less stressful with the T56 Magnum 6 speed.
In addition to the raw performance of the T56 Magnum, I have to comment on the service and installation kit from American Powertrain. While it is possible that I experienced wonderful service because of our personal and professional relationship, I have heard similar accolades from many other American Powertrain customers. It is a simple matter of you call..they deliver. In the end, that’s all any of us want, right?
The installation kit was as complete as any product I’ve seen. The bellhousing, hydraulic throwout bearing, clutch, pilot bearing, driveshaft yoke, crossmember…it was all there and very elegantly made. The crossmember was really unusual…it’s a nicely formed piece of 6061-T6 aluminum that looks kind of like a wing. Unfortunately we could not use it in our installation because of the dropped body mounts and the engine setback. Bummer.
The other item that I wanted to point out again [you’ll see this in the video] was the unique shifter system. It is adjustable not only for position on the trans, but the position of the shifter handle on the plate as well. In addition, the tension of the shifter is externally adjustable…you can actually adjust with a screwdriver the spring tension that centers the shifter between gears. I like this a LOT!
I still miss my Gearvendors overdrive, but this T56 Magnum 6 speed from American Powertrain is getting me over my grief nicely.