T56 Magnum evaluation [long post]

[bret]

First off, here is a link to a video that we did that outline some of the installation and some of the features of the T56 Magnum:
http://www.youtube.com/watch?v=1oXQG96aNLU


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 from American Powertrain 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, Mike Copeland…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.

[dontlifttoshift]

Thanks Bret. I have been considering a change in transmission suppliers and this was quite helpful.

[eric1967]

Thanks for the info Bret. How many miles have you put on it so far? It is great that you take the time to post your experiences with the 48 hour Camaro. Thanks Eric

[GeoffP]

Great video - thanks for sharing! I have loved T-56 tranny's ever since I got my hands on my first one in the late 90's!

[cspecken]

Did I miss something, I always thought that if you go with a T56 it required a lot of excess cutting and possible modification to the firewall. Has something changed with the housing that no longer requires those modifications?


Thanks, Chris

[Goober]

Thank you for this independent review. I was on the fence about the magnum without knowing how high you could twist it and still make clean shifts. Guess I know where my tax return is going.

[bret]

As far as cutting, ifcwe had used the stock height subframe mounts instead of the half height units...and had not moved the motor back about an inch, I think it would have slid right in there. As it was, we cut the very top out of the tunnel...a piece about 6" wide and about 18" long...and made a new one. Pretty simple stuff. We used rivets and seam sealer to install the new piece because we didn't want to mess with cleaning off all the existing Dynamat to weld it in.

As far as shifting...I routinely upshift at 6000rpm. At optima I probably shifted up and down 10 times per lap (wasn't really counting at the time) it was always quick and clean...just the way it should be.

One more observation...I'm not a transmission expert, nor do I really want to be. While I'm confident it would be possible to prowl around and gather all the components necessary to make this swap work, I'm also confident that the complete kit from American Powertrain took days...maybe weeks, off the installation. It's not just what they sell...its what they know. Their knowledge and advice could save you not only time but maybe a lot of money by avoiding mistakes.
I know this sounds like a paid infomercial for American Powertrain, but it is only coincidental to offering accurate and relevant advice to some fellow hotrodders. Those guys are my friends, but let's face it...there's a whole lot more of you!

[bret]

Forgot to answer the mileage thing...

So far we've run maybe 30 autocross laps, only about 15 road course laps, and probably 500 street miles. We installed the trans right after the Ft. Worth Goodguys show in October. I waited to do this evaluation until I had some significant seat and track time on it.

[andrewb70]

Did I miss something, I always thought that if you go with a T56 it required a lot of excess cutting and possible modification to the firewall. Has something changed with the housing that no longer requires those modifications?

Thanks, Chris

Great review Bret.

Chris, yes, to fit a T56 into a GM A-body requires more tunnel surgery than what is required for a F-body. However, as Bret pointed out, the mods are not crazy. This and various other forums are filled with information and pictures that will give you an idea as to what is involved in putting a T56 in an A-body.

Andrew

[cspecken]

Great review Bret.

Chris, yes, to fit a T56 into a GM A-body requires more tunnel surgery than what is required for a F-body. However, as Bret pointed out, the mods are not crazy. This and various other forums are filled with information and pictures that will give you an idea as to what is involved in putting a T56 in an A-body.

Andrew

Thanks Bret for the great video and commentary on the American Powertrain T56. Andrew, I have been on the fence about the TKO 600 and T56. It sounds like from the video that the 2-3 shift problems in the TKO a lot of people have may not be the transmission at all! I am still not sure I need a six gear, but I know I will be in the market soon for my engine and transmission and I will be calling American Powertrain up.


Chris

[barraza]

Bret
Perfect solution to your problem, but brings up an obvious question. Is the gearvendor for the muncie for sale? I have a one owner 68ss that I'm not going to cut the floor on, and I want to keep the original shifter in the original position. I talked with you and took a close look at it in Nashville, and it may be just what I need. I don't have enough power to hurt the muncie either. Interested?

[bret]

Ha...sorry...it's already tagged for my 67 big block 4 speed Chevelle. Talk to Gearvenvors...they have all kinds of them!

[andrewb70]

Thanks Bret for the great video and commentary on the American Powertrain T56. Andrew, I have been on the fence about the TKO 600 and T56. It sounds like from the video that the 2-3 shift problems in the TKO a lot of people have may not be the transmission at all! I am still not sure I need a six gear, but I know I will be in the market soon for my engine and transmission and I will be calling American Powertrain up.


Chris

Chris,

The T56 Magnum is a much more technologically advanced transmission than a TKO. The generally poor shifting quality of the TKO can be traced back to its relatively small brass synchronizers and a heavy (but strong) gear assembly. The Magnum has a heavy gear assembly as well, but it uses the fancy pants, dual cone, double throwdown synchros, that really help with the shift quality.

Andrew

[Samckitt]

fancy pants, dual cone, double throwdown synchros,

Huh?

[andrewb70]

Huh?

C'mon now...those are highly technical terms...

Andrew

[Samckitt]

I'm thinking I'm going with the Magnum behind an LS2 in my Monte. I had an LT1/T56 in it before with a Hurst shifter and loved it. Can I use a straight short rod style shifter like that on the magnum? I don't want a long curved like dog hind leg chrome shifter. And I can't decide on gear ratio, leaning towards close ratio even though it will see little track time. I assume the other T56 I had was wide ratio, from 95 F body, had .50 6th gear. And was going to use LS7 clutch with stock GM Camaro aluminum bell housing.

[sjaroslo]

Wow, what an incredibly helpful post and terrific video. Thank you for sharing.