Auto to manual conversion. If you could do it over....regrets, pitfalls, long term opinions???
I converted my Duster from a 904 to an 833 when I installed the 340. Muscle cars should have manual transmissions. It's a whole different car. That's not to say that auto's don't have their place, I'm leaving the 904 in my Dart. I have the numbers matching drivetrain for that car which is part of it, and it's a 1 of 1280-ish GT model so I got a little apprehensive about cutting it up for the 4 speed. The other is that I need an "easy" car to drive sometimes, and since the GT is a power steering/auto/AC car it fits the bill to leave it that way.
AJ makes some really good points with his remarks on gearing. That's the only con as far as I'm concerned with the 4 speed set up in my Duster (although to be fair I'd have the same issues with an auto). I have a 340 with a Lunati 60404 cam (advertised 276/284 duration, .513/.533 lift), and the car doesn't really wake up until it's past 3k rpm. Which shouldn't have been a surprise since the cam is rated for 2,200-6,400 rpm and lunati calls for 3.73's with it. I'm running 3.55's in the car now, which works, but it needs more gear down low. Problem being is that I drive it on the freeway on a pretty regular basis, so, 3.55 is about as high as I want to go because if you can't maintain 75mph on most California freeways you're a speed bump. But 3,450 rpm isn't exactly a good cruising rpm for long distances, and that's what I have to turn with 3.55's and 26" tall tires to maintain 75mph.
The solution for me anyway is I bought a T56, and if I had been smart I would have gone straight to it instead of converting to the 833 first. Do the tunnel once, do the carpet once, not have to mess with the modified z-bar for the headers for my 340, and gear it so taking off is a piece of cake. Initially I had planned 3.91's with the T56, but I think I'm actually going to go to 4.30's. Because even 4.30's and 26" tires will put me at 2600 rpm in 6th at 74mph. 3.91's would take me down to 2,400 at 75, and that's pretty much the bottom of what I can cruise at.
But like I said, those issues are related more to my engine build than the transmission. If I had a more mild 340, or a 360 with better low end torque, the 833 with 3.23's would be just fine. And I could run a less aggressive clutch, which would make that a little easier than what I've got now without going hydraulic like I have to on the T56. Not that a hydraulic clutch is a bad thing at all, but it just adds to the expense of things. Especially if you can modify your own z-bar to fit with the TTI or Doug's headers.
I debated the t56 6 speed viper trans and the passon 4 speed hemi overdrive.
I went passon and cruise with my Hurst ram rod and 4.30 gears. Overdrive acts like 3.55 gears and I cruise around 2700 rpm.
The t56 I felt I would never use all 6 gears with a .5 overdrive i believed it would be too much or if I went taller gears in the rear I would never use the first 2 gears. But that is just my 2 cents worth.
I mainly cruise backroads and rarely hit the highway so 6th would hardly ever be used.
The 5 speed I was warned I would blow the trans up with my small block stroker and w2 heads.
Not all the T56's have a .50 6th. The Magnum T56 I have for my Duster is a .63 6th. There's a few different common gearsets for the T56's. Mine's a 2.66/1.78/1.30/1.0/.80/.63, which works pretty decent as far as ratio splits are concerned.
Someone transplanted a 4spd in my 67 belvedere.
Pros:
Fun to shift gears
More control of Rpms
Great to do burnouts
Cons:
Hurts my knee after to long I'm only 35 lol.
I don't care much for the Z bar set up
Cruising thru parking lots shakes like hell with 3:23 sure grip.
Can never get the clutch adjusted quite right.
I'd say for my next project I'm going with the T56 with hydraulic clutch set up
Dustin
All of your "cons" are clutch problems. Not even normal issues that come up with a clutch, but actual signs there's something
wrong with yours. I run a dual compound organic/ceramic clutch with all the manual linkage and don't have any of the problems you describe. And I need more gear than I've got with 3.55's. Not saying that a T56 with a hydraulic clutch isn't the way to go because that's what I'm going to do, but the problems you listed are symptoms of a poorly adjusted or damaged clutch, not problems that come from a 4 speed set up in general.
