Paul Workman

Note especially how the ZR-1 lurches forward, every time the C5 shifts - testimony to the Zs broad torque curve and rpm ability.

Quotable quotes (from the video)...

"Ha!" ... "Huh?" ... "You're not catching him!"

Tom400CFI

I'd say it's more a testimony to the ZF6 and the driver of the ZR-1...obviously, he shifted just as many gears/time in that roll races as the C5 did. You couldn't see his shifts which indicates that he shifted FAST....which you can not do with a T56.

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mike100

The ZF6 gear spread doesn't do the LT5 any favors, but it is more about the sweet part of the powerband covering a wider range of engine speeds on 32v engines. You can make an LSx run pretty well though, but you tend to get the lumpy cam side effects in order to pull hard to 7000 rpm.


But back to the ZF vs argument... the Ford MT-82 gear box part of the reason new mustangs are so fast. First gear is around 4:1 ratio and 5th gear is 1:1. If you could GM-ize the bell housing and input shaft , then you would have a good replacement for small v8's.

Tom400CFI

How so? It has pretty similar ratios as the T56....

mike100

yes, classic ratios...one size fits all? hence the point I was trying to make with the Getrag licensed Chinese made MT-82. It is also a light truck sized transmission that weighs 124 lbs or so. I wish the ZF had the 3.66 first gear nd only one (useful) OD.

Tom400CFI

I got you now. That is obtainable with a ~4.70 rear gear.

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Dominic Sorresso

Yeah Mike. An actual 5 speed would have been nice w a 6th OD but I assume it was also done for emissions and MPG purposes. HAving now driven BMWs w 8 speed DCT, you gotta love how each shift only drops rpms by 500. Imagine an LT-5 staying up there in the power band through the gears.
I will say that w my 4.10s in there now, even with the Z06 19s, makes 6th gear passing driver friendly.

mike100

It isn't close ratio but it is closer ratio and also avoids the golf ball sized pinion gear you would have to run to get 4.88 rear gears, lol. Not to mention that a mild 6th gear OD works fine with 3.55 or so gearing.

MT-82 v ZF6
--------------
3.66 ----2.68
2.43 ----1.80
1.69 ----1.29
1.32 ----1.00
1.00 ---- .75
.65 -----.50

bjankuski

I never understood this, I have a T56 in my Firebird and and I have probably power shifted it 1000 times and never missed a gear, the T56 is very easy to shift fast. Stock shifter and all.

Tom400CFI

IDK what to say. This is pretty subjective since most don't time their shift events (although I have).

I've had a T56 in a Trans Am, a 3rd Gen Camero, my C6 and our CTS-V.

I've tried to flat-foot shift them 100's of times -I've been successful maybe 90% of those times? Not too good. Anyways, I can do it, but not as fast as I can the ZF6....no way. On top of that, there are all the missed shifts. And that has happened in several ways;
1. Synchro just isn't fast enough, "blocks" my effort during the clutch pump, I come off the clutch and...I'm not in gear. Pass blown. This happened many times in all my T56 cars.
You said stock shifter, so...
2. 2-3 shift, shifter "clicks" as if it had gone into 3rd, and is in the "3rd" location....but it's really in "no man's land", release the clutch only to discover that you're in no gear. Pull shifter back to neutral (which it "clicks" back to neutral) then try again...it works, but you've lost the pass. *This happened in the C6 NUMEROUS TIMES. Talk about maddening.
3. Shifter will not go into 1st gear. Won't do it. CTS-V
4. Shifter will not go into reverse. Won't do it. You can push the shifter until the **** flexes so far it's hitting the ash try door...won't go into reverse. CTS-V


None of these problems has ever happened to me in the stock shifter'd ZF6. I've never missed a flat foot shift with the ZF6. I've timed one of my shifts at .2 seconds, clutch in to clutch out. These differences are fairly objective, to me. Maybe you had/have a "good" T56? IDK. It sounds like yours works really well...which is awesome. That's what you want/need it to do.


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