T56 install in a 97 Cobra

[Grappler]

Has anyone done this or have any information or good links to information? I am looking to upgrade the tranny since it needs replaced and I'm trying to find out if it is a direct bolt up or how many changes will be needed for the conversion. Thanks

 

[DirtySanchez]

Has anyone done this or have any information or good links to information? I am looking to upgrade the tranny since it needs replaced and I'm trying to find out if it is a direct bolt up or how many changes will be needed for the conversion. Thanks

I've been researching this a bit for my 99. D & D Performance (http://www.ddperformance.com/) sells T56's and conversion kits. You'll need an adaptor for the cross member and a shorter driveshaft. You'll also want to swap out your rear end gears, as the T56 is quite a bit taller than the T45 in 1st and 2nd gear. Personally, I'm going with the Viper T56 instead of the Cobra T56 because it's tougher, and the 6th gear ratio is .50 instead of .63. The taller 6th gear will allow me to cruise at about 2400 rpms at 80 mph with a 4.56 rear, as opposed to about 3000 with the Cobra T56.

Here are the gear ratios:

Trans .. Gear Ratio
t45cobra .. 1 3.37
t45cobra .. 2 1.99
t45cobra .. 3 1.33
t45cobra .. 4 1.00
t45cobra .. 5 0.67

Trans .. Gear Ratio
t56cobra .. 1 2.66
t56cobra .. 2 1.78
t56cobra .. 3 1.30
t56cobra .. 4 1.00
t56cobra .. 5 0.80
t56cobra .. 6 0.63

Trans .. Gear Ratio
t56viper .. 1 2.66
t56viper .. 2 1.78
t56viper .. 3 1.30
t56viper .. 4 1.00
t56viper .. 5 0.74
t56viper .. 6 0.50

And here's a comparison of final drive ratios with different rear ends:

Trans .. Rear ..1st .2nd .3rd .4th .5th .6th
t45cobra 3.27 11.02 6.51 4.35 3.27 2.19
t56cobra 3.27 08.70 5.82 4.25 3.27 2.62 2.06
t56cobra 4.56 12.13 8.12 5.93 4.56 3.65 2.87
t56viper 4.56 12.13 8.12 5.93 4.56 3.37 2.28

Assuming you have stock wheels/tires, you can find the rpm at a given speed by multiplying MPH * RATIO * 13.1. E.g. 80 mph in 6th gear on the Cobra T56 with a 4.56 rearend is 80 * 2.87 * 13.1 =~ 3007 rpm.

To find mph from rpm, the formula is .076 * RPM / RATIO. E.g. redline speed for 1st gear with a T56 and 4.56 rear is .076 * 6800 / 12.13 =~ 42 mph.

 

[SnakeBite98]

just got my 98 back from JBA with a new T-56 in it two days ago, i love it. you need a shorter driveshaft and different crossmember as well. you also need a new bellhousing as they differ between the T-45 and T-56, but most places sell them together. D&D is the place to get it, i got mine from a buddy that works with ford so i got a deal on it. install was pretty cheap. i have 4.10's and haven't had a real chance to open it up yet but if you get gears i would probably go with 4.30's. also, you might want to do a clutch while your in there, saves money.


P.S.---you will need a Dallas MustangSpeedcal to get the speedo dead on, even with the speedo gear switched over mine was off by 20mph by 80 mph.

 

[Grappler]

Thanks for all the GREAT information. Now, I just have to find a shop that will do it and that I feel comfortable with. I'm planning to just go with a SPEC Stage III clutch while they are doing the tranny to save the labor cost later. Will 4.30s fit without any modifications to the rear end? And, does the Speedcal support the 4.30 gear sets?

One last thing, with stock tires, how usable do you think 1st will be with the 4.30s in the rear end and either the Cobra T56 or the Viper T56?

I lied, that wasn't the last thing but I think this is. What shifter do people typically use with the T56? As I'm sure I'll just order it with everything else.

 

[DirtySanchez]

One last thing, with stock tires, how usable do you think 1st will be with the 4.30s in the rear end and either the Cobra T56 or the Viper T56?

T56 + 4.30 won't be much different than T45 + 3.27 off the line. The T56 has a much taller first gear. The final drive ratio for T56 + 4.30 1st gear is only 3% higher than T45 + 3.27 1st gear. The steep rearend won't really kick you in the pants until you hit 2nd.