Transmission and rear end combo

I recently got my 99 Cobra back on the road with the 5.3l BBS motor and an looking into a stronger transmission and a rear end rebuilt. I was thinking about going with the TUET11011 Tremec t56 Magnum with 4.30 gears in the rear end. Does this sound like an appropriate combo for me? I'm open to input as well. Let me know your thoughts. Thanks!

What's the plan for the car? What's the power band? What's the shift point?

It's a fun weekend car, I shift at 7400rpm, and it makes great power from 4000 up. Very linear power curve actually.

I'd keep the T-45 til it breaks, I have a couple hundred more HP than you still using the oem T-45. For N/A you do want to go with 4.30's, the stock 3.27's won't do your motor justice.
Upgrading to 31 spline half shafts is an option while you have the rear end apart.

Do you think launching at the track will kill the t45 with a decent set of tires? That's my big fear.

What’s your current rear end setup now. 4.30 or 4.56 is a good gear for a n/a setup. But if your still irs the transmission will be the least of your worries if you “launch” at the track.


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I have the IRS still with 3.27s, but it has a full tilt boogie bushing set, and when I rebuild the pumpkin it's getting a Detroit true-trac and level 5 half shafts along with gears. I'm doing a whopping 13.0 at 110 right now on street tires, and I'm far from happy with that.

I have the IRS still with 3.27s, but it has a full tilt boogie bushing set, and when I rebuild the pumpkin it's getting a Detroit true-trac and level 5 half shafts along with gears. I'm doing a whopping 13.0 at 110 right now on street tires, and I'm far from happy with that.

I have the IRS still with 3.27s, but it has a full tilt boogie bushing set, and when I rebuild the pumpkin it's getting a Detroit true-trac and level 5 half shafts along with gears. I'm doing a whopping 13.0 at 110 right now on street tires, and I'm far from happy with that.

I have the IRS still with 3.27s, but it has a full tilt boogie bushing set, and when I rebuild the pumpkin it's getting a Detroit true-trac and level 5 half shafts along with gears. I'm doing a whopping 13.0 at 110 right now on street tires, and I'm far from happy with that.

Sorry about that, I posted in an area with no service, so I guess it posted a few times. If an admin wants to delete a few of those I welcome it.

T-56 and 4.11's.

03-04 Cobra

H&R race springs with koni or bilstein sports
3.73 gears with complete FTBR kit,
and don't worry about the 1999 axles.

keep the T45 until it or the clutch goes.

you will like the DTT.
I dont think a BB stroker needs more gear than 3.73

Do you have subframes or FLSFCs?

I have Bilsteins in the rear already, buy stock springs. I still don't have FLSFCs yet. I want more gearing but don't want to wind it out to far in the highway. That's why I was thinking that t56 with the wide ratio would be a good option with a set of 4.30s. first gear is 2.98 in the t56 and like 3.27 or something on the t45.

My full engine setup is an 11.5:1 5.3 BBS with Fox lake ported 03 Cobra heads, bullet custom grind cams 242/237 112lsa, bbk long tubes, Sullivan performance intake, 47lb injectors, acufab oval throttle body, 90mm Cobra maf, catted h-pipe and borla stinger cat back.

shurur said:

H&R race springs with koni or bilstein sports
3.73 gears with complete FTBR kit,
and don't worry about the 1999 axles.

keep the T45 until it or the clutch goes.

you will like the DTT.
I dont think a BB stroker needs more gear than 3.73

Do you have subframes or FLSFCs?

Click to expand...

Still needs more gear than 3.73

Unless you got a different T-56 first gear is 2.67. I wouldn't consider it wide ratio. I liked it a lot better than the 3650 behind my BBS. I had 3.90's with that car. But I also had a blower hanging off the front of the engine.

Sixth gear is .62. You should be able to figure out cruise RPM from there. I really wanted to swap to the .50 6th to get the freeway RPM down.

The part number I listed in the original post has a 2.97 first and .50 6th. It's TUET11011. You can find it on the Tremec website.

My apologies. I missed the Magnum part. So yeah, you'll get the long overdrive.

I just discovered Promotion Powetrain, and their t45 rated to 700hp. It's cheaper than the t56 and I don't need any conversion parts. So when I explode the input shaft in my t45 that's what I think I'll do.