T-56 viper box behind 545 cobra

[AC-460]

My cobra has a 460 stroked to 545 its pushing 650hp and 650lb torque I've got a c6 behind it at the moment and 2.88 jag diff . I want to change to a manual and are looking at a T56 viper box .50 6th and going to 3.54 Diff and I doing the right thing?
AC-460

[RICK LAKE]

AC-460 With the torque your 545 is pushing and the rearend change to 3.54, you are getting into running on the edge. The T-56 needs some help with forks, main shafts and 1-2 gears set. Go to G-Force and look up the kit to do this. They up the torque and HP rates to 800HP and torque with better input shafts and cluster of gears. Not cheap, but will hold up over long term. You didn't say what you are doing with the car, racing, autocross, show and shine?? Going to a 3.54 and having a what first gear ratio? First gear in any trans with a 3.00 or higher is never used and a waste of time. I have 3.31 and don't use first with a 3.06 custom trans. Down the road I may drop the rearend to a 3.07 ratio. The problem is the lower the gear you go the weaker the carrier in the Jag rearend is. I have a 2.88 as backup If I go racing and blowup the 3.31. I also would change the rearend to the 2.88 with the 6 spd richmond and be OK. I run pilot tires, no slicks, drag radials, autocross tires or Billboards. I would also tell you to look into the new Richmond super street 5 spd. It is more stronger and better designed to handle your power plant. The gears are straight cut and not heli gears with a 20-30 degree angle. Little more info would really help with your questions. Rick L.

[Powershift1038]

The T56 in a 2003/2004 SVT Cobra can take the kind of power you are making, and more. My '03 Cobra is currently at 450 rwhp with 461 tq. I have a new Whipple supercharger (and supporting mods) waiting to go on.. pushing me to 600 rwhp. I have NO fear of any trans failures. There are also numerous '03/04 Cobras owners who are running large single turbos.. making 750+ rwhp with the T56. The only trans mod I, and others making big power numbers, have is swapping to a 26 spline input shaft for added strength. It's probably easier to find a Cobra T56 vs. a Viper box too.

[AC-460]

I run the car on the road and on the track. My first option was to go for TKO600 and run a 3.31. Then I found that quicktime where making a bellhousing to take the TUET 1806 t56 viper box. With a .50 6th and 3.54 gears I can run 70mph at 1600rpm and have the 3.54 diff for mind blowing accelaration in the lower gears or should I just stick to the TKO 600 also thinking of running an aluminium flywheel and a McCleod twin plate clutch

[Powershift1038]

Oh yea.. here are the different gear ratios for both transmissions...

'03/04 Cobra T56
2.97/2.07/1.43/1.00/.80/.62

Viper T56
2.66/1.78/1.30/1.00/.74/.50

[undy]

I had a 03 Cobra and the Viper spec T56 is a stronger unit, more than just a different input shaft. There were several of the other Cobra guys that were busting the T56s and replacing it with Viper spec units.


Dave

[Powershift1038]

I was just trying to throw out another option. For the 650hp and 650lb torque he is running... a Cobra T56 would be more than enough, and easier/cheaper to find.

[undy]

Originally Posted by Powershift1038

I was just trying to throw out another option. For the 650hp and 650lb torque he is running... a Cobra T56 would be more than enough, and easier/cheaper to find.

I agree.. A cobra weighing <3000 lbs there shouldn't be a problem. I do hate that blasted weak 10 spline input shaft though..

[Powershift1038]

Originally Posted by undy

I do hate that blasted weak 10 spline input shaft though..

That is why I already upgraded mine to the 26 spline... BEFORE I install my new Whipple. HA HA!

[Double Venom]

For what it is worth department, I ran all T-56's in all DoubleVenom's (Viper powered Cobras for the newer guys) the Double Venom II was rated at well over 700 HP with well over 660 lbs of torque. Not that you don't need to follow any other posts, but pay particular attention to post #1. 1st and 2nd are WEAk, the main outboard spline may give you problems and if you do any hard shifting (Drags), you may end up ugrading the shift forks.

Unless you like to pull "wheelies" from a stop sign or redlight, first gear is useless, second not much better. That is why the Stock Viper with a T-56 will come with a "skip shift- which most guys including the Viper guys will disconnect.

For our purposes I like the 3:55 gear for all around use. When my family gave away the first DV at the third Spring Fling the car with street tires and low (for a Viper) HP was turning 11.00 flat at the Drags and broke records at Run N Gun.

I only went through one T-56 when the syncros started to go bad.
DV

[RICK LAKE]

Double Venom Ed I was there for the fun year at R&G. The only car to run wheelie bars. Or you where trying to adjust the back bumper. If I recall you did wear out that trans at R&G for the 1/4 mile. I did like that car with a 488 cube motor. I just could not get over the strange exhaust tone the car made. Rick L. Ps didn't you bend the wheelie bar at R&G?

[RICK LAKE]

Powershift1038 Yes there are guys running stock t-56 trans with 800 HP turbo motors. Those trans missions do last than long. If you blue print the gear clusters, and have the end play tight they will last for awhile. The gears are not made of 9130 steel and they are not straight gears in the cobras. The viper trans had better parts inside because of the Torque rating on the 488 motor. It's not about HP, It's about the torque load that the drivetrain has to with stand. Add soft tires like slicks and the breakage increases twice as fast. A trans and 2,400.00 will give you a bullet proof box with a 800-900HP and 1000ft of torque rating. Side note, couple of weeks ago at E-town, a 331 mustang with single turbo, blew apart his T-56. He was in the 700 HPrange with 10" slicks. OIled the track down and junk all over. Something to think about. Hope you guys are running safety blankets for the trans. Just a Thought. Rick L.

[Double Venom]

Rick,
Smilin' here. I didn't think anyone noticed I bent the bars! That's why we took them off!
DV

[ByronRACE]

IMHO, I'd run the Viper T56 (i.e. with the Viper input shaft) and you should be just fine. If you want to go crazy, use one of the newer "Tranzilla" or "G-Force" gear set models.

I have a Viper T56 behind mine and it makes well over 800/800. I shut it down on the dynojet 248 at 760/760 at 5500rpm having just barely reached peak torque. That was about 1400mi ago when the engine had about 100mi on it and no damage yet, and I've visited 7K regularly. According to the logger, it's at the limit of 83lb/hr injectors at 7000rpm, so that's a lot at the rear wheels. And, that's with a *stock* viper trans, and 3.50 rear gears with 335 road race compound on the rear which does not slip in 3rd on up...so that transmission can handle some real torque. There's a lot of viper guys out there making 700-1200hp through these transmissions.

On the other hand, I've seen the ford-splined T56 break at less power. A friend sheared the input shaft off his in a blown 408 Mustang making 700rwhp or so. He was in 4th gear at WOT when it happened. I've seen another one in a lightning pickup snap the input shaft on a 1-2 shift. So far, I've never seen the viper input shaft fail.

Byron

[Badger]

All good advice from the guys running the Viper engines. The item not really mentioned in all this conversation is the Jag diff'. I think that's the weak point. (with the HP mentioned) If I had to choose a twin-disc clutch I'd go with a complete (including flywheel) Tilton unit. I love my T56 on the hiway with PS2 tires, as their lower overall diameter allows 2200 RPM at 80 mph in 6th with the coupes stock 2:46 diff', anything under that engine speed with the cam I have won't run smoothly. Badger

[ByronRACE]

I'm running a custom 12" single disk kevlar/kevlar clutch provided to me by Bruce Couture at Modern Driveline (www.moderndriveline.com). Hydraulic master/slave setup with an internal slave (no clutch fork). Pedal effort is less than a stock 5.0L Mustang, can hold 1000hp, and has absolutely perfect street manners. It came all ready to go for the application (385 Series Ford to Dodge Viper T56), along with all the other goodies I needed right down to the special pilot bearing to adapt my industrial 429 crank to the dodge pilot. I'd recommend you talk to those people if you want to do a conversion like this...I couldn't believe how easy Bruce made this happen.

The comment about cruise RPM is very important to think about, as I've found out. Running 3.50 rear gears in my car with a healthy solid-roller cam that peaks way up beyond 7K, I find myself in 4th gear most of the time in slowish CA freeways, and occasionally in 5th...but hardly EVER in 6th; I'd be doing 90+mph on the freeway to get enough rpm to get off the cam lope. The engine doesn't really smooth out until 2400+ rpm. Fantastic for silver-state or land speed racing, but unless you're running a docile cam, the gear spread makes the 2nd overdrive all but unusable. If you lower the rear end ratio, then 1st and 2nd are an even bigger smoke show. I picked 3.50 because I'd finish the 1/4mi in 4th gear (according to the math and assumptions I made). Any lower and I'd be finishing in 5th. I may go to 3.70 now that I've turned the power down some. My traction won't be as bad, and I'll finish the 1/4 at lower speeds now, so I should still finish in 4th. Take the time to do the math and figure out what your cruise rpm needs to be; you'll have a happier combo.

[RICK LAKE]

Badger What do you want to know? Stock rear end will hold about 450-475 HP with the 27 spline stub shafts. After this you start to twist the stubs in the carrier. 2.88 carrier is the weakest carrier of the Jag rears. Higher the gear ratio the better the carrier. There are 4 carriers. For my car, I got the CWI 30 spline stub shaft kit, installed a locker and everything else is chromemoly tubing. The other thing a added was an LPW rear cover for the diff to add pressure to the carrier caps. It's a support cover. This will stop cap walk. With all my up grades the rearend is good for 600/600 HP and torque. I limit the dragracing, way too hard on this rearend. I only rev the motor to about 1,400 and leave. NO SLICKS. A watts linkage is another good kit to add to the Jag rearend. Decooney here on CC has pictures and designed it for ERA cars. Great responce to it. It stops rearend from rolling over. Again it's about putting the right parts togeather. The most important thing, IMO is shocks and springs for the rearend and wheel alignment. Wheel alignment is a biggie. I spent 3 1/2 hours seting up my car on a alignment machine, Camber, front and rear, Caster, and real important, front and rear toe. Thrust angle is also needed. You can ONLY do this after ride hieght is setup with your body wieght in the drivers seat to start. If you are adding someone else on the pass side this all changes. You need to find some one with scales for this setting up of the car. You wouldn't believe the different with before and after. Alignment is next, Video the car taking off, and then start on the springs and shocks. Rick L.

[AC-460]

What do you fella's think about aluminium Flywheels?

[AC-460]

Do you think I'd be better off sticking with the TKO600 (26 spline input)

[ByronRACE]

The TKO600 is a fine transmission, and 5 speeds is honestly enough in a cobra unless you can picture yourself needing a double-overdrive. However, it does not feel the same as a T56. It's a bit more notchy, not quite as smooth, and so on...just different.

Considering my crankshaft weighs more than some engine blocks, I felt that the mass reduction of an aluminum flywheel over a steel flywheel would be a bit like putting a carbon fiber handle on a sledge hammer. If you're building a 385 series (460), I would save your money and run a steel flywheel; I really doubt the difference will be noticed. If you've taken steps to make for a light rotating assembly, then go all the way. By the way, even though I'm a short stroke low compression 429 running an industrial unlightened 429 crank, big heavy i-beam monster truck (crower) rods, and pistons that look more like diesel parts than gas parts (intentionally had them built with a beefy top ring land), this is *by far* the fastest neutral-revving V8 I've ever built, so I've learned that just because it weighs a lot doesn't mean it isn't going to rev.