How much is too much? & T-56 install

[David_Ingermann]

Okay, here's the deal. I think i'm decided on doing a T-56 instead of a TKO. What install issues might I expect to face with this change aside from the drivesaft length? Also, in your experience, how much power is just too much for the street, and what's just right for street and track use in your opinion? (I'll be running 12" wide simi-slicks through the new IRS if that matters) Thanks for reading and contributing!

[CraigS]

I have 400 and would like another 75-100. I hope to get that from my 408 this winter.

[David_Ingermann]

Just bumping to see if anyone else wants to put in their 2 cents.

[Hankl]

Well, I have the older IRS, and I'd still go with the TKO because of the drive shaft length,
it can be a bit too short with the T-56. One of the Coupe owners just posted that with a
T-5, .63 final with 3.27 Rear gears, He's turning 1750 RPM at 70 MPH. That would translate
to a Bus Load of shifting a close ratio six speed just to reach highway speeds.

As to HP, 400-450 is more than enough in one of these Coupes to impress anyone.

Hank :cool:

[HCP 65 COUPE]

I agree with Hank a 6speed is over kill heck the original cars had top loader 4 speeds and 385hp and could nearly get to 200mph at Leman's. 400-450 at the wheels will be well into super car territory with 3-4-5 or 6 speeds I think most chose a 5 speed because its an easy install parts are available and it has a street oriented over drive. The T56 has a double over drive that IMO is a complete waste in a light weight car. If I had it to do over again I might consider a close ratio custom 4 speed with a .8 or so over drive and a very tall 1st gear.

[turbonut48]

Use C.S advice: Enough is enough, too much , is just right !

[wirelessnut]

I've been pondering the same problem as David. I've decided to put in a Coyote motor(400+ HP) with (3.55 Torson) final. I would like the T-56 double overdrive for highway use (.50 final). Good MPG on the highway. I've used the Tremec AP to look at the difference between the TKO and the T-56. I know I would never see 6th gear unless on the highway tough.

[proauto]

I plan on installing the T-56 magnum 6-speed. I chose that for two reasons. First, I wanted the 2.66 first gear instead of the 3.27, which is the most common in the 5 speeds. Second, with the 2.66 first gear trans, it's a close ratio gearbox similar to the original top loader. I wasn't really concerned about the overdrive gears. With such a light weight car, I felt that the steeper first gear would be more usable without having to quick shift out of first gear. I'm also running a 3.55 rear gear.

[loeffler1]

With this amount invested in motoring what do you care about mileage? You'll be doing a lot of lower gear driving anyways just to hear the sound. I bet I don't get 10 MPG rumbling through towns in lower gears. I figure the lost savings in gas mileage is worth the extra smiles in lower gears.

[Bob Cowan]

Gearing is always a quandary. There's no such thing as the perfect gear. It's always a compromise in one way or another. You have to look at what kind of driving you'll be doing the most of, and then gear it appropriately.

As for power, there's no such thing as too much power, only not enough control. My engine makes around 600hp, and I'd like a bit more.

[mstephenson51]

Bob, it sounds like you built what I am planning to build. Any chance you can direct me to your build pics?

Sorry to bogart the thread.... So, exactly what ppl are saying about gearing and trans. There are a few basic factors going into trans design (for race, street, show, whatever): Ergonomics (where you and your shifter end up), Speed in corners vs when to shift, and speeds in straights vs rpm. So to me a 6 sp is perfectly acceptable in most cases, if you gear for what you are wanting. And some people like a few extra shifts going thru town, bc that gives a little more driving enjoyment and thrill. ;0)

[cChrisM]

The gearing in my 03 Cobra Terminator T56:

Gear Ratio
1st - 2.66
2nd - 1.78
3rd - 1.30
4th - 1.00
5th - 0.80
6th - 0.63
Reverse - 2.90
Final Drive - 3.55

[afaa]

My LS2 roadster runs a T56 (2.66, 1.78, 1.3, 1.0, 0.80, 0.62) and a 3.9 final drive.

If and when I build a coupe I think I'll use a TKO instead. I find I start off in 2nd gear quite often unless parked facing uphill and even then it is a real short shift. We don't have the nice highways in Australia that the US has.

[David_Ingermann]

We don't have the nice highways in Australia that the US has. Trust me, you have nicer highways than Michigan does... Pretty sure most third world countries do too.

[Plebeian]

On the track you can use pretty much all the hp you can throw at it. On the street it depends on how well your car is set up and if there are any driveability concerns such as a wild cam, etc.. Most of the time I dial my boost to make 550-600 rwhp on the street and have found that to be the sweet spot for traction depending upon road conditions, air temps, and the age of my drag radials. If your running BFG TA radials 300 rwhp can be a handful. Cheers.