which tranny to go with?

[Draco]

I am still deciding on a tranny and I am considering the TKO II or the TTC T56 six speed. I know the TKO is a good fit but I am looking for some input on the T56. Is anyone using this tranny and what are the pro's and con's to this set up. I have a 393W with a ford 9". The HP is probably 425-460 range. with similar TQ

Draco

[Draco]

Anyone out there?

[Mr.Fixit]

The tremecs are cheap, but work pretty well. I have put the TKO behind 520 inch BB's that made almost 700 ft/lbs and not killed them, you just gotta remember at that much torque to not stomp the heck outta it as other parts may break and you might just do a burnout at 100 mph and crash. You also cannot slam shift them like a gorilla, it takes a little finesse to speed shift them, but you should anyway so you don't spin out when you grab third gear. I don't like the T56 all that much, thwey are bigger, heavier, similar shifting, and cost more. But we all have different tastes, some guys actually paint their cars yellow?

[Bart Carter]

Sounds like you are not worried about a specific type of racing where you could use 5 close ratio gears and have a 6th for OD.

So, if you don't need gearing for acceleration above 150 MPH, the 5 speed would be everything you need.

In other words, 99.9 % can use the 5 speed TKO for all their needs.

[Back in Black]

With 3.00 rear end gear set. 1st is usable only just off the line, and you need 2nd gear FAST. Do be careful not to go with a low rear end ratio with these transmissions, as you have 6 speeds to work with, and 1st and 2nd ratios in the tranny are usually low enough all by their lonesomes.

[Draco]

I have a 3.50 gear for the rear. My concern was when deciding between the TKO and the TKO II. The feeling I was getting from Tremec owners was that the Tko's 5th was too tall at .68. With the TKO II the 5th gear was less of an overdrive and more useable, but is it a comfortable cruising gear at higher speeds?? That's why the T56 six speed becomes a consideration.(ya know .."best of both worlds") I haven't researched the Richmond yet, so to ensure some peice of mind I guess I better explore it too.

Draco

[Bart Carter]

Draco,

That's the point. If you don't need to gear for over 150 MPH acceleration, the 4 speeds are fine and 5th is an overdrive.

With the TKO II, 25.7 inch tire, and 3.50 gears, at 6500 RPM 1st is 43, 2nd is 71, 3rd is 105 and 4th is 141.

But with that much HP, I think 3.27 would be better. 1st is 46, 2nd is 76, 3rd is 113 and 4th is 151.

With your engine, this would work out well.

[ST]

I've got about 500 miles on the new car and most of those are highway miles. I decided to go with the TKO and the 3.54's, I'm not at all sorry. It's a little more enjoyable when you're only at 2000rpm's at 75 mph. I don't miss the toploader one bit.
However, if it was mainly driven on the track I would go with a different combination.

[ls1ac]

I have the T56 with 3.73 rear. I do feel it is the best of both. 2-5 are great on the track and 6 just putts along the highway and 1 is an easy start. I have the aftermarket with the mech speedo output and the wide lower gears and the close overdrive. I was told that the 6th gear is parasitic but I have not been driving at 180 so I can not say for sure.

[HighPlainsDrifter]

Draco;
There is one important thing to consider with a 9" solid rear, that is the driveshaft length and U-joint bind on a real short driveshaft. Seeing as the 6 speed is longer , the 5 speed is a better choice. Cars with an independent rear don't worry about the up and down U-joint bind angles. The other option is to move the engine farther forward to make a longer drivershaft.
Good Luck,
Perry.

[Aussie Mike]

Hi Draco,

Personally I like the T56. It has a good spread of ratios. The ratios in mine are as follows:
1st 2.66
2nd 1.78
3rd 1.30
4th 1.00
5th 0.74
6th 0.50

The standard TR3550 ratios are:
1st 3.27
2nd 1.98
3rd 1.34
4th 1.00
5th 0.68

The taller 1st and 2nd in the T56 makes for a much closer ratio box without the huge gap between 1st & 2nd that the TR3550 has. I plan to run a rear end ratio around 3.9 or 4.11 so the lower gears should provide some great performance but I'll still have a good cruising gear with the 0.50 overdrive in 6th.

The T56 has the same or better torque rating as the TKOII depending on which model. They range from 330lb/ft to 550lb/ft where the 3550s range from 350lb/ft to 475lb/ft. They are standard fitment in the V10 Viper and 007s new V12 Aston Martin so I figure they must be tough.

I'm running a Gen 3 Chev LS1. These motors make great HP numbers but their torque is higher up in the rev range. I figure the closer ratio box will help get the best out of it.

Perry is right about the length of these boxes, very long. The driveshaft in my car will work out to be about 15" long. Other things to think about is that the standard shifter location works out to be a long way back (there are ways around this). Also it only supports an electronic speedo. The standard integrated bellhousing may also be a problem unless you find a Mustang box. Sallee Chev sell a T56 that bolts up to a normal aftermarket bellhousing or scatter shield using an adaptor plate on the front of the box.

Sallee has a good site with pics and dimensions on their T56
http://www.sallee-chevrolet.com/BorgWarner/t56pics.html

And the T56 page at tremec which gives all the part numbers an ratios for the different models.
http://www.ttcautomotive.com/English/products/T-56.asp

Cheers

[Bart Carter]

There is a specific T56 for a Ford. It is an aftermarket item.

Be sure you look into this as it has its own ratios and dimentions.

You don't have to adapt a Chevy or Viper box.