T56 Six Speed, Possible?

[adamls]

Anyone installed a manual six speed in one of our trucks? If so anything I should watch out for or bumps in the road? Pictures?

[Cheyenne Super]

... but it will work. I took some measurments today, it will be difficult but not impossible. A T56 is the same dimensionally as a 700r4/4l60e. The main problems are going to be setting up a clutch master cylinder and getting the shifter in the proper location. In my truck the shifter will come up 4 inches behind the extreme fron edge of the seat (bench). With a little fabrication the shifter shouldn't be too much of a problem. For the clutch master, I have seen an add for a custom install clutch pedal bracket and clutch master. That leads me to the final problem, $$$$. The best deal so far is a place called Trans AM creations. They didn't have one in stock, but a lt-1, engine brackets and accessories, tranny, computer, harness, drive shaft, pedals, pedal brackets, and a lot of other odds and ends would run around 3k. Not bad considering some computer reprogramming and a new harness to get going.

[Huck]

Or, you can go with a late model 1/2 ton 5 speed and I can walk you thru the install. Paid $650. for mine with 10K miles on it. A six speed will need lots of HP to pull in 6th as our trucks have a lot of wind resistance. Will also need a 373 or so rear to take advantage of all them gears. Have a 6spd in the vette which is great but can't imagine a 6speed in the truck ---my 5speed 5th pulls most hills with no trouble from a 300HP 350. Think this thing thru carefully before throwing $$$ at it. Huck

[Longhorn Man]

Huck points out some very good things there.
The 6 speed is a double overdrive.
I just look at it as more shifting and more clutch wear, and lots of $$.
I don't doubt it would be cool though.

[Cheyenne Super]

i wouldn't say it is a double over drive, but 6th is .62 vs. .73 on a 700r4. My engine should be pushing 425-430 at the flywheel. As for the truck 5 speed that would be fine but it is limited to 350-375 hp. I know guys that have broke them with less power than that. As far as the money a good 700r4 with torque converter with warranty will cost about the same give or take a couple of hundred dollars.

[SCOTI]

If I remember correctly all GM LT-1 style T-56 6spds manufactured after 94 ARE double overdrive w/5th gear around a .73 or .76 & 6th gear is a .50. I think a better alternative would be the Richmond 6spd because the gear splits are closer & 6th is a .76 or optionally a .62.

[Cheyenne Super]

.5 overdrive. but the universal t56 has a .62 6th.
either way with a 3.73 final drive i will be fine on the highway.

[Longhorn Man]

Exactly...double overdrive.
I thought that was kinda stupid when it was new...and honestly, I still do.

[Cheyenne Super]

... overdrive is the step from 1.0 to .5 would be to great of a rpm drop due to the lack of momentum at the speed overdrive is selected.

[Smooth68]

All this talk about gears 5th and 6th....forget about it! Just think of all the fun with 1st through 4th!!!