T-56 gearing?

[Ghostyman25]

What gear ratio does everyone run with the t-56? Does anyone have info on the trans gear ratios themselves? Ive heard that there very high geared and that 3.73/4.11's arent even enough to balance it out to normal power feel in the 5 speeds. Id like one down the road(no way in hell my v6 could push it with 3.42's) but id like to avoid having to get 5.73 gears and not being able to drive over 20.

[Aloicious]

I use 4.88's on 29 inch tires with mine.

the trans gearing depends on which trans you're using. the 1994-97 LT1 and 98-02 LS1 T56's are: 2.66, 1.78, 1.3, 1.00, .74, .50, R2.90

I've got more info on different gearing and ratings on my swap writeup that can help you here:
http://www.gmtruckcentral.com/articles/t56.html

[Ghostyman25]

Thanks,would you say with 4.88's you lost any driveablility or mpg's? I dont plan on keeping the 4.3 but im not going to buy a t-56 if its gonna take 5.73's with the v6 and then i have to go down to 4.88/4.56's when i put in a built v8.

[Aloicious]

no, with the T56 gear ratios what they are, I GAINED alot of drivability AND all around MPGs when I put in 4.88s over my stock 3.73s. but my comparison is with the 4L60e that I removed, so depending on what 5 speed you have, and its gearing, you may feel different. what you want to do is look at your final drive ratios for each to get an idea of what it will do.

your final drive ratio is basically transmission ratio multiplied by transfercase ratio (nothing there for 2wd), multiplied by rear end ratio. it gives the absolute ratio and is best to use for comparisons like this.

If I assume you've got the wide ratio NV3500 in there right now with 3.42s, your final drive ratios for each forward gear going from first to 5th in order would be:
13.71, 7.97, 4.75, 3.42, 2.50

on a T56 with 4.88's your final drive ratios in order from first to 6th would be:
12.98, 8.69, 6.34, 4.88, 3.61, 2.44

so since gear ratios effectively multiply torque, lower gear ratios (higher numerically) put more torque to the wheels, but also raise RPM, where higher gear ratios (lower numerically) will keep the RPMs low, but put less torque to the wheels.

so in essence, you may feel a small loss in first gear, however you'll be able to hold it out a little longer, and you'll feel a gain in every other gear, and you'll be able to cruize in overdrive at a slightly lower RPM if you swapped to a T56.

[Blue94]

Your going to be running into alot of headaches with doing the trans swap for the 4.3 and then going to a V8 later. Since a 4.3 is the same as a GenI SBC you will have to run an LT1 bellhousing, flywheel, clutch and transmission on that motor and then if you drop in a LSx motor for the V8 swap you talk about then you have to swap to a LS style bellhousing, clutch, flywheel and transmission or atleast change the input shaft in the LT1 style T56 as the input shaft is a different length between motors.

Now by going to a GenI SBC instead of a LSx swap then you can swap all the parts over to that motor but then again I dont know what your plan of a V8 swap entails.

[Ghostyman25]

Your going to be running into alot of headaches with doing the trans swap for the 4.3 and then going to a V8 later. Since a 4.3 is the same as a GenI SBC you will have to run an LT1 bellhousing, flywheel, clutch and transmission on that motor and then if you drop in a LSx motor for the V8 swap you talk about then you have to swap to a LS style bellhousing, clutch, flywheel and transmission or atleast change the input shaft in the LT1 style T56 as the input shaft is a different length between motors.

Now by going to a GenI SBC instead of a LSx swap then you can swap all the parts over to that motor but then again I dont know what your plan of a V8 swap entails.

I plan to buy a little truck as a DD and hopefully eventually go 6.0 or 5.7 block with 5.3 heads/intake. Basically i think it would be better to get the ls style and just wait. Thanks for all the info aloicious and im currently running the 4l60e but i severely want a standard so i think ill just find a case and put in my old nv3500 for now.