jdthedj10

1994 stock 5.0, automatic, stock 2.73 gears, previous owner said it had a shift kit in the tranny. Standard takeoff 1st to 2nd is lightning quick, under heavy acceleration high rps show a highly delayed shift from 1st to second with a heavy launch forward. I am running 2500 rpm at 75 mph on the interstate with overdrive and cruise control on and get 18mpg. I have 3.73 gears to install but before I do, will this cause me to run upwards of 3000 rpm on the interstate? Is this normal?

jdthedj10

BTW, I assume that the gears are stock, The previous owner can't tell me if they were ever changed. I will say that it will NOT break traction from stand still to WOT takeoff. According to this chart they should not be stock,

Transmission Type...............................3.55 Gears 3.73 Gears 4.10 Gears
AOD AODE (automatic transmission).......1800 RPMs 2000 RPMs 2300 RPMs
4R70W (automative transmission)..........2000 RPMs 2250 RPMs 2350 RPMs
T5/T4 (manual transmission).................2000 RPMs 2250 RPMs 2350 RPMs
TR3650 (manual transmission)...............1900 RPMs 2250 RPMs 2350 RPMs
T56 (6 speed manual transmission).........1600 RPMs 1800 RPMs 2150 RPMs

jwog666

that sounds high for rpm, but tire size comes into play as well. the only way to know for sure is to pull the cover off and get a look at the numbers stamped on the pinion, or if the limited slip works properly, mark a tire and the driveshaft, and then count how many times you have to spin the driveshaft to get the tire to move 1 revolution. if it takes 2 and 3/4 turns then you have 2.73, if it takes 3 3/4 turns then you have 3.73 installed

88 orangepeel notch

+1 ^^^

If your truly running that rpm at 75, then you already have steeper gears installed. Do as jwog described and count the rotations. It'll get you real close to the ratio you have. They're definitely not stock 2:73's.

As for the sluggish shifting at WOT, maybe it does not have a shift kit in it, or it was installed incorrectly. You should be getting a chirp from the tires from 1st to 2nd shifts at least. Maybe 2nd to 3rd depending on tires and what gears are in the rearend. When I ran an AOD with a shift kit, it shifted gears faster than I can with my T5 now.

Derf00

The delayed shift from 1st to 2nd at WOT and throwing you back the way it does could be the shift kit. Shift kits look to physically change the shifting characteristics of the transmission by using different springs and/or modified pistons in the valve body to obtain the desired results. They used to be one of the only ways to modify the shift characteristics of an automatic tranny.

Wouldn't have anything to with what RPM vs speed you're running at though.

jdthedj10

Ok, I jacked the car up, 1 rear side. Marked the tire with tape and a dowel rod in the ground. (mark started right on top of the rod). Marked the drive shaft as well horizontally. Rotated the tire 1 complete revolution. My drive shaft rotated 2 3/4 turns. This is with 245, 45, 18 tires.

jdthedj10

wow, I can't figure out how to edit my post but, that was supposed to be 1 3/4 turns on the driveshaft to make 1 tire revolution.

jwog666

that cant be correct, they never made any 1.75:1 gears

88 orangepeel notch

You'll need to get both rear tires off the ground to do this. If I'm understanding your statement of only raising one rear tire.

movielover40

Sounds like you already have 3:73 rear end if your pushing that many rpm's.