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4l80e on the street. What rear gear?

740atl

Gear acquisition syndrome
Joined
Apr 17, 2010
Location
USA
I'm thinking about using the 4l80e behind the v8. What rear gears are people using with this transmission? I know there's a few v8 people out there with 4l80's behind them.

What rear gear do you have and what's your rpm at 70mph?

Also, does the 4l80e have an appreciable rpm drop once the converter locks? something like 300-500rpm?

Inquiring minds want to know.
 
RPM difference when the converter locks depends upon load. If you're coasting, it will be negative (engine spins faster when TC locked).

The math is pretty straight forward to figure it out yourself, this calculator even has a big list of transmissions from you to pick from: http://www.grimmjeeper.com/gears.html
 
I have a 700 r4 with .76 OD, 3.73 rear gears I turn 2450 at 70 with converter locked. I will probably go to a numerically lower gear when this one breaks, but I am a cruiser more than a racer
 
Tire size is a big factor also when choosing rear gear. I started with 3:73 and found it to be a little too low for me with the turbo set up. I ended up doing 2 different rears because its so easy to change complete rears with the ladder bar set up and have a 3:08 rear I run with the stock tires and 3:27 rear with the 235/60/15 drag radials. Locked up it will cruise 70 below 2200 rpm
 
3:31 is what I put in the 940 (cause, drop in 960 axle). still kinda tall with the 225 55 16 (I think..) all seasons I've been running, but around town it's fine. It really wasn't that bad on the highway either, it turned in an average of around 20mpg's going to and from the mountain meet a few years ago.

rpm drop with lockup will depend on how tight the converter is and where you are in the rpm range.
 
I will say I've been using mine as a daily on and off for about 3 years and on and off. My commute is highway mostly, the car has a 225/50r17 lockup 80e and 3.73 gears and it is..... Absolutely awful. I plan on doing 3.27 asap. 70mph is around 2650 rpm and you can literally watch the gas gauge going down as your driving. And it goes down with the quickness
 
I will say I've been using mine as a daily on and off for about 3 years and on and off. My commute is highway mostly, the car has a 225/50r17 lockup 80e and 3.73 gears and it is..... Absolutely awful. I plan on doing 3.27 asap. 70mph is around 2650 rpm and you can literally watch the gas gauge going down as your driving. And it goes down with the quickness

That's kind of where I'm at right now. 25" tires, 3.92 stock 242 rear, 0.72 od. 70 is 2600ish.

Right now the car has a stockish v8 (cam, headers). Won't the performance tank if I drop in a 3.31 with the 4l80?
 
That's kind of where I'm at right now. 25" tires, 3.92 stock 242 rear, 0.72 od. 70 is 2600ish.

Right now the car has a stockish v8 (cam, headers). Won't the performance tank if I drop in a 3.31 with the 4l80?

Do the math on the different first gears and final drives.
Multiply the current first by the current rear. See what final drive comes out the same with the different first gear.
Then compare current OD x rear with the new OD x rear.
 
What engine is it behind?

lt1

Do the math on the different first gears and final drives.
Multiply the current first by the current rear. See what final drive comes out the same with the different first gear.
Then compare current OD x rear with the new OD x rear.

it is a little tough with a 4L80 as it has a .75 final, so a more "fun" final drive ratio to go with the first 2 gears (2.48 and 1.48) that doesn't end up spinning the engine high on the interstate is a little tough.

Generally you'd compensate for that with a good converter and stall speed. a number of folks are running 3.08 8.8's in the ellis world. Those ratios also work out fairly well in a turbo application by stretching the gears a little and cutting some of the tq multiplication that tends to result in instant tire smoke
 
I have a 700 r4 with .76 OD, 3.73 rear gears I turn 2450 at 70 with converter locked. I will probably go to a numerically lower gear when this one breaks, but I am a cruiser more than a racer

I'm planning a future 700 r4 (gearing, I believe, same as the OP's later designation gearbox).

Using the V8 calculators, I settled on a 3.36 final gear for my 70 Malibu with SBC. This puts first gear in the ~ 10:1 torque multiplication (ignoring a stalled converter) and the highway RPM at 70mph was in the lower 2's.

Insert "it really depends upon the application, there is no perfect final gear answer" comment(s) here.
 
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