automatic and 410 ?s

jl99cummins

jl99cummins

hooked
Joined
Mar 26, 2009
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196
Just wondering if anyone has 4.10's and dd with a automatic. What is mpg? What is cruising speed at 70mph (tires you are running)? I am throwing around the ideal of swapping from 3.55 to 4.10's. Just trying to why the pros and cons. thanks
 
Looks like you have 33's in your avatar, I had 33's on my 99 Auto I used to own and it was a little sluggish around 55 mph. I think you will really like 4.10's w/33's & a auto....now a 5spd....no I love my 3.55's with my 5spd!
 
I have the 4.10 and love them for around here. I'll run about 1900 around 60-65
 
4:10 and auto

Tires are 305/45/22. 70 mph =2200-2250 rpm.
Acceleration is toooooo quick, gear bound by the end of most on ramps. Can usually break tires loose up to about 40-50 mph rolling into the throttle. Freaks people out when you go around them and lite the tires at 50, especially if they have their window down.:lolly: Switching to 3:54-55 tomorrow to try it out. Still get upwards of 20 mpg usually.
 
I got 18.2 mpg on a 188 mile trip. cruising 60 it runs about 2000rpm. It has a 66 silver bullet 380cc p pump on a 24v with 7x.012 injectors. With the 4k springs it'll hit 120mph.
 
I am running 295/60/20's now instead of the 33's in my avatar. This might help alittle bet, at 55 3rd gear locked i am turning right at 2000, od locked running real close to 80 I am at 2000. I just want to lower the od speed. Guess I will have to find a set and see how well I like it.
 
With 4.10 you'll want 33's minimum, or you'll be wound up at highway speeds. 70mph @ 2100rpm for me. Originally had 3.55's, and I wont ever go back unless I ever need to go faster than 130mph lol. Get around 18mpg at 65mph. I'd get better if I didn't have a "large" single and so much fuel.

Sent from my DROID3 using Tapatalk 2
 
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410's and 35 inch tires here, 70 is right around the 2k mark. 16 to 18 mpg usually
 
Like the others said, just over 2000 RPM around 70-75mph, 18-20 on the lie-o-meter, (around 18.6 hand calculated) on some tiny ~stock sized tires. Putting some heavy ass 20's and 33's on today and we'll see how well she does. But i've been dd'ing it with these tires since october. Just had my trans built last month. Thats where you get fuel economy back is with a better TC (i know it doesn't change interstate, but in town HUGE difference)
 
LReiff said:
3.73s are the magic gear!
Click to expand...

I've debated going to 3.73 ratio with a smaller tire.

Currently running factory 4.10 ratio with a 315-70-16 (~34.6") tire on stock dually wheels. At ~70 it's about 2k rpms. I haven't had the speedo recalibrated. Speed is based on GPS. I haven't calculated mileage. Converter is shot, and trans needs a rebuild. My longest trip during the week is to work, which is 17 miles.

According to gear calculators, a 4.10 should be changed to 4.56 to compensate for that tire size.
 
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Ktown6.0 said:
I've debated going to 3.73 ratio with a smaller tire.

Currently running factory 4.10 ratio with a 315-70-16 (~34.6") tire on stock dually wheels. .
Click to expand...

Sorry, my tires are 315-75-16.

Is it okay if my excuse is I haven't had enough coffee?
 
jl99cummins said:
I am running 295/60/20's now instead of the 33's in my avatar. This might help alittle bet, at 55 3rd gear locked i am turning right at 2000, od locked running real close to 80 I am at 2000. I just want to lower the od speed. Guess I will have to find a set and see how well I like it.
Click to expand...

To lower your rpm cruising you'd have to go to something like a 3.31. A 4.10 will raise your rpm.
 
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Too high of gears (numerically low) will kill fuel economy. You'd be so low in rpm that you'd be constantly under the turbo. From my experience you want to keep cruising rpm between 1800-2100. Engine setup will be the determining factor as to where the rpm should be for the best fuel economy. 4.56s are too slow.
 
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that is about were i am at bgbldodge. All I am wanting to do is drop from 80mph to 70-75 mph to stay at 2000rpm. Just wondering if I changed the gearing if it would help. 1900 rpms on up seems to be happy medium for my setup.
 
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