4x4 Gear swap -> 2.73 Rear

[Spdrcer34]

Jack Flash:

What are the drivetrain spec's on your Explorers and the Ranger?

We all know gearing isn't the 'END ALL' solution to increased mileage.

Does the Rangers have had numerous motors over the years.....even a Diesel at one time was available here in the USA.

And the Explorer has had 4 engine options, 5 or more transmissions, not to mention they were available in 2WD, 4WD, and AWD.....

Ryan

 

[rudypoochris]

The speedo and tire OD calculated from tire spec is definitely wrong. At 2500rpm I SHOULD be traveling 83mph with my gears. I am actually only traveling around 76-77mph confirmed with GPS. The speedo reads 74mph. This makes me think I possibly have 3.55's in there despite the axle code on the door being "41". If I do have 3.55's, I agree, switching to 2.73's would be murder at this point.

I have pretty much thrown the gear swap idea out the window though as it doesn't really seem to be economical, practical, or even possible while maintaining 4x4. Unless I want 3.08's. Also, I happen to like the gearing in the first 4 gears. The way 5th is now it is NICE never really having to shift accept for very steep uphills (granted I am typically cruising 2400+ rpm so I am in torque band), but I would gladly trade a couple more shifts if I could get some better flat economy. Where I live it is all flat, all the time. Low wind, etc. etc. Something like a .68 or .70 ratio instead of .79 would be nice. Wind is really what would kill the Explorer though with this kind of gearing. If I did take it to a windy area and there was say a 20mph breeze going. Things might start to get annoying. We will see. Summer project any way.

Thanks for the input. I agree chassis dyno is a must. I am going to try and get it on a good dyno that allows loading (not fixed inertia/dynojet) for accurate measurements from 600-4600 or so. I bet peak power will be ~125hp depending on what camshaft I have.

 

[Fordmandan87]

2.73 gears were put into the f 150s they suck hard core. the motor nearly bogs out every time I put it in drive and it winds the **** out of the motor. btw the motor in this one is the un killable 300 straight six that my brother made me convert to automatic. stick with your 3.27 gears and with no offence intended slow the f**k down if you want to get better gas mileage. you can also try accelerating to 2500 rpm max and then shifting and stick to around roughly 1750rpm hwy.(this has worked for me personally) another thing you can do is to hold a constant steady throttle. now you said that you have gotton 23+ mpg be extremely happy with your 4X4 most new ones dont get that

 

[briwayjones]

Rudy,

I have owned 5 Explorers all with 5 speed manuals and have never driven anything but a Explorer with a 5 speed manual as a personal vehicle. IMO you don't want to go higher than 3.55 in any Explorer and especially not any higher than 3.55 in an Explorer with a 5 speed manual. In an Explorer with a manual 3.55s are going to give you the best MPG you can get. Some Explorers came with 3.27s but that is too high. The engine has to work to hard to move the vehicle. I have gotten up to 25MPG with a 3.55 Explorer and there is still room for improvement. I run at about 2000RPM at 70MPH and at 2500RPM at 75MPH.

Second, you will literally not even move the Explorer with a manual transmission and 2.73 gears. One there isn't really enough power in the 4.0s at the gearing and two the clutches in them won't handle it. You will burn out the clutch in no time flat. They have trouble enough moving a 3.55 geared Explorer with a manual on anything but flat ground. You can put 2.73s in it but, you won't get it moving. If you do get it moving you'll burn out the clutch in less than a week (probably just a couple of days). You won't get it moving on a hill. You won't get better MPG, you'll get much worse.

The numbers on the paper are not indicative to real life. For example, in most vehicles you could put larger engines than what they have in them, have more power and get better MPG than what they are getting now. Even though on paper it will say you'll get less MPG.

It's a real bad idea. Moreover you say you want to get 30MPG. Well the guy that gets the best mileage on this site "Aldive", who gets 34MPG, does it with 3.55 gearing.

 

[CopyKat]

Here is what stock 3.55 is set up as. with stock 235's

235's have about 698 Rev's per mile at 65 Mph With .79:1 OD RPM's are at 2122, with 3.55 gears

Now you want to get down to 1600 RPM's at 65 MPH with a .79:1 OD, and same 3.55 gears. You need to find a tire that has a 526 Rev per mile.

So basically slap on a set of 38.5" rubber out back and take her for a spin.

Based on my calcs that should get you 1600 RPM. So it should equal your 2.73 gear change.

 

[CDW6212R]

Tires have different weights, much much heavier as they get larger.

I thought that I read recently that Al has 3.73's?

 

[briwayjones]

I thought that I read recently that Al has 3.73's?

Maybe he does, I thought he had 3.55s, I may be mistaken.

Edit:
I just checked, I was mistaken he does have 3.73s. Even more impressive.

 

[CDW6212R]

That's good because I'm swapping from 4.10's to 3.73's soon. I think that 3.73 is the best gear for 29-30" tires and OD for the 4400 pound truck.

 

[rudypoochris]

Well he is also running hydrogen and a bunch of other mods, switches the game up a bit. I don't plan on going that route for multiple reasons personally.

 

[carlover]

his mileage was achieved far before the HHO experiment. He's pretty much the guru of gas mileage on this site. i will be trying some of his mods on my lifted explorer with a goal of 25 mpg average.

 

[p100ki]

By the time you spend all the money to get better gas mileage isn't actually cheaper to buy a beater for day to day driving? My Explorer does pretty decent gas wise but i daily drive an $800 '99 DOHC Neon that's actually damn fast and gets 34mpg. I have a freaking huge four door V10 dually to haul trailers and big junk. Every car has a purpose and i don't see putting a grand into an Explorer to get the less gas mileage than a thousand dollar four banger.

 

[briwayjones]

That's good because I'm swapping from 4.10's to 3.73's soon. I think that 3.73 is the best gear for 29-30" tires and OD for the 4400 pound truck.

Do you need gears?

 

[CDW6212R]

I have the spare front/rear 3.73 axle housings now, another 12k front soon, plus an older 1993 3.73 LS rearend. After installing brakes from a 2003 Crown Vic, I'll have two sets of rear disc brakes, a 4.10 LS rear and front, and the 93 3.73 rear. Who needs gears?

 

[sn0border88]

Your going to get a custom OD gear made? And install it in an inherently weak, aged transmission? In a boxy SUV ~15 years old?

To save money on gas?????


You see to have done some research to get all of those numbers you have been posting so I can assume your not an idiot by any means. So please, leaving economy out of the question explain to me why this would be feasible/cost effective?

Have you figured out the cost of getting a new gear made + time and parts to install it. Have you figured out how long it will take with your new "improved" economy to make this actually worth it?

 

[p100ki]

Your going to get a custom OD gear made? And install it in an inherently weak, aged transmission? In a boxy SUV ~15 years old?

To save money on gas?????

That's the exact same thing i was wondering in my post. I drive minimum 75 miles per day if i go nowhere but work. That is why i own a gas mileage car. No matter what you spend you're still not going to beat a thousand dollar four cylinder beater. All you're going to do is make your 4wd worthless for what it was made for.