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3.73 vs 4.10 gears - fuel economy?


DCman

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I've thought about doing that for years.
Before I got my Ranger I had a B2200 Mazda and I spent like the first 5-6 years convincing myself it wasn't 4WD.
Good ol' truck, but no lockers or LSD's available for that rear end.
The 7.5" gear in the Ranger is more open to mods like that.
 


cbxer55

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In looking, apparently Detroit Tru Trac isn't available for the 7.5. Powertrax Lock Right Locker is though.


Also Motive Gear Differential Carrier.


And Motive Gear Ring and Pinion 4.10s

 

gaz

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Jackstand,

Fuel economy

I have only owned 1 four cylinder Ranger, it came with 25" rubber and 4:10's. It took everything in the world and my Grandma's skilled, feathering foot to get 18 mpg from it. That engine was supposed to get high 20's. I finally decided that it was because the gears were so tall.

Though my BII was set up the same exact way and performed the exact same way, 25" rubber with 4:10's and couldn't get it over 18 mpg...until I put 32's on it, then it would manage over 25 mpg on the highway???

My experience is different with the v6 Ranger though I am reluctant to offer it for this question specific. Instead I will offer a point of interest; I once owned a "dual purpose" motorcycle, it looked like a dirt bike but handled mire like a street bike. It could go 128 mph but felt like it was going to fall to pieces from a 6 six dropout.

The manufacturers tried to make one thing perform two tasks, it was because of this that I learned to build a vehicle to do one thing right and make it do it safely. I chose fuel economy in inclamate weather (sort of 2 things but it worked).

Since you aren't shooting for a trail wrangler, choose the tire size for your gears that keeps your engine in it's torque curve while driving, then you will experience maximum fuel economy. Since it is also using it's torque effectively, hills will not be an item of concern ..)
 

DCman

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DCman

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Jackstand,

Fuel economy

I have only owned 1 four cylinder Ranger, it came with 25" rubber and 4:10's. It took everything in the world and my Grandma's skilled, feathering foot to get 18 mpg from it. That engine was supposed to get high 20's. I finally decided that it was because the gears were so tall.

Though my BII was set up the same exact way and performed the exact same way, 25" rubber with 4:10's and couldn't get it over 18 mpg...until I put 32's on it, then it would manage over 25 mpg on the highway???

My experience is different with the v6 Ranger though I am reluctant to offer it for this question specific. Instead I will offer a point of interest; I once owned a "dual purpose" motorcycle, it looked like a dirt bike but handled mire like a street bike. It could go 128 mph but felt like it was going to fall to pieces from a 6 six dropout.

The manufacturers tried to make one thing perform two tasks, it was because of this that I learned to build a vehicle to do one thing right and make it do it safely. I chose fuel economy in inclamate weather (sort of 2 things but it worked).

Since you aren't shooting for a trail wrangler, choose the tire size for your gears that keeps your engine in it's torque curve while driving, then you will experience maximum fuel economy. Since it is also using it's torque effectively, hills will not be an item of concern ..)
My '98 is 3.45 geared with 5-speed and I regularly get 26-27 mpg.
Tires are still the stock P205/75R14s that are supposed to be on it. Across the board, those tires are generally around 25" tall.
My truck is fuel injected, which can increase fuel mileage by around 15% (varies depending on your driving style), so if your Ranger was carbureted, it still should've been around 22-23 mpg.
Its interesting that the fuel mileage increase so much, by the change in tire size.
I suspect it could do with where the engines power peaks occurred at a given highway speed.
Seems you were spinning the engine way faster than it needed to be, thus the low fuel mileage.
Taller tires slowed your engine down and probably put it at a more efficient rpm.
That's IS a surprisingly dramatic change, though.

EDIT: Decided to do the math...Didn't include OD gear, because I don't know if your old truck has the same ratio as mine, so this was all calculated in 4th gear (1:1).
@ 60 with 25" tires, engine's turning 3306 rpm. With 32's, it's only 2583. A difference of 723 rpm.
That's quite a bit.
Essentially, the taller tires are making the engine think the truck's only going 46 7/8 mph.
 
Last edited:

cbxer55

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DCman

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I guess it just isn't offered at CARiD. Because the list of options there didn't offer it for the 3.0. Only for the 2.3 and the 4.0. Although I can't imagine the 7.5 is any different for the 3.0.

Thanks for the info.
Don't know why that is, but I learned a long time ago, if you're going to post, "its no longer available...", you better check with the manufacturer first or else people are going to shove it down your throat every time.
No harm, no foul this time around. Chalk it up to a learning experience.
 

cbxer55

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Well, at Amazon when I did a check your fit, it came up with "This does not fit your 1998 Ford Ranger."

Below is a review from Summit for the part.

"Nice solid well built unit,.... But... Eaton failed a lil in their R&D. The spacer that comes with the unit does not fit older 7.5 ford rear ends. Had to grind down the spacer that came with, and did not get it right, so now I have a stuck spacer and can not get it out to re-adjust my pinion depth. I wonder if Eaton will step up to the plate and help me with this..... Summit has my permission to give Eaton my contact info. ...... If they do, I will up-date this review "
 

DCman

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My question would be...how old is that comment?
I mean, how could Eaton list a Truetrac for a Ford 7.5" rear end, if it didn't exist or had known problems?
Could be things have been rectified since that statement was posted.

...but hey, we're getting off subject. If you wanna continue this, PM me, otherwise, drop it please.
 

cbxer55

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Why should I drop it? It's only slightly off topic since the thread is on rear end gears. I brought up that I want to do the gears along with ditching the Open axle. From what I understand, the Tru Trac won't work on older 7.5 axles. I guess the 3.0 is considered older, since CARiD doesn't list it in the options for this item. And I am certain since that reply was on Amazon, that it is valid. I don't want to gamble and buy something I can't use. So I am looking for other options to get where I want to go.

I've been here sine 2009, you a few months. I've seen what goes on here on threads, it happens everywhere. I am a member of many forums, both auto and motorcycle. All threads wander a bit here-and-there. Leave it to the forum moderators to decide what's appropriate. And btw, I am a moderator on two other boards, both Lightning forums. I do not tell people to "drop it, please" on either. As long as everything stays respectable, I let it ride. If you want to "drop it", don't reply to my post. Don't feed the animals. ;-)

I was actually hoping that someone who has an older Ranger had already done this and would say, "hey, I've done that and this is what I used." Lots of members here, it still may happen. LMAO!
 
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racsan

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I ditched 3.45’s for 4.10’s in a 94 2.3 but have had 3.73’s in a couple orher 2.3 rangers. Id rather have the 4.10’s vs 3.73’s based on my experiences and useage. 3.45’s I wouldnt want at all, its just too steep a gear unless your on flat ground all the time and you never, ever tow.
 

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I don't think a 2.3 should ever have anything but 4.10 or lower. 3.54's are fine in a larger engine with the power to keep chugging without working hard, but on a 4 cylinder the engine has to work way too hard to keep up with the gears and you just end up loosing fuel economy.
 

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I ditched 3.45’s for 4.10’s in a 94 2.3 but have had 3.73’s in a couple orher 2.3 rangers. Id rather have the 4.10’s vs 3.73’s based on my experiences and useage. 3.45’s I wouldnt want at all, its just too steep a gear unless your on flat ground all the time and you never, ever tow.
Wait... people try to tow with a 2.3??
 

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