Rear Axle Code F7 swap on a 2.5l

[fixing_franklin]

Has anyone put a LS 7.5/4.10 rear end on a 2wd 2.5 w/ manual trans. I'm not terribly concerned with gas mileage. I just want to know if anyone has done this, what do I have to do in order to swap them, different drivetrain? Any noticeable difference from the 7.5/3.73, good?bad? aside from the higher rpms on the highway?

 

[RonD]

Haven't done it but as long as new rear end is from a Ranger then it will just bolt in
The 4.10 doesn't change things that much, but you should notice faster 0-50mph

Disconnect drive shaft, flexible brake line, e-brake cables
Support frame well
Have another jack to support rear end
There are 4 u-bolts, 2 on each side, that hold the rear end to the leaf springs, they are often rusted pretty bad on the threads, you can try to remove the nuts but its often easier to just cut them off and use new ones, they are not expensive

Limited slip needs an additive in the gear oil, but you can buy the oil with additive already mixed in
If you already have gear oil then you can buy a small bottle of additive

Plan on doing the rear brakes, there were 2 sizes, 9" and 10" measure twice buy once, lol
I would get new slaves

 

[fixing_franklin]

Haven't done it but as long as new rear end is from a Ranger then it will just bolt in
The 4.10 doesn't change things that much, but you should notice faster 0-50mph

Disconnect drive shaft, flexible brake line, e-brake cables
Support frame well
Have another jack to support rear end
There are 4 u-bolts, 2 on each side, that hold the rear end to the leaf springs, they are often rusted pretty bad on the threads, you can try to remove the nuts but its often easier to just cut them off and use new ones, they are not expensive

Limited slip needs an additive in the gear oil, but you can buy the oil with additive already mixed in
If you already have gear oil then you can buy a small bottle of additive

Plan on doing the rear brakes, there were 2 sizes, 9" and 10" measure twice buy once, lol
I would get new slaves

That's awesome to know, and I'm sorry if it's a dumb question but what slaves?

 

[fixing_franklin]

Also RonD what difference would it make if I swapped my 7.5 with an 8.8 rear end, I hear a lot of the time that the 4.56 is great for the 2.5, but I also hear that about the 4.10. I'd like to run 31s one day, but I highly doubt that I'll get to it just because I have such high miles on this engine, she runs great but I don't plan on spending a fortune on it.

 

[alwaysFlOoReD]

Slaves = slave cylinders.
Attached to the backing plate. Uses hydraulic fluid to push the shoes against the drums.

 

[RonD]

No difference with using a Ranger 7.5" or 8.8", users choice, same swap, Explorer 8.8" is not bolt in needs modifications

You can go here to see how tire size changes "actual" rear axle ratios: https://therangerstation.com/tech_library/Gear_Tire_RatioChange.shtml

Say your stock Ranger had 27" tires and 3.73 rear axle
If you changed it to 30" tires then actual ratio would be 3.36, thats what it would drive like

If you changed to a 4.14(4.10) axle then with 30" tires it would drive like it does now with 27" tires

Look on drivers door label to see stock tire size


+1 to what alwaysFloored said, rear slaves are also called brake cylinders

 

[fixing_franklin]

Slaves = slave cylinders.
Attached to the backing plate. Uses hydraulic fluid to push the shoes against the drums.

I've always just called them wheel cylinders, but yeah I plan on doing some maintenance to the junkyard axle.

 

[alwaysFlOoReD]

Yes, wheel cylinder would be a correct term. Brake cylinder another. Slave is used because of the "master" cylinder that provides the distribution of the pressurized hydraulic fluid.

 

[19Walt93]

I'd recommend doing some math before you start the project. Going to 4.10's from 3.73's is about a 10% change, if you're changing tire size too you may end up losing ground. You can look up the diameter and revs per mile for the different tires and divide to come up with the effect it's going to have. 4.10 sounds like a lot of gear until you factor in the overdrive ratio in your trans, usually around 30%. If it's .67 like the T5 in my Mustang that would make the 4.10's act like a 2.75 axle on the highway, taller tires would have the same kind of effect.

 

[fixing_franklin]

I'd recommend doing some math before you start the project. Going to 4.10's from 3.73's is about a 10% change, if you're changing tire size too you may end up losing ground. You can look up the diameter and revs per mile for the different tires and divide to come up with the effect it's going to have. 4.10 sounds like a lot of gear until you factor in the overdrive ratio in your trans, usually around 30%. If it's .67 like the T5 in my Mustang that would make the 4.10's act like a 2.75 axle on the highway, taller tires would have the same kind of effect.

All I'm running right now is 205/65/15s, which is actually smaller than factory, I will do the math before I change tire size, thank you.

 

[sgtsandman]

4.10 gearing with the 2.5L is a good match with stock tires. If you are certain you are going to go to 31" tires in the future, you will certainly be going backwards. As mentioned before, there is a chart in the Tech section on the effects of gearing with different tire sizes and engine RPM.

For example, on my 2011, putting 4.56 gearing in it puts it comfortably in the tow/haul range of the scale but pushes the boundry of over reving the engine with the stock 29" tires if I were to choose to go back for say, winter tires or something. Consider carefully what you want to do and have all your items in place before you spend the money one way or the other. Since you expressed a strong doubt of ever getting 31" tires, you may want to take that into consideration and just go with the 4.10:1 gearing.

 

[RonD]

If stock tires were 27" and current tires are 25" with 3.73 ratio, then the actual ratio now is 4.03

Just FYI

 

[alwaysFlOoReD]

If stock tires were 27" and current tires are 25" with 3.73 ratio, then the actual ratio now is 4.03

Just FYI

No, the actual ratio hasn't changed....
The virtual ratio has changed.
Semantics, I know.?

 

[RonD]

No, the virtual ratio would then be 3.73, 4.03 would be actual ratio, lol