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Differential question(s)


v8318cid

Well-Known Member
Joined
Jul 19, 2009
Messages
164
City
Sumter SC
Vehicle Year
2010
Transmission
Automatic
Ok, I have a '10 Ranger with the 2.3l and automatic (love the truck overall, but...). According to the specs (not to mention several forum posts), the gear ratio on this setup is 4.10. From what I can tell, the manual is 3.73. Is the difference in the ratio the reason why the manual gets significantly better fuel economy? Also, does anyone know why the 4.10 is the only option for the 2.3l/auto setup? I am pretty sure the higher the number, the better equipped the vehicle is for towing. My beef is that I don't plan to tow anything. Why, then, do I need a towing ratio? Could I not get better mileage out of a lower ratio or is the 2.3l not capable of lower gears?
Thanks.
 
The mileage drop is because the automatic sucks up so much of the engines energy. A lot of it is converted into just heat, but there's alot of slippage, etc. Especially in the torque converter.

A manual is directly linked, and pretty much all the power gets through, minus a very small amount for friction in the gears. Manuals almost always exceed automatics in terms of fuel economy, and all of them will at the least match it.

The auto is also notoriously slow, so a deeper gear ratio (4.10) helps acceleration.

Question time:

Do you predominantly drive one the highway? or city driving?

3.73 might help on the highway. 4.10's are better for slower speeds and accelerating a lot.

4 cylinders like to rev, they don't mind cruising around at higher RPM's.

It is certainly capable of lower gears, and they could work better for you, if under the correct circumstances.
 
The auto has a slightly taller OD gear (0.75:1) vs. the manual (0.79:1), so that would partially offset it.

I agree though, unless you're running some funky small tires on it, stick with the 4.10s. It'll be super-gutless if you go taller. Doubtful you'd get much, if any, MPG improvement.
 
I drive a bit of both, although I'm mostly concerned with highway. Guess my "other" car spoiled me since it has such a wide difference between city driving and highway.
I appreciate the info either way. I have always considered myself fairly competent when it comes to mechanics, but have never fully grasped the concept of the differential gearing. The explanation of the two OD gears helps as well. I'm not sure I totally agree with the arguement about the energy absorption of the auto vs the manual, but again, I'm no expert. I keep hearing that the differences between the two are quickly disappearing, economy-wise.
I've noticed the RPMs run significantly higher on a 4 cylinder regardless of transmission setup. Was never sure why, unless it had to do with a higher end power band (if that makes sense). I have a V6 that turns 1400 RPMs at 55, and the 2.3 turns about 2100 or so at the same speed.
I tend to run stock on my vehicles. Changing things only gets me in trouble. My 92 was modified somehow by the previous owner and threw the speedo off by about 7 mph. Took me forever just to recal the speedo on it. Dealer just gave me the fish eye when I asked about having it done. Something about it being gear driven rather than computerized. Sort of like asking about having a carb tuned... =)
 
I'm not sure I totally agree with the arguement about the energy absorption of the auto vs the manual, but again, I'm no expert. I keep hearing that the differences between the two are quickly disappearing, economy-wise.

Imagine if you will, trying to drive a fan, with another fan (like setting 2 box fans aganst eachother) to transfer energy from one to the other. Not exactly very efficient. A clutch will just clamp the two pieces together and not allow any slippage.

Now they've got torque converters just a bit more efficient than that :icon_rofl:, but the principle is the same. The newer torque converters are also being installed with a special clutch to actually lock it, which helps a lot. Also pretty sure some transmissions also have the ability to lock up in 1:1 gears or O/D gears.

I think the Rangers of that era have the the locking torque converter, I'm not sure about the transmission, still a lot of loss of power from slippage. You can prevent that by ramping up the pressure in them, but then they shift really, really hard. And the potential for other problems rising as a consequence.

I haven't really kept up with automatic technology. Had nothing but problems with them in years past, and eventually just quit driving/messing with them. Everything they do to increase efficiency, the manual already had, and has had since forever.
 
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Not a bad analogy. I know older automatics, especially those that didn't have lockup converters, always had a certain amount of slip to them which inherently caused lower efficiency. Modern transmissions with lockup converters, and the more-impressive continuously variable lockups (GM uses something like this as the converter has the ability to vary the application of the lockup clutch) allow for minimal to no slip once locked. Lockup can occur in OD, direct drive, and even second in some setups, although almost certainly electronically controlled transmissions only. I'm not sure what model transmission is in the 2010 yet, other than it is a five-speed. It has a lockup converter, but from what I've seen so far, it only locks in 5th(OD). Interesting that apparently the planetary gearset doesn't actually have a separate piece for the 5th gear. It apparently locks the OD (what would normally be 4th in a 4-speed) and 1st simultaneously to achieve one of the speeds. Anyone else heard this before?
 
i believe the difference in rpms between the 4 cyl and the v6 is just that. 2 extra cylinders will result in fewer rpms at a given speed over the 4 cylinder. the 4 cyl needs more rpms to make the same speed as the v6, or any other 6 cyl really. and a v8 would need fewer than a 6 cyl.
 
Generally speaking the gear ratios in manual transmissions are lower than that of automatics. I don't see why the Ranger would be any exception. This would be my guess as to why it uses a 3.73 gear. And the fuel consumption is as mentioned earlier, the auto uses a lot more energy to run. Newer technologies have greatly reduced the energy consumption though, especially these newer 6 speeds Ford has made. They have also started making bigger pans for higher fluid capacity to help with heat which adds to longevity as well.

i believe the difference in rpms between the 4 cyl and the v6 is just that. 2 extra cylinders will result in fewer rpms at a given speed over the 4 cylinder. the 4 cyl needs more rpms to make the same speed as the v6, or any other 6 cyl really. and a v8 would need fewer than a 6 cyl.

I think what you might be trying to say is peak torque hits at a different rpm in a 4 cylinder than a V6. Any difference in rpms is purely gears. If a direct swap was possible and you just swapped motors (not the trans or diff's), you would still require the same rpms in 5th gear at 70mph on the 4 cylinder as you would on the V6.
 
i believe the difference in rpms between the 4 cyl and the v6 is just that. 2 extra cylinders will result in fewer rpms at a given speed over the 4 cylinder. the 4 cyl needs more rpms to make the same speed as the v6, or any other 6 cyl really. and a v8 would need fewer than a 6 cyl.

That is a common mis-belief. RPM is RPM and is measured at the crankshaft. 2 vehicles with the same trans. and rear gear ratios, one with a 4 cyl. and one with an 8 cyl. will turn the exact same rpm at the same speed. The only difference is the number of pistons swinging from the crank.
 

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