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Discussion Starter · #1 ·
I got the 3.73's in mine and I am kinda glad I did. The truck has plenty of power and it keeps the RPMs right at 2000 at 70mph...

Keeps the mileage good and I'll still be able to tow anything I want.

What are your opinions?
 

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I like my 4.10s :)
 

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Discussion Starter · #4 ·
I wonder how low my revs will be when I go with 315's with the 3.73 gear...

maybe i could cruise at 80mph doing 2k rpms?

if so that would be ideal and it probably wouldn't kill mileage...
 

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CamaroSS said:
if so that would be ideal and it probably wouldn't kill mileage...
The extra rolling mass will kill your mileage. Even though they're taller, there's a lot more rubber to turn over.
Greg
 

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Discussion Starter · #6 ·
I don't think it will be drastic...my brother went from like 29's to 32's on his ranger and only lost 1 or 2 MPG...

I think 610 lbs. of torque is plenty to turn 315's...

maybe I need to do exhaust to balance it out

:D
 

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From a towing standpoint, the CTD likes to pull in the well published "sweet spot" of 2,200 RPM. Mind you, this is for sustained, heavy towing. Heavy towing is anything around the max weight listed for the truck or above.

With my 3.73's, I need a speed of about 75 mph to be in the sweet spot. Out west with speed limits of 75 mph and long stretches of interstate, the 3.73s really shine. On the east coast, with 65 mph speed limits, 4.10 would keep the rig in the spot better.

Long grades and heavy loads are another factor. With the EZ and pulling 15,000 lbs, I need to downshift into 5th and drive by EGTs on the big hills. Keeping the RPMs up in the power range can be best appreciated pulling heavy.
 

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On my ride home, I would have sworn that I had gotten 4.10's and even went as far as to double check the specs. I didn't think that the trans was low enough to turn 2000 RPM's at 70 or so. My last truck (auto) ran about the same, but was a higher revving engine and it's sweet spot was about 2600-3000, so since this one redlines at about 3200-3300, I was surprised that cruising speed with 3.73's was such a high percentage of the max speed. It just sounds like it's roaring all the time, but then again I am used to the whine of the old one and not the thunder the new one leaves behind. I can definitely get used to this though, just thought it was a little high for 3.73's. What RPM's are you guys with 4.10's and the 6 speed running at 70MPH? Just curious how much difference it makes.
 

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I think something like 2,300-2,400 at 70...
 

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me1magoo said:
On my ride home, I would have sworn that I had gotten 4.10's and even went as far as to double check the specs. I didn't think that the trans was low enough to turn 2000 RPM's at 70 or so. My last truck (auto) ran about the same, but was a higher revving engine and it's sweet spot was about 2600-3000, so since this one redlines at about 3200-3300, I was surprised that cruising speed with 3.73's was such a high percentage of the max speed. It just sounds like it's roaring all the time, but then again I am used to the whine of the old one and not the thunder the new one leaves behind. I can definitely get used to this though, just thought it was a little high for 3.73's. What RPM's are you guys with 4.10's and the 6 speed running at 70MPH? Just curious how much difference it makes.
Your first ride home is typical of many of us. A 24V diesel is a different animal and the truck it is in had been designed for work - towing capacity, not the normal gearing for a soccer mom or a quiet cruise in a land yacht! It takes some time to get used to it :).

Our trucks are different from what the masses are driving. Cool, huh? :thatfunny
 

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Oh yeah, I love it. I grew up in a 72 GMC Astro sittin on top of a V8-92 Detroit, so I can handle the "different" part. I definitely feel the difference from my last truck, I just hope and pray that the real difference is the LACK of visits to the dealer's shop. It does run higher RPM's than I would expect, especially b/c these 6 cyl's are usually low RPM high torque monsters. A V-? engine will always run higher R's than an inline engine and I just felt it a little odd to run at that high of a percentage of max RPM cruising. I am definitely tired of the "soccer mom" of diesel trucks, strange that Ford only stocks auto's at the dealer and when I asked them why, they said "How many people do you really see WORKING these trucks?"...."Most people just buy them to have a big truck and don't really NEED the diesel power or use it" SO< I bought me a Dodge, cuz I need to work mine and I didn't want to wait to special order to get a 6 speed and risk the extra cost of losing EP, etc. I see that the 410's don't add too much to the cruising engine speed, but about 200 RPM's over mine. At 70, I'm at right about 2200.
 

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My truck runs about 2000 RPM at 70MPH with 33x12.50x17 from Schwab. I think their tires run small (diameter). Mine barely measure 32" across and this is fairly close to the size tire that came on the truck. I'm thinking of upping to 35's. Any advice on this since I have the 3.73's as well?? I know this subject comes up all the time. I don't tow and if I do, it would be light at that. Thanks from the newbie.
 
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