Just wondering if anyone out there with a 6.0 has 35's (325/60 R20 if you want to be specific) and 4.10 gears. If so, what mileage are you seeing? If the 4.10's were not stock (which they probably were not), did you see an improvement on power when you made the change? Any negatives with the change? Just hoping to get some real world feedback.

I am seriously contemplating a gear change from the stock 3.73's to the 4.10. I know it isn't a huge change, but I think it may be worth it in the long run (which is hopefully a 100,000+ miles). In theory, power & mileage would improve both around town and on the interstate while at the same time, lowering my egt's and reducing strain on the drivetrain.

 

I had a '92 Explorer and I wanted taller gears than the stock 3.73s. The guy who did the work said I couldn't even tell I had a gear change if I did 4.10s. I did 4.56 and loved it.

 

my old truck had 4.56 in it and i had thirty nines it drove well seemed to even out to about stock ride quality and mileage i guess it all depends on what tire it is and how heavy also 4.10 might be good for what your running

 

I have 3.73s with 35" tires right now under my 6.0L automatic and if I do a change I'll go to 4.30s. 4.10s would put everything back to stock ratios, but 4.30s would have a little more grunt and leave room for 37" tires in the future.

 

I had an 03 with 35's and I changed to 4.10's and I was not happy with the results. The power gain was hardly noticeable until I was towing max capacity and the fuel mileage drop was an issue. If you are not towing all the time I would recommend you leave the gears alone. I recommend you take some of the money for the gears and upgrade the exhaust and get a programmer from Matt. You will notice better throttle response and better mileage and save some coin....

Just My $.02

 

It is interesting how much the feedback differs from person to person. I have posted and read different things on here as well as called and talked to a number of different people (gear shop, 4x4 shops, Spartan Diesel, Innovative Diesel, Icon Vehicle Dynamics, and I think one or two more places) and it is amazing how radically different the feed back has been from one person to the next.

Some people say the stock gears will lend themselves to the best milage, some people say the 4.10's and some say the 4.30's. Power wise, there are some differen opinions as well.

I am about at the point where I think I am just going to have to do a gear change in order to know something with any type of confidence. I will say though that it does seem to be somewhat consistant with everyone that if I was running 37's, the 4.30's would not only be the gear of choice, but highly recommended to actually do.....almost makes me want to go to the 7" lift at 37's.....the only thing stopping me is that I don't want to have to step up any higher to get in the cab nor lift a cooler (or anything else) up even more to get it in the bed.

Money aside, I thought that 4.10's would be the best gear for the 35's....but I can't seem to get consistant feedback....very irritating.

By the way, I do have a tuner and a TB exhaust. I haven't been running the tuner much nor anything crazy....don't want to blow the heads....was thinking that gears would be safer for the long haul (not that I haul much).

 

I considered the same thing as you and done lots of research and talked to people that did the swap. General bottom line is if you do not tow very much adn the truck is primarily empty you will not get the MPG saving from any gear swap as 3.73 is optimal.

Hwever the more often and heavier you tow the more you will benefit from the taller gear swap. Now if you are considering 37's I would do the gear swap as well to put the engine back in the optimal operating range.

In my opinion you do not need to swap the 3.73 even going up to 35's. I went up to 35's an lost 2MPG (to 13MPG City and 17MPG HWY) and little power on the lower end. However after testing varius tunes the best benefit for me was the added Spartan Aggresive Race tune which appeared to recover my lost 2MPG and more than added the power lost.

Hopefully this assists.

 

Here is a question. What would have better power, mileage & lower EGTs......Option 1 - 5.5" of lift, 35x13's on a 20x10 wheel & 3.73 gears or Option 2 - 7" of lift, 37x14's on a 20x10 wheel & 4.30 gears?....and what if a tuner was thrown in the mix?

Still interesting how there is a debate on what gear is best for 35's (specially if you take money out of the equation.....not that I am loaded, but just for the sake of arguement) but with 37's, everything seems to point to 4.30's.

 

So a 6" lift with 35's and 4:10 gears will make you lose around 2mpg?

 

If you are going to all that exspense changing gears you really ought to change to something that's gonna make a difference! If you want stock while running 35's go 4.10 gear, but you really ought to just go with the 4.30 gearing, you will be very pleased, especially when you hook up a trailer and tow!! That is my plan on my Excursion with a 6" lift and 35's......

 

Quite strange::: You ask for advise and when you get it your disappointed. I am sure if you are asking a shop that will charge $1000-$1500 for a gear change what to do they will tell you change the gears..... I spent around $600 and helped a friend that is a Ford Diesel tech install them for $0.... I still was disappointed. My fuel mileage dropped nearly 2mpg and the only time I could noticeably tell the truck had lower gearing was when I was towing 12K... 4.30 gears might have made a difference but at what fuel cost??? most likely around 3-4 mpg... So do your gear change and we will see you back on the boards complaining about fuel mileage....

 

If it sounds as though I am disappointed, then lets make sure we are clear on what the dissapointment is......I am dissapointed that the advise I have been given upon request conflicts so much. Just looking at this thread alone, there are differences on what 4.10's would do as well as what gear would be best.

So currently, my only dissapointment is that I can't find one common piece of data or pattern in my quest for information.

 

Here ya go. If you are running a 33" diameter tire on a 3.73 gear stock, you would need to regear to a 3.95 gear if you go to a 35" tire to get you back to your stock ratio. If you go to a 37", you would need a 4.18 to get back to stock. So a 4.10 gear and 35" tires you would still be at a more aggressive ratio than you are at a 3.73 and a 33'' tire.

 

4.10s and 35s go hand in hand; take it from someone who made the MISTAKE of getting 4.30s instead of 4.10s. The only and I mean only reason to go to 4.30s is if you know for a fact that you're upsizing to 37s. Otherwise you'd be taking your engine out of it's power band and it would run out of steam near the top end.

 

Keep in mind though that your 7.3L has a lower power band than my 6.0L. The 6.0L peak horsepower is 27% higher rpm and peak torque is 25% higher rpm. That makes quite a difference in gearing.

<table width="450"><tbody><tr valign="top"><td colspan="2">Horsepower @ rpm</td></tr> <tr valign="top"><td>5.4L V-8 </td><td>255 @ 4500</td></tr> <tr valign="top"><td>6.8L V-10</td> <td>310 @ 4250</td></tr> <tr valign="top"><td>7.3L V-8</td> <td>250 @ 2600</td></tr> <tr valign="top"><td>6.0L V-8</td> <td>325 @ 3300</td></tr> <tr valign="top"><td colspan="2">Torque (lb ft) @ rpm</td></tr> <tr valign="top"><td>5.4L V-8</td> <td>350 @ 2500</td></tr> <tr valign="top"><td>6.8L V-10</td> <td>425 @ 3250</td></tr> <tr valign="top"><td>7.3L V-8</td> <td>525 @ 1600</td></tr> <tr valign="top"><td>6.0L V-8</td> <td>550 @ 2000</td></tr></tbody></table>