I have a 2001 Excursion with the 3.73 gears combined with the V10. I also pull a 9,000+ lbs camper. I took a trip to the mountains this past weekend and noticed how this truck struggled up the hills. I could pull most hills in third gear until we reached the mountains. I then had to drop to 2nd for some of the longer and steeper pulls as 3rd would loose speed. In second gear the truck will gain speed so I know the engine is up to the task but I would like to stay out of 2nd as much as possible. I watched the transmission temp really start to climb when I hit second. I backed off a bit near the top of one long pull (over 7 miles of 5% grade) just because the temp was rising quite rapidly. As a side note, I plan on upgrading the transmission cooler. Luckily the outside temps were around 65 so the temp never got REALLY high but I did hit 227 at the very top of the hill. After that it dropped fairly quickly.

Some friends of ours were pulling their ~8,500 lbs camper with their 2001 F250 with the 7.3 diesel and he was in 3rd on the same hill that took 2nd for me. We have the same transmission and I'm pretty sure the same gearing. I know a diesel will pull hills better than a gas engine but I kept wondering how much of a difference taller gears would make. I have heard figures of around $700 per axle to change the gears but I wanted to know how much of a difference would it really make. Would I still have to drop to 2nd or would 3rd pull a lot harder. That's a lot of money to drop unless the payoff is worth it.

I know gas mileage would suffer when unloaded but I figure it might increase a bit when towing if it meant using 3rd instead of 2nd. I'm sure there is no easy answer but I would like your opinions. Especially the folks who have first hand experience.

 

Changing the R&P gear on V10's is a very common mod discussed on this forum. It's done to keep the V10 engine in the sweet spot of the RPM power curve better, when towing uphill.

What size tire do you have on your rig? Do you have a lift?

Any other mods?

Stewart

 

Yep, like Stewart says, Changing gears to the 4.30 will make it shift and tow a lot like the diesel, especially with a heavier load.

I went with 4.56, since I might want to go to 35's someday. I have 33's on there now. The difference when towing anything over 8000 lbs is dramatic. No more slowing down on steep hills, no more shifting just to get over a overpass hump, etc.

Just remember, the Ex with V10 and 3.73 is rated to tow up to 9000 lbs. The closer you get to that 9000lb limit, the more you need to change the gearing. Like night and day.

 

That is generally not the case with the V10. 3.73 gears are really not suited to the V10 for towing or MPG. The V10 makes best power and best MPG at higher RPM than the 3.73 gears have. My truck has 4.30 gears and (with a few mods) I get 16 MPG empty highway driving.

 

I think he is right, otherwise why did Ford settle on 3.70's? They make the best power but not the best mpg with lower gears (not towing).

 

I don't have a lift and I'm running the stock tire size. (I think)

I've been reading several threads discussing the axle ratio and have found some good information. I just know that I've added several things to the truck that just didn't live up to the "hype" if you will. Each of those things were an improvement but I'm looking for a huge difference if I'm spending a grand or more.

I still like this truck and on the flats it's a great combo. It will pull in overdrive with no problem unless you hit a long hill. That's when it drops to 3rd which does a great job. That is until you hit those really big hills. The hill that brought me to 2nd gear climbed 1,500 ft in 6 miles. While I don't pull hills like that everyday I do love mountain camping and I would hate to think of buying a larger truck.

 

Stock tires are 265/75-R16's and Ford matched them to 3.70's for best mileage. (not towing).......taller gears are known as higher gears (lower numerically)

 

That's what I have.

 

You won't find any one thing that makes a huge difference. It really does take a combination of small things to get the V10 where you want it.

Think about gearing like this:
Higher gears (3.73 ratio) keep RPMs lower at any given speed when compared to lower gears (4.30 ratio).
Contrary to what some people think, lower RPMs don't always equate to better MPG.
The key is getting the RPM at the best range for a particular vehicle and engine.
This is especially true at highway speeds with wind resistance.
In the case of a heavy wind pusher like the X, lower RPMs mean you have to give it more throttle to maintain speed because the V10 "power band" doesn't really start until about 2,500 RPM.

Your engine has to have enough power to efficiently move the X. Can you imagine a 2 liter 4 cylinder in the X? It would use more gas than a V10 because you would have to bury the throttle to make it move the X. That under-powered 4 cylinder is just an exaggeration of the V10 at low RPM, but you get the idea.

 

How often do you tow in the mtns?? I live in the mtns. and regeared my 66 F100,, just jumping to 3.70's made a HUGE difference,,, and my mileage increased, due to not working as hard and not having to have my foot in it,,, my 77 is next,, so I would highly recommend it,, you WILL notice it!!

 

It might be petty but v10 with 3.73 is rated at 10,000lb towing capacity.

To the OP, you might wanna try a tuner, about 1/2 cost of gears and might be enough for what you wanna do.

 

I just did it last summer. Made a big difference in towing, a lot less shifting of gears. We took a 6500lb trailer out to Wyoming and it handled any grade we saw with ease.

I think I lost about 1 mpg hwy non towing, but haven't really taken it on any extended trips not towing since the change to be sure.

 

Rest assured, you lost MPG non towing.

 

Can I get this weeks winning lotto numbers?

 

I don't quite know everything, but those numbers will cost you.