Since I cannot get a response to this question in the gears section. I'lll present it to you guys.

I have a 2001 Ford Expedition 5.4L 4wd w/3.31 gears (9.75 rear/8.8 front), and stock P255/70-16 tires. Gross towing weight at stock configuration is 6300. After market additions are the hitch receiver and Hayden tansmission cooler.

This year we bought a hybrid travel trailer, which grosses at 4750. Before that we had a popup that weighed significanlty less.

On the flat land the truck felt slightly more sluggish than w/the popup. But, when we hit some hills going to the Shenandoah National Park in October, it was pathetic.

I've considered the cost of a diesel F250/350 w/a diesel, but they are too much, especially w/any hit that I would take on the Expedition. So, I ordered, and I hope I am on the track here, 4.10 gears w/master installation kits from Reider Racing. I am also going to upgrade my tires to a LT265/75-16 (D tow rating).

Has anyone done a similar change on a similiar vehicle (Expedition/Navigator/F-150, etc)? Has anyone that is knoweledgable on this topic seen this change? If so, am I on the right track?

I don't see an upgrade in the camper at all for at least few years, so this RV setup will have to last us a while. And, I don't see being able to move to a different truck until the better half's car is paid for. What I am really looking for is some reinforcement (and/or constructive criticism) that I am on the right track here in my thinking.

 

4:10 is a great tow ratio gear. You must however keep in mind that your fuel economy when not towing will suffer greatly and your RPM's will be alot higher! More RPM=More gas! As far as swapping out the gears.... it is not an easy project! There are shims and variances that need to be set correctly. You will need alot of specialized tools to do this. You could possibly do it the old fasioned way with grease smudges to see where the gears are meshing, but you will probably be better off to bring it to a shop for the work! I have done gear swaps in my jeep, it is easier to work on and it's only a jeep. I have also installed lockers in differentials, those are pretty straight foward. This is just my opinion..... but I would definately take it to a shop!

 

I've been wanting to do a 4.10 swap for a long time now, but just can't quite take the $1200-1400 plunge. Keep in mind, since you are going to a "taller" tire in the LT265, your effective ratio is going to be higher than 4.10....without doing all the math, I'd say it's going to be around 3.90:1.

I second 4x4freek's recommendation of having a shop do it. I took my Expy to a drivetrain shop here in Houston and we all looked at the front diff together. They said it's a real #$@$%# to get in and out of the front while the rear is fairly straight forward. I tried to smooth talk an uncle who has a full-blown shop in his warehouse where he builds race cars and his response was to go back to the original size tires (I've got LT285's). He said it would be a lot cheaper and tons easier. When I asked him if I should do it myself (I've rebuilt several engines and done a couple frame-offs), he suggested otherwise....said it's not overly difficult, but takes some specialized knowledge, tools, etc. I guess he just didn't want to waste a whole day on my gear change.

You might try a search of the topic on this forum. I seem to remember a guy who did it 4-6 months ago and was not overly enthusiastic with the results. He said he expected more power from the swap.

Good Luck.

 

Thanks for the replies. Using the calculators, I suspected my final ratio would end up in the 3.90's area w/the bigger Lt tires. But, w/o going to a huge tire, I wanted something that was a better towing tire than the P255's. I probably could stick LT245/75-16's on to get the same height as 255/70's, but they are so darn small on an Expedition. The current gears, 3.30's, are pretty pathetic when you are towing and you get away from ground that is not 100% flat. I obviously expect some hit on the gas mileage, but when you figure the difference in the monthly payment and insurance btwn my current Expedition and an F-250 PSD, the gas is a smaller bill. Maybe in a few years. When we are just out running around, w/o a need to pull something or carry a lot of stuff, we use the better half's 2002 Passat. Exceptional gas mileage.

I, w/o a doubt, am going to take it to a shop to have the gears installed. If it isn't brakes and tune up stuff, I won't do it myself. I saw on the other threads where people go up to 456's in Expeditons/F-150's, but that must really kill them. Especially the folks who are replacing 3.08 gears.