5.4 ujor gear ratios

[Btgass1]

Hey guys, I have a 2005 e350 with a 5.4 and a 6” ujor conversion. Currently I have a d60 in the front and a sterling in the back. Both have e 3.73s. I’m weighing my gear options 4.10, 4.56, 4.88. Does anyone have driving experience with those ratios or some input on what I can expect from each. Also, I have 35’s and a penthouse top. Working on a build out for the interior replicating and rb 50

Thank you I’m advance

[motovan_mn]

I think Justin from UJOR CO recommends 4.56 or 4.88 for the 5.4 on 35's.

I drove his personal rig on BFG 37's w/ 4.88 gearing and it felt like it revved pretty high, but it was peppy. I have 4.56 on my 6.8l V10 and it cruises on the highway just a hair over 2k rpm.

Maybe try sending him an email?

[TheLetterJ]

A have a 5.4 with 35" tires and 4.56 gears. If I never towed, it'd be about right... but I do tow a small-ish (7k lbs) toy hauler regularly and a car/trailer occasionally and while it gets the job done, the power is lacking and I find myself in 2nd gear screaming A LOT. I recently purchased 5.13 gears to put in (haven't installed them yet) which is pretty deep, but switching just one ratio is not worth the cost/effort involved to me. You will not find me in the fast lane. All that said, I'd say to go with 4.88 if you tow, or 4.56 if you don't. If you think you'll ever go with bigger tires, definitely go with 4.88.

[Btgass1]

Awesome guys thanks for the feedback. I don’t tow much weight, 3 rail moto trailer, or a small 13’ boat. My main focus is good highway manners without towing.

The letterj, what can you cruise at without towing running the 4.56?

Thanks again for the input

[deserteagle56]

Mine is the V10, with 4.56 gears...but it has no trouble cruising along at 70-75 mph. I think about 2200 rpm @ 75 mph with 33" tires. Matter of fact, I remember checking my GPS unit after a trip to Utah a couple years ago and saw at one point I'd hit 91 mph. (80 mph speed limit) Those engines (both the V8 and V10) thrive on higher rpms, doesn't bother them a bit.

[TheLetterJ]

I'm not a fast driver, and my wife does most of the driving anyway (she doesn't drive particularly fast either) so we typically don't go over 70. I don't have a tach so I don't know the actual rpm, but using an online calculator shows just 2150rpm at 70. It is definitely comfortable at rpm's much higher than that. When I switch to 5.13, it shows about 2400rpm at 70, 4.88's would be 2300rpm on the same calculator. Had I gone with 4.88 from the get go, I'd probably have been happy.

https://www.yukongear.com/calculator...1_RPM_21.08.23

[martinli]

What about 4.3 gears for the 35s with 5.4?
That should get you nearly where Ford used to setup OEM with 245s out of the factory.

[Twoxentrix]

IMHO; you need to determine what you’re trying to accomplish & most important to you; the gas engines make their horsepower at higher rpm (and for most the stated engine HP is usually based on a 3,000+ rpm range).
If you're trying to balance gearing & tire size to maintain rpm’s at the initial OEM standard then you haven’t accomplished much to help move/pull (what will be a heavier Van) up hills or steep grades (both slow or high speed)…or if you are towing.
***I think member TheLetterJ has supplied all the right info & advise in his two previous posts.

[Mikerson]

To the OP, considering your use case, I’m guessing you’ll be happiest with 4.56. I have 4:30 gears and run about 34” tire. My van weighs in just over 8000lbs and I routinely tow our 21 ft fiberglass boat up winding 9% grades. I’m guessing the boat/trailer weigh in around 5000lb. I’m down in second floored climbing these grades, but it has enough to keep going. The van easily cruises at 80 on the interstate (though, as expected, it’s thirsty at those speeds). Sometimes I wish I had gone with 4:56, but I wanted to be around the factory 3:73 ratio/tire combo since we do a fair amount of high speed long distance travel.

Do you have steep grades where you are?

[Btgass1]

Hey guys thanks for all the information. I’m going to go with the 4.56 swap. Hopefully I’ll have it done in the next few weeks and I can update.