Should I switch gear ratio?

[7river]

I have a 94 E350 w/ E4OD and 4:10 gears. 245/75/16 tires
I normally don't tow anything but will be towing a 3k trailer sometimes. I may even tow a 20' trailer loaded to move next year, but maybe I switch back for that trip?

On trips we weigh in at 9-9.5k single wheel.

Will the 3:55 gears help fuel economy much? I have a 93 F250 I picked up for parts. It is 4x4 but pretty sure it has the 3:55 gears.

How do you do the swap and is it very hard?

 

[Blind Driver2]

I would keep the 4.10 gears. My truck is normally unloaded and feels like it could use more gear.

 

[riotwarrior]

First the rear would be a direct axle swap just pull from one and install the entire axle assembly into the other. That's easy....however I'm thinking you have a 2wd but uncertain so if it is then ya swap is a basic remove replace...one day!

As for your 4x4 having 3.55 gears unless it's a 4sp or C6 trans that's not likely...I'd bet same gear set you have. Look at the door tag and see what the axle code is and report here we can assist with that deciphering!

You may gain mileage some may agree with that, I however do not feel that the swap inherently would be significant gains that outweigh the bennefit of 4.10 gears for towing, maybe adding another OD like a gear vendors on the back of your E4OD....then you have better mileage when not loaded, ad the decent gears for towing!....

JM2CW

Al

my bad....van diff wont swap with truck sorry have to dissasemble parts and re n re ring and pinions...sorry miss read the e for f didnt have glasses on this am

 

[junk]

I have 3.55's in my crewcab and pulled small trailers all over with it. If I towed heavy or in really hilly terrain I might think about the 4.10's. In general with a factory sized tire I feel the 3.55's do well for general commuting and small trailer pulling. When I say small trailer I'm thinking under 7,000 lb.

 

[tjsea]

pretty sure the van rears are different from the trucks.

 

[Hydro-idi]

i would keep the 4:10 gears for your vehicle. They are a great gear ratio when you need to tow something. 3:55 gears might gain you a little mileage, but not worth the hassle and loss of towing performance in my opinion.

 

[IDIDieselJohn]

I'd also say keep the 4.10's. Just slow down abit if your one to cruise over 75mph. You have OD, so 4.10's aren't that bad.

 

[Blind Driver2]

I'd also say keep the 4.10's. Just slow down abit if your one to cruise over 75mph. You have OD, so 4.10's aren't that bad.

You shouldn't need to cruise over 75

 

[jaluhn83]

3.55 with a ZF and turbo works pretty well for me. You can always drop the trans into low if you need more power. My biggest problem is the torque curve isn't in the right spot with my gearing for towing. I'm thinking seriously about going to a 3.73.

You should see some improvement from the 3.55s, but I doubt it's enough to be worth the work. Same with running a GV overdrive. Lots of money and effort for ~10% better mpg. For the pickup folks axle swaps are a good way since you can pick up another rear end pretty easy and cheap and the swap is just a few bolts in and out. (Ok, big pain in the rear bolts, but still....) 4wd fronts are a pain for the TTB folks, and ring and pinion swaps are a whole nother can of worms.

 

[Shadetreemechanic]

It will definitely net you a couple of miles per gallon unloaded. For towing it depends on your preferences. I have 3.55s and I routinely tow 9K plus, but leave it in fourth and cruise at 60. I recently had a 7.5k camper behind the truck for 700+ miles and it was the first time I thought 4.10s would have been nice. Basically I didn't quite have the ump to pull the smaller interstate hills and maintain 70 in 5th, but towing 70 in 4th was too wound out for me and dropped my mileage to 9 mpg.

 

[JwS]

I did exactly the swap you are thinking about a few years ago, first off Tjsea is right, the van axles are narrower and have different spring seat locations than the the pickups, so you can't swap the whole axle from that truck, but the internals are of course the same.
I didn't see as much mpg improvement as I hoped, but it did a little bit. It does get the revs down and make things quieter in the cab when cruising on the highway though, which is kind of nice if you are driving alot. I have no problem with van (about 9000lbs) and a 3000lb trailer, which I have towed cross country, but it is no ball of fire, I guess I typically run around 65mph, much faster and you will start to drink diesel regardless of your ratio. If I did it again I might get something in between, but it isn't worth changing again and I am pretty happy with it. I guess I would just say don't expect a huge change in mpg to pay off the cost of the change... I would guess the schoolbus weight is around what I have in my rv, so probably pretty similar.. Oh, if you don't have a turbo then stick with the 4:10, it will be a dog with 3:55s I would guess, and you'll be struggling up hills...
JwS

 

[7river]

Thanks for such detailed responses. I'm going to keep the 4:10 gears. Extra time is something I don't have right now, so if it's not a big gain then it's an easy choice!