I have been wondering about a rear gear change for my 1996 E-Super Duty bus. It currently has a 460/E4OD with a 4.63 rear. Tires are 32" tall. Loaded weight about 13,500#. I am wondering if i can get away with changing to a 4.10 or 3.73 rear gear. It does have a large frontal area to shove through the air. Eventually I am swapping a Cummins diesel into it, but the rear gear is pretty noisy now.

 

I'm not up to date on what the OD ratio is in the automatics, but if it's a .70 ratio, then that puts you at around 2000 rpms in OD at 60 mph with the 4.63 rear. You can get by with a lesser ratio with the diesel, but I don't think I'd try it if keeping the 460. My 99 SD F250's 7.3 turns about 2 grand at 70 in 6th gear with 3.73's and 32" tires. Which the 7.3 has no trouble with. Even towing a small camper and fully loaded, you can set the cruise and it'll sit there happy as **** going up and down rolling hills. The only hill in east Texas you might have to downshift on is the one leading into Rusk on US 84 from the east. Or the one coming south on US 69 out of J'Ville.

 

The E4OD has a 0.71:1 overdrive ratio.

 

In the Ford manual, the E-Super Duty has a maximum CGWR of 20,000 with the 460 and 4.63 rear gear. That is the only ratio available from the factory.
The Super E-350 with the 460 and 3.55 rear gear has a CGWR of 15,000 and with a 4.10 it is 18,500. Seems to me that the 4.10 should be no problem at my weight of 13,500 and the 3.73 might be good also. Am I thinking right? Does or has anyone around here tow with a 460 (7.5) and a 3.55 gear?

 

The difference there is due to the torque multiplication factor, not the load rating of the suspension.

 

Yes, but one definitely affects the other in real world use. You have to have the torque to move the weight efficiently.

 

That's what I meant in my answer. I doubt there was a change in the ratings in the springs.

 

I'm revisiting this. Anyone have any new ideas on how well a 4.10 gear set might work in my bus? I have another trip to Colorado in June, so I won't change anything until after that.

 

Just got back from my 2,000+ mile trip. After paying close attention to everything, I think the 4.63 rear gear is just about right for the 460/E4OD combination. When I do make the Cummins diesel swap, I will probably go to 4.10 gears.
Averaged about 7.7 mpg as long as I kept the cruise at 65mph.

 

Pics of the bus? That mileage would kill me, but I guess it's not too bad for such a heavy vehicle with the large frontal area.

So do you use this for road trips? Any camper mods?

 

Pics in my Profile.
We pretty much now use it only to haul my Cobra replica but are planning to use it more since I am starting a Cummins diesel and 5R110 trans swap. That should get me above 10mpg.

 

Saw your pics. Pretty neat setup, like an enclosed car hauler. I am assuming that the Cobra is adequately secured in case of a collision or panic stop. I always see those vans for sale and think that they would make a nice starting platform for a camper build.

So what made you choose a Cummins swap? I know number of people have done them (mostly on trucks) and they turn out pretty nice. Not sure about fitment in the van due to the length. I wonder what kind of mileage/drive-ability you would see out of a ford diesel that was designed for the Econiline from the factory. Maybe a 7.3 Powerstroke or even a turbo 7.3 IDI. Both were offered as options for the Econoline and could provide fairly decent power/mileage (I have no idea about mileage for your setup, but on my NA IDI e250 I average 16-18 hwy. Could be higher with the right trans/gearing combo). I believe they also offered the 6.0L diesel in the Econoline platform. Just a thought and it would probably be less custom fabrication work.

Not saying "Don't do it", just wondering why you picked one over the other?

 

I just prefer the Cummins engine over the Ford diesels and I also happen to have one in my shop.

 

It's always nice to use what you already have. When you do the swap make sure you take pictures and post them up. I will be interested to see how it goes and if it fits nicely.

 

I went ahead and installed a 3.73 rear gear. It did lose a little acceleration, but it is still perfectly acceptable. The bus really has a better "demeanor" with the engine rpm dropping at highway speeds and it may be getting a little better fuel mileage. Also, the 4.63 gear was a little noisy anyway. I think the 460 likes it and the Cummins will love it.
Also found a set of 2006 E450 6.0 diesel front coil springs for cheap on that auction site. When I got them, they measured the same height, wire diameter, and number of coils. I went ahead and changed them. The ride height was exactly the same. It seems the 2006 diesel uses the same spring as the 1996 E-SuperDuty 460. I guess if I need more height after the engine swap I will install a set of Air Bags or something.