Would anyone have recommendations between 3.73 vs 4.10 both are available in the local classifieds and not sure if anyone has recommendations for which one would be better for a supercab 4x4 1985F250. Plan on having larger than stock tries and doing some towing but not much? Seems other discussion on other forums everyone seems to suggest 4.10? I have a 460 that I will probably switch at some point to EFI
Since you are new you've surely not read much, if any, of my "transformation" of Big Blue from a rough-rider to a smooth(er) riding truck set up for overlanding. And one of the things I did was to go with a D60 and SuperDuty springs with an RSK. Major difference!
But I also installed a Scotty the mad porter-built 460 that was set up for EFI but I ran a carb on it for the first year. And all the while I was kicking myself for not having gone to 4.10's instead of 3.55's. Second gear starts with the ZF5 were just a bit too tall with the 33" tires as the engine just didn't want to pull below 1200 RPM.
However, when I installed the EFI I discovered that the issue had been the huge lower EFI plenum which wasn't designed for having fuel in the air. It was soooo big it was like having a tunnel ram intake on the engine. But with the EFI system squirting the fuel into the intake ports it now pulls fine from idle all the way up.
So now I'm happy with the 3.55's and I'm glad I didn't go with 4.10's. If I'm towing I stay in 4th gear and it has all the power I need. And if I'm running light I drop it into 5th and turn about 1900 R's at 65 MPH, just purring right along. ("Light" is a relative term as BB has a winch, dual batteries, 3KW inverter, 2HP/4 gallon onboard air system, electric bed cover, and lots of other accessories so he weighs ~6600 lbs w/o a driver.)
Stating the obvious here, the front axle ratio needs to match the rear. So unless you are planning on changing the rear axle ratio you need to get the same thing you already have.
That said, what you're probably thinking is that getting a new front axle is a good time to consider a gear ratio change. If you can find a front axle with what you want you only need to re-gear one axle.
Sorry, no '80 - '86 Ford trucks
1997 F-250HD crew cab short box, 460, E4OD, 4.10 gears
1971 Bronco, 302, NV3550 5 speed, Atlas 4.3:1 transfer case, 33" tires
2015 E-450-based 28' class C motorhome, 6.8L V-10
I did read some but not a full deep dive, I was actually hoping to find a picture of your truck. So the only reasonably priced front ends with matching back in combos I can find are 4.10 and 3.73. I do, down the line plan on going EFI as I will be living up in the cold mts and would like the easy for sure starts...So between the two gears you would say the 3.73 would be the better route if I am not doing anything too crazy and she is just mostly overlanding with occasional towing and some off-roading to get to far and away places out here in Utah?
My god she is gorgeous! what size rims and tires are those. I have an automatic, but I don't know for sure what "C" version it is. I am pretty new to learning the specific guts to my truck or vehicles in general
The wheels are 10" wide and the tires are 285/75R16 Falken AT3W Wildpeaks, which are 33" in diameter. The bumper is from Warn and was on the truck when I got it. But there was no winch, so I added a 12K Smittybilt as well as an aux battery to run it.
A 460 of our era only came with one auto - the C6. That's a 3-speed with no overdrive and no clutch in the torque converter so it is always slipping. So I really wouldn't want to go as low as 4.10 since that will give you 3000 RPM at 65 MPH. Compare that to 2700 with 3.73's and 2600 with 3.55's - still using the C6. And all of that is with 33" tires. I'm turning 1800 at the same speed with the ZF5 in 5th, or 2400 when in 4th. (I have 250 RPM in the C6 calcs for torque converter slippage.)
No Slide locks. Built Nov 1979. Thanks for theinfo on the bumper, etc. I want something like that on mine! Where is the aux batt? I assume it charges with the rest of the system, or a stand alone to the winch?
1980 Ford XLT F350
400 Engine (rebuilt to 406)
Holley 2300 500 CFM manual Choke Carb
Under Restore (1st time)
Interesting that you don't have slide locks on a truck built in Nov of '79. Supposedly they didn't phase out the slide locks until of March of '81, and even then several plants continued to install them. So I wonder if yours have been changed out.
As for Big Blue, the factory aux battery sits on driver's side where the coolant recovery reservoir usually goes. I've included two pics below, the first showing BB now with the EFI, and the other showing it as it was with the carb.
The aux battery supports both the winch as well as the 3KW inverter - which powers the air compressor, among other things. It is charged by the 130A 3G alternator, and the two batteries are paralleled via a 200A Cole Hersee Smart Battery Isolator. Those isolators close when either battery voltage is above 13.2V for 2 minutes. And the batteries are isolated when both battery voltages are below 12.7V for 1 minute. But I can force parallel for one minute with a switch in Mission Control.
Let me ask you, if I ended up putting a 6R80 tranny instead of the C6... would that change your answer on the gear ratio? I lost my opportunity for 3.73 and even though she's a tank and can't crawl off the line fast... wouldn't the 4.10 give me a little more push?
The 6R80 wasn't made in the 460 bolt pattern, so while there are ways to attach it they are expensive. This one from Speed Gems is $1895 and it doesn't include the required controller for the transmission, which is another $1249. So all up, not including the transmission, you are looking at $3144.
But yes, with the two overdrive gears of .87 and .69 you could easily go to lower differential ratios. But the E4OD has a .71 OD ratio, so you could go with that tranny and still use lower ratios in the diffs. And there's no $1895 adapter needed as the E4OD bolts right to the 460. And there are $800 controllers for it, so instead of $3144 you'd be looking at $800.
HOWEVER, you said you might go with EFI. If you were to go with Ford's EEC-IV or EEC-V EFI system you won't need a controller for the E4OD as the ECU controls both the EFI and the tranny.
Thanks for being a wealth of knowledge...I plan to rework the axle to a Dana 60 first and then head to the inside, so I wanted to make sure I got the gears right for the later inside work. I do see rebuilt E40Ds everywhere. I want to make her as reliable as possible but also fun to hit the gas pedal and burn the dollars down the road.