[Mech E]

I'm looking to re-gear my truck, mostly so I can pull a toy hauler. I'm currently running 3.55 gears and 35" tires. Without weight, she is a dog. With weight, I'll probably turn my transmission into a puddle of burnt fluid and clutch remnants. After reading up on the GCWR of these trucks, it looks like they can only tow the max weight if they have 4.10 gears. I'm thinking that with my tire size, I should probably go for 4.56. And if that ends up being too low a gear for me, I'll just step up to some 37's.

What experience have you guys had with gears, tire sizes, and towing?

 

[cjfisher]

Mech,

Is this an automatic? I have 3.55 gears as well and have pulled 19.5k behind my 7.3 without problems. That is a bit on the heavy side granted (I don't often pull that much) and I did pick a route home with the fewest/smallest hills to go over. I don't however have 35 inch tires... 3.73 or 4.10s will probably be better suited for your chosen tire.

Cj

 

[Mech E]

Yeah, it is an auto. 1996 F-250 BTW. I do not want to re-gear twice, so I would rather go overkill and get bigger tires to go back in the other direction. Not much arm twisting required to get me to go bigger on tires. 19.5k is very heavy for an OBS. Max is about 12k for a 1996 F-250, and that is only if it has 4.10s and stock tires. Can I pull the weight with my current setup? Probably. I just don't want to KO my transmission. Or do 20 mph up a mountain on an interstate.

 

[cjfisher]

I have a RTO6610 manual transmission to help. I'm in a 97 F350 crew cab... I don't know what other upgrades you may have - my truck is stock apart from the transmission. We have a couple of things working against us in the tow capacity arena (at least stock) - low power. Ford programmed torque is 450 ftlbs whereas, the international version had a 620 ftlb tune and later 7.3s came with 525 ftlb (maybe even 550 ftlbs). No intercooler to help with the egts so the fueling map is very conservative to avoid melting things. My own opinion is that the 3.55s are ok if you have the right gearing in the transmission and available torque from the engine. If you check out the ratings of the new Fords, it is insane what they can pull (and I believe that the SRW still use a version of the Sterling axles that we have). Look up Lt. Dans Project Shamu build. He has an automatic that is built. His posts may give you some ideas. From the sounds of it with your like of big tires regearing to 4.10s is probably the best route.

Cj

 

[Mech E]

I did check out Lt. Dan's build. I read a lot more than I post lol. My truck is mostly stock for now, but it does have an intercooler. I'm actually tearing down my spare 7.3 next weekend and getting that to the machine shop soon to get worked over. Eventually not enough power will not be an issue for my truck (and I'll start a project build eventually). A transmission build is also in the future. I aim to keep the auto, which is not something I thought I would ever say. I have only had a couple of autos in my lifetime, I tend to prefer manual shift. However, this is a multipurpose truck for me. It needs to highway tow and still be fairly off-road capable. I've actually taken it up the dunes at the Imperial Sand Dunes in Southern California. I also have taken it down to the Baja 250 races down in San Felipe and ran it through most of the course (not actually racing, just goofing off before and after race day). The auto is especially nice when sitting in line for 4 hours waiting to get back in the states...

Yeah, I've seen the GVWR and GCWR of the newer trucks. Absolutely insane capacities, and I might want to upgrade if I were to tow heavier than 12k. But I don't foresee ever wanting to get a trailer past 30 feet in length. I like to be able to get back into areas not really fit for trailer camping. Trailers get to be a pain to maneuver in tight spots once you get past 30', IMHO. Also, I don't ever want to deal with DEF, EGR coolers, etc.

So, 4.10s might be good for me, but I'd rather go over just a bit. Maybe 4.30?

 

[Sbluke55]

I would do 4.30's. I plan on going to them when I have the cash. I have 37"tires.

 

[Lt.Dan]

So I'm in almost the same boat (and thanks for reading my thread!), but I went from 35's and 4.10s and towing 13,000lbs through some pretty big hills, to 35s and 3.73's with the same trailer and I HATE it!!! Unloaded, 3.73s is much more fun, and normal freeway driving is much nicer. But when I have the funds, I will be going to 4.30s. The 4.10's were definitely nice, but I feel just a little bit more gearing was needed, a lot of the times it didnt have enough torque to hold 4th, and 3rd was too wound out, so I had to slow down, and some times it was the same with not having enough torque in 3rd, and 2nd was too wound out. 4.30's and 35s I think would be a nice tow setup.

 

[Mech E]

Sbluke55, what is your current gear setup? Do you haul trailers with it?

Thanks for the feedback LT. Dan! The toyhauler I am getting has a gross of 12k, so very similar to your trailer weight. And the only difference in our trucks (for the most part) is mine is a short bed. Really digging your flatbed setup, especially how it was made to carry your SXS. I have a 2019 YXZ and would not mind having a way to load it on the bed and was debating on doing a flatbed setup as well. But now that I'm getting a toyhauler, the point went moot. I'm thinking maybe I will do 4.30's. I do want to go 37's for the tires eventually. HMMWV tires can be had for cheap lol. So I'd rather have the room to go bigger. And if it still too low geared, I can always get bigger tires! My biggest concern is going too high and having to re-gear again. I like wrenching, but man do I hate setting up gears... I think I'll keep gathering more first hand experiences, weigh my options, and then go for it. One thing is for sure though, the 3.55's I have now make my truck a dog. Even when pulling my YXZ on a single axle flatbed trailer, the truck has a hard time getting out of its own way in the lower rpms.

 

[Lt.Dan]

I have quite a few motor mods that are not listed, including T500 pump, the 66mm Wicked turbo, w/ AB injectors, intercooled, the built trans, custom e-fuel system, and some pretty aggressive tuning, along with some little stuff here and there. I'm able to push the truck much harder now than when I first bought it. For instance, now I have the truck shift at almost 3700 rpms! It really screams at that high of rpms, but it sounds so nice, and the engine really seems to like it, and helps with keeping the boost on in between shifts.

I know I have officially tapped out the capabilities of the stock 130cc injectors, so I hope the jump to 238/80's will help and maybe I can stay with 3.73's. We'll see.

 

[Mech E]

I'll have loads of power later after the rebuild of my spare engine. It'll be getting a cam, valve springs, and head studs. I have an adrenaline HPOP, had to replace the current one so I upgraded a bit. Sill undecided on which injectors and turbo I'll run, but 300/300's sound pretty good lol. I'd love to get my RPMs up to that range, I bet it screams! But for now, I'm just trying to keep the 7.3 in my truck running until I can get the spare engine built, and I want to still be able to take the YXZ out and play. I just got done replacing the up-pipes (bad, bad exhaust leak) with bellowed pipes, fixed the fuel line on the back of the passenger side head (really bad fuel leak when cold), and rebuilt all 8 injectors. All that work should keep me going for a bit longer at least. She smokes black now with the injector rebuild, so I'm wondering if the injectors are not stock. I'm not sure, but I suspect that this truck's previous owner(s) had done a number of mods including a chip. I think the chip got pulled but maybe they left modified injectors in it? I'm not sure how to find that out other than to pull them again and have them flow tested, which I'm not in a hurry to do...

 

[Mech E]

Alright, I'm about to buy the gears in a day or two (along with a bunch of other parts lol). But the question now is, from whom should I buy the gears from? After much research, I found that several gear makers offer nothing for the Dana 50, the prices vary DRASTICALLY between vendors, and some ratios are harder to find than others. Do you guys have any preferred vendors for gears? Right now I'm leaning towards Yukon gears from Amazon... But I found National Drivetrain might have better gears for better prices... Oh the tough choices in life...