Intro - Gearing Question

Few notes now that others experienced with what or near what you have have now commented.

First, everyone seems to be saying that you should try it out before you spend the money. It's probably not necessary.

Also, a lift on one of those trucks is probably going to be more for looks than anything else. I believe the only people who make a functional suspension system for those leaf sprung trucks is Thuren Fab. Otherwise all you're gaining are approach and departure angles. You will probably need a leveling kit for the 35s to fit properly in the front. But you may be happy with how your truck sits without going any higher.

Here's a pic of my f250 7.3 with 35" bfg tires. Like I said, I don't think it was lifted. Only leveled. As you see, it wasn't a small truck. Your tires are going to give you quite a bit of height.



The last thing I wanted to touch on is that I believe the mounting for a Four Wheel camper is actually to the bed from the factory. Like the put eyelets or brackets in your bed and that's how it's done. I don't think they do it another way for their brand. They may if requested though.

The tires I’m running are about 34”s and I’m very happy with the 3.54 gears in my Dodge/ Cummins. I have all the power I could ever need pulling over the high mountain passes in Colorado with the overdrive turned off. And when the overdrive is turned on it’s great for good economy on the regular highways cruising at 60mph to 75mph or better.

I agree the 3.73 gearing will be more than adequate for the load you are carrying. My father had 3.73 gears with a 7.3 and he hauled a 16,000 pound FW for about 50k miles with it. So you will still have plenty of power for the measly 2000 camper.

On a side note, lifts and campers don't go well together. Before you invest in the lift, see how far you can go first. Make a few trips with the camper and see if you need the lift to go where you want to go. I had a stock F350 Crew Cab and always surprised folks on where I showed up. Also, make a spacer for the bed and put the camper on it. You may be surprised that the extra height makes the rig unstable enough that you won't be able to take advantage of the lift anyhow.

Lastly, unless you have talked to Four Wheel Camper about the construction, bolting it to the bed may not be strong enough to withstand the rigors of even easy off roading. The bed flexes a certain amount and the camper is designed to be basically rigid. With spring loaded turn buckles, the bed can flex a certain amount under the bed.

I had a 95 f250 7.3 w/5 speed and 4:10s and 35"tires, Had high rpms on the highway and poor mileage.I was carrying a FWC keystone or pulling a 23 ft toy hauler. I was thinking of going down to 3.73 for the mileage. I am now driving a new f350 6.7 srw with 3.55 gears and 35s and hauling an older S&S or pulling the toy hauler with no problems. I would try out the tires first and then see what you think before spending the money on a gear change.

They're probably going to do something about that picture. Here's a link to a handy thing I discovered for posting things here. I bookmarked it.

https://dl.dropboxusercontent.com/u/201045551/Forums/PhotoUpload/RV.NET-Photo-Upload.html

With the five diesel trucks that I've owned, I would say that I never experienced anything with stock gearing that made me think that something bad would happen to the drivetrain. Your modification list is very mild and I wouldn't worry about it. You are already dealing with parts that were engineered for heavier duty use than what you've described you'll use the truck for.

But, I can understand why a couple of the manufacturers have offered lower gearing. I'm not saying it would be a terrible idea, but it will affect drivability. Your best bet may be to do a google search on the rpm that the truck should be cruising at. You'll find answers quick. As far as I've ever heard, anything lower than 2000 is a golden area for mileage. As far as what's best for cruising with a heavy load on or attached, the latest information that I can give you is that the 1997 dodge that I mentioned cruises at about 2200 at 70mph on the highway. When a grade comes, I push my foot down and the truck goes and there is plenty of pedal left. No need to downshift or anything.

You'll have to experience the truck with a load on. It's unbelievable how more weight won't affect your power.

4.10 gears wouldn't be a bad idea at all. All I'm saying is I wouldn't think it necessary.

Do you know anyone with 35" tires with a newer ford bolt pattern that would let you bolt them on for an hour or two? That would give you the best idea of what I'm saying for now. They may rub a bit with no lift in the front, but they should still bolt up and clear I believe. Somebody is welcome to comment and let me know if I'm wrong. I believe my 1999 had just a leveling kit and there was plenty of room.

The trans and other parts of the drive-train is part of the issue. If I regear, it will lessen the stress on the rest of the driveline. Rears are stupid and purely mechanical. They aren't going to fail unless you're doing something stupid or not maintaining it. The engine and trans on the other hand are going to be working much harder with the extra width/diameter/weight of the tires plus the 5000lbs of load.

Being new to diesels, and specifically the 7.3, does anyone know the best RPM for it? I thinking that may make the decision easier. With the stock gears and new tires, the RPMs will be around 1830 at 70. That seems awefully low, with 5000 extra pounds. I would think it be better to have the RPMs closer to 2200, which is where it'd be with the 4.30s in OD.

I appreciate the input you guys are giving. For eye candy, here is a picture of the new wheels/tires. The ones in the background are from my old truck, a lifted '96 Bronco. Hated to give that up, but really wanted something that could tow better.



Don

-

I'd leave the 3.73s and try it out first. I had a 1999 F250 7.3 with a 6-speed and it had 3.73s and 35's. I never hauled a camper with it, but I towed with it more than a few times and I never felt like rehearing it would help anything.

It did great at 70 mph too. For reference, I also have had a 1996 f350 cc/lb and it had 4.10s and a 5-speed. It was okay, but if I remember correctly it was tacking over 2500 at 70.

These diesel motors have so much grunt that it doesn't affect things all that much if you throw bigger tires at it.

These things been said, 35" is the max is probably go on the stock gearing. After this, and maybe even with this tire change, you'll be affecting transmission reliability.

I currently have a 1997 cc/lb Dodge Cummins with a 5-speed and 3.55 gears. I have a lot of plans for it. But my camper probably weighs 3500lbs (I think would be a close guess), and it has 285s on it now. It does fine. But 35" tire height is the eventual plan, and the way it handles things now, I don't foresee myself wanting to re gear.

There are a lot of reasons to change gears, but your truck would be just fine IMO of you left it stock. Especially if your camper is going to be as light as a Four Wheel brand one is.

Edit: I just carefully read the post and want to ad this...I also have a 2006 Dodge Cummins that has 35" tires and a built automatic transmission in it. The truck has 3.73 gears and would like to lock/unlock quite a bit when towing over very hilly terrain. This is one of the reasons I looked so hard for a manual in my 1997. I'm a truck driver and didn't particularly like the lack of transmission control when towing with the other truck. But it never shifted out of OD or unlocked the torque converter on the highway.

Another thing you can look at doing for more control is installing a torque converter lockup switch.

Agreed on the 4.10s w/ 35's; may want to also consider inspecting/rebuilding/replacing the factory rear LS (if equipped) while you're at it... same labor once you have the diffs pulled. If not present from the factory, the Detroit TruTrac has some great reviews for both the F&R applications

Re: transmission management, especially re: converter lock/unlock, take a look at the Banks TransCommand. I've run one since my rig was nearly new and have been completely happy with it- locked converter in 3rd & OD, with firm (NOT harsh) shifts.

BBF

That 7.3 is a great engine (bullet proof) the 4:10s will do fine, the engine will make up the difference with whatever mods you want to do. Had one in a 99 350 dully that was everything you would ever want!

Good luck
Wes

4.10's is an ample adjustment without hating normal highway rpms. Turning the big tires is harder than hauling that camper.