Fred the Van. The More We Explore's Adventure Van Build Thread

[sixstringsteve]

I'm tearing the front axle apart, and trying to decide on gearing while I have it apart.

I'm pretty sure I have 3.73s right now. It's the 7.3L EB, and I'll be on 35s (possibly 37s). I will be towing ~6000 lbs regularly. What gear ratio do you guys think I should go with? I'm thinking 4.10s. 6k lbs isn't a ton, especially for that engine, and I will be on the highway a lot, so I don't want to go too low. Thoughts?

 

[DzlToy]

If you know the horsepower and torque curves for that engine, i would start there. A 12 valve Cummins makes peak torque with the least amount of fuel usage around 1600 rpm. I would presume a V8 to be slightly higher. So find that and calculate tire circumference, ring and pinion ratio, several transmission ratios and cruising speeds you are likely to encounter.

 

[snowaddict91]

Here's a torque curve diagram (psd is white). I think this may be truck-specific, but vans should be close.

I have stock 4.10s in my 7.3 f250 with 285s and I start losing mileage after 65 mph roughly. I think 35's and 4.10s would be a good fit for your van. Maybe some of the truck guys on here running 4.10s and 35s will chime in.
Sweet van btw! Saw a green rb 7.3 in pocatello last weekend pulling an airstream and had to do a double take. It even had a giant roof rack! It was a good looking combo!

 

[sixstringsteve]

I've been doing some research online. It sounds like the truck guys are running 4.30s with 37s. It sounds like either 3.73s or 4.10s would work with 35s. 3.73s will get better highway MPG, and 4.10s will have better torque curves for towing. I may just leave the 3.73s in for now and see how it does, then add gears later if needed.

 

[DzlToy]

Based on those curves, i would want to see about 1800-1900 rpm at your expected cruising speed. If you post trans model, gears and tires, i can put them in my spread sheet and spit out some numbers for you.

 

[silvrzuki77]

Hey dont want to clutter the ujoint thread, my friend is running 37's with 7.3 and 4.10 gears. Pretty easy to find superduty stuff in 4.10. With your body length 37's would be a good choice. I am running 37's on the 6" lift.

 

[guidolyons]

4.10 is a super common easy to find gear ratio. I have 7.3L, ZFS5-47, 37" BFG KM2 and 4.10 gears. 65MPH is ~1900RPM, 70MPH is ~2100. It's not build for cruising the highway.

So, give the 3.73 you already have a try and see how you like it before you decide.

Grimmjeeper grear ratio calculator (lots of preloaded transmission and transfercase ratios, or you can plug in your own) very useful to see what RPM you'll be at in each gear

http://www.grimmjeeper.com/gears.html

 

[sixstringsteve]

Hey dont want to clutter the ujoint thread, my friend is running 37's with 7.3 and 4.10 gears. Pretty easy to find superduty stuff in 4.10. With your body length 37's would be a good choice. I am running 37's on the 6" lift.

Is it a van or a truck? Got any pics? Any regrets with going with 37s? Do you have the 7.3 and 4.10s by chance?

 

[sixstringsteve]

4.10 is a super common easy to find gear ratio. I have 7.3L, ZFS5-47, 37" BFG KM2 and 4.10 gears. 65MPH is ~1900RPM, 70MPH is ~2100. It's not build for cruising the highway.

So, give the 3.73 you already have a try and see how you like it before you decide.

Thanks for the feedback.

 

[jjohnny350]

Hey dont want to clutter the ujoint thread, my friend is running 37's with 7.3 and 4.10 gears. Pretty easy to find superduty stuff in 4.10. With your body length 37's would be a good choice. I am running 37's on the 6" lift.

silvzuki77, did you have to trim any at all with the 37s and 6'? I am thinking about going that way for my next van. Yours looks great by the way.

 

[silvrzuki77]

So far no on the trimming. I am not 4x4 yet so I haven't had a chance to flex it out. If you have a stock bumper it will need to be modified to fit. I do rub on the springs with the tires. My rims have 4.5 back spacing.

 

[normal_dave]

So sixstringsteve causes me to switch off the "lurking mode"... thanks!

I'm watching the UJOR portion of your build, as that may be the next step for me... but your trailer conversations and goals sound pretty familiar. I too stared at the Airstreams at the campgrounds, but decided as nice as they were, and expensive, I didn't feel right shaking the insides of one of them to pieces on our excursions.

Enter the domain of the cargo trailer conversion. Careful, it can be an addictive path, one that might fit your goals listed above just about right. key points to consider, low entry cost, steel structural frame walls/roof, we chose leaf spring axles for ground clearance. Nothing on the market met our needs, so we just built what we wanted leaving room for more mods down the road as our needs changed.

Here's our simple build: camp, kaykak, mountain bike, gear hauler, modular. Probably overkill for some of the Expeditions here, but I'll bet it can handle a majority of the trips most of us do.

http://www.tnttt.com/viewtopic.php?f=42&t=48345

 

[sixstringsteve]

I'm so tempted to go with 37s. They're not that much more expensive. I'm not thrilled about rubbing on the springs. Do you guys with 35s rub on the springs too?

For now, I've decided to stick with my 3.73s and see how they do. Since I'll be driving on the highway a lot, and I probably won't be towing more than 6k lbs, 3.73s might make the most sense. If I ever go up to 37s then I plan on swapping to 4.10s.

I almost have enough video footage for the first two episodes of this build thread. Stay tuned.

 

[sixstringsteve]

Here's our simple build: camp, kaykak, mountain bike, gear hauler, modular. Probably overkill for some of the Expeditions here, but I'll bet it can handle a majority of the trips most of us do.

http://www.tnttt.com/viewtopic.php?f=42&t=48345

Oh great, there goes the rest of my day. What does your trailer weigh?

Thanks for posting that, I'll be reading every word. We share similar concerns about beating up an airstream. There just aren't many options out there that can handle rough roads. I'm excited to see your solution.

We were just planing on leaving the airstream somewhere for a week or two while we traveled the rough roads in the van. We'll see how that plan works out.

 

[sixstringsteve]

I'm leaning towards the Cooper ST Maxx tires (my favorite tire I've ever run), or the new BFG K02s. I wasn't a fan of the KO1s in the snow and off road, but I've heard a ton of good things about the KO2s.

What's important to us:
- true 3 ply sidewall
- tread that's road-friendly
- tread & rubber compound that work extremely well in snow and ice
- tread that's decent off road. I don't need a mud terrain, but I don't want to be slipping and sliding everywhere if it starts to rain and turns to mud.

If I'm honest, 95% of my driving will be on pavement, so that's the first priority.