Ford F700 Build
- Thread starter hdemetrious
- Start date
tanglefoot
ExPoseur
Looking sharp! For long, self-sufficient expeditions, you may want to space above the cab for storing gear/fuel/water/etc. A deck would be cool but might not be very practical. You can always roll out a mat on the ground and set up some chairs instead.
Great, resourceful build.
Great, resourceful build.
Code Monkey
Observer
As for your 'RPM' problem, increasing the RPM of the 12 V Cummins is not desirable if the goal is to have a higher cruising speed - what is preferable is a lower RPM. Lower RPMs == less noise, less fuel consumption and less wear as long as you are not 'lugging' the engine.
So gearing and/or wheels/tires are probably the best solutions. On a big truck like that you can maybe find an aux transmission with an OD that will work well - as has been suggested.
Not sure what diffs are available for that truck, but for mine (a 1 ton Dodge DRW with the same engine and same problem - I have 4.10 or 4.30 diffs) I am going with 3.73 diffs and 19.5" wheels/tires. My trans already has an OD gear (.73). At 60 MPH it RPMs are about 2.2K which is a bit high as max torque is about 1600 RPM. Closer to 1800 RPM would be about right for 65 to 70 MPH without a light to medium load on a stock engine.
I am betting that higher (lower numerically) gearing for your truck may be hard to find, so an aux. trans with an OD would be probably the best solution. If you get the right one (if possible), you may be able to use it as a 'splitter' which will give you a whole new set if gears (1st high and low, 2nd high and low, and so on), which would be really nice because diesels have a narrow power/RPM range and do much better with close ratio transmissions. For the non-light trucks (like your commercial sized truck), a splitter is not unusual at all - you should be able to find one. I had one on a 2WD farm truck - but it was in the diff, not between the trans and the diff.
One downside of such an aux. though, is that it usually will not work with when you are in 4WD (IIRC I saw a front diff on your truck) - unless you can divorce the transfer case from the trans and put the aux. trans between the trans and the transfer case. Otherwise you probably want to disable the aux. when using the 4WD (i.e., make sure it stays in 1:1 mode). This is probably okay as you may have a pretty good reduction in 4WD low and may not want to use 4WD Hi. I don't know your use case - just something to take into account.
Myself, I would like a splitter that works in 4WD mode too as I anticipate taking my truck up into the mountain in snowy conditions at normal road speeds to ride a snowbike/etc., so it would be nice to still have the splitting function in both 4WD and 2WD. Problem is I don't know any robust 'splitter' aux. transmissions that do that for my rig hauling the weight I will be hauling. I've not heard good things about the aux. transmissions for light trucks like mine and a huge thing like that Spicer aux. is just too big and heavy for my truck (and probably wouldn't work in 4WD anyway).
So gearing and/or wheels/tires are probably the best solutions. On a big truck like that you can maybe find an aux transmission with an OD that will work well - as has been suggested.
Not sure what diffs are available for that truck, but for mine (a 1 ton Dodge DRW with the same engine and same problem - I have 4.10 or 4.30 diffs) I am going with 3.73 diffs and 19.5" wheels/tires. My trans already has an OD gear (.73). At 60 MPH it RPMs are about 2.2K which is a bit high as max torque is about 1600 RPM. Closer to 1800 RPM would be about right for 65 to 70 MPH without a light to medium load on a stock engine.
I am betting that higher (lower numerically) gearing for your truck may be hard to find, so an aux. trans with an OD would be probably the best solution. If you get the right one (if possible), you may be able to use it as a 'splitter' which will give you a whole new set if gears (1st high and low, 2nd high and low, and so on), which would be really nice because diesels have a narrow power/RPM range and do much better with close ratio transmissions. For the non-light trucks (like your commercial sized truck), a splitter is not unusual at all - you should be able to find one. I had one on a 2WD farm truck - but it was in the diff, not between the trans and the diff.
One downside of such an aux. though, is that it usually will not work with when you are in 4WD (IIRC I saw a front diff on your truck) - unless you can divorce the transfer case from the trans and put the aux. trans between the trans and the transfer case. Otherwise you probably want to disable the aux. when using the 4WD (i.e., make sure it stays in 1:1 mode). This is probably okay as you may have a pretty good reduction in 4WD low and may not want to use 4WD Hi. I don't know your use case - just something to take into account.
Myself, I would like a splitter that works in 4WD mode too as I anticipate taking my truck up into the mountain in snowy conditions at normal road speeds to ride a snowbike/etc., so it would be nice to still have the splitting function in both 4WD and 2WD. Problem is I don't know any robust 'splitter' aux. transmissions that do that for my rig hauling the weight I will be hauling. I've not heard good things about the aux. transmissions for light trucks like mine and a huge thing like that Spicer aux. is just too big and heavy for my truck (and probably wouldn't work in 4WD anyway).
Chazz Layne
Administrator
If it were my truck, I'd want both.
It really depends on you I suppose. If you like sitting up high and getting a birds-eye view, then go for it. In my case, I end up on my roof rack at some point on more than half of the trips we take - sometimes for the view, sometimes to get the picture. I've often wished for more space up there to stretch out and relax.
Nice job on the build so far, I look forward to seeing the finished product.
hdemetrious
Adventurer
Second fuel tank inastalled. I now can carry 150 gallons of diesel.
hdemetrious
Adventurer
Departure Angel
How important are departure angles? I plan on putting two spares under the truck in the rear. This will give me 15 inches clearance from the ground up. The length of the this rack will go from the back of the rear tires to the end of the camper. Is this a problem?
How important are departure angles? I plan on putting two spares under the truck in the rear. This will give me 15 inches clearance from the ground up. The length of the this rack will go from the back of the rear tires to the end of the camper. Is this a problem?
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LowTech
Dirt Track Traveler
You can draw a line from the bottom of your rear tire to the first thing that will touch (lowest) in the rear. That would be your departure angle. How important, . . . that depends on where you take it. I cross loads of washes out here in the west deserts and some of them are pretty narrow. So for me it's really important. As the front climbs the other side the rear can drag if not given enough angle.
re departure
I would say that of the things that you can control, this is one of the very important. I takes very little amount of land contour change to ground your rear end. It is much easier to work with a poor break over angle. Like mentioned by low tech, draw your line and do your best not to compromise it.
I would say that of the things that you can control, this is one of the very important. I takes very little amount of land contour change to ground your rear end. It is much easier to work with a poor break over angle. Like mentioned by low tech, draw your line and do your best not to compromise it.
hdemetrious
Adventurer
Right now the departure angle is 30. If I put the spares underneath the angle will be 20. The alternative is to mount the spares on the back of the camper. Since I have double doors in the rear I would have to make a carrier that swings out of the way so I can open the rear doors. So its either put them underneath where they are out of thr way. Or on the back where I would have to swing them out of the way each I want to access the rear doors. What do you guys think.
Photomike
White Turtle Adventures & Photography
If you are planning on using the doors a lot I would not do it. If the rear doors are for occasional use then sure.
Other options than under at the back that I see are on the roof of the cab, roof of the camper or on the left side where the old logo is (this would only hold one), or on the front with a mount in front of the grill (one also).
Other options than under at the back that I see are on the roof of the cab, roof of the camper or on the left side where the old logo is (this would only hold one), or on the front with a mount in front of the grill (one also).
Cat Jockey
Observer
Dropping from 30 to 20 is a pretty big decline for a spare tire. You won't even need to leave your state to find off-pavement roads where that difference will keep you from getting somewhere cool.
Ambo doors are stout, but as a benefit, a swing out rack can have a padlock on it - a good one. No padlock key - no break open doors in anyway shape or form. Bonus security feature as well as being able to carry a few other things as well on a rack. You can also implement fold out shelving, etc., for use at camp when the rack is open. Some cool examples on this site about tire carrier racks. Yours will just be bigger, with more room for more cool stuff.
Dig the change of plans you took and scoring the f700. Pretty sweet.
hdemetrious
Adventurer
Thanks for all the input. I'll put the spares on the roof. That will mean less fabricating and no comprise on the departure angle.
That One Guy
Adventurer
I think that's a great idea. That's part of the reason I built a roof rack for my van.
hdemetrious
Adventurer
Winch Position
The way the winch is mounted causes the front bumper to extend 31 inches from the front of the truck. Does this effect my approach angle to the extent that I should move the winch?
The way the winch is mounted causes the front bumper to extend 31 inches from the front of the truck. Does this effect my approach angle to the extent that I should move the winch?