My tow pig/DD build thread. F350/Cummins 6.7/twins/6R140

[bad12jr]

Nice inventor use there. I need to redownload a copy of it.

Sent from my x2 somewhere

 

[me2]

You can simply remove the springs alltogether and use a pair of radius arms and a panhard bar for side to side location.

Which is exactly what I did for the rear air ride suspension on my '99. See my build thread for it.

The panhard bar is very problematic on these trucks. To get decent bag weight capacity without a leaf and to get decent bag volume such that you get a good spring rate, the bag pretty much needs to go behind the axle if you aren't lifting the truck. When you do that, it pretty much forces the panhard bar above the diff and the geometry of doing so messes up the axle motion.

I'm striving to build a suspension without the panhard bar this time. If I was going to use one again, it would go behind the axle, where the length and geometry are more favorable.

Or do the same with 4 links instead of radius arms.

Long, triangulated links are fine for race cars, but not Superduty trucks with 6,000 pounds on the rear axle going around twisty mountain roads. You need long bars to get the link geometry right for zero squat/ anti squat. A good 4 link calculator is your friend.

The other issue with triangulated 4 link systems on Superduties is that the fuel tank on the driver's side of the driveshaft takes up the space right where you want the one link to go. The exhaust system takes up the other side. Which is why all the Superduty 4 link systems I have seen have the links outside the frame rails. There is probably room for a single torque link, which is why I am thinking its a plausible solution.

If you just want to use the leaf springs with some air helper bags you could just add a set of single axle mount traction bars and let the combination of the spring and the traction bar control your wrap.

I'm intending to emulate the Firestone R4Tech system in using a single leaf to place the axle and bags (air springs) to be the primary lifters. The problem with that setup is axle wrap under braking and pulling loads. Simple traction bars work OK with stock springs which have much more leaf content to control their part of the axle forces. However, you lose that when you get down to a single leaf spring, thus making more advanced torque control necessary.

Sure you could put a shackle on each end of the leaf spring - but that is a TON of work.

Seems like a single (factory OEM) piece bolted in to me. Am I missing something ?

 

[TurboM700]

The elephant in the room.

I haven't been talking about it, but it was driven home during our trip and it needs to be addressed, so here it is.

The cab on my F350 is too small. It needs to be extended.

Our F350 seats 5 people. There were 5 of us and our dog on this trip. We were mostly very comfortable while travelling except the person sitting in the middle in the back seat doesn't have a headrest, which makes it difficult to nap in that position. It would also be nice if the back seat(s) reclined a bit for more comfort.

Our trailer sleeps 10 people. We don't intend to take 10 people on trips, but we do want to take more than 5 people and we are planning to have another child. Our truck needs more seats. There is no way around it.

We took 2 vehicles on one camping trip in July. That works for small trips close to home, but it doesn't work on our long adventure trips. It isn't just to and from the destination that needs 2 vehicles, its all the side trips that happen while we are at the destination. And its way nicer to have 2 parents in one vehicle managing kids when travelling long distances than to have 1 parent in 2 vehicles each having to manage kids.

And it isn't just the camping and adventure trips where we are having this problem. Its weekend trips around home and ski trips in the winter.

We've discussed this several times. Seating capacity aside, our truck works great. But we'll probably need to take at least 2 more people along on our trip next summer and just about every family trip we make as long as keep the truck.

My wife and I have discussed going to a travel trailer and pulling it with an Excursion. We've also discussed MDTs and HDTs. I even chatted with a few MDT owners. We've also discussed motorhomes. We don't want any of those solutions.

So I've started looking at extending the cab on my F350. Its a crew cab long box. The wheelbase is 172 ish inches.

Addng another crew cab section to the existing cab would add 35 ish inches to the cab.

Adding a Super Cab section to the existing cab would add 16ish inches to the cab.

Converting from a long box to a short box would free up 16 ish inches of space on the frame.

No matter what, the frame on my truck (any Ford truck) needs to be cut and welded to accept a cab extension. This is because it rises behind the cab to support the under side of the box. Thus the lowered, under the cab, portion of the frame needs to be extended no matter what cab extension is added.

I ran into a guy who extended his crew cab with a supercab section. He loves it except that he feels its too small to allow for comfort while travelling long distances. I think most people feel that way about the rear seat in Supercabs.

I don't want to extend the wheel base of my truck any more than I have to. If I added a Supercab extension and swapped from a long box to a short box, I wouldn't have to change the wheel base at all. If I went with a full crew cab extension, I'd have to lengthen the wheelbase by 19 inches and lose the long box that I love so much. I feel that increasing the wheelbase by 19 inches is too much.

The "best" solution I have come up with thus far is to add 8 inches to the doors and cab section of a Supercab extension. That would require an 8 inch increase in wheel base and swapping the long box for a short box. That would give the rear seat am extension length of 24 inches, which is approaching the rear seat extension in a Quad cab.

Then there is the issue of matching the interior trim.

My truck is a King Ranch. To my knowledge, you can not get the King Ranch trim in a Super Cab truck. So there are no King Ranch rear seats or trim panels for a Super Cab extension, especially not one lengthened 8 inches.

All this leaves me with a headache. I am presently discussing my options with a nearby company that has done a few cab extensions.

Why am I discussing all this now and what does it have to do with the swap ?

I don't want to swap the 6.7 into my truck and then realize it wasn't the right truck for our needs.

I've known about the impending cab space issue for a while, but always thought that we could "make due". Our recent trip drove home the fact that "making due" would be more painful that I realized and that our trips are probably going to be more frequent that I realized. The cab issue needs to be addressed.

When I think about it, this project is starting to get ludicrous. The "To Do" list reads
- engine/transmission swap
- front and rear suspension upgrades
- cab extension and box swap.

That is a lot of work. Is it really necessary ?

I keep thinking that surely there must be some other way to do this.

But there is no way we want to give up or 5th wheel trailer. Its way too nice to travel and stay in when we are on our adventure trips. Its what makes going on these trips feasible and comfortable. There is something to be said for getting a good night's sleep every night while away from home and having all your gear along and organized.

So we need a vehicle to pull the 5er and it needs to seat more than 5 people. The easiest way I can see to do that is to extend the cab on a Superduty truck.

At this point its not too late for me to change my mind about doing the swap and/or the truck entirely and going a different route. It seems extreme (to me) to do all this work on a stock truck to get a vehicle that works for us and yet it also seems to be the easiest (and by far the cheapest) way to do it.

I need to come to grips with a few things about the cab extension before moving ahead with the swap. It shouldn't take long as I have calls in to a couple people familiar with doing them.

I have run into this same issue when traveling my self. Not so much as with kids but freinds. We make 2-5 trips a yr snowmobiling out west. I have a trailer that can carry 6 sleds plus 2 on the truck. Truck can only care 4 grown males maybe 5.

If your going thru the hassle of lenthing a truck frame go for the extra cab not extend cab. You will thank your self later. I have ridden and driving a 6 door crew cab truck before and on the Highway/Interstate you really couldnt tell a difference even intowns it wasnt that big of a deal. Drive it like there was a 30ft trailer behind you and your fine.

I will say after reading your entire thread I really think you need to look into a Motor home or a MDT. You are not going to be happy with the performance off a light duty truck. Not to mention if you ever have to sell it to get something bigger you have the aportion of a truck that not many people will want.


Just my 2 cents.

 

[me2]

I have run into this same issue when traveling my self. Not so much as with kids but freinds. We make 2-5 trips a yr snowmobiling out west. I have a trailer that can carry 6 sleds plus 2 on the truck. Truck can only care 4 grown males maybe 5.

Glad to hear we are not alone. We are running into it all the time. Same old story, the truck will haul whatever we need for equipment, be it skis and gear, kayaks, bikes, 5th wheel trailer, etc, but we need to take 2 vehicles for the people.

If your going thru the hassle of lenthing a truck frame go for the extra cab not extend cab. You will thank your self later. I have ridden and driving a 6 door crew cab truck before and on the Highway/Interstate you really couldnt tell a difference even intowns it wasnt that big of a deal. Drive it like there was a 30ft trailer behind you and your fine.

I'm sure I could drive it, but I can't see how parking a 191" wheel base (172 + 19) truck would be fun or practical.

I will say after reading your entire thread I really think you need to look into a Motor home or a MDT.

Motor homes are expensive and they depreciate like crazy. And its impossible to find a floor plan that is even remotely as good as our 5th wheel trailer.

MDTs don't work at all for us.

You are not going to be happy with the performance off a light duty truck.

Did you read that I took said truck, stock, on a 2700 mile trip and was pretty happy with it ? I don't see how swapping in the Cummins, upgrading the suspension and adding a few seats would change that.

 

[me2]

TurboM700, does the 6 door CC you rode in get used as a DD ? What did the owner think of it ?

Was it a LB or a SB ?

Thanks

 

[Hotrodtractor]

The panhard bar is very problematic on these trucks. To get decent bag weight capacity without a leaf and to get decent bag volume such that you get a good spring rate, the bag pretty much needs to go behind the axle if you aren't lifting the truck. When you do that, it pretty much forces the panhard bar above the diff and the geometry of doing so messes up the axle motion.

I'm not following why the panhard bar needs to be above the rear axle when the bags are behind the axle - I assume your messed up travel geometry is a function of the allowable area for the bar to reside in - personally I would make it so the bar either mounts just ahead of or just just behind the bags - make it nice and long and parallel to the ground at ride height and all will be well.

Also FWIW - the Kelderman system for stock height 08 trucks have the bags on top of the axle - if they can do it - I'm sure you can do it.

Long, triangulated links are fine for race cars, but not Superduty trucks with 6,000 pounds on the rear axle going around twisty mountain roads. You need long bars to get the link geometry right for zero squat/ anti squat. A good 4 link calculator is your friend.

A properly designed set of triangulated 4 links can work just fine in a towing app - but the bars and mounts are beefy in nature for sure.

The other issue with triangulated 4 link systems on Superduties is that the fuel tank on the driver's side of the driveshaft takes up the space right where you want the one link to go. The exhaust system takes up the other side. Which is why all the Superduty 4 link systems I have seen have the links outside the frame rails. There is probably room for a single torque link, which is why I am thinking its a plausible solution.

Agreed - the fuel tank needs to be relocated - that seems like an easy task on such a project truck. Although I know that a system could be designed to handle the loads

I'm intending to emulate the Firestone R4Tech system in using a single leaf to place the axle and bags (air springs) to be the primary lifters. The problem with that setup is axle wrap under braking and pulling loads. Simple traction bars work OK with stock springs which have much more leaf content to control their part of the axle forces. However, you lose that when you get down to a single leaf spring, thus making more advanced torque control necessary.

Why drop to a single leaf - I went for a softer ride with my tow rig using a softer spring rate multipack spring intended for lifting a truck and used lowering shackles with it - the combination gave me an awesome ride, good control, and I handled the additional load carrying capacity issues with a simple set of helper bags. To control the torque I am designing a simple set of traction bars that shouldn't limit the travel of the system or cause any binding issues through its normal operating range. When running empty I have just a minimal amount of air in the bags.

Seems like a single (factory OEM) piece bolted in to me. Am I missing something ?

Just bolting on the factory parts really screws with the geometry if you go to shackle each end like that. Plus I would be leery of the side to side control with that setup if you strip the oem packs down to a single leaf all in the hopes that you don't have to run a panhard bar. That seems like a lot of extra work to solve a problem that might not really exist.

 

[me2]

I'm not following why the panhard bar needs to be above the rear axle when the bags are behind the axle - I assume your messed up travel geometry is a function of the allowable area for the bar to reside in - personally I would make it so the bar either mounts just ahead of or just just behind the bags - make it nice and long and parallel to the ground at ride height and all will be well.

Also FWIW - the Kelderman system for stock height 08 trucks have the bags on top of the axle - if they can do it - I'm sure you can do it.

A properly designed set of triangulated 4 links can work just fine in a towing app - but the bars and mounts are beefy in nature for sure.

Agreed - the fuel tank needs to be relocated - that seems like an easy task on such a project truck. Although I know that a system could be designed to handle the loads

Why drop to a single leaf - I went for a softer ride with my tow rig using a softer spring rate multipack spring intended for lifting a truck and used lowering shackles with it - the combination gave me an awesome ride, good control, and I handled the additional load carrying capacity issues with a simple set of helper bags. To control the torque I am designing a simple set of traction bars that shouldn't limit the travel of the system or cause any binding issues through its normal operating range. When running empty I have just a minimal amount of air in the bags.

Just bolting on the factory parts really screws with the geometry if you go to shackle each end like that. Plus I would be leery of the side to side control with that setup if you strip the oem packs down to a single leaf all in the hopes that you don't have to run a panhard bar. That seems like a lot of extra work to solve a problem that might not really exist.

The devil is in the details when building an air ride system.

 

[Vader's Fury]

I would not worry about the extra length. It is not as bad as you seem to think it is. I am speaking from personal experience. I have an F-450 that I drive for work as my service truck and it has a 200" wheelbase. It is also a drw. Don't get me wrong, it does take a different aproach to drive it, but once you get used to it you will not notice it as much. It is harder to park than my crew cab (will not fit in a single parking space, have to pull through 2) but not so much that I can not use it to go to walmart, lowe's, home depot, etc.

I daily drive this truck and over the last 3 years have put over 100k miles on the truck. No fenders bent or hitting anything so far (knock on wood). I also pull a trailer a few times a month with the truck. Anything from deck over 16-25' flatbeds to 24' enclosed wells cargo trailers. No fifth wheel trailers, but I believe it is easier to drive with a 5th than a pull behind trailer. (I have a 30' 5th and had a 40' previously)

The only time I would see the added length being a problem would be when you are trying to park the camper at a camp ground. I would assume that you are usually reserving pull through camping sites but know that is not always possible. I would say if you had to back into a camp site and the roadway was not very wide that it could then become an issue.

If I was you I would go with the full door extention and not the extended cab for a number of reasons.

1. As explained above, I don't believe that the added length of the wheel base will affect your driving as much as you fear.

2. The longer wheel base might help with the ride of the truck as the front end will have more time to recover from whatever has upset the suspension before the rear will have to deal with it.

3. I have an extended cab truck and the back seat is bout useless except for carrying cargo and tools. While there is a seat back there, watching a full grown adult fit back there for any length of time is quite comical. (I stuffed a buddy of mine back there after having to pick him up from a bar late one night for about 45 mins)



Just my .02

 

[Bustedknuckles]

For the last time he doesn't want a Dodge. And the only non stock parts are the trans controller and adapter plates. Everything else is OEM.

Sent from my x2 somewhere

So a twin turbo 6.7 cummins is oem in a ford?

 

[me2]

So a twin turbo 6.7 cummins is oem in a ford?

No, but I can fix it. I refuse to touch a Ford 6.4L.

 

[me2]

I would assume that you are usually reserving pull through camping sites but know that is not always possible.

Only rarely do we park in a pull through. We often seek out primitive campsites.

Our trailer is over 40 feet long.

I was lucky with my old truck because even though it was a short box, it also had a short wheel base. 156 inches or so. I used a fixed, not sliding, hitch in it. I could generally get in everywhere.

I am lucky with my new truck because its a long box, so the truck/trailer angle is never a problem. That being the case, I can almost always jacknife the trailer where it needs to go.

I would not be so lucky if I extended the cab on my new truck with a full crew section. I think the combination of 191" WB plus the short box plus a 40 foot trailer would be trouble for a lot of places we like to go.

I get a headache every time I think about this problem.

 

[Denver]

What about just seating the additional people in the 5th wheel? I believe all you need is a hard wired communication device and maybe a special license.

 

[me2]

What about just seating the additional people in the 5th wheel? I believe all you need is a hard wired communication device and maybe a special license.

Its not legal nor do I think its safe.

 

[me2]

 

[Bustedknuckles]

Holy Mother that black one is sweet!!

 

[me2]

Holy Mother that black one is sweet!!

I like the black one too.

I think the extended trucks look better with a slight lift, which is easy to accomplish with the air ride install.

The cab extension will require repainting at least part of the cab, so my options are open for changing things up a bit. I don't particularly like the King Ranch exterior scheme, so it would probably go.

I wonder how an extended truck would look in white, with black accents, dressed up like this. I'd probably keep the stock 20 inch tires and rims. I'd need longer running boards for the cab extension, so they would need to be replaced as well.

On the downside, I'd lose the long box. I've waited forever to have a long box and now I'll be losing it. And it would no longer fit in our 24 x 24 garage in winter.

It seems a shame to cut up my 08 since its in such great shape. Its not too late for me to sell it and get a different truck for this project. I don't know what I'd save doing that though.

I'm happy that I'm considering all this while my truck is still stock and in one piece.

 

[TurboM700]

TurboM700, does the 6 door CC you rode in get used as a DD ? What did the owner think of it ?

Was it a LB or a SB ?

Thanks

Heck no. Its a purpose built road trip truck. I dont like DD my CCSB truck. THats what I have my TDI for.:evil

Owner still loves it wouldnt trade it for the world. His has a mild built 7.3 (maybe 400hp) with a zf6 and LB dually. Its a pulling machine and it does everything we have asked for it to do. '

I would do it in a heart beat to my truck but when I'm triple pulling im already at 68.5 feet and the legal limit is 70.

Me2


I'm Sorry missed that part about the road trip and you being happy with the stock truck. You did mention deprecation of a motor home.

Do you not think shoveling a 6.7cummins in a KR with a 6r140 behind it will hurt the value of the KR? In my mind you will have a bastard of a truck that no one will want to buy. Atleast I know I wouldn't want to.

Not trying to talk you out of this as it seems like a cool project.

 

[me2]

Heck no. Its a purpose built road trip truck. I dont like DD my CCSB truck. THats what I have my TDI for.:evil

Each to their own. I respect that. I really like DDing my 08, but I probably go different places than you do. I'm always hauling "stuff".

Owner still loves it wouldnt trade it for the world. His has a mild built 7.3 (maybe 400hp) with a zf6 and LB dually. Its a pulling machine and it does everything we have asked for it to do.

Can't argue with that.

I would do it in a heart beat to my truck but when I'm triple pulling im already at 68.5 feet and the legal limit is 70.

I'm at 59 feet with the stock cab, without a trailer behind the 5er. A 20 foot boat puts me at 79 feet. I've never been stopped. I'd be at 81.5 feet with the cab extended. That might get me stopped.

I'm Sorry missed that part about the road trip and you being happy with the stock truck.

Don't be. It was good discussion.

Do you not think shoveling a 6.7cummins in a KR with a 6r140 behind it will hurt the value of the KR? In my mind you will have a bastard of a truck that no one will want to buy. Atleast I know I wouldn't want to.

a) I still have my '99 with the 5.9 Cummins and the ZF6. Can't bare to sell it. It needs work from being stolen, but where would I find a better (second) truck for ~10K ?

b) If I wanted to sell my '99, I'd part it out. I've already advertised it and everything but the engine would sell in a heartbeat, for good money. I'd get more for it as parts than from selling it outright.

c) I figure the engine swap on the 08 will cost less than $5K and the cab extension $5-$10K, depending on some factors. I paid $30K for the base truck and I've now got 30K trouble free (to me, anyway) miles on it. I'll probably keep it for the next 10 years or so. A new truck like it costs $60K and isn't twin turbo'd nor does it seat 6-8 people. A new truck depreciates $25K in the first 5 years. How am I going to lose on this deal ?

d) What other alternative do I have to pull a big 5er and haul 6 to 8 people with ?

I took another hard look at MDTs while on our trip and I still don't get them.

And even if I did, a good used MDT, not one that is clapped out from 300,000 miles of delivery service is $40K, and doesn't have a cab that seats 6 to 8, nor does it have a bed on it, nor does it have a high power engine, nor the right gear ratio, etc, etc, etc. Buidling a generic MDT into a great tow vehicle for us is more work than doing the swap and cab extension on my 08. And I think I'd enjoy my 08 more.

I don't want to be a trucker. I don't need to have the biggest tow vehicle in the campground to prove anything. I want the smallest, nimblest, easiest truck to drive that will do the job.

An HDT is totally out of the question. Its not even a starter for us.

We briefly spoke of getting a Sprinter van and pulling a travel trailer, but they ain't cheap either and then I still need a truck on the side for a DD.

Not trying to talk you out of this as it seems like a cool project.

Its good discussion when its two way, which this is.

 

[CSIPSD]

Excursion and a tow buddy...

 

[me2]

VF: will the F450 go through a drive through order line that has a turn in it ? Would it if it was a SRW ?

Sorry this thread turned into a tow vehicle discussion, but after the trip I felt the swap couldn't proceed until the question of the cab was dealt with.