C5500 TopKick 4x4 Crew Cab Build
- Thread starter NeverEnough
- Start date
NeverEnough
Adventurer
Update on my TopKick build
Even though I purchased my chassis in early July, things kept coming up to prevent me from going to Riggins, ID to pick it up from the owner. So after weeks and weeks of postponing everything, my wife and I finally jumped on our GS' and rode up to Riggins via Sun Valley (and lots of fire action on the side of the road) and drove the truck back to Utah.
With the actual truck in hand, I started verifying all of the assumptions in my plans from the GM upfitter information. So far, no surprises. And the chassis is in great shape.
Wheels and Tires. The upfitter wants me to put the new wheels on first, which makes sense. Turns out that 8 lug 22.5 rims are in short supply these days. And I can't go any wider than 7.5 inches without running into clearance issues with the Topkick front suspension. The "tire doctor" at Bridgstone provided me with an excellent analysis (free) of the impact of different tire choices for the rig. He was extremely knowledgable and helpful. Base upon his information and everything else I've read, I'm going to go with a 255/70 on/off road tire. It's about 38 inches in diameter, which will boost the chassis up about 3 inches from its current height. While I could go a lot bigger, it gives me the clearance I need while staying close enough to the truck's intended performance. If, at some point, I decide I want to get more crazy for serious off-road action, I'll probably put a smaller box on a different chassis.
Components that impact design. I've read just about everything I can find on different approaches to the all important toilet/black water issue. For our needs, which frequently involve supporting a lot of tag along guests, none of the composting units have enough capacity (that are road worthy). My second thought was the EcoJohn, despite it's hefty footprint, but I cannot justify 12K for a toilet, especially one that consumes fuel. Even their least expensive unit is far to expensive to justify, IMHO. So I've resigned myself to sticking with the world of holding tanks. I had a clean-out built at my office for our current rig, so it's convenient, and there's some options for handling grey water that can stretch the efficiency of the system. If anybody out there has other options, let me know.
The only other component I'm still going round on is how far to go with hydronic heating using and Espar 17,500 BTU unit. I'd like to try some in-floor heating loops, in an effort to limit the blowers just to heat things up fast. Jury's still out........
Even though I purchased my chassis in early July, things kept coming up to prevent me from going to Riggins, ID to pick it up from the owner. So after weeks and weeks of postponing everything, my wife and I finally jumped on our GS' and rode up to Riggins via Sun Valley (and lots of fire action on the side of the road) and drove the truck back to Utah.
With the actual truck in hand, I started verifying all of the assumptions in my plans from the GM upfitter information. So far, no surprises. And the chassis is in great shape.
Wheels and Tires. The upfitter wants me to put the new wheels on first, which makes sense. Turns out that 8 lug 22.5 rims are in short supply these days. And I can't go any wider than 7.5 inches without running into clearance issues with the Topkick front suspension. The "tire doctor" at Bridgstone provided me with an excellent analysis (free) of the impact of different tire choices for the rig. He was extremely knowledgable and helpful. Base upon his information and everything else I've read, I'm going to go with a 255/70 on/off road tire. It's about 38 inches in diameter, which will boost the chassis up about 3 inches from its current height. While I could go a lot bigger, it gives me the clearance I need while staying close enough to the truck's intended performance. If, at some point, I decide I want to get more crazy for serious off-road action, I'll probably put a smaller box on a different chassis.
Components that impact design. I've read just about everything I can find on different approaches to the all important toilet/black water issue. For our needs, which frequently involve supporting a lot of tag along guests, none of the composting units have enough capacity (that are road worthy). My second thought was the EcoJohn, despite it's hefty footprint, but I cannot justify 12K for a toilet, especially one that consumes fuel. Even their least expensive unit is far to expensive to justify, IMHO. So I've resigned myself to sticking with the world of holding tanks. I had a clean-out built at my office for our current rig, so it's convenient, and there's some options for handling grey water that can stretch the efficiency of the system. If anybody out there has other options, let me know.
The only other component I'm still going round on is how far to go with hydronic heating using and Espar 17,500 BTU unit. I'd like to try some in-floor heating loops, in an effort to limit the blowers just to heat things up fast. Jury's still out........
NeverEnough
Adventurer
Panels, panels, panels
My office has little boxes of sandwich panel samples all over the place. There's some very cool stuff out there and I'm encouraged that the transportation industry is changing their ways.
The basic design of the body hasn't changed, but I have toyed around with some "all panel" variations, based on some samples and simple joinery tests I've done. I'm hoping to make a decision within the next two weeks on which way to go: metal superstructure/frame with mechanical/adhesive panel attachment (traditional), all composite panel and pultrusion, or a hybrid.
A couple of engineers from the floor/deck vendors are doing a few calculations for me to see if the "all composite" approach can be attached to the chassis rails without a big subframe and sills. These new composite truck body floors are quite amazing- 2.5lbs/sqft., 2 inches thick, R10, and just about bombproof (in fact, some of the manufacturers got their boost from building light-weight armour sandwich panels for the military). The wall and roof panels will come in around 1.2lbs/sqft, including pultrusions, but not including window and door weight.
If I can go all composite, the shell, subframe, and slideout shell will come in under 2500lbs., which would really be something to pull off. That would keep the fully decked-out box under 5,000 lbs. with full tanks, and the whole rig in the 15,000lb range.
My office has little boxes of sandwich panel samples all over the place. There's some very cool stuff out there and I'm encouraged that the transportation industry is changing their ways.
The basic design of the body hasn't changed, but I have toyed around with some "all panel" variations, based on some samples and simple joinery tests I've done. I'm hoping to make a decision within the next two weeks on which way to go: metal superstructure/frame with mechanical/adhesive panel attachment (traditional), all composite panel and pultrusion, or a hybrid.
A couple of engineers from the floor/deck vendors are doing a few calculations for me to see if the "all composite" approach can be attached to the chassis rails without a big subframe and sills. These new composite truck body floors are quite amazing- 2.5lbs/sqft., 2 inches thick, R10, and just about bombproof (in fact, some of the manufacturers got their boost from building light-weight armour sandwich panels for the military). The wall and roof panels will come in around 1.2lbs/sqft, including pultrusions, but not including window and door weight.
If I can go all composite, the shell, subframe, and slideout shell will come in under 2500lbs., which would really be something to pull off. That would keep the fully decked-out box under 5,000 lbs. with full tanks, and the whole rig in the 15,000lb range.
Ford Prefect
Expedition Leader
Cool!
As you already know, I am sure, those things have remarkably little flex in the frame, that means you have a lot more flexibility in the design of the camper. Obviously you still need to allow for some flex, but not too much really. There were some really good ideas for you in Jay Shapiro's build thread.
Perhaps, and this is my opinion, so I hope you will forgive me, but you have not had it mentioned so far; I have heard multiple times that the sliders tend to be very much a weak point for the off road RV market. You potentially can find the entire thing falling apart around that. Then again the sky could fall too, soo... Just saying that you may want to consider that area very carefully before you do it, and if you do it make sure you build it in a way that will be strong for you.
You are right to make the slider a manual, or at least a manual back up. It is generally unwise to have a reliance on mechanical things controlling that stuff on an off road vehicle. Besides you never want mechanicals to control you bed by themselves. If you cannot, for instance, raise a roof and the bed is mushed to the ceiling when the roof is down...
On the rocks in the duels. I drove a dump truck right out of college, always in the rocks and dirt roads, I mean it was construction sights, they were everywhere. I believe that I Had twice, perhaps three times gotten rocks in there, and once I got a big chunk of ice. All you really need to do to get one out is have a nice chain with hooks on the end along with you. Wrap the chain around the rock, hook the hook back onto the chain. Stick the other end of the chain behind the front tire, and start backing up. Pop that sucker right out of there no big deal. I HAVE seen guys put a hole in their sidewalls, but it is hard to do (IMHO) You have to be rather hard on the truck in the first place, driving it like a crazy and the tires are the least of your problems anyhow.
On the John, I really like the ones that allow you to drain the liquid onto the tail pipe when you are driving down the road. It evaporates everything for you, does not make a mess, and it does not require you to keep in the hold for very long either.
Anyhow... It looks like a GREAT rig idea. I would love to come up and see it some time, if you would be willing to let me. Ever need a spare hand on a wrench let me know. I am just down the hill in Happy Valley. The 15K LBS sounds like a great deal there, for what you are doing. What a nice looking rig, can't wait!
Cheers, and I look forward to your build!
Brian
As you already know, I am sure, those things have remarkably little flex in the frame, that means you have a lot more flexibility in the design of the camper. Obviously you still need to allow for some flex, but not too much really. There were some really good ideas for you in Jay Shapiro's build thread.
Perhaps, and this is my opinion, so I hope you will forgive me, but you have not had it mentioned so far; I have heard multiple times that the sliders tend to be very much a weak point for the off road RV market. You potentially can find the entire thing falling apart around that. Then again the sky could fall too, soo... Just saying that you may want to consider that area very carefully before you do it, and if you do it make sure you build it in a way that will be strong for you.
You are right to make the slider a manual, or at least a manual back up. It is generally unwise to have a reliance on mechanical things controlling that stuff on an off road vehicle. Besides you never want mechanicals to control you bed by themselves. If you cannot, for instance, raise a roof and the bed is mushed to the ceiling when the roof is down...
On the rocks in the duels. I drove a dump truck right out of college, always in the rocks and dirt roads, I mean it was construction sights, they were everywhere. I believe that I Had twice, perhaps three times gotten rocks in there, and once I got a big chunk of ice. All you really need to do to get one out is have a nice chain with hooks on the end along with you. Wrap the chain around the rock, hook the hook back onto the chain. Stick the other end of the chain behind the front tire, and start backing up. Pop that sucker right out of there no big deal. I HAVE seen guys put a hole in their sidewalls, but it is hard to do (IMHO) You have to be rather hard on the truck in the first place, driving it like a crazy and the tires are the least of your problems anyhow.
On the John, I really like the ones that allow you to drain the liquid onto the tail pipe when you are driving down the road. It evaporates everything for you, does not make a mess, and it does not require you to keep in the hold for very long either.
Anyhow... It looks like a GREAT rig idea. I would love to come up and see it some time, if you would be willing to let me. Ever need a spare hand on a wrench let me know. I am just down the hill in Happy Valley. The 15K LBS sounds like a great deal there, for what you are doing. What a nice looking rig, can't wait!
Cheers, and I look forward to your build!
Brian
Last edited:
NeverEnough
Adventurer
Getting down to the nitty gritty
So I'm pretty impressed with FRP/extruded foam panels and fiberglass pultrusions- strong, non-corrosive, great thermal properties, etc. In fact, given the samples we've put together, I'm considering going from a 2" OD to 1.5" OD for the wall/vertical panels. I'll lose a little bit of insulation, but I'll save a lot of weight (mainly on the exterior extrusions by being able to go from a 4"x4" angle to a 3"x3" angle). The materials for the basic shell (including slideout) are still coming in under 2500lbs, which is very cool.
I'm hoping to make my decision on vendors this week, then order the panels and pultrusions. It will take about 4 weeks for everything to be manufactured and shipped to Utah, and I'm guessing another 4 weeks for the basic body to be assembled.
I'm toying with the idea of building a little cargo trailer out of fiberglass structural components and panels to match the camper. In fact, I might have that done first as an assembly "warm-up", to get a little experience with the materials.
So I'm pretty impressed with FRP/extruded foam panels and fiberglass pultrusions- strong, non-corrosive, great thermal properties, etc. In fact, given the samples we've put together, I'm considering going from a 2" OD to 1.5" OD for the wall/vertical panels. I'll lose a little bit of insulation, but I'll save a lot of weight (mainly on the exterior extrusions by being able to go from a 4"x4" angle to a 3"x3" angle). The materials for the basic shell (including slideout) are still coming in under 2500lbs, which is very cool.
I'm hoping to make my decision on vendors this week, then order the panels and pultrusions. It will take about 4 weeks for everything to be manufactured and shipped to Utah, and I'm guessing another 4 weeks for the basic body to be assembled.
I'm toying with the idea of building a little cargo trailer out of fiberglass structural components and panels to match the camper. In fact, I might have that done first as an assembly "warm-up", to get a little experience with the materials.
NeverEnough
Adventurer
Load test on the TopKick
So my brother needed some sand delivered to his house in the upper reaches of Boutiful, UT (a coupe of miles of 10% winding roads) and since the wheels have not yet arrived, I offered my truck. We loaded up 4 tons of sand in the bed and took to the road. I was amazed that the Topkick barely even felt the load. I jumped onto the freeway and was at 65 by the end of the on ramp without the slightest strain. Best of all, the truck handled the climb up to his house like the load wasn't even there.
Since that load of sand was about 3,000 lbs more than what my camper will weight, I'm pretty excited about my decision to go with the Topkick.
And while I was picking up some shims for a valve job on my dirt bike, look what happened to drive into the parking lot at Plaza Cycle:
http://webhosting.web.com/imagelib/...res/TOPKICKPORTRAITweb.jpg&target=tlx_pic5iyc
Chris Marshal built that rig and it's absolutely incredible. I'm going to give him a call to get a quote on a new front bumper for mine. Those are 48" tires, with hydraulic booster to turn them. It'll make my 39" tires look tiny by comparison.
So my brother needed some sand delivered to his house in the upper reaches of Boutiful, UT (a coupe of miles of 10% winding roads) and since the wheels have not yet arrived, I offered my truck. We loaded up 4 tons of sand in the bed and took to the road. I was amazed that the Topkick barely even felt the load. I jumped onto the freeway and was at 65 by the end of the on ramp without the slightest strain. Best of all, the truck handled the climb up to his house like the load wasn't even there.
Since that load of sand was about 3,000 lbs more than what my camper will weight, I'm pretty excited about my decision to go with the Topkick.
And while I was picking up some shims for a valve job on my dirt bike, look what happened to drive into the parking lot at Plaza Cycle:
http://webhosting.web.com/imagelib/...res/TOPKICKPORTRAITweb.jpg&target=tlx_pic5iyc
Chris Marshal built that rig and it's absolutely incredible. I'm going to give him a call to get a quote on a new front bumper for mine. Those are 48" tires, with hydraulic booster to turn them. It'll make my 39" tires look tiny by comparison.
LandCruiserPhil
Expedition Leader
Very cool corner bumper lights on Marshals truck.
Nice to hear the about strong performance from the Top Kick. Should make a comfortable expo vehicle, something most others in your class lack.
Ford Prefect
Expedition Leader
Wow, very cool looking. I like the rear bed too. What is the deal with the front being SO much higher than the rear, was he in the middle of a lift or something?
NeverEnough
Adventurer
Finally! New wheels and tires arrived and installed!
After 5 weeks of waiting, finally got the new wheels and tires mounted and installed. I'm still amazed at how expensive 7 wheels and tires can be, and it's not like I bought anything fancy.
The drive from the tire shop to the upfitter showed me that I'm in for a much smoother ride, while my speedometer has been rendered quite useless. Tomorrow they start the chassis mods.
And the wheels finally are in proper scale with the truck. Not sure why they put such dorky little things on at the factory. But now it actually looks like a truck.
After 5 weeks of waiting, finally got the new wheels and tires mounted and installed. I'm still amazed at how expensive 7 wheels and tires can be, and it's not like I bought anything fancy.
The drive from the tire shop to the upfitter showed me that I'm in for a much smoother ride, while my speedometer has been rendered quite useless. Tomorrow they start the chassis mods.
And the wheels finally are in proper scale with the truck. Not sure why they put such dorky little things on at the factory. But now it actually looks like a truck.
NeverEnough
Adventurer
Made some decisions, jury still out on a few more...
After a fair deal of completey unscientific testing, I've made a few decisions about how to proceed.
Most significant is putting to bed the method and means of attaching my camper body to the chassis. I've decided to have an aluminum "bed" fabricated that will act as a type of subframe for the camper body. The bed will be permantly mounted to the chassis in accordance with standard GMC upfitter guidelines for flexible mounts, very similar to this:
The bed will address the concerns over point loads associated with directly mounting the composite body to the chassis, as well as provide me with the ability to remove the body using camper jacks if I need to. The fabricator is giving me a price to build a "flatbed" that can be attached to the new bed, in case I want to use the truck in that fashion (why not?).
I've still got some more testing to do on the candidate body panel materials. I'm hoping to get the decision behind me soon so we can start actually building the box.
I've also got to finalize the design details of the nested slideout system and the dual-purpose liftgate (acts as a hauling platform for two enduros and also supports the "roll-out" room when the rig is parked). My concern with the slide-out is making sure there's a tight weather seal while in transit, since standard t-molding will not work well.
I've been fishing around for referrals of cabinet makers that have experience working with composite panels, so if anybody is in the know, please share......
After a fair deal of completey unscientific testing, I've made a few decisions about how to proceed.
Most significant is putting to bed the method and means of attaching my camper body to the chassis. I've decided to have an aluminum "bed" fabricated that will act as a type of subframe for the camper body. The bed will be permantly mounted to the chassis in accordance with standard GMC upfitter guidelines for flexible mounts, very similar to this:
The bed will address the concerns over point loads associated with directly mounting the composite body to the chassis, as well as provide me with the ability to remove the body using camper jacks if I need to. The fabricator is giving me a price to build a "flatbed" that can be attached to the new bed, in case I want to use the truck in that fashion (why not?).
I've still got some more testing to do on the candidate body panel materials. I'm hoping to get the decision behind me soon so we can start actually building the box.
I've also got to finalize the design details of the nested slideout system and the dual-purpose liftgate (acts as a hauling platform for two enduros and also supports the "roll-out" room when the rig is parked). My concern with the slide-out is making sure there's a tight weather seal while in transit, since standard t-molding will not work well.
I've been fishing around for referrals of cabinet makers that have experience working with composite panels, so if anybody is in the know, please share......
NeverEnough
Adventurer
Progress report:
1. The chassis extension is almost finished up. We used a couple of forklifts to evaluate the frame twist before starting, and so I'm curious to see how much, if any, more pliable the thing becomes after the extension. For all practical purposes, we couldn't get the frame to twist at the 194" factory wheelbase- the wheels just come off the ground. No wonder Mogs n'such are preferred for serious off-track work!
Here's some pics of her all cut up:
2. Work on the subframe started. It'll probably take at least two to three weeks to get that wrapped up. They're also building me an aluminum flatbed trailer frame for the "matching" trailer. It will also be dual-purpose: the cargo box will be detachable, allowing the trailer to be used as either a flatbed or as an enclosed cargo unit. The modified v-nose of the trailer also has a small bathroom.
3. I made a decision on a panel manufacturer and panel compositition: Plascore, 2" polypropylene honeycomb core with fiberglass reinforced polypropylene skins, with a thermally fused polyester veil on the skins to create a bondable surface. I should receive a couple of larger sheets this week to move to the final testing before ordering a semi-load of the stuff. The skin material is in short supply, so it'll probably be two months before the big load arrives.
4. I'm expecting a few more samples to do some more testing on the final interior treatments. I've been testing a "carbon ink" electric radiant material with very impressive results. It's being marked in the US under the brand "CarbonicHeat". It's less than 1/32" thick, flexible, and easy to work with. The challenge has been finding a radiant floor "sandwich" that pushes most of the heat up. After testing a variety of flooring materials, I've decided to go with a commercial-grade vinyl flooring for the top layer. There's a huge variety of styles, it has the right properties for the radiant system, it can handle all sorts of abuse, and it's cost effective. I've been testing a few thermal barrier materials as well as a few reflective insulation products under the carbon film. I've got three more combinations to test, then I'll post what I've decide, along with manufacturers and some pics.
5. This week's research project is to explore leveling/camper jacks and how to use them not just for leveling and lifting the camper from the subframe, but also to help secure the camper to the subframe.
Sorry my posts are so imageless. Things should get more exciting once the box gets underway.
1. The chassis extension is almost finished up. We used a couple of forklifts to evaluate the frame twist before starting, and so I'm curious to see how much, if any, more pliable the thing becomes after the extension. For all practical purposes, we couldn't get the frame to twist at the 194" factory wheelbase- the wheels just come off the ground. No wonder Mogs n'such are preferred for serious off-track work!
Here's some pics of her all cut up:
2. Work on the subframe started. It'll probably take at least two to three weeks to get that wrapped up. They're also building me an aluminum flatbed trailer frame for the "matching" trailer. It will also be dual-purpose: the cargo box will be detachable, allowing the trailer to be used as either a flatbed or as an enclosed cargo unit. The modified v-nose of the trailer also has a small bathroom.
3. I made a decision on a panel manufacturer and panel compositition: Plascore, 2" polypropylene honeycomb core with fiberglass reinforced polypropylene skins, with a thermally fused polyester veil on the skins to create a bondable surface. I should receive a couple of larger sheets this week to move to the final testing before ordering a semi-load of the stuff. The skin material is in short supply, so it'll probably be two months before the big load arrives.
4. I'm expecting a few more samples to do some more testing on the final interior treatments. I've been testing a "carbon ink" electric radiant material with very impressive results. It's being marked in the US under the brand "CarbonicHeat". It's less than 1/32" thick, flexible, and easy to work with. The challenge has been finding a radiant floor "sandwich" that pushes most of the heat up. After testing a variety of flooring materials, I've decided to go with a commercial-grade vinyl flooring for the top layer. There's a huge variety of styles, it has the right properties for the radiant system, it can handle all sorts of abuse, and it's cost effective. I've been testing a few thermal barrier materials as well as a few reflective insulation products under the carbon film. I've got three more combinations to test, then I'll post what I've decide, along with manufacturers and some pics.
5. This week's research project is to explore leveling/camper jacks and how to use them not just for leveling and lifting the camper from the subframe, but also to help secure the camper to the subframe.
Sorry my posts are so imageless. Things should get more exciting once the box gets underway.
NeverEnough
Adventurer
I checked out a couple of M2's, you're a lucky man! I'm dabbling in enough uncharted territory that it'll either be a fun success or a truly spectacular failure. The delays in waiting for materials is driving me nuts. One of the downsides of not staying on the beaten path....