NPR 4wd conversion and camper build thread.
- Thread starter javajoe79
- Start date
javajoe79
Fabricator
Thanks everyone. I am really excited to get this thing on the road.
Anyone want to chime in about welding to the frame? The manual has strict limits on it but I am thinking that it is over cautious. Has anyone seen any failures of the frame from welding? I think I will bolt most of the things I do but several things have already been welded as you can see.
Anyone want to chime in about welding to the frame? The manual has strict limits on it but I am thinking that it is over cautious. Has anyone seen any failures of the frame from welding? I think I will bolt most of the things I do but several things have already been welded as you can see.
SkiFreak
Crazy Person
I am surprised that no one has commented on welding brackets directly onto the chassis rails.
From memory, the body builder's guide advises against this.
Everything on the standard OEM chassis is bolted or riveted, which should be a bit of a clue.
Maybe I am wrong, but I don't think I am.
From memory, the body builder's guide advises against this.
Everything on the standard OEM chassis is bolted or riveted, which should be a bit of a clue.
Maybe I am wrong, but I don't think I am.
Straight from the horse's mouth to your ears:
The frame material is a heat treated, carbon manganese, low alloy steel with good weldability. The frame has a 80/40 mm modular hole spacing standard.
Obviously, Isuzu wishes to err on the side of caution, i.e. warranty claims, idiots with Wal-Mart welders or just idiots in general. There is a proper procedure for welding this type of steel, as I do not presume it to be "un-weldable" under any/all conditions. That said, I am not a metallurgist, Maybe a call to a respected upfitter or a high end fab shop with experience building luxury pre-runners from OEM vehicles with heat treated frames, for example, would answer our questions.
The frame material is a heat treated, carbon manganese, low alloy steel with good weldability. The frame has a 80/40 mm modular hole spacing standard.
Obviously, Isuzu wishes to err on the side of caution, i.e. warranty claims, idiots with Wal-Mart welders or just idiots in general. There is a proper procedure for welding this type of steel, as I do not presume it to be "un-weldable" under any/all conditions. That said, I am not a metallurgist, Maybe a call to a respected upfitter or a high end fab shop with experience building luxury pre-runners from OEM vehicles with heat treated frames, for example, would answer our questions.
Truck frames such as these are designed to flex. A bolted joint is held together by friction, and will give a little. A riveted joint accomplishes the same thing, but also acts to resist shear as it is used in a joint where movement normal to the joint is undesirable. The rivet fills the entire hole as opposed to a clearance hole for a bolt. This being said, both considerations are desirable where flex is present. This is why most cross members are bolted or riveted. A welded joint is a bonded joint and will crack where excessive flex and sharp forces are present where there is nothing to absorb the transitional forces if not properly designed/welded. In other words, it's possible to fix too much strength/stiffness into a component. Now, with suspension mounts, the springs absorb the movement and not the joint assuming it's properly welded out. Also to note, this is another reason for bushings in track arms and panhard bars. The bushings absorb sharp transitional forces and thereby protect the welded mounts on the frame and axle. I hope this makes sense. Keep this in mind when designing your suspension system as well as your camper mounting design.
All in all, this is generalized and each circumstance is individually designed by a mfr's engineers at each location to satisfy a set of constraints.
- Andy
All in all, this is generalized and each circumstance is individually designed by a mfr's engineers at each location to satisfy a set of constraints.
- Andy
One other thing to note is the mfr is speaking from a few standpoints. One of which is protecting the vehicles electronics. Another of which is stated above, chassis flex. These are manufactured as bare chassis's and a variety of equipment is mounted to the chassis. The mfr is concerned with limiting chassis flex which will inevitably crack a welded mount and this could end up very badly.
- Andy
- Andy
declinetostate
New member
I might be off but I am not liking most of what I am seeing. The rear link suspension might work for a highway vehicle but the set up and clearance lost doesn't look like it will work on anything more than dirt roads. I would hate to hit anything with a break over angle. I think the axles are solid. I think the engine and trans are solid. I think the rear suspension would be easier to cut loose and do over. Whether that means going back to leafs or doing a link set up. It really depends on what you want the truck to do. When watching the show I was bothered that he was welding everything to the chassis. Just because you can weld does not mean you should. Make sure you look at all aspects before you move forward. I would worry about front drive shaft length and clearance. I would also make sure he installed a chassis cross member at the engine. He removed some cross braces when doing the engine swap. My only worry is that there was something he could not work past and ended up letting it go. I think you can make this into a great truck. I cant wait to see how it progresses. Just don't get stuck on making his stuff work.
javajoe79
Fabricator
I agree on the break over angle. I plan on shortening the wheelbase probably 2'. It's currently 147". The suspension flexes pretty good as is though. I jacked the right front up until the tire was nearly a foot from the ground and the rear was firmly planted. I may redo the 4 link structure though as it hangs fairly low or redo the rear suspension all together. I also don't really care for the air bags. I may do something more like the rebel off road truck. Of note though is that the air bags are empty in thise pics. They come up about 10" when inflated, so with a load a good bit less. I definitely want more than 10" of travel though.
The front shaft will be long. I may do a 2 piece shaft with a carrier bearing in the middle. I have a driveshaft shop a block away from my shop and he treats me well.
I agree though, I'll be thoroughly going over all his work. Most of it is only tacked in.
javajoe79
Fabricator
A couple updates as I work my way into this truck.
I pulled the oil pan off of the 6BT to flip it around to a rear sump. The block is the same front to back so you can just rotate the pan 180*. Pretty cool! Anyway I have to find the correct oil pickup tube to work with this pan as a rear sump or I will just fabricate one. Good news to is that the engine looks very clean inside with visible crosshatching still on the cylinder walls. Before I put it back together I will have a look at some bearing. Anyway the reason I flipped the pan is because the sump was really close to the front axle. This will allow me to move the drivetrain forward maybe 10". This is necessary because to get the wheelbase I want to work with the wheel wells in my current camper, 117", I would end up with a rear driveshaft only 20" long. That seems too short to allow much suspension travel. I have access to a parts truck that I will be pulling the radiator and intercooler out of as well as some other parts. Once I get those mounted in the stock location, I will move the drivetrain forward as far as I can and down maybe an inch as the lines on the injector pump are too close to the cab when it's close and I worry about them touching at some point. I am planning to use a mechanical fan if I can come up with one that will flow enough air and clear everything. The water pump on the cummins is up high and a large fan wouldn't fit. Electric is my backup plan.
On to the rear axle. They fabbed a kinda backwards 4 link on this thing so I am going to change it. The geometry doesn't make sense as is with the anti squat way off. They even have the upper links longer than the lower links. I am going to swap location of the links and raise the frame side mounts by about 5" each. This will get rid of the low hanging crossmember they built, correct the anti squat and allow me to fab a bolt on structure for the frame end of the 4 link bars. I may keep the panhard bar setup they made or fab a watts link. Still haven't decided on springs. I don't like the airbags and at 10" of total travel I don't think they will work so I will probably end up with a coil spring setup and some adjustable shocks from King front and rear.
I am selling the wheels and tires and switching over to hummer wheels and tires. Cheap and slightly bigger than what's on there. I am ditching the big round ARB led lights and the bar they fabbed for them. Already sold two of the lights. If anyone needs them I am selling the other two as well.
I am going to narrow the flatbed they built and delete the sloped rear section. Then I will mount it solid in the back with spring mounts along each side like is customary. Then my camper will mount to the flatbed with the same poly body mounts I was using on the pick up frame before. Again the truck came with parts I don't need so I am selling the winch that was mounted on the flatbed. It's a new Warn 9.5 XPS. I am keeping the 16.5 Warn for the front.
Here are some pics as it sits.
I pulled the oil pan off of the 6BT to flip it around to a rear sump. The block is the same front to back so you can just rotate the pan 180*. Pretty cool! Anyway I have to find the correct oil pickup tube to work with this pan as a rear sump or I will just fabricate one. Good news to is that the engine looks very clean inside with visible crosshatching still on the cylinder walls. Before I put it back together I will have a look at some bearing. Anyway the reason I flipped the pan is because the sump was really close to the front axle. This will allow me to move the drivetrain forward maybe 10". This is necessary because to get the wheelbase I want to work with the wheel wells in my current camper, 117", I would end up with a rear driveshaft only 20" long. That seems too short to allow much suspension travel. I have access to a parts truck that I will be pulling the radiator and intercooler out of as well as some other parts. Once I get those mounted in the stock location, I will move the drivetrain forward as far as I can and down maybe an inch as the lines on the injector pump are too close to the cab when it's close and I worry about them touching at some point. I am planning to use a mechanical fan if I can come up with one that will flow enough air and clear everything. The water pump on the cummins is up high and a large fan wouldn't fit. Electric is my backup plan.
On to the rear axle. They fabbed a kinda backwards 4 link on this thing so I am going to change it. The geometry doesn't make sense as is with the anti squat way off. They even have the upper links longer than the lower links. I am going to swap location of the links and raise the frame side mounts by about 5" each. This will get rid of the low hanging crossmember they built, correct the anti squat and allow me to fab a bolt on structure for the frame end of the 4 link bars. I may keep the panhard bar setup they made or fab a watts link. Still haven't decided on springs. I don't like the airbags and at 10" of total travel I don't think they will work so I will probably end up with a coil spring setup and some adjustable shocks from King front and rear.
I am selling the wheels and tires and switching over to hummer wheels and tires. Cheap and slightly bigger than what's on there. I am ditching the big round ARB led lights and the bar they fabbed for them. Already sold two of the lights. If anyone needs them I am selling the other two as well.
I am going to narrow the flatbed they built and delete the sloped rear section. Then I will mount it solid in the back with spring mounts along each side like is customary. Then my camper will mount to the flatbed with the same poly body mounts I was using on the pick up frame before. Again the truck came with parts I don't need so I am selling the winch that was mounted on the flatbed. It's a new Warn 9.5 XPS. I am keeping the 16.5 Warn for the front.
Here are some pics as it sits.
javajoe79
Fabricator
Here is the build so far on my camper box that was originally meant to go on my S10. Big change of scenery for this project but it works out well as the camper was always built bigger than the S10 with an idea towards eventually putting it on a bigger truck.
http://www.expeditionportal.com/forum/threads/144522-1999-Chevy-S10-ZR2-Camper-build
http://www.expeditionportal.com/forum/threads/144522-1999-Chevy-S10-ZR2-Camper-build
Did I understand correctly that you are planning to push the front axle forward 10"?
That seems significant in a cab over truck, especially with large wheels and tires. Since you are remaking the rear suspension, would it be better to move the axle and camper to get where you need to be? I am being an arm-chair quarterback here; I am sure you have all of this figured out
That seems significant in a cab over truck, especially with large wheels and tires. Since you are remaking the rear suspension, would it be better to move the axle and camper to get where you need to be? I am being an arm-chair quarterback here; I am sure you have all of this figured out
javajoe79
Fabricator
My bad I suppose I should have clarified. I am moving the engine forward. The front axle will stay put. I had to flip the oil pan to allow clearance to do this. The rear axle was previously moved back about a foot and made the wheelbase 147". With my camper on the truck, based on the wheel well I already built in the camper, I will end up with about a 117" wheelbase when I move the rear axle up. This will then leave some of the frame sticking out the back that I will cut off at an angle equivalent to the angle on the back of the camper.