Britboaters
Observer
I retired 3 years ago, and my wife and I got a large 5th wheeler and a 3/4 ton Dodge diesel. We live in SC and have travelled Out West over the last 3 years, including Overland Expo, spending about 6 to 7 weeks each trip in AZ, NM, CO, etc. I was getting tired of towing such a large rig (10,000 lbs) and started getting inspired by some of the rigs we saw at Expo.
In February this year we did a 4 week self drive safari in Botswana and Namibia. A Ford Ranger truck, an Alu-Cab "hard top" rooftop tent, a GPS and the two of us had a fantastic time. A complete opposite to the 5th wheel, and such a memorable trip.
So we decided we needed to downsize. We looked at several different ideas, and as usual got lots of inspiration from Expo. Particularly "Rebelzilla", a 4 wheel drive conversion to an Isuszu NPR crew cab. Finally we setted on a couple of key criteria for us - a bed my wife could walk around to "make", and a separate toilet with a door.
This meant ideas such as Lance slide-in camper wouldn't work. So, doing some layouts, we decided a 14 foot long box would be about right.
We looked at 4WD drive options for Isuzu NPR, but felt the truck too small. We then looked at Isuzu FTR, a 26,000lb truck; but finding appropriate front axles, etc got complicated. We really wanted the FTR as it is a cabover design, so great visibility, and the cab had enough space for my wife to lay down behind the front seats.
We finally settled on a GMC C4500 4x4 Topkick. This is a 17,500 lb GVWR 4WD truck. We found a 2007 single cab diesel with 100,000 miles in FL, so nice and clean. WB of 152". For the 14 ft box we need to lengthen the frame to 176" WB, one of the factory options. This will be the first task, when I get the truck this weekend.
After studying the GMC Upfitters manual, I believe I can move the axle back, and lengthen the frame behind the axle, rather than cutting the frame.
Some statistics:
GVWR 17,500 lb
Chassis / cab weight about 8,300 lbs, to be confirmed
Payload 9,000 lbs
14 ft standard delivery truck box, 150 lbs/ft = 2,100 lbs
Box contents estimate 2,000 lbs
House batteries - 6 x 6v golf cart 500 lbs
40 gallons fresh water 350 lbs
Other stuff about 1,200 lbs, - additional diesel, propane, spare wheel, winch bumper, etc
Total "load" about 6,300 lbs
So total truck weight, with tanks full about 14,500 lb estimated.
Trying to keep front axle load at about 6,250, and rear about 8,250 lbs.
Planning on 335/80R20 Michelins or Contis; so with these weights, 30 psi front, 45 psi rear. This is the recommended pressure for highway speeds !!!
It looks like an offset of 5.5 inches on 11" rims should allow me to use same wheels back and front. Two valve holes will be required though.
Planning on 3 point mounting of body using some rubber bushings I found at a company called "Lord". This will require a subframe to be added to the standard box.
So, I'm posting all this here cause I think it's a good idea to "give back" a little to the Forum, as I've got so many good ideas here.
Also I'm very interested in any help I can get along the way.
So I'll be posting photos as I make progress, and reaching out for help, please.
Hope some of you find this interesting
Bob
In February this year we did a 4 week self drive safari in Botswana and Namibia. A Ford Ranger truck, an Alu-Cab "hard top" rooftop tent, a GPS and the two of us had a fantastic time. A complete opposite to the 5th wheel, and such a memorable trip.
So we decided we needed to downsize. We looked at several different ideas, and as usual got lots of inspiration from Expo. Particularly "Rebelzilla", a 4 wheel drive conversion to an Isuszu NPR crew cab. Finally we setted on a couple of key criteria for us - a bed my wife could walk around to "make", and a separate toilet with a door.
This meant ideas such as Lance slide-in camper wouldn't work. So, doing some layouts, we decided a 14 foot long box would be about right.
We looked at 4WD drive options for Isuzu NPR, but felt the truck too small. We then looked at Isuzu FTR, a 26,000lb truck; but finding appropriate front axles, etc got complicated. We really wanted the FTR as it is a cabover design, so great visibility, and the cab had enough space for my wife to lay down behind the front seats.
We finally settled on a GMC C4500 4x4 Topkick. This is a 17,500 lb GVWR 4WD truck. We found a 2007 single cab diesel with 100,000 miles in FL, so nice and clean. WB of 152". For the 14 ft box we need to lengthen the frame to 176" WB, one of the factory options. This will be the first task, when I get the truck this weekend.
After studying the GMC Upfitters manual, I believe I can move the axle back, and lengthen the frame behind the axle, rather than cutting the frame.
Some statistics:
GVWR 17,500 lb
Chassis / cab weight about 8,300 lbs, to be confirmed
Payload 9,000 lbs
14 ft standard delivery truck box, 150 lbs/ft = 2,100 lbs
Box contents estimate 2,000 lbs
House batteries - 6 x 6v golf cart 500 lbs
40 gallons fresh water 350 lbs
Other stuff about 1,200 lbs, - additional diesel, propane, spare wheel, winch bumper, etc
Total "load" about 6,300 lbs
So total truck weight, with tanks full about 14,500 lb estimated.
Trying to keep front axle load at about 6,250, and rear about 8,250 lbs.
Planning on 335/80R20 Michelins or Contis; so with these weights, 30 psi front, 45 psi rear. This is the recommended pressure for highway speeds !!!
It looks like an offset of 5.5 inches on 11" rims should allow me to use same wheels back and front. Two valve holes will be required though.
Planning on 3 point mounting of body using some rubber bushings I found at a company called "Lord". This will require a subframe to be added to the standard box.
So, I'm posting all this here cause I think it's a good idea to "give back" a little to the Forum, as I've got so many good ideas here.
Also I'm very interested in any help I can get along the way.
So I'll be posting photos as I make progress, and reaching out for help, please.
Hope some of you find this interesting
Bob