Truck Conversion & Toterhome Community - View Single Post - 101 questions about doing my own conversion...

truckguy · 04-25-2006, 05:37 PM

Hi People. I'v been lurking here for a few days, trying to piece everything together in my mind for converting a HDT into a motorhome for RV travelling. I've got a ton of questions...

A bit myself first... we presently have a 32' 5er we pull with a 2000 Ford F250SD diesel. We just returned from a 3000 mile trip to Sacramento. The combo works pretty well, but we found the truck to ride quite rough on the California roads. Fuel stops were a headache too. The tank on the Ford is small. Power was adequate but not plentiful. Fuel economy was 11 MPG or so. A bathroom and room for the kids to move a bit while travelling would be great.

The 5er is a nice size and we are pretty comfortable in it, but I find they need a lot of maintenance. They aren't designed the best. Everything is sort of too light and hard to work on.

I am very mechanically inclined. I've built a lot of stuff in the past. I am a good welder, but body work is not my forte. I'm good at wiring and plumbing. Woodwork is not my thing either.

I've driven medium duty tandem trucks with 10 and 13 speed transmissions, but only for a few days and that was 10 years ago. I have my air brake ticket, but I'm rusty. I've never ridden or driven a class 8 truck and the medium duty trucks I was driving (International and Mack) weren't in the best shape.

I've looked at motor homes and they look like high maintenance to me as well. Like a 5er with a drivetrain. They don't seem to be very big inside either and only the expensive ones have an 11 or 12 litre engine. Most of the floor plans are for retirees, not families. And I don't like the auto transmissions either. Kills MPG and something more to break.

I've looked at bus conversions, but the shells are really expensive for what you get and they look to require as much work as converting a HDT, maybe more. Most of them use 2 stroke GM engines, so an engine swap is almost a must, the roof will need raising, there will be rust to fix in the front and rear subframes, etc. (Lots of bus specific stuff looks harder to work on.) I hate the automatic transmissions in buses. A HDT appears to be lighter than a converted bus too.

One thing I hate about both buses and motorhomes is not having anything between you and the front of the vehicle if you are ever in an accident. The driver's compartment on most motorhomes is set back 3-4 feet from the windshield, but there isn't anything substantial in front of the driver. Just fiberglass and air. I've never been in an accident, but I'd rather be in my pickup with sheetmetal, a frame and a diesel engine in front of me and an airbag in the steering wheel than be at the wheel of a motorhome.

I don't need a completed conversion for a few years, but I'd like to start piecing things together and planning. Our RV situation has been bothering me a bit lately and I'd like to get a direction finalized and start moving towards it. As it is I am going to spend some money and time updating our truck and trailer, but if I can see getting a HDT conversion going in the next year or so, I'll go light on the pickup and trailer upgrades.

I quite like what spooner has planned for his Pete. I'd like to curve the sidewalls on my conversion like he is doing on his.

So... on with the questions...

1) Ride quality and noise. Can a heavy duty truck (single rear axle, KW, Pete or Volvo) with a large "box" on the back be made to ride nicely on rough interstate roads ? As good or better than a Ford Superduty ? (Which isn't saying much...) How noisy are these trucks under load ? Can these trucks be made to ride as nice and be as quiet as a bus conversion ? (MCI 102,say) Is anyone converting the front axle to air ride ?

2) Fuel economy. Can one get 11-12 MPG out of a HDT conversion running 60-65 with a light foot ? Assume we keep the roof line as low as possible and streamline everything we can and keep the weight down. 13 speed, double OD ? 3.08:1 rear end ratio ? Or taller ? 2.73 ?

3) This question might cause an argument... what is the best conversion candidate ? KW T2000 ? Pete 379 ? Volvo 770 ? Something else ? I want something really aerodynamic with a good ride and quiet.

5) Height ? How high are the frame rails on these trucks and how high does the floor need to be above that ? And then how high does the roof need to be above that ? And how much does the overall height have to do with aerodynamics and fuel economy ? Is anyone lowering the chassis on these trucks or running smaller tires ?

6) Length/Turning Radius/Single or Tandem ? What is the "Back of Cab" measurement on the various HDT ? I guess by BOC, I mean to behind the drivers seat as everything from there back will be motorhome as far as I can tell. (I am thinking of doing something like spooner is.) If I run a 36 foot box with say 2 slideouts and stay weight conscious, can I get away with a single rear axle ? What sort of wheelbase and turning radius will it have ? Can anyone comment on parking in tight quarters, ie not drive through stalls ?

7) Basement Rustproofing ? When I look at the MCI busses, the entire basement and frame for that matter is made from Stainless steel or aluminum. And even then there can be corrosion problems. If one looks at the basement and frame of an Eagle, one typically finds RUST, to no end. So... how does one build the basement on a HDT conversion so it doesn't rust ? The only thing I can think of is to frame the lower stuff out with aluminum and use fiberglass expoxy panels ? I can't see using steel for it or am I being too picky ?

8) Box details ? Is anyone making their box 102" wide ? Some busses and some "toy hauler" trailers are now 102" wide. What sort of steel is being used in the walls ? (1.5" square tube x 1/8" wall ?) Is anyone worried about the integrety of the box in case the truck is laid over or rolled ?

9) Frame stretching ? I've helped stretch the frame on a couple MDTs, but I didn't pay much attention at the time. If I remember correctly, we cut the frame at an angle, spliced in another piece of frame and then plated the inside and outside, welding the channels. Is this how it is done on a HDT ? I doubt it as I don't think the rails can be welded. So how is it done ? Is a second carrier bearing added for the driveshaft ?

10) Levelling ? Does a HDT need a hydraulic jack kit like a motor home does or can they be leveled with the air bags like some of the buses conversions are ? (By adding special valves and maybe converting the front axle to air ride ?)

11) Exhaust System ? It appears to me that most of the aerodynamic HDTs have the exhaust stack exiting behind the cab, right where my box would be. What does one do to fix this ? Put a muffler under the truck with an exhaust exit out the side ?

What else am I missing ?

Thanks.

04-25-2006, 05:37 PM	#1
truckguy Junior Member Join Date: Apr 2006 Posts: 7	Hi People. I'v been lurking here for a few days, trying to piece everything together in my mind for converting a HDT into a motorhome for RV travelling. I've got a ton of questions... A bit myself first... we presently have a 32' 5er we pull with a 2000 Ford F250SD diesel. We just returned from a 3000 mile trip to Sacramento. The combo works pretty well, but we found the truck to ride quite rough on the California roads. Fuel stops were a headache too. The tank on the Ford is small. Power was adequate but not plentiful. Fuel economy was 11 MPG or so. A bathroom and room for the kids to move a bit while travelling would be great. The 5er is a nice size and we are pretty comfortable in it, but I find they need a lot of maintenance. They aren't designed the best. Everything is sort of too light and hard to work on. I am very mechanically inclined. I've built a lot of stuff in the past. I am a good welder, but body work is not my forte. I'm good at wiring and plumbing. Woodwork is not my thing either. I've driven medium duty tandem trucks with 10 and 13 speed transmissions, but only for a few days and that was 10 years ago. I have my air brake ticket, but I'm rusty. I've never ridden or driven a class 8 truck and the medium duty trucks I was driving (International and Mack) weren't in the best shape. I've looked at motor homes and they look like high maintenance to me as well. Like a 5er with a drivetrain. They don't seem to be very big inside either and only the expensive ones have an 11 or 12 litre engine. Most of the floor plans are for retirees, not families. And I don't like the auto transmissions either. Kills MPG and something more to break. I've looked at bus conversions, but the shells are really expensive for what you get and they look to require as much work as converting a HDT, maybe more. Most of them use 2 stroke GM engines, so an engine swap is almost a must, the roof will need raising, there will be rust to fix in the front and rear subframes, etc. (Lots of bus specific stuff looks harder to work on.) I hate the automatic transmissions in buses. A HDT appears to be lighter than a converted bus too. One thing I hate about both buses and motorhomes is not having anything between you and the front of the vehicle if you are ever in an accident. The driver's compartment on most motorhomes is set back 3-4 feet from the windshield, but there isn't anything substantial in front of the driver. Just fiberglass and air. I've never been in an accident, but I'd rather be in my pickup with sheetmetal, a frame and a diesel engine in front of me and an airbag in the steering wheel than be at the wheel of a motorhome. I don't need a completed conversion for a few years, but I'd like to start piecing things together and planning. Our RV situation has been bothering me a bit lately and I'd like to get a direction finalized and start moving towards it. As it is I am going to spend some money and time updating our truck and trailer, but if I can see getting a HDT conversion going in the next year or so, I'll go light on the pickup and trailer upgrades. I quite like what spooner has planned for his Pete. I'd like to curve the sidewalls on my conversion like he is doing on his. So... on with the questions... 1) Ride quality and noise. Can a heavy duty truck (single rear axle, KW, Pete or Volvo) with a large "box" on the back be made to ride nicely on rough interstate roads ? As good or better than a Ford Superduty ? (Which isn't saying much...) How noisy are these trucks under load ? Can these trucks be made to ride as nice and be as quiet as a bus conversion ? (MCI 102,say) Is anyone converting the front axle to air ride ? 2) Fuel economy. Can one get 11-12 MPG out of a HDT conversion running 60-65 with a light foot ? Assume we keep the roof line as low as possible and streamline everything we can and keep the weight down. 13 speed, double OD ? 3.08:1 rear end ratio ? Or taller ? 2.73 ? 3) This question might cause an argument... what is the best conversion candidate ? KW T2000 ? Pete 379 ? Volvo 770 ? Something else ? I want something really aerodynamic with a good ride and quiet. 5) Height ? How high are the frame rails on these trucks and how high does the floor need to be above that ? And then how high does the roof need to be above that ? And how much does the overall height have to do with aerodynamics and fuel economy ? Is anyone lowering the chassis on these trucks or running smaller tires ? 6) Length/Turning Radius/Single or Tandem ? What is the "Back of Cab" measurement on the various HDT ? I guess by BOC, I mean to behind the drivers seat as everything from there back will be motorhome as far as I can tell. (I am thinking of doing something like spooner is.) If I run a 36 foot box with say 2 slideouts and stay weight conscious, can I get away with a single rear axle ? What sort of wheelbase and turning radius will it have ? Can anyone comment on parking in tight quarters, ie not drive through stalls ? 7) Basement Rustproofing ? When I look at the MCI busses, the entire basement and frame for that matter is made from Stainless steel or aluminum. And even then there can be corrosion problems. If one looks at the basement and frame of an Eagle, one typically finds RUST, to no end. So... how does one build the basement on a HDT conversion so it doesn't rust ? The only thing I can think of is to frame the lower stuff out with aluminum and use fiberglass expoxy panels ? I can't see using steel for it or am I being too picky ? 8) Box details ? Is anyone making their box 102" wide ? Some busses and some "toy hauler" trailers are now 102" wide. What sort of steel is being used in the walls ? (1.5" square tube x 1/8" wall ?) Is anyone worried about the integrety of the box in case the truck is laid over or rolled ? 9) Frame stretching ? I've helped stretch the frame on a couple MDTs, but I didn't pay much attention at the time. If I remember correctly, we cut the frame at an angle, spliced in another piece of frame and then plated the inside and outside, welding the channels. Is this how it is done on a HDT ? I doubt it as I don't think the rails can be welded. So how is it done ? Is a second carrier bearing added for the driveshaft ? 10) Levelling ? Does a HDT need a hydraulic jack kit like a motor home does or can they be leveled with the air bags like some of the buses conversions are ? (By adding special valves and maybe converting the front axle to air ride ?) 11) Exhaust System ? It appears to me that most of the aerodynamic HDTs have the exhaust stack exiting behind the cab, right where my box would be. What does one do to fix this ? Put a muffler under the truck with an exhaust exit out the side ? What else am I missing ? Thanks.