medium duty 4x4 cab chassis choices

[haven]

An article in the Winter 2007 issue of Overland Journal points out that there are only two cab/chassis sold in USA that have
-- a GVWR of more than 20,000 lbs, and
-- single rear wheels from the factory.

They are the Mercedes Unimog U500, distributed by Freightliner in USA, and the International 7300. The U500 is equipped with Michelin 315/80R22.5 tires. The 7300 has several options, including 385/65R22.5 and 445/65R22.5

If you're OK with dual rear wheels, there are several additional choices for an all wheel drive Class 6 or Class 7 vehicle.

Freightliner offers Meritor front-drive axles on its Business Class M2 106 and 106V models.

Sterling Acterra offers a front drive axle from Fabco as a factory option.

UD Truck has an OEM relationship with Pioneer 4 Wheel Drive to convert the UD 3300 cab forward truck to all wheel drive. Pioneer uses Meritor products.

Ford's F-650 and F-750 trucks are available with 4x4.

The GMC Topkick 5500 (GVWR 22,000 lbs) is available with 4x4.

If a GVWR between 17,500 and 19,500 lbs will work for your camper, the Dodge 5500, Ford F550, and GMC Topkick 4500 are available with all wheel drive and dual rear wheels.

Tulsa Truck Manufacturing can convert a dual rear wheel truck to super singles. They are very experienced in changing all manner of medium trucks over to front drive axles.

Another company that converts dual rear wheel trucks to super singles, and adds a steerable drive axle is RUF Inc. They convert the Mitsubishi FM cab/chassis, as shown here

http://www.ruf-inc.com/fm_features.htm

Edit: In fact it appears that RUF Inc won't do single rear wheel conversions. For details, read the messages below.

Chip Haven

 

[Robthebrit]

For a road going U500 you get 22.5 inch rims. It also available with standard mog 20 inch wheels running 395/80r20 tires, typically Mitch XZLs.

Once you have standard mog rims there are lots of different tires but most are not speed rated for 70mph.

Rob

 

[haven]

RUF axle photo

I think the rear axle in the photo is intended for dual rear wheels, after all.
Chip Haven

 

[fisher205]

Darrin AT RUF isn't doing super singles. If anything it's just the opposite. Go to his website and read his explanation. Marmon- Harrington is doing the conversions. The picture was was just driving it with a single on.

 

[haven]

Safety considerations

I guess we have to take RUF-Inc off the list of companies that will convert to super singles. Darrin Fink's concern seems to be to limit the liability he could face in the event that there was an axle or hub failure. Plus customer safety, of course!

CHip Haven

 

[boblynch]

F650 and F750 4x4s

Ford's F-650 and F-750 trucks are available with 4x4.

Great summary info. However, I don't think the F650 and F750 are factory 4x4 options. You need to go to Tulsa or others for a conversion.

Bob

 

[mhiscox]

I guess we have to take RUF-Inc off the list of companies that will convert to super singles. Darrin Fink's concern seems to be to limit the liability he could face in the event that there was an axle or hub failure. Plus customer safety, of course!

CHip Haven

Don't anyone think Darrin is just being picky about this. The group doing a major driveline modification would almost inevitably be the principal defendant if there was any failure that could even remotely be traced to the change.

Fuso Trucks would not support Darrin changing to single rear wheels on the FG, and it looked long and hard at the 4x 4 conversions Darrin has had Marmon-Harrington do. There was apparently not an air-over-hydraulic axle for current FM that was acceptable, so Darrin's big campers have had to have duels. (Though he suspects that with the new FMs having full air brakes, some SRW options might be possible on the 2008s.)

The bottom line, having extensively discussed SRW swaps from him, is that I believe that if Darrin doesn't put SRWs on an expedition truck, it's because the manufacturer won't support the change. My (admittedly not-fully-informed) opinion is that many of the DRW-to-SRW conversions done by people like Tulsa Truck are not advocated--and are sometimes vigorously opposed--by the manufacturer of the chassis.

Mike Hiscox
'77/'95 Unimog 416 DoKa Expedition Camper
'05 Sprinter mid/tall Expedition Camper

 

[jayshapiro]

F-650 Conversion

Great summary info. However, I don't think the F650 and F750 are factory 4x4 options. You need to go to Tulsa or others for a conversion.

Bob

Correct... it is only possible to get factory 4x4 up to an F-550. (and on the GM models only up to the Kodiak/Topkick 5500) - Beyond that you need to do it yourself.

We've just had Tulsa do the 4x4 & Super-Single conversion on our F-650 and they did an amazing job. There are pictures and a description of it here. Ron at Tulsa has been building 4x4's for 30 years and their yard is filled with Internationals, Freighliners, Fords, etc. all waiting to be converted and all with 20,000lb+ GVWR's.

I was initially hesitant about doing it after-market and like the Overland Journal article was limiting myself only to Factory options. DON'T. People like Tulsa (and Munroe engineering as well) do a great job, and ultimately use the same Meritor / Marmon axles that the factories do.

Cheers,
Jay.

 

[kerry]

Some school districts in Colorado use 4WD schoolbuses. I don't know what chassis they are built on, Bluebird, Thompson? Some of the shorter buses might make for an interesting conversion.

 

[Mobryan]

Some school districts in Colorado use 4WD schoolbuses. I don't know what chassis they are built on, Bluebird, Thompson? Some of the shorter buses might make for an interesting conversion.

Lots of the older ones were International's, I've not seen a new IH 4x4 bus, but I'm sure they still make them.


Matt

 

[Jeep]

We are doing a conversion on an IH bus when the parts arrive (45-60 days). Marmon Herrington makes a complete conversion kit for the job, on the new trucks you have to work with the engineers to relocate the DPF so you don't void the engine warranty. The job rolls out the door at around $35 000.

Just as a note for anybody buying a used truck equipped with a Dana 135 rear axle, make sure the housing isn't bent. We have replaced several housings on Topkicks, they were bent from the leaf spring perch out, we suspect that overtorquing the U bolts starts to crush the tube and weight and gravity finish the job. The housings are very thin and the metal is very soft, they tend to crush more than bend when trying to straighten them. The guts are quite light for a diff with the physical size, the ring gear is also riveted on. A 3 dressed up as a 9 if you like! I have had far less issues with the 135 in the F-550.

 

[boblynch]

Please post build pics of the IH bus when the parts arrive. I think there a number of folks that would be interested in following along.

 

[kerry]

Description of a converted 4wd school bus:

http://www.skoolie.net/forum/viewtopic.php?f=12&t=340

 

[Chucaro]

Just a question from Australia.
Are you people converting the Toyota Coaster 29 seater bus to 4WD ?
Here in Oz we are converting the compact buses like the Toyota Coaster, Mazda T3500 and Hinos among others to a motorhomes.
There are few Coasters which have the Toyota Land Cruiser transmission gear and are converted to 4wd. They are excellent units for conversion.
I converted a Mazda T3500 to a motorhome but I did not converted to 4wd.
Cheers

 

[haven]

Here's an updated list of medium and heavy truck chassis with all wheel drive, sorted by GVWR. -- Chip Haven


Truck chassis with 19,500 to 33,000 lb GVWR
and front drive axle as factory authorized equipment
--------------------------------------

Freightliner Sportchassis P4XL
crew cab
GVWR 19,500
Cummins and Mercedes engine options
Allison transmission
4x4 standard
single rear wheels standard


Ford F550
single and crew cab
GVWR 19,500
International Powerstroke V8
dual rear wheels


Chevrolet Kodiak C5500
Regular and Crew cab
GVWR up to 26,000 lbs
GM-Isuzu Duramax 6600
Allison transmission
dual rear wheels


International CXT
crew cab
GVWR 26,000 lbs
International 466DT I6 diesel
Allison 2500HD transmission
4x4 available
single rear wheels may be available


International 7400
Single or crew cab
GVWR 27,000-39,000 lbs
International DT466 or DT530 engines
Manual or automatic trans
4x4 available
super single rear wheels may be available


NIssan UD with Pioneer 4 Wheel Drive conversion
single cab
GVWR 20,000 and 33,000 lbs
Nissan Diesel MD-230 I-6
Allison 2500RDS 5 speed auto trans
dual rear wheels, size 11 R 22.5
wheelbase 150, 177, 193 in.


Sterling Acterra w/ Fabco front drive axle
www.fabcoautomotive.com/news/news_acterra.htm


Mack Granite tri-drive chassis
has front drive axle, and two rear drive axles


Mercedes Benz Unimog U500
stopped importing in 2005, may not be possible to buy new



Vehicles with 4x4 by aftermarket conversion
------------------------------------------

Ford F650
regular, super and crew cab
GVWR 26,000
Cummins 6.7L ISB 200 I6 standard
Caterpillar 7.2L optional


Mitsubishi Fuso FM
conversion to 4x4 by Darrin Fink's RUF, Inc