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Thread: Medium Duty Ambulance FAQ (Freightliner, International, GMC, Chev)

  1. #1
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    Default Medium Duty Ambulance FAQ (Freightliner, International, GMC, Chev)

    There is a lot of valuable information particular to medium duty ambulances being buried in various build threads. So I am proposing that we have an FAQ (Frequently Asked Questions) specific to the medium duty chassis ambulances. By this I suggest the C4500, C5500, International and Freightliner chassis vehicles.

    I will dedicate this top post to links to various build threads. Read this thread as the "master thread for Ambulance to Camper conversions FAQ"

    Ambulance-Camper-Expedition-Rig-Conversion-FAQ

    Medium Duty

    Ozrockrat FL60 Freightliner-ambulance-conversion-project

    rirenz FL60 Buying-amp-Building-a-Medium-Ambulance-into-an-RV-

    rossvtaylor FL60 From-Freightliner-ambulance-to-RV-we-hope!

    scooter421 International 4700 1994-International-4700-Conversion-Begins

    Dirtfarmer515 C4500 New-here-just-got-an-Ambulance

    MNtal FL50 The-Rambulance-FL50-Freightliner-Ambulance-Camper-Tow-Rig-Conversion

    If anyone has a thread we need to link to send me a PM and I will include it in here.
    Last edited by Ozrockrat; 05-26-2016 at 02:11 PM.
    2007 Freightliner Dualcab Ambulance conversion. Check it out here
    FJ75 Landcruiser 6 wheeler (Converting to an AmboCamper)
    1963 BMW /2 with a Ural Sidecar.

  2. #2
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    Tires and Rims

    This is the one I get most questions about.

    There are basically 3 types of hubs used on the medium duty rigs:
    8 on 275mm (these seem to be the most common. Especially if you want hydraulic disk brakes. The rear axle will probably be rated up to 15,000 lbs.
    10 lug hub pilot . Same as most later model commercial trucks.
    10 lug budd. Older trucks and you can generally tell by the tapered lug nuts.

    If you are still looking for a rig I would suggest you put a priority on the 10 lug hub pilot type hubs. This will give you infinitely more choices for wheels/tires.

    What size wheel can fit? (these are a couple of handy calculators: Everything, Tire Size Comparison)
    Without a lift and minor trimming:
    MNtal has fitted 275/70R22.5 (37") duallys to his rig with minor trimming.

    Sawzall engineering and 4" lift
    I have 365/80R20 (43" x 14.5") on mine with very minor rubbing on the steering arm at full left lock (polish not break type rubbing)

    Rims
    8 on 275:
    -I run 20 x 11 military surplus beadlock rims. These originally came on the RG-31 MRAP. There are a lot of them about but they are hard to find. If you go with these you need to run an MPT type tire such as the 365/80R20. (MPT tires have a bead wall that is shorter than normal). I also had to drill out the stud holes to fit my current stud size.
    -20x8.5 alloy military surplus. Probably OK to run the G177 11R20 but you will need to check the bead size on both the tire and the rim.
    -Another option is the 20x9 alloy rims off the MXT International. These are about as easy to find a rocking horse poop. Tires are basically limited to the Continental MPT's in the USA.
    -You can get 22.5 dually rims with the 8 lug pattern. Check the truck wreckers and also look at the RV wreckers as a number of RV's had them and got an easier life.
    -Another option if you want to go singles is the duplex disc wheels they use on the front of cement trucks etc. These are also hard to find now.
    - There are also the European rims that they use on MAN trucks. They run a locking ring and can be used with the 365/80R20 tires. About 400 euros each plus shipping.

    10 lug hub pilot:
    Spoiled by choices
    Accuride Duplex Disc Rims for singles (i.e. Cement truck) 29378SP, 29683SP, 29374SP are the 12.25". 29380SP, 29376SP, 40036SP are the 13". 41140SP, 41142SP are the 14". My SWAG (scientific wild arsed guess) is that the 29378SP would be the best option as it is basically a rim with the mounting surface very close to the outside of the rim. That is assuming your rim mount surface is about 20" difference between front and back like mine is. Back 71” face to face, Front 91” face to face.
    Last edited by Ozrockrat; 05-28-2016 at 10:24 PM.
    2007 Freightliner Dualcab Ambulance conversion. Check it out here
    FJ75 Landcruiser 6 wheeler (Converting to an AmboCamper)
    1963 BMW /2 with a Ural Sidecar.

  3. #3
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    Transmissions
    2007 Freightliner Dualcab Ambulance conversion. Check it out here
    FJ75 Landcruiser 6 wheeler (Converting to an AmboCamper)
    1963 BMW /2 with a Ural Sidecar.

  4. #4
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    Seating
    2007 Freightliner Dualcab Ambulance conversion. Check it out here
    FJ75 Landcruiser 6 wheeler (Converting to an AmboCamper)
    1963 BMW /2 with a Ural Sidecar.

  5. #5
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    Default Axles.

    Send me any links/info you want included. My input will be Rockwell Mertior and hopefully Axletech as a separate thread.

    Take your title down to Freightliner and get signed up for DTNAconnect. It will give you access to your parts including the actual diff carrier code. Then you can use this chart to define if you have a limited slip or no spin diff. Basically if you have a "F" for the 9th character it is an open diff. If you have anything else you are lucky. You should also be able to read this straight off you diff tag.

    Attachment 347170

    My axles are RS 15-120 rear and FC941 front. The width is Back 71” face to face and Front 91” face to face.
    Last edited by Ozrockrat; 05-26-2016 at 05:35 PM. Reason: Rockwell axle identification chart added
    2007 Freightliner Dualcab Ambulance conversion. Check it out here
    FJ75 Landcruiser 6 wheeler (Converting to an AmboCamper)
    1963 BMW /2 with a Ural Sidecar.

  6. #6
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    Default Engines

    MNtal's excellent summary.

    Quote Originally Posted by MNtal View Post
    .
    Personal Opinion / Preference Ranking
    .
    8.3L Cummins - 1/2 million mile motor, and as reliable as death and taxes. More power than you can shake a stick at. They put them in 60-80,000lb city busses and rod the poo out of them. In-frames are fairly easy to do and can be done for $2-3000.
    .
    5.9L Cummins - Baby brother of the 8.3L. They are very capable of moving 25-35k lbs all day long but slightly more susceptible to heat issues in large vehicles, or vehicles pulling a lot of weight. They are the probably the most common Diesel Engine in the US other than the Ford 7.3L.
    .
    DT466 International – Reliable as they are loud, also a 1/2 million mile motor. The only other motor I would consider but definitely not my first choice.
    .
    CAT 3126 – Respectable engine, slightly more expensive, Only engine I do not have personal experience with.
    .
    T444E International – DT466’s little brother, meh
    .
    Mercedes – I wouldn’t touch them *****.
    2007 Freightliner Dualcab Ambulance conversion. Check it out here
    FJ75 Landcruiser 6 wheeler (Converting to an AmboCamper)
    1963 BMW /2 with a Ural Sidecar.

  7. #7
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    Default Cruise Control Switches. Part Numbers

    Freightliner FL60 1999. These are supposed to be the part numbers for the cruise control switches for one running the 24v ISB Cummins. (not sure how cruise works on the mechanical injection ones)

    A22-41425-000
    A22-41425-001

    In theory the wiring is already in place including the links to the Cummins ECM.

    More to follow if I get it working
    2007 Freightliner Dualcab Ambulance conversion. Check it out here
    FJ75 Landcruiser 6 wheeler (Converting to an AmboCamper)
    1963 BMW /2 with a Ural Sidecar.

  8. #8
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    Mar 2009
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    Phoenix AZ
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    Default Cummins 5.9 Freightliner FL60 1999 Oil Pressure Sender options

    This is more for record keeping and helping those searching for Cummins oil pressure problems.

    I have been having an ongoing intermittent check engine light. After getting a couple of tools to run diagnostics it came down to oil pressure low. Now my truck has a good old manual gauge so I could confirm there was nothing wrong with the oil pressure so it was just the feed that the ECM was seeing. Not a big deal I thought. New sender and check the wiring and I am all sorted. But Cummins threw a wrench into the works. It seems like the old sensor/sensor ( cummins 3408428 ) is now replaced by a switch ( 4076930 ) and a wiring harness ( 3164755 ) and it needs an ECM re flash to work. It also turns the variable reading into a set 55psi effectively creating a dummy gauge.

    Some some more google analysis I found a couple of possible alternatives. 1 was an International part number and when I checked it out it would require rewiring. The other ( Cummins 4921511 ) has been superseded a number of times ( 4326849 ) is a straight replacement and does work.

    So to summarize for the inter web searches. Cummins ISB 24v
    Oil pressure sender sensor 3408428 can be directly replaced with a 4921511 or 4326849 sensor directly from Cummins. At least it worked OK on my 1999 Freightliner.
    2007 Freightliner Dualcab Ambulance conversion. Check it out here
    FJ75 Landcruiser 6 wheeler (Converting to an AmboCamper)
    1963 BMW /2 with a Ural Sidecar.

  9. #9
    Join Date
    Mar 2014
    Location
    Minnesota
    Posts
    999
    Egad! Another ambulance thread! Wonderful!!

    Here's a list of all the ambulance manufacturers I could find - there may be others, but these are at least out there:

    • American Emergency Vehicles (AEV)
    • Braun
    • Crestline
    • Demers
    • E-1
    • Excellance
    • Frazer
    • Frontline
    • Horton
    • Leader
    • Lifeline
    • Marque
    • McCoy Miller
    • Medic Master
    • Medix
    • Med-Tec
    • National
    • Osage
    • PL Custom
    • Road Rescue
    • SWAB
    • Taylor Made
    • Wheeled Coach
    Bob Renz
    Project ID: The Fambulance

  10. #10
    Join Date
    May 2013
    Location
    ny
    Posts
    756
    This is on eBay.
    Thought it might be of interest to someone.

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