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How to Make the Airline Connections on the SMI Supplemental Braking System Part # SM99243


Looking to purchase SMI Air Force One braking system for my 1998 Holiday Rambler Endeavor diesel pusher with Freightliner chassis . However am not sure which air lines to tap into. From front of coach is one approx.1/2 in. light green supply line? and one approx. 1/4 in. light green line running to drivers side valve body and one approx. 3/8 in.metered? light green line running from drivers side valve body to passenger side valve body. There are no black lines. There are also 2 red lines running from front of coach into the passenger side valve body. There are no red lines run between the valve bodies.


Expert Reply:

There are two airlines that must be spliced into on the coach which will then run to the air tank assembly included with the SMI Air Force One Supplemental Braking System part # SM99243. One of these lines is for supply-air and the other is for metered-air.

The supply-air line is a 5/8" diameter hose (usually green but not always) which goes from the service relay valve to the braking air tank (see first photo). Once you find this line you will need to cut it in half and install the supplied push-to-connect air line t-fitting. Don't forget to drain the coaches air tank before severing this line.

The metered-air line is a 3/8" diameter hose (usually black but not always) that will be located on the spring-brake/quick-release valve (see second photo). You can identify this valve by looking for the label which should read “spring” or “emergency”. You will again need to cut the line in half and install the supplied push-to-connect air line t-fitting.

Unfortunately, the color of the airlines will not always be a constant therefore you will need to identify the diameter of the line and source before making the connection. If you are weary of installing the system yourself I strongly recommend taking the motorhome to a quality auto mechanic at your local RV service center as they would be able to install the unit for you.

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expert reply by:
Conner L

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