1977 airstream 31'

beekman · 02-29-2004, 07:32 PM

My Father-in-law has a
airstream down in cabo and wants in brought back to san diego.
My question to anyone out there is the tow vehicle has to have a vacuum line to make the trailer brakes work. I have never heard of this arrangnment. I thought all airstreams just used a standard electric drum brake system. Is this possible on this 1977 airstream?
Please let me know what this vacuum line connection from the tow vehicle to the trailer could be needed for.

Beekman

59toaster · 02-29-2004, 08:36 PM

I read somehwere the Andy with InlandRV might be able to hook you up with the right parts. www.inlandRV.com

Your other alterantive is to convert it to electric brakes. Just need backing plates and possibly drums. not as expensvie as it sounds and the worst part of the job would be the wiring.

davidz71 · 02-29-2004, 09:30 PM

I have a '77 Excella 500 31' with the vacuum hydraulic disc brakes and they are fantastic. You need a source of vacuum, I used a vacuum port off the back of my manifold on my '01 Chevy 2500hd and it has worked fine. I tied into the vacuum system going to the brake booster on my '92 Chevy z71 4X4 for the vacuum source. I then ran a in-line check valve a foot or so down the line from the manifold connection. I used airbrake hose with 3/8 fittings. I then ran the airbrake hose inside the frame all the way to the back bumper. I used a 3/8" fitting connected to a 1/2" female industrial air fitting and fabricated a mounting plate to fit it next to the 7 pole electrical trailer connection. The trailer has a 3-4' air hose with a 1/2" male industrial air fitting that plugs into the female fitting I placed under the rear bumper. It provides the vacuum necessary for the brake booster on the trailer tongue. The brake controller mounted on your dash will provide the current necessary to release the booster which will apply pressure to the hydraulic lines.

It has been an excellent system although some who don't understand it will recommend you chunk it for electrical drum brakes which are definately inferior. There are systems which will eliminate the vacuum hose from the vehicle and actually replace the entire booster system on the tongue. Andy at Inland RV has material on the system but be aware it is over $1000 best I can remember. It cost over that to have the factory convert your system over to drum brakes.

Last, do a forum search and you will find that I did a full explanation on what parts I used. I can send you a few pictures of my setup if you want.

suprtrker · 02-29-2004, 11:12 PM

I have a 1977 International With the same set up. Stop If the breaks work don't change them. This is what I did. Go to your local wrecking yard and ask them for a 12 volt vaccume pump. I know that some Cads have these on them thats where I got mine from. After you get the pump Find a place to mount it on the front of the hitch on the airstream. I ran a hose to the vaccume break system and Wired the pump to a switch witch I could turn off and on. I also added one way valve between the pump and the booster. Cost me thirty dollers and works great. I have not had any trouble with this set up. These vaccume breaks are so much better then Elec. breaks. I live in washington state and what ever way I go I have to cross mountians. What a breez with this system. Not onley this but I can change towing veichles with out having to set up the vaccume hose on the towe unit. If you need I can send pictures Of how I set this up.

beekman · 02-29-2004, 11:39 PM

Thanks Guys so much;

That really makes sense now, my father-in-law is in no-way
a mechanical guy and when he told me about the vacuum line he didn't know exactly why it was needed. He even suggested that I shouldn't even worry about hooking it up which even made me more concerned. I own a 2004 Ram Diesel which has a vacuum pump that supplies vacuum for the brake booster, interior ventilation system etc. Running a line to the rear shouldn't be a problem but I'll need the female hardware to mate to the supply hose on the trailer.

Thanks again davidz71 and suprtrker for the info.

Beekman

davidz71 · 03-01-2004, 06:46 AM

Check local industrial pneumatic drill (air supply) houses for fittings or go on line to www.grainger.com for them. Also, some of the Buick Grand Nationals used a Delco vacuum pump which one of the past forum members used. It had a pressure switch and would cut off at a predesignated value.

Inland RV Center, In · 03-01-2004, 08:25 AM

Using a separate vacuum pump for the disc brake system, eliminates the need for a vacuum supply from the tow vehicle.

CAUTION. This setup has a limited supply of vacuum.

As an example, if you pumped your brakes, about three times, you will very quickly run out of vacuum, which results in "NO" brakes.

A mechanical vacuum pump cannot begin to supply the same amount of vacuum that the engine can.

Keep this fact in mind, and you should not have a problem.

Andy