DD-3 to Spring Brakes Installation Guidelines and Tips

This is for installing the Spring Brake Chambers and QR-1C Valve only at this time. Since it is a single brake system, you will want to update and change it to a dual system.

 2 ea. 30/30 Spring Brake Chambers
 1 ea. QR-1C Valve, this is a two-way check valve, for anti-compounding of brakes when both service and park brake is engaged at the same time and to pressurize the emergency side of your spring brakes.
 Tube or jar of joint compound, do not use Teflon tape.
 Approx. one foot of 5/8 OS dia. DOT Nylon tubing. Get more, you never know when you might need some. I had some left over from the installation of my AD-9 air dryer.
 2 ea. Push Lok or Compression fittings for the above tubing. One with 3/8” MP, this goes onto the delivery port of your rear relay valve. One with ¼” MP, this goes onto the Balance Port on your QR-1C.
If you are going to reuse your existing hoses and fittings off of your DD-3’s, make sure they are in good shape.
You may need other assorted brass DOT fittings depending on your installation.

Safety First

Park your coach on a level surface.

Block all wheels so the coach does not roll in either direction.

Step One

Using the coach or shop air, bring your air pressure up until governor sneezes or at least 100 psi, release the Park Brake. Shut off your engine, turn off battery switch and take your keys with you.
Go under the drive axle and look at and take pictures of how the DD-3’s are mounted. Also, check and measure the position of the slack adjuster arm to the brake chamber bracket, this is of course if your slacks are set correctly. Measure from center of pin location on clevis to the surface that the chamber is mounted to. Write that measurement down in the note pad you are using for this project. Hopefully, your slack arm is greater than a 90-degree angle. You will see the importance of this later.

Step Two

Completely remove all air from system and tanks! You don’t want any hoses whipping around when you unhook them.

Mark all of your airlines for correct installation later. Remove your DD-3’s, airlines and inversion valve. Pay particular attention to the two hard lines to the inversion valve, one is for the lock port on your DD-3’s, the other if for the emergency port. You will be plugging the emergency line and hooking up the lock port line to the Supply Port on your QR-1C.
If you have spacers between the DD-3’s and mounting bracket, you will not need them to install your new Spring Brake Chambers.

Step Three

Clean the surface of the mounting brackets, make sure they are flat and have no burs. This is also a good time to grease all of the points in your slack adjusters and anything else that needs attention. You’re under there anyway, might as well make the most of it.

Step Four

Now the fun begins. I’m sure that you have read all you can on spring brakes and the installation of them, you are ready to make them fit properly. Right?
Make sure the new spring brakes are in the caged position. As you are tightening the spring cage bolt notice it should be moving in. Now follow the instructions that you read
for cutting the rod to the proper length. The length I ended up using was 2 ½” from the face of the chamber to end of the rod.
You should already have the jam nut on the rod. Install the clevis and tighten to specs. Back off the slack adjuster arm away from the bracket. Makes it easier to install and does not cause any clearance problems.
I suggest you do one side at a time. Install the spring brake chamber on your clean bracket and tighten nuts to spec. Move the slack arm towards the clevis so you can insert the pin and cotter pin. Now adjust your slack adjuster as you would normally do when you adjust your brakes. At this point, you should notice the slack arm is more than a 90-degree angle to the rod. Remember when the service brake has applied the arm and rod should be as close to a 90 degree right angle as possible.
Now go ahead and install the other side, using the same procedures outlined above.

Step Five

You will install the QR-1C in the same location as was the inversion valve.
My relay valve was directly above the old location of the inversion valve. You may have to drill one bolt hole to mount the QR-1C, the other one should work fine. Remove a plug on one Delivery side and install your nylon fitting. Install the other nylon fitting in the balance port on the QR-1C. Slide nylon tube into fitting on the relay valve and hand tighten. Then slide the other end in the fitting on the QR-1C. Tighten all fasteners and fittings. Now connect the lock pipeline to the Supply side of your QR-1C, you will need a 90 elbow to do this. Should have been one on the old inversion valve, mine did.

Step Six

Now go ahead and install all of the hoses in the proper location. Make sure there will be no rubbing as they pressurize or from coach suspension movement.

Step Seven

Make sure all connections are tight, cotter pins installed and everything in order.
Now is the time to air up your coach. I used shop air and brought it up to 60 psi. Then got under the coach and listened for any leaks. Now bring up the air to 100 psi and release the Park Brake Valve. Make at least three or four service brake applications. Have someone do that while you go under to look and listen. Watch the action of the slack arms, rods and service hoses. At this time if all is well, check your spring cage bolt, it should be loose, go ahead and remove it and put them in their storage locations on the spring brake.
Now release the Park Brake, you should hear air exhausting from the QR-1C valve at this time. This is when your springs are doing their work to keep your coach from moving. Make several service and park brake applications, go under the coach and double check everything.
Go back under and using a bottle of soap and water, coat all air fittings and look for bubbles.

Step Eight

If you feel comfortable with the installation and know your brakes are working properly, take it for a test ride. I would suggest a short one at first, then crawl under coach and check again. If you have an IR temperature gun, and you take it for a longer ride, stop and take a reading of the rear axle drums. Making sure you don’t have any brake drag.

Congratulations, you have successfully installed and upgraded your rear brake system.

Disclaimer: Phoenix Coach will not be held responsible for the installation by you or another party, this document is for illustrative purposes only.

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