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  • Rebuilding an exhaust brake

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    This article will detail my used Pacbrake install. Part numbers listed are the ones i used, unless noted, and what i know works. This can be used with vacuum or air cylinders and controlled by the Cummins ECM, a throttle switch, or manual momentary switch. As of 3-20 all parts still available from Pacbrake except the brake housing. Much of this info can be found on Pacbrake's website in PDFs L2016.pdf for brakes C14024/C14024E/C14025,  and L1018.pdf parts list. Do yourself a favor, download and read both. They are linked below. 

    If you have a manual transmission there is plenty of room around the vacuum cylinder. In automatic trucks the transmission dipstick tube will need to be bent slightly. Slide a long 1/2" extension about 8" down the tube and push it towards the driver side of the truck. It would help to have someone under the truck to hold the bottom of the tube while doing this. Bend a little at a time. It took me a couple tries to get it where i wanted it and it is a tight fit. Make sure the cylinder does not touch the tube at all.

    NOTE: If you are putting this on an automatic truck I highly recommend a converter lock up switch. Ibmobile has an excellent write up that will walk you through every step and works perfect. I used his write up to build mine.




     Brake housing C10293 (used) $-trade

     Vacuum cylinder C11828 (used) $-trade

     Solenoid valve C11829 (new-eBay)         $90.31

     Superlube C18037 (new-eBay) $14.75


     1/8" npt to 1/4" tube (air brake line) need 5.



     1/4" push to connect fittingsScreenshot_2020-03-19-21-41-23.png.4663e04f7c402b14c3c96a7fe82a94b9.png

     1/8" npt mufflerScreenshot_2020-03-19-23-26-16.png.e42531c82adbc8fd98f0a0e3dfff189b.png


     TE Connectivity:

     Terminal for Cummins ECM (5 for $2.33/free shipping)Screenshot_2020-03-19-21-36-41.png.1ea20ccde569b4e306abe9222e302ff6.png

    If you want a pre-terminated wire for the ECM try this:     3164263 Cummins


     GARAGE STASH: I keep most electrical items i used on hand but most all can be found at any auto parts house.

     Relay base (Amazon)

     Mini toggle switch (Amazon

     Blue LED (Amazon or eBay)

     18 gauge wire, heat shrink, non-insulated connectors

     Zip ties

     Bosch relay -- resistor or diode suppressed

     Metal for solenoid bracket

     #4x1.5" machine screw/nuts for solenoid (2)

     Vacuum tee

     1/4" vacuum hose

     1/4" air brake line -- local Parker store

     Diode from ford crown vic under hood fuse box (photo below)




    Disconnect both batteries.

    Start with brake housing (#1 in pic). It should have the bracket for the cylinder bolted to it.Screenshot_2020-03-19-22-34-30.png.00f997239c8fe6e5fd9ad8345f190466.png

    Butterfly must move freely. Clean as needed.20200311_083430.jpg.dc08cad6b4d5deb44f448edd54a3b2ca.jpg

    Remove the 2 1/4" bolts from butterfly and 3 bolts from the cylinder bracket. Shaft and bracket must be removed and installed together. Pay attention to how the butterfly bolts to the shaft. It is not flat and must be put back together correctly. Do not force the shaft out of the housing. I had to soak and heat mine for 2 days to get it to turn. When it started moving i used an air chisel to tap it up while turning it with vise grips clamped on the lever that the cylinder attaches to. There are sealing rings on the shaft--do not damage them. Polish shaft and clean shaft holes in housing. I used fine crocus cloth and WD-40 to polish the shaft and some fine sanding drums from my porting kit to clean up the bores in the housing that the shaft rides in.  I used copper anti-seize and Pacbrake Superlube to lube everything up. The shaft and bracket must be installed together.  Make sure to use lock nuts on the butterfly when putting it back together. Also make sure that the butterfly does not touch the inside of the exhaust housing. It should pivot freely and not stick or rub.20200311_155327.jpg.f3b3a26a2117630ee53d4b45aa33235f.jpg

    Blasted, polished, lubed.

    Make sure your cylinder doesn't leak vacuum. Mine leaked.  I removed the rivets from the rear cap and it slid off. I carefully removed seals from piston, cleaned everything up and wiped seals and cylinder walls with Superlube. I do not have a source for new seals. Reassemble. No photos because I didn't think it would work but it did.20200311_163244.jpg.3ae661041ae59fd9254c473a9a09ac2f.jpg

    Assembled, tested, working.

    Install brake on truck per Pacbrake instructions. Check around everything for clearance and tighten downpipe evenly. Auto trans will need dipstick tube tweaked as described above.20200317_152941.jpg.9a49f9a2494facde29ca233a27d777ca.jpg

    Unbolt factory fuel filter housing from intake and move aside( do not remove fuel lines), unbolt connector from the Cummins ECM on the driver side of the block and unplug. I think it is a 4mm Allen bolt.  There is a small rubber plug in the #20 ECM location. Remove it with a small pair of needle nose pliers or push it out from the inside with a paperclip. Install wire w/terminal 1062-20-0144 into location 20. Push it firmly and pull back to make sure it locked. I had to push harder than expected but it locked in nicely.Screenshot_2020-03-20-00-00-08.png.a307d35e3b10955516af54a3d67d89bc.pngReinstall ECM connector and fuel filter housing.

    Mount solenoid and relay. I made a bracket from a piece of sheet metal i had and used #4 machine screws and nuts with loctite to attach the solenoid to the bracket.  I used an air horn bolt and grounded both with that bolt. The solenoid and relay can be mounted anywhere thats convenient as long as you can route the vacuum lines safely. 20200319_173919.jpg.021d01edec25b833f92c0baaa4202479.jpg

    Wire relay, switch, led and solenoid to this diagram. It needs to be wired to a key on 12 volt source. If using a relay with a diode do NOT switch connections at 85 & 86.20200327_061716.jpg.666566b272869c76b8263c47789f7324.jpg20200324_160458.jpg.bd69b2f524bd8084fec2fb804b10d28f.jpg

    I used a diode to protect the LED from current spikes from the coil of the vacuum solenoid. I get them from the underhood fuse box of ford crown vics. I do not have a part number for it. My LED is wired to light when the brake activates. If you want it light when the switch is on connect it to load side of the switch.

     Hook up vacuum lines as shown below. Screenshot_2020-03-20-00-19-39.png.8f4be6d2ac632c69b40484fcade212ce.png

    NOTE: If you are using a DOUBLE ACTING AIR CYLINDER simply plumb your air supply into the solenoid at vacuum supply location and REVERSE lines going to the cylinder. You will probably want some kind of regulator between your air tank and the solenoid. Play with air pressure to control the moving speed of the cylinder. I do not recommend a single acting spring return cylinder with this brake housing. From my research, the brakes that use a single acting cylinder also use a spring on the exhaust housing lever.

    Reconnect batteries, reset APPS, and check operation.

    NOTE: The way above is how i wired mine. Be aware the brake will apply anytime the throttle is closed and the exhaust brake switch and key are on. There is no input from vehicle speed, gear selected or anything else. The brake opens as soon as the throttle is off idle. 


    My mostly finished install.


    NOTE: The 2 following install options will work but I have not wired a truck using either of these 2 methods. The throttle switch only way will make the brake apply as soon as the throttle is at idle and the exhaust brake power switch is on. This was the 2nd option in Pacbrake's instructions.

     The momentary switch wiring will only work when the throttle is closed, exhaust brake power switch is on, and you manually activate the momentary switch.



     Pacbrake throttle switch kit C11911

     Plumbing is the same.

     Use this basic diagram.20200320_065308.jpg.a1ab8dbfc910290f0295460ef6f4a926.jpg

    If wanted, add light at power switch or throttle switch. 

    Instructions for adjusting throttle are in L2016.pdf from Pacbrake.



     I am recommending using the throttle switch as a safety measure in this install.  This prevents brake activation with throttle open.Wiring will be same as above with the addition of a normally open momentary switch. Throttle and momentary switch must both be closed for brake to activate. The switch can be any normally open momentary switch mounted anywhere that is convenient for you. You can find foot activated exhaust brake switches if you shop around.20200320_082341.jpg.3e6b17762973f94f964cceddfe527cc2.jpg


    L2016.pdf L1018.pdf

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