Pacbrake

Pretty much everything on the bottom side of the coach: Steering, wheels, tires, brakes, suspension
oldcobia
Posts: 109
Joined: Thu Jan 27, 2022 7:56 am
Location: N. Florida

Re: Pacbrake

Post by oldcobia »

Confident it is vacuum pump. Hose runs to vacuum reservoir and a t close to pump to cruise control. Just got word pump cannot be fixed. Over $400 for new one. Any suggestions for replacement that’s not so expensive. Thanks
1995 Safari Sahara 35’ 5.9 Cummins MD3060
TDJohn
Posts: 552
Joined: Sun Oct 27, 2019 11:34 pm

Re: Pacbrake

Post by TDJohn »

Here are some reasonably priced pumps at Summit Racing. The one that is priced higher, seems like much better quality, but who knows...

https://www.summitracing.com/parts/aaz-64-1509

https://www.summitracing.com/parts/hla-009428087


Note, the Pac Brake wiring diagram B (their updated version) will not work for your coach as it is set up to only turn the air compressor on when the Pac Brake is in use. Being that you also have air horns, this will not work, or at least will not be safe.
I suggest diagram A as yours is set up already, plus adding a second relay as Brett correctly explained.
John
'95 Serengeti, Cummins C8.3-300
Allison 6spd.
wolfe10
Posts: 222
Joined: Sun Oct 27, 2019 4:12 pm

Re: Pacbrake

Post by wolfe10 »

Ya, should have one relay for running compressor ONLY.

No need for a relay for grounding (activating) the solenoid.

Here are my noted from how I wired mine:

PacBrake Compressor Wiring UPGRADE: 1997 Safari Sahara

Relay: 40 amp 12 VDC
Signal terminal: Ignition hot source (plenty of them right there in the engine room). 12 or even 14 gauge wire is fine it is just serving to close the relay. To be safe, put a fuse at the power source-- 5 amp is plenty. TO PRESSURE SWITCH. FROM PRESSURE SWITCH TO RELAY SIGNAL TERMINAL.

Signal ground: to chassis ground
Power source/Power in: large-gauge (8 minimum) from chassis battery with fuse sized for 25% more than amp draw of pump installed at battery end. If you have fit a pump with higher than OE amp draw, upsize wire, fuse and relays.
Power out: Power out: to air compressor

Now, the system is powered any time the ignition is on. The compressor runs on GOOD voltage with large gauge wire from chassis battery, not through small wire, small relays and pressure switch. Total cost for wire, wire terminals and relays under $15.

And, while you are at it, look for a nice clean, dry location for the compressor. A location that works on the '97 Sahara is just in front of the inverter in that same basement compartment. I set up a muffin fan in front of it running from the power out terminal of relay #2 so it is on only when the compressor is on.

Brett
Brett and Dianne Wolfe
Ex: 2003 Alpine 38'. Ex 1997 Safari Sahara. Ex 1993 Foretravel U240
Moderator, FMCA Forums 2009-2020
Chairman, FMCA Technical Advisory Committee 2011- 2020
Moderator, http://www.dieselrvclub.org/ (FMCA chapter) 2002-
stuplich@ymail.com
Posts: 1146
Joined: Mon Oct 28, 2019 8:51 am

Vacuum pump (was: Pacbrake)

Post by stuplich@ymail.com »

Mel
'96 Sahara 3530, mine since '01
250 hp 3126 Cat, MD3060 Allison
oldcobia
Posts: 109
Joined: Thu Jan 27, 2022 7:56 am
Location: N. Florida

Re: Pacbrake

Post by oldcobia »

Found out that reason mine wasn’t working was a bad 12v power feed to 30 on relay. Just ran another power feed but now have misplaced pressure switch. Go figure. Realized I am suffering from mental pause. I’m trying to understand how mine will work. Compressor will come on at key to on position. Pressure will build up then shut off when pressure reaches maximum per pressure switch. I have a momentary switch on floor. Also light on dash. So when I activate floor switch I have to hold floor switch on to activate cylinder. I’m assuming light will come on dash to show system is working. Am I correct or off base? Thanks for all your input
1995 Safari Sahara 35’ 5.9 Cummins MD3060
TDJohn
Posts: 552
Joined: Sun Oct 27, 2019 11:34 pm

Re: Pacbrake

Post by TDJohn »

oldcobia wrote: Sun Feb 20, 2022 7:07 pm Found out that reason mine wasn’t working was a bad 12v power feed to 30 on relay. Just ran another power feed but now have misplaced pressure switch. Go figure. Realized I am suffering from mental pause. I’m trying to understand how mine will work. Compressor will come on at key to on position. Pressure will build up then shut off when pressure reaches maximum per pressure switch. I have a momentary switch on floor. Also light on dash. So when I activate floor switch I have to hold floor switch on to activate cylinder. I’m assuming light will come on dash to show system is working. Am I correct or off base? Thanks for all your input
That is correct description of how your Pac Brake was/is set up to work.
If you want to take the load off of the pressure switch and to provide better power to the compressor, you could add another relay as Brett suggested. This relay would use the pressure switch as a signal only, to turn on the compressor when more air pressure is needed. This is a wise improvement, but not a must, especially if electrical is not your strong point.

The pressure switch is usually located on the compressor. I'm not 100% sure what you mean by "you now misplaced the pressure switch"?
John
'95 Serengeti, Cummins C8.3-300
Allison 6spd.
oldcobia
Posts: 109
Joined: Thu Jan 27, 2022 7:56 am
Location: N. Florida

Re: Pacbrake

Post by oldcobia »

My pressure switch is located at compressor. I thought it was bad so I took it off to replace. I put it somewhere so I could replace it. Now after finding out problem may have been something else I cannot find my safe place I put it. Blaming it on my mental pause. There’s about 3 different switches listed for the Pacbrake with different pressure limits. Any suggestions on which one? Thanks
1995 Safari Sahara 35’ 5.9 Cummins MD3060
TDJohn
Posts: 552
Joined: Sun Oct 27, 2019 11:34 pm

Re: Pacbrake

Post by TDJohn »

Considering that your compressor runs the air horns too, you might want something that at higher psi.
My coach is in storage, so I can't help you with part numbers.
John
'95 Serengeti, Cummins C8.3-300
Allison 6spd.
oldcobia
Posts: 109
Joined: Thu Jan 27, 2022 7:56 am
Location: N. Florida

Re: Pacbrake

Post by oldcobia »

Pacbrake update, I got compressor running as it should be. Airhorn works great. First time I used it people in neighborhood thought a tug boat was coming up canal. Hope to try Packbrake system tomorrow. Hopefully it will operate both systems. Also installed vacuum pump like was suggested. Used the small one used on Ford diesels. Works ac controls great. Going to see if it will work on cruise control also. List is getting smaller. Thanks again for all input from members.
1995 Safari Sahara 35’ 5.9 Cummins MD3060
Bilmac36
Posts: 75
Joined: Sun Oct 27, 2019 10:06 pm

Re: Pacbrake...and new Ford Vacuum Pump for Cruise

Post by Bilmac36 »

I have the vacuum pump with me and plan to install this trip. But have honestly pondered while under Connie how to actually get to it to be able to do the replacement. I saw two bolts in existing OEM pump that I should be able to get removed. What angle and from where did you do the actual replacement. I think we have same year coaches. Thanks.
Connie = 1995 Continental 8.3L w/Ally 6 spd.
r/Willie
'95 Safari Continental, Cummins 8.3L, Allison MD3060
Post Reply