jacobs exhaust brake 24v to 12v

[lightsOUT]

has anyone ever tried to put a jacobs exhaust brake on a 12v that originally came on a 24v?

 

[ata]

Check with a Cummins shop. I'm sure you will have to put the 60# valve springs in the 12 valve. Other then that it should work fine.

 

[CKelley1]

as ata stated change the springs and it will work as good as a jacobs can but the bd air or pac air will work 10x better. genosgarage has the spring compressor cheap and only takes a couple of hours to change

 

[dresslered]

"... jacobs can but the bd air or pac air will work 10x better"



Not sure what 10x better means, but I carry a heavy camper and have 131k on the OEM brakes with the Jacobs (not to mention that I have never heard of a failure as I have with the other brands). I like the fact that the jacobs operates off of the ECM as well as my gear shift mounted switch.

 

[MonkeyMagic]

has anyone ever tried to put a jacobs exhaust brake on a 12v that originally came on a 24v?

I am running a Jacobs exhaust brake off a 2001 24v on my 98 12v... I also had 60lbs exhaust springs installed... It works flawlessly... can't imagine anything working 10x better... if something did work 10x better, it would launch you through the front windshied...



Because the Jacobs brake off the 24v I got, was wired into the PCM (for throttle on/off), which I didn't have on the 12v... . I used a PacBrake microswitch that mounts under throttle pedal for on/off, and a stick shift mounted BD push-pull type switch for the master on/off. I didn't actually buy the BD switch, as they want a ton of money... I bought an identical switch from a truck store, designed to control a two speed rearend.

 

[lightsOUT]

I am running a Jacobs exhaust brake off a 2001 24v on my 98 12v... I also had 60lbs exhaust springs installed... It works flawlessly... can't imagine anything working 10x better... if something did work 10x better, it would launch you through the front windshied...



Because the Jacobs brake off the 24v I got, was wired into the PCM (for throttle on/off), which I didn't have on the 12v... . I used a PacBrake microswitch that mounts under throttle pedal for on/off, and a stick shift mounted BD push-pull type switch for the master on/off. I didn't actually buy the BD switch, as they want a ton of money... I bought an identical switch from a truck store, designed to control a two speed rearend.

thank you. this was what i was looking for. basically this is my situation. i have the brake off of my 2000 which i took off my truck (its a pulling truck now). my uncle who has a 98 12v was wondering if it would work on his. i was wondering about that wire you were talking about.



another idea i had was... could you just not hook that wire up? then you would manually have to turn the brake off and on right?

 

[CKelley1]

the jacobs uses a orifice in a butterfly to achieve 60 psi back pressure at maximum rpm at sea level. it's efficiency drops 2. 7 % for every 1,000 feet of elevation chang and even at sea level the braking power drops from 130 bhp at maximum rpm to about 20 at 800 rpm in a straight line. combine the two and there is 10 times more braking power at my 7,000 feet elevation and lower rpm that you normally operate at. the jacobs and banks are old technology the bd and pac keep a 65 psi back pressure at any elevation and any rpm this gives you a constant 150 bhp going from a jacobs to bd is like going from candle to a florescent. i have a pile of jacobs in my shop floor to prove it.

 

[CKelley1]

we mount our microswitch on the pump linkage rather than the pedal but does the same i actually like a toggle switch mounted to the shifter better than the jacobs or two speed switch and is only $3 can send pix of all three switches mounted. we run a fleet of trucks and i do not think we installed any two the same way

 

[dresslered]

"another idea i had was... could you just not hook that wire up? then you would manually have to turn the brake off and on right?"



LightsOUT, the ECM wire does not need to be hooked up and I doubt the 98 12v would even support it. You can toggle it manually as you suggested. It is only nice when shifting when you don't want the brake to come on.

 

[CKelley1]

that works just as good. the only thing the micro switch does is to cut the brake off during shift. on a 12v retrofit you are going to wire the switches in series anyway. with the toggle or two speed mounted on the shifter it is very easy to turn on and off as you shift it is also very easy to mount the micro switch on the pump it takes me less than 10 minutes to mount one.