Jake switch help

[Kitt]

All-

I am looking into why the jake brake doesn't work right on my 8v71, which the PO had disconnected because "it didn't work right." The first issue was that the switch on the governor was bypassed, which then just "allowed" manual control... or didn't shut off when expected. Not good.

My next task is where I need help - getting the switch on the governor set up right. The governor has the non-Jacobs high idle air actuator installed (just the actuator, no switch). The microswitch for the jake is on top of the governor. I'm assuming that it should activate the jakes in a "no fuel" situation but not at idle so leaving the dash switch on won't cause the jakes to kill the engine, right? I haven't taken the bus out on the road yet to try and see if the jakes activate at the right time yet because right now when the engine is idling they come on intermittently.


View from the bedroom, on top of the engine

Does anyone have a setup like this? How should the microswitch be adjusted? I don't use the high idle, so I could certainly remove the actuator and out in the Jacobs buffer switch, but I'd rather not spend the money if I can make things work right with what I already have.

p.s. I have the Allison 740 and there isn't a clutch switch installed. Once I get the issue above resolved I'm going to install the proper lock-up sense switch on the transmission so the jakes only come on when I am decelerating and the transmission is in lock-up.

Thanks everyone.

[luvrbus]

Do you have Jakes on both banks on the 05 if you do post some photos of the air horn so people wanting to install Jakes on the 05 and 01 can see the work involved to install the Jakes on the right hand bank. 

Most 05's and 01 Eagles just came with Jakes on the left bank fwiw

The Micro switch you have is a common setup on the older engines not the best but it works sometime lol if you don't need the fast idle there was a guy on Ebay selling the buffer switches for under a 100 bucks .

Remove the micro and on the other side it should have a diode when those go bad or somebody removes it that will cause your intermittent of the Jakes engaging at idle  

The buffer is the way to go if the guy on ebay is sold all of his I have a stash I bought from him and you can have one for what I paid contact me through the Eagles board I think you are a member there

good luck

[Kitt]

Thanks for the info, Clifford. I'm assuming that the diode is external to the switch (not part of the switch) and in that case there is no diode. I'll have to dig one up and get it on there.

Looking back at the switch and when it contacts, in the position I took the photo the switch is sometimes engaged and sometimes not. Like it is right on the hair's edge of activating and sometimes does. Do you know how that switch should be adjusted and at what point (in the motion of the linkage) should the switch be activated?

If I do replace the high idle with the Jacob's buffer switch it is really an easy thing to do? From what I've read I just need to go out and get tachometer gun (my bus doesn't have a tach) to verify the idle speed and no-load max. Right?

I'll run out and take a photo of the air horn and valve cover area. I don't envy the mechanics at all...

[Kitt]

Looking again at the setup and watching the mechanisms all move on top of the governor, I can only figure that the microswitch in the location were I have it will only ever sense when my foot is off the pedal. If that's the case, then that switch setup could let the jakes operate at idle and when stopped (not optimal). Unless I'm figuring wrong, the lock-up sense switch on the transmission in combination with the existing microswitch would keep the jake from engaging while the engine is idling and/or at a stop by function of when the transmission would be in lock-up and not. Right?

Clearly the buffer switch (the real one from Jacobs) is then the best way to go since that truly senses a "no fuel" in the governor which is when I really want the jakes on.

[Kitt]

Oh, and here are the pictures of the valve cover under the air horn. A tight fit...