Jake operation

[Mike in GA]

Having a set of jakes installed on my MC 96a3 - 8v92TA.
    I am confused about my choices for switches to operate them.
    If I understand correctly, I need a switch that goes, 'off-low-high' on the dash and something called a Fast Idle Buffer switch on the engine.  With this setup the Jakes will come on automatically every time I let off the accelerator (provided they are switched on.)
    Others have said that I can get by with the 'off-low-high' dash switch and a foot pedal/treadle to operate them when I choose. The downside here I am told is that I must avoid actuating the jakes and being on the accelerator at the same time.
     Do I have this right?  If so, what do members recommend? (Having  a hard time finding the above buffer switch.
Thanks for your input.
Mike in GA

[bevans6]

My thinking is that you don't want the jakes to come on when the rack is not in the no-fuel position, which is not the same thing as when you are off the accelerator.  People have done what you suggest, but the right switch is the better way.  You don't "need" the three way toggle switch, mine are set up with a simple on/off that enables all of the jakes, not just one bank then two banks.  I do have the correct high-idle buffer switch.

I don't know what the actual downside of having the jakes on by accident at idle, or with the accelerator pedal engaged.  Obviously the exhaust valves will be opening and the injectors will  be injecting fuel, but I don't know the risks of that happening.  I can imagine all sorts of funky things happening inside a turbo if it gets filled with unburnt fuel and that gets ignited...

Brian

[TomC]

The combination buffer/high idle switch that mounts on the governor is a pricey switch.  I chose to just use as simple buffer switch, thus eliminating my fast idle-although I can do fast idle with my King Cruise control.  I also recommend you use the off/low/high switch.  If you have your Jake properly adjusted, then the low switch position only activating one head will come in handy-rather then turning off and on the Jake as you slow down to much.  You could put a simple micro switch on the gas pedal so that when you push on the gas pedal, the Jake would deactivate.  But the advantage to the governor mounted buffer switch is that if you're up against the high speed governor, and start to over speed the engine, with the Jake turned on, it will activate the Jake no matter what position the gas pedal is in-sort of a saver mode for over speeding the engine.  Good Luck, TomC

[papatony]

Tom C is right you want a choice of light breaking and hard breaking. If you go with only the on or off you will be in full break all the time.

[Lin]

We went with a standard buffer switch and gave up the high idle.  I haven't missed it yet and, as Dallas used to say, a brick can work as a high idle switch.  I connected the Jakes with high and low but used two separate switches rather than one 3 position switch.  I like the arrangement quite a bit.  The second switch is powered through the first.  The first switch turns the Jakes on low (one bank).  Flipping the second switch turns the full system on.  You can toggle back and forth from high to low using only the second switch, or you can leave it in high and toggle on and off with only the first switch.

[JackConrad]

I installed a 3 PSI NC pressure switch in my air throttle. I first installed a pressure gauge and found it took 5 PSI to start opening the throttle. So the 3 PSI switch turns off the jake before the throttle starts to open.  We also installed a 65 PSI NO pressure switch in the transmission lock up test port. This turns off the jakes when the transmission comes out of lock-up mode (Jakes provide no braking when the transmisssion in not in lock-up mode).  We went with a simple on or off dash switch (all or none). After 12,000 miles we are very happy with our installation and we still have our fast idle.  Just "Our Way" and it works for us. YMMV.  Jack

[Lin]

Jack-- my Jakes turn off when the transmission comes out of lockup.  I thought that that was the default.  I was told we could change something at the transmission to keep it in lockup if the Jakes were active.

[JackConrad]

Something has to tell the Jakes when the transmission comes out of lock-up, maybe you already have that switch?  I know one busnut that added a solenoid that allowed him to take pressure from the main line test port and run it through the solenoid into the lock-up test port to keep the torgue converter in lock-up mode. Only downside, I was told, was that it you did not turn off the solenoid as you came to a stop, it would kill the engine.  Jack

[Lin]

I keep meaning to look into that.  I have a dash light wired to come on when the Jakes are on-- not just when the Jake toggle is on-- so I can see them going on and off depending on the transmission mode.  The switch to keep the transmission in lockup, and therefore Jakes engaged, would be useful in coming down winding grades in low gears which have a tendency to drop the Jakes when you really want them.

[luvrbus]

Why even worry the 2 strokes don't have enough oil pressure at low rpms to make the Jakes work right big waste of wire and switches for 2 stage brakes on a 8v71


good luck

[Lin]

Clifford, I figured you would chime in but I sure have to say, I does love my 2-stage.  Maybe they work better on a little 5a than they do on those massive Eagles.  A 10,000 pound weight difference could change things a bit.

[TomC]

When I pull my car, I weigh just under 35,000lbs.  With my 8V-71 Jakes adjusted by Don Fairchild, when coming down the Grapevine (5 miles of 6% grade) I have to switch from single head to both heads, or I would be left with having to turn them on and off the whole time.  I can say without a shadow of a doubt, that having a two position Jake switch is both convenient and gets used.  Good Luck, TomC

[luvrbus]

What gear 2nd or 3rd TOM and I know you have a low rear gearing a 2 stage will do you no good with a coach with 3:33 rear gears in 4th coming down the grape vine been there to many times.
Don is a good friend of mine and I tell him 2 stages on the 2 strokes are a waste of wire for the average Joe we all do it different and you being a x trucker is a little different than most of these guys you know how to start a descend on a long grade you never put your safety first by relying on Jakes they fail OBTW I also know how to adjust a Jake and I will not install a 2 stage for the average person just my way gives him less to think about when white knuckling down a incline


good luck

[TomC]

I cruise at 58mph which is 1850rpm (V730 with 4.56 and 11R-24.5's).  That's what I come down the Grape Vine at since RV's are not affected by the truckers speed limit-so I'm in third.  Coming down from Shaver Lake, Ca, the hill is more towards 8%, I gear down to 2nd and come down at about 40mph.  I was on highway 4 from highway 395 to Angels Camp and went over Ebbits pass-never again!  I was in 1st the whole time (on the east side) and extremely thankful for my Jake Brake.  Good Luck, TomC

[Lin]

Tom,

That is the issue I was referring to.  Although I have not been in that situation much, it would sure be nice for the Jakes to work in 1st and 2nd gear.  This would require keeping the transmission locked up.