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How Can A Jacob Brake Improve On Its Own?
I started to title this thread, “Can a Jacob Brake Improve On Its Own?” but I already know the answer to that. I want to know how.
I drive my bus enough to be familiar with its behavior and its sounds. I mostly pull a 2400 lb car that I can barely feel is back there but I sometimes pull a 16,000 pound trailer that pushes its way around like an over grown gorilla.
I left Ohio on a quick round trip to northern Vermont in September pulling the car. I told my wife that it seemed the Jake was holding me back more than usual. It has always worked great but it seemed better.
We swung through Ohio, hooked up the trailer and started south, not thinking about the Jake any more. Going south on I-65 down the hill into Goodletsville just north of Nashville, I was amazed that the Jake was holding me back well on that hill with the trailer attached. I have went down that stretch 50(?) times with that configuration and I know how it normally behaves. This was better. Much better.
I am now in the northwest pulling the car and I know the Jake is working better than it used to out here. I am familiar with these roads in the bus. Like I said, it has always been good, but it is better. I am always careful on mountain passes, starting slow and in a lower gear but I know the behavior of this bus and I know, or think I know, the Jake is working better.
No work has been done. How is this possible? Am I more insane than what I have been led to believe?
Davy
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6 Replies
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Davy,
You are in the zone and completely in tune with Your coach. You have become a Prevost Ninja ! With enhanced senses You can probably tell when there is a 2# drop in tire pressure. How many miles did it take ?
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Davey,
If you were to expect the Jake would be repairing itself overnight when you are not using the coach you probably would be wrong. But the Jake gets its signals from a couple of wires that go under each valve cover and my best guess to answer your question would be related to loose terminals or poor connections that will work intermittently.
But as you know I make stuff up when I don’t know the answer and that is what i just did.
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Is it possible you had the Jake on the medium setting, and then put it on high?
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You may not have had all 6 cylinders working before. Bill told me at the seminar our Jakes on the low setting is 4 cylinders and the high settings bring on the other 2 for all 6. I just had mine checked at DD in Ocala while getting a tranny service and there is no mistaking the Jake is working even at idle. They also confirmed there is no settings in the computer regarding Jake control, it’s either on or off controlled by 2 wires as Jon pointed out.
You may have had an electrical connection snafu that has corrected itself.
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Your turbo boost gauge is a visual indicator of how hard the Jake brake is working.
If my memory serves me, on LOW I see as much as 7 psi, and on HI as much as 12 psi.
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Mine has low and high and I leave it on high at all times. It has been on high since the day I bought the bus. I have read the argument for better fuel mileage without it but I like to slow down when I let off the gas pedal.
Thanks for the responses.
Davy
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