Author Topic: How to effectively test a new Jake Brake Installation in Flatland?  (Read 2801 times)


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I'm finally putting all the peices together for a full set of Jakes for the old bus...missing a few 24V solenoids (anyone know of any) but hope to have it altogether by next week.  The bus will be in the shop for a week or so, but my main question is:

How does one effectively test the proper operation of a Jake installation in Flatland?  I darn sure want to test its' effectivness before I start over the mountains to come home.  I'm led to believe, from some of the more learned ones on the boards, that higher RPM's increases the braking power of these things  so testing in 3rd gear aroundsay 1900-1950 turns would seem to be a practical place to start.  Then switching in one bank, observe braking back up to 1900-1950 and switch in the second bank....grab steering wheel tightly (avoid white knuckle syndrome) and observe braking effect.

Would that sound about right?   Any sane suggestions would be appreciated.


Offline boogiethecat

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Re: How to effectively test a new Jake Brake Installation in Flatland?
« Reply #1 on: May 23, 2006, 05:40:13 AM »
I think you have the right idea.
What you want to do "first" is test that they work at all, not necessarily how much.  So (this is how I did mine ) get out on a flat road somewhere where few are around,
get her going as fast as you dare in the last gear you have, and turn the jakes on.  You'll immediately feel the effect if they work.  Try a single bank first and get a feel for
how much braking power is happening, then speed up again and try more banks.  You should feel more.

If/when you're satisfied that they work, try the same test in a lower gear, they'll slow you down much faster.   You'll get a feel for them this way.
But the real test will be on a grade... once you've satisfied yourself that they do "something" on the flat land, the only way to find out how much they will actually do is come down a hill using a speed/gear as if you didn't have them, and play with them.  You'll immediately see what they are capable of.  As your confidence builds, you'll get the hang of using them, and figure out how much faster you can safely go down that hill, keeping in mind that they may fail someday and you may have to remember how slow you used to come down that grade.  But if that happens, your brakes will be nice n cool and ready to slow you down to a reasonable speed... then you can safely proceed just like you did in the old days.

Yes, they work better as RPM is higher.  But you'll be able to feel them at almost any RPM so it's not really that important for a test.

What kind of solenoids do you need? What engine/year etc... I may have a few sources or ideas for ya

« Last Edit: May 23, 2006, 05:43:43 AM by boogiethecat »
1962 Crown
San Diego, Ca


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Re: How to effectively test a new Jake Brake Installation in Flatland?
« Reply #2 on: May 23, 2006, 06:45:42 AM »
I didn't expect a response so quickly.  You must be a 'night owl' up so early in the AM!

My engine is a NA 8V71 of the 70's vintage. No electronics.  I'm going to need (4) solenoids (24VDC) a buffer switch and a clutch
switch, although there are differing opinions about the clutch switch..but my thought is that if the Engineers who designed this thing
felt one was necessary...that's why they included it.

I was studying the wiring diagram... and looking at the selector switch for switching either one bank or both and I find an error in the second diagram unless the selector has the ability to energize two poles of the switch at the same time.  Down, would be "off"  deenergizing the top pole.  Center position would conceivably switch in one bank (energizing the
top pole (?) ) and Up should only energize the lower pole and switch back to one bank.  Or that's the most cleverly designed switch I've ever seen!

My mechanic tells me that a simple On/Off switch is the best and most simple situation on a Detroit because when you want 'em...
use 'em all.  Being two cycle the RPM's will fade rather quickly.  Concur?

If you can lead me in the right direction for the solenoids and clutch switch I'd be appreciative.  I understand that there's a new (encapsulated) buffer switch....and the seller mentioned that he didn't have a required bracket for the governor housing.??????

Thanks for the comeback


Offline phil4501

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Re: How to effectively test a new Jake Brake Installation in Flatland?
« Reply #3 on: May 23, 2006, 08:45:36 AM »
How much should oe expect to pay for the set up you have on the same engine? Were you able to keep the fast idle?

Offline JackConrad

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Re: How to effectively test a new Jake Brake Installation in Flatland?
« Reply #4 on: May 23, 2006, 11:26:27 AM »
I have what you need.  I know we are not supposed to advertise on here, so email me if you are interested.  Jack
Growing Older Is Mandatory, Growing Up Is Optional
Arcadia, Florida, When we are home