Author Topic: Jake Brake combinations on 8V71  (Read 16672 times)

Offline Buffalo SpaceShip

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Re: Jake Brake combinations on 8V71
« Reply #15 on: June 23, 2006, 08:38:35 AM »
I think the reason two-strokes may not be as effective is because with four-strokes there's a full rotation where the exhaust valves are closed and compressing. Here's a nice graphic (with sound): The two strokes are always either intaking or scavenging/ exhausting, so I don't see how they could ever be as effective.

My 8v71 with Jakes wasn't near as dramatic of a deceleration/ hill holding as I had expected. I just have the on-off (both banks), so I wouldn't find a single bank very useful. But I do a lot of high-altitude driving where I live, so that might make a difference, too (less denser air??). And the downgrades are fairly dramatic. My Jakes might not be adjusted right, either.

Jack, if you haven't set yours up yet, go ahead and run the wires from the front for multi-bank and then you'll be set if you decide you need them. Add the relays and switches after you run the on-off for awhile and find you want more options.

But I also like the KISS principal... that's why I have a GMC & MUI engine.  ;D

Brian Brown
Longmont, CO
Brian Brown
4108-216 w/ V730
Longmont, CO

Offline Hobe

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Re: Jake Brake combinations on 8V71
« Reply #16 on: June 23, 2006, 03:12:57 PM »
The Jakes work real good but not as good as on a 4 stroke. I have had them on 4 different coaches and all were eather on or off. When going down the road I leave my on as they are a big help when you let your foot off the gas pedal, To go off the Inter State. Saves brakes and makes slowing down a lot quicker. There for I vote all or nothing. Fred North Florida Bus Conversion. By the way they do not make near as much noise as they do on 4 stroke.

Offline JackConrad

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Re: Jake Brake combinations on 8V71
« Reply #17 on: June 23, 2006, 04:20:33 PM »
Thanks for all the replies.  When I prchased my Jakes, I found a deal on Ebay.  I purchased 14  24 volt Jake "masters". Every one has a solenoid.  I plan to run wires from each Jake to a terminal strip strip in the engine compartment.  This will allow me to connect them in any combination I want to try. the only parts I still need are the longer fuel jumper lines if anyone has any or knows of a good "cheap" source.  Jack
Growing Older Is Mandatory, Growing Up Is Optional
Arcadia, Florida, When we are home

Offline niles500

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Re: Jake Brake combinations on 8V71
« Reply #18 on: June 23, 2006, 06:07:11 PM »
Jack - I have the 2 speed on my 8v and I use both - although my "brick" is aerodynamically challenged as apposed to some of the sports car models - probably why half jake works better sometimes in combination w/ my wind resistance quotient (but I more than make up for it in the mass/gravity category) - half jake is great for the rolling hills where your trying to not overspeed on short downhills - FWIW

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Re: Jake Brake combinations on 8V71
« Reply #19 on: June 26, 2006, 08:57:08 AM »
After going over the installation of the Jakes on my engine last Friday I learned a couple of things. (ain't life wonderful?)
 He added a solenoid inside the governor ($345.00) in place of the High Idle Solenoid which will give me both the High Idle back and does the switching 'on' of the brakes.  It's all or nothing. 

There's either a Master or a slave on each cylinder (the slaves are connected, each to a master) and the new solenoid allows only operation of all 8 simultaneously.  Remember though, that these are 4 valve heads the jakes only close TWO of the 4 valves.  Another reason that Jakes on a Detroit aren't as noisy as on, say a Cummins.

After getting my 'hands on' classroom lesson of the day I came away from that meeting with two things in mind.  First, the quality of the product from Jacobs, and secondly the joys of knowing and having a top mechanic like Dave who not only knows what he's doing but is willling to take the time to explain the where, when and why of what he's doing.

My unqualified thanks to "Uncle Ned" for sending me and my Bus to Dave! ;D



Offline TomC

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Re: Jake Brake combinations on 8V71
« Reply #20 on: June 26, 2006, 09:19:35 AM »
NCBob- You can change the wiring to accomplish the high-low switching if you want.  If the power is from the dash, the you have a wire going back to the controlling solenoid.  Then instead of having this wire going directly to the two heads, bring that power wire back up to the front (the easiest would be just to get a 50ft 3 wire extension cord to run back up to the front). Use a double pole double throw switch.  Power in the middle of the switch. One side will be one head only other side of the switch will be both heads on either throw of the switch (so you don't power both heads on low).  But maybe just keep the straight on/off.  Good Luck, TomC   
Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.