Installation of Jake Brake on 88 8V92 DD

[Pete Masterson]

The exhaust-type jake brake on my coach is fully integrated into the DDEC. It operates when switched on and you remove your foot from the throttle. It also activates a program with the transmission to downshift (as speeds allow) to increase the jake braking power. (I have found this aspect to be annoying, at times. I've heard of some who have had the computer reprogramed to give an alternate down shifting program with "mode on".)

In general, the jake brake, as it is set up, is quite satisfactory. It's not a crutch so much as a convenience. I always have the option to step on the service brake to slow the vehicle. The jake is at its best when holding a steady speed on a long downgrade. Since it is integrated into the system, I usually leave the enable switch in the "on" position so that the jake engages during normal slowing for a stop signal, etc. Its slowing assistance simply allows reduced pressure on the service brakes, probably extending brake lining life.

Due to the design of the S-60 engine (95 and later 42/43') the jake provides more slowing force than is possible with the 8v92 (as I understand).

I did discover one bug in the system while traveling across Texas (and I thank whomever it was that explained it to me). I was puzzled that when entering a town with a "no jake brake rule" that sometimes the system would not return to normal operation after leaving the town. But then the next day, the jake system worked as expected. It's been discovered that turning off the jake brake system, _while_ the jake is activated, causes the system to be unable to reactivate until the engine (and DDEC) is shut down and restarted. Switching the jake system off while the jake is _not_ active works as you'd expect. (So, I've learned to never turn off the jake system unless it is inactive.)

So what happened when the jake didn't respond as expected (after blundering into the 'bug')? I just pressed harder on the service brake and stopped as needed. Other than the surprise of not having the system operating when it was expected, it was no big deal. Inconvenient, perhaps, but still, not a serious issue.

Pete Masterson

'95 Blue Bird Wanderlodge WBDA 42

El Sobrante CA

"aeonix1@mac.com"

my coach is for sale: http://www.aeonix.com/bbforsale.html

On Jul 25, 2009, at 10:39 AM, Gregory OConnor wrote:

If you want a jake on a ddec I would find out what would be the advantage of running it with the ddec. I bet for the most part the ddec will put restrictions on applying the jake making it idiot proof. like disabling the jake at low speed and disabling the jake when the tps is showing the operator has a foot on the throttle. problem with both is ;I can see where these prompts can stop you from stopping and ;no idiot should be driving a bus.
Many onroad truckers remove the if-than-dont-apply statements from the code, one way or another. they measure stopping force with HP. Curt do you know the stopping force of the jake and Allison retarder? The retarder on CurtS bus is way more powerful than that on my 94pt bus. I'm not a fan of relying on a Jake or the Brakes for that matter but I am a fan of Jake assistance and stopping. I am considering adding a Jake.
Greg of'Tim&Greg
94pt
free man, Horse died and sold the boat on friday.



--- In "WanderlodgeForum@yahoogroups.com", towanda692006@... wrote:

Thanks Curt,

This confirms what I was told as well, We haven;t bought the set yet, so I think I will pass. I haven't found very many technicians who have any knowledge with the old DDEC I system. We were offered a Jake set, minus wiring for $600, which seemed worth reserching.

Thanks for your response.

Ken and Patti Marsh

89 WB40 Towanda

--- On Thu, 7/23/09, Curt Sprenger wrote:

From: Curt Sprenger

Subject: Re: [WanderlodgeForum] Installation of Jake Brake on 88 8V92 DD

To: "WanderlodgeForum@yahoogroups.com"

Date: Thursday, July 23, 2009, 11:41 PM

Ken,

There is no upgrade to a Jake Brake from the Transmission Retarder that I know of. The two units are independent. You use one or the other. I'm in no way an expert here, but I believe you turn OFF the Retarder (switch) and then use the Jake Brake. That is what I have done on our Mechanical Detroit 8V92, and I've been in touch with an Allison dealer to confirm this. My research tells me that you install the Jake for the DDEC, then take the coach to a dealer for re-program utilizing the Jake Brake and making the ECU work properly. Hope this helps.

Curt Sprenger

1987 PT38 8V92 "MacAttack Racing"

Anaheim Hills, CA

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