How do I know if I have a Jake Brake?

Scott & Heather · August 14, 2011, 07:47:30 PM

So, I've searched the forums...a bunch. And though this may be a silly question, how do I know whether I have a Jake Brake or not? I have the switch on my panel indicating "Hi" "Lo" or "Off", but I've never noticed the coach behave in a way even when turned on "Hi" that indicates it's doing anything to help me slow down. As my sig states, it's an '84 MC9 with an Allison automatic (lever) and a rebuilt 6v92. Also, I have cruise control, but it has never worked. I noticed that the coach has a round whole in the floor that was plated with aluminum and it has a shift pattern plate on the dash. Seems to me it was a manual-to-automatic conversion. I'm stumped on the Jake for sure....

luvrbus · August 14, 2011, 08:13:34 PM

Only way to be 100% sure is to remove a valve cover and take a look

good luck

akroyaleagle · August 14, 2011, 08:37:10 PM

Take a flashlight and go to the engine.
Shine it down the side of the head between the head and the blower.
If you have jakes there should be a shielded wire going into the head on each side.
You would also need tall valve covers.

Scott & Heather · August 15, 2011, 05:14:42 AM

luvrbus, Bummer, I hope I can figure it out before doing that...but if I must.
Joe, I'll check around today...see if I can find some shielded wire headed into the head. Not truly sure what would constitute tall covers since I have nothing to compare mine to. But interestingly enough, my coach spent most of its service life in Toronto, Wisconsin, Michigan. So when they did the repower in 2001, my guess is that Jakes were left out. No mountains out there.

bevans6 · August 15, 2011, 05:40:49 AM

You really have to look, it's no good guessing. In order to have Jake brakes, they have to actually be there, they have to be installed correctly (big issue is the oil bridges between the master and slave units coming out of adjustment, mine had 1/4" gaps), they have to be adjusted correctly (spec is .062" or thereabouts, masters of adjustment have their own spec, mine were set at around 1/8"), they have to be wired correctly (mine had one of the terminals terminally loose and making only intermittent connection), the buffer switch or other switching mechanism has to work and be adjusted correctly, and the main switch up front has to be wired right (no prize for guessing how mine was wired...).

Perhaps I too will have working Jake brakes soon!

Edit: - for those in or near Toronto, Harper in west Toronto did the blower install on my bus and re-did the jakes at the same time, and ran the rack. No clue how they got it so far wrong.

Brian

buswarrior · August 15, 2011, 07:02:57 AM

Harper recently sold off the Detroit Franchise to Wajax.

Harper seems to be focusing on their truck dealerships now.

Over the last decade or so, they had lost a lot of good young wrenches.

Not much 2-stroke stuff around for them to work on in these parts anymore, hardly ever see anything on their lot like that. And big transit does all of their 2 stroke work internally.

Your experience, no doubt, is symptom/cause/outcome of those decisions for so many to move on.

For a busnut, the search for competent 2 stroke wrenches is never done, and assumptions about the DD dealer may be costly...

happy coaching!
buswarrior

Scott & Heather · August 15, 2011, 10:01:00 AM

Interesting. Well then, it looks like I'll not have jakes for a little while at least. Too many other projects. But I'll add this to the list...no wires were back there and the head covers look short rather than tall (compared to photos of tall covers that accommodate jakes...this has been bugging me for a while, so now I know. Thanks!

Jriddle · August 15, 2011, 07:05:04 PM

My 9 has the switch and has no Jake. I'm not sure if it ever had them but plan on getting them installed. With switch in place I thought it had a set of Jake at some point but maybe the switch was put in and not the engine brake?
It has a 6v92.

John

Scott & Heather · August 15, 2011, 07:08:31 PM

John, my situation exactly. 1984 MC9 with a 6v92 repower and auto tranny. Switch is there, but no jakes.

buswarrior · August 15, 2011, 07:15:49 PM

Not unusual for the jakes to be stripped out at some point in the coach's life.

Parted out on the engine re-build to lower the bill is popular.

One less thing for the driver or mechanic to complain about.

etc etc etc.

happy coaching!
buswarrior

Scott & Heather · August 15, 2011, 07:25:06 PM

Quote from: buswarrior on August 15, 2011, 07:15:49 PM
Not unusual for the jakes to be stripped out at some point in the coach's life.

Parted out on the engine re-build to lower the bill is popular.

One less thing for the driver or mechanic to complain about.

etc etc etc.

happy coaching!
buswarrior

And that's a bummer for us. I'll probably wait until I need to do major work on my 6v92 to mess with jakes. As much as I would love them, they are low on the list....that is until I have to go down a big long hill....

Jriddle · August 15, 2011, 07:29:32 PM

That is until I have to go down a big long hill....

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I went down one yesterday in Montana on the way home. I thought it would be nice to have them. I would think a brake job or two would justify the installation. That is if you are running the west.

John

Scott & Heather · August 17, 2011, 05:07:08 AM

Quote from: Jriddle on August 15, 2011, 07:29:32 PM
I went down one yesterday in Montana on the way home. I thought it would be nice to have them. I would think a brake job or two would justify the installation. That is if you are running the west.
John

We will be at some point. Likely two years from now. In any case once again, the board has taught me something about my coach.