Jake Brake Wiring Options - Add Hi/Lo?

GnarlyBus · June 14, 2017, 12:45:16 PM

When I bought my bus I was told that it had Jake Brakes, but the switch didn't do anything so I fig'd they were removed when the engine was rebuilt. Two years later I pull the valve cover to find them under there. The connections were greased and not working so I fixed the wiring. My bus has a SPST switch to control the Jakes. So they're either ON or OFF. I have a 6v92.

Can I rewire the jakes to have "LO" turn on the left side of the engine and "HI" turn on both sides? Is that how it's done?

I've attached a wiring diagram I've drawn up. Does this work?

Iceni John · June 14, 2017, 12:59:26 PM

You'll need a SPDT switch with a diode. I did this when I rebuilt my Jakes, but just one bank of Jakes on a 6V92 does tiddly squat. I always use only both banks now.

John

GnarlyBus · June 14, 2017, 01:02:07 PM

I was thinking that just one bank might not even be worth rewiring. Maybe I'll just leave it as it is.

luvrbus · June 14, 2017, 01:09:39 PM

Save the wire the 2 stage Jakes are a waste of good wire on a 2 stroke

GnarlyBus · June 14, 2017, 01:24:05 PM

Sounds like I'll skip the mod then. Glad I asked first!

PP · June 14, 2017, 03:43:07 PM

I have used the single stage on mine once since we purchased the bus almost 10 years ago. It was a long gradual grade of less than 4%. My switch was broken (literally-the toggle knob was broken off and left in the on position) when we bought the bus so I installed a new DPDT which turned out to be a godsend when the hi idle switch went t.ts up and left the Jakes in the on position. You know what happens when you step on the fuel and the Jakes are still on, you get a lot of smoke with no go. Thankfully before I ruined anything, I flipped the switch off and continued down the road. Jakes are manually operated now and always seem to only use the hi setting when needed. Longwinded, but hope that helped,

Will

Geoff · June 14, 2017, 04:40:15 PM

I have two stage Jakes on my 6V92TA and I use one bank in my travels. It is good for long declines when both banks slow you down too much. I have the correct Jake 3-position switch with the Hi-Lo-Off plate. I only had to run a 3-wire cable from the engine to the driver's area. I sold a set of Jakes to someone on this board with the 3-position switch and plate, I hope he used it.

--Geoff

luvrbus · June 14, 2017, 07:58:34 PM

He owns a MCI 9 probably has a 3:36 rear gear and a 4 speed Allison 2 stage Jakes are worthless on his setup IMO

GnarlyBus · June 14, 2017, 09:40:32 PM

I've got the Allison AT-740 if I'm not mistaken. I'll get the feel for the full Jake brake experience and go from there. I was thinking it might not do much in a LO setting. Thanks everyone!

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Lin · June 14, 2017, 09:58:41 PM

This controversy comes up now and then. I have a two stage Jake on my 8v71. I probably use it on low more than I do on high. There are grades that I can just coast down on low but would slow down too much on high. I have two separate toggle switches; the second switch is powered through the first. I prefer that to having it all on one switch.

Geoff · June 15, 2017, 01:44:27 PM

Jake bridge clearances make a lot of difference on how strong your Jakes work, even on a 6V92TA. There are two clearance gauges on Detroit 2-stoke Jakes. I only have the .064 gauge and the Jakes are next to worthless on that setting. So I did a little research and learned that you can set them at .064, and then turn the set screw in one full turn more. Now I have Jakes that actually work! One bank, or two banks-- you can feel them slow the bus down.

--Geoff

GnarlyBus · June 15, 2017, 02:16:48 PM

Hmmm. I was wondering about the clearances. Having just rewired my Jakes, I haven't gotten the chance to test 'em out on the road yet. One week and I'll be moving somewhere else here in Central Oregon.

I found the manual for Jake Brake Install in the 92 and I've attached the section on the adjusting the clearances. Is this what you're referring to? I may have to adjust them soon.

Iceni John · June 15, 2017, 02:51:09 PM

Quote from: Geoff on June 15, 2017, 01:44:27 PM
Jake bridge clearances make a lot of difference on how strong your Jakes work, even on a 6V92TA. There are two clearance gauges on Detroit 2-stoke Jakes. I only have the .064 gauge and the Jakes are next to worthless on that setting. So I did a little research and learned that you can set them at .064, and then turn the set screw in one full turn more. Now I have Jakes that actually work! One bank, or two banks-- you can feel them slow the bus down.

--Geoff

That's almost certainly why my Jakes are bloody useless on one bank, and fairly underwhelming on both. (I did however come down Cajon Pass without touching my brakes at all, so they're OK for 6% grades, but that's with a 4.1 axle.) I set mine to a tight 64 thou, but still not appreciably less than that. Everyone told me to not set them tighter on a DDEC engine or Bad Things would happen - are the camshafts that different between MUI and DDEC? Barring the engine over won't tell me if I've run out of clearance because the Jakes' valves won't open without oil pressure and closed solenoids.

Is there anyone here with a DDEC 92 who has set their Jakes tighter than 64 thou?

John

luvrbus · June 15, 2017, 03:03:58 PM

John, .059 is used on the DDEC and the cams are different than a MUI engine ,I have used the .059 Jake gauge on DDEC's for years and it has never caused a problem yet

Iceni John · June 15, 2017, 03:36:03 PM

Quote from: luvrbus on June 15, 2017, 03:03:58 PM
John, .059 is used on the DDEC and the cams are different than a MUI engine ,I have used the .059 Jake gauge on DDEC's for years and it has never caused a problem yet

OK, good to know, thanks. I'll buy a 0.059 gauge and try it. I can't imagine another 5 thous would cause valve crash, especially if Geoff cranks his down so much on a MUI.

Thanks, John