Skip to main content ↑ ↓
Topic: Adding a Jake brake  (Read 4914 times) previous topic - next topic

Re: Adding a Jake brake

Reply #60 –
Did you have second and second lockup? If I'm slowing, there is no problem selecting and getting the right gear. The problem comes when starting downhill without any throttle.

P

Re: Adding a Jake brake

Reply #61 –
I don't know how a Jake acts with an automatic transmission, but we have a term out here called a "flat land jake"
When a stick shift is accelerated with the Jake on it causes the motor to drop revs much quicker than normal allowing for faster shifts. Oh yes and it makes a hell of a racket.

Re: Adding a Jake brake

Reply #62 –
Quote from: oldguy –
Does anyone know were the trans computer is located and how to wire it so it would get the signal to shift down.
The Allison ECU on our coach is mounted on the firewall under the dash in front of the driver seat.  Don't know if the same on your newer coach.

Reprogramming the ECU must be done at an Allison shop.  The photos below show my ECU when I removed it to send it in for repair.  You can see the sticker that indicates when it was reprogrammed for the original owner of the coach (same time he had the exhaust brake installed).


Re: Adding a Jake brake

Reply #63 –
Quote from: Olde English –
I don't know how a Jake acts with an automatic transmission, but we have a term out here called a "flat land jake"
When a stick shift is accelerated with the Jake on it causes the motor to drop revs much quicker than normal allowing for faster shifts. Oh yes and it makes a hell of a racket.
Any Jake with an automatic transmission I've driven does not activate until your foot is totally off the accelerator. Then, just before the vehicle stops, the Jake disengages automatically. The 2 cycles don't make nearly as much noise but not quite as effective as in a 4 cycle.

You must be saying that when you accelerate with a manual gearbox and go to shift to the next gear, the RPM drops faster that when the Jake is turned off. That would make a much faster shift with a crash box. Excellent.

Pierce

Re: Adding a Jake brake

Reply #64 –
This is my second trip to Whistler with the Jake. Last week going home it quit and then going down the longest hill, I was just goin to
apply the retarder and it came on. It worked all the way down the hill and I switched it between 3 and 6 cylinders and then it quit for
the rest of the trip. Over the weekend I checked the plug that is up by the valve cover. It was loose so I took pliers to the female part
of the plug and the trip up to Whistler Sunday night, the Jake work flawlessly. I added the retarder once on the trip.

Re: Adding a Jake brake

Reply #65 –
This is my second trip to Whistler with the Jake. Last week going home it quit and then going down the longest hill, I was just goin to
apply the retarder and it came on. It worked all the way down the hill and I switched it between 3 and 6 cylinders and then it quit for
the rest of the trip. Over the weekend I checked the plug that is up by the valve cover. It was loose so I took pliers to the female part
of the plug and the trip up to Whistler Sunday night, the Jake work flawlessly. I added the retarder once on the trip. I left the
Jake switch in the on position so the Jake comes on when the throttle is released. In that position in cruise the Jake will come on
as soon as I go over the set speed. All I have to do it manually shift down if I need more braking.

Re: Adding a Jake brake

Reply #66 –
It is sure nice having both the Jake and the Retarder. There is some hills at Whistler that I go down in 2nd gear just off idle and
the retarder is perfect for that. In the snow there is more control with the retarder and it comes on quicker. On long hills if the
Jake isn't holding I can add one notch on the retarder and hold my speed or I can use the retarder to slow the rig down so the
trans will shift into a lower gear and then the Jake will hold. Some of the grades are 9%.

Re: Adding a Jake brake

Reply #67 –
Quote from: oldguy –
It is sure nice having both the Jake and the Retarder. There is some hills at Whistler that I go down in 2nd gear just off idle and
the retarder is perfect for that. In the snow there is more control with the retarder and it comes on quicker. On long hills if the
Jake isn't holding I can add one notch on the retarder and hold my speed or I can use the retarder to slow the rig down so the
trans will shift into a lower gear and then the Jake will hold. Some of the grades are 9%.

Old guy, read here and elsewhere you shouldn't use retarder, cruise, Jake etc on slick surfaces.  Whats your secret?

Re: Adding a Jake brake

Reply #68 –
Yes I have read that and I agree if either one comes on with the throttle. When bringing the coach home after buying it I forgot
to take the retarder off and I took my foot off the throttle and the coach slid and I quickly put my foot back on the throttle and
everything was fine. I think I prefer the retarder for the snow as it is more predictable. I will use the Jake in the snow also on the
long hills. I put a foot peddle in and I have to shift down manually so again I'm in control. The M11 is usually running from
1200 RPM to 1500 RPM so the Jake doesn't come on vary hard. In driving in snow the retarder joy stick has to be in the off
position. I feel I have more control this way and my snow tires are on the rear. When driving rear drive cars I always shifted
down.

Re: Adding a Jake brake

Reply #69 –
The Jake is the most effective at higher RPM and on our 2-cycle, it never is strong enough to cause the rear tires to lockup on wet roads. If there were to be a question, I would switch to 3 cylinders instead of 6. Plus, the Jake is only secondary to the service brakes. Waiting to get underway until morning black ice has melted is always a good idea.

I never turn it off, it's on all the time.

We never drive in snow with the coach as even one trip on wet treated roads can cause a lot of future corrosion with the design of our undercarriage. No matter how well you wash it afterwards, some residue will always remain.

Pierce

Re: Adding a Jake brake

Reply #70 –
Well Pierce being a skier not much choice as the best skiing includes snow on the road. I put in a foot peddle so I can put it on
manually or have it work when the throttle comes off. I also want to put in a second peddle that will shift it down automatically
when the second foot peddle is installed. First I have to find the ECU for the transmission, any one know where it would be
on a 99 U320

Re: Adding a Jake brake

Reply #71 –
Quote from: oldguy –
First I have to find the ECU for the transmission, any one know where it would be on a 99 U320

That is getting close to when they moved it to the basement but first look behind the carpeted kick panel just beside where your left foot sets when you are in the drivers seat. If it isn't there then it most likely is hid in the basement somewhat behind and above the HWH compressor on the basement wall.

Mike

Re: Adding a Jake brake

Reply #72 –
Thanks Mike I will check tomorrow.

Re: Adding a Jake brake

Reply #73 –
I have checked, the only boxes I find in the basement are the ABS and the box for the leveling system. Nothing behind the kick
panel. I have tried to trace the wires from the shifter, no luck. I don't even know what EUC looks like.

Re: Adding a Jake brake

Reply #74 –
Quote from: oldguy –
I don't even know what EUC looks like.

If it was behind that kick panel just below the shift pad it looks like a little silver box about 3" wide and 5' long by 2" thick.

I bet it is hid behind that kick panel as when they moved it to the basement it will be in plane sight right where you were looking. 
Somewhere here on the Forum is a pic. of both locations. I will see if I can find them and post a link.

Mike

Here is a link to a thread for what one looks like for about your year model
Chassis construction photos from Don and welding on your FT

I can't find the pic. of the one hid behind the kick panel

Re: Adding a Jake brake

Reply #75 –
Mike the cable from the shifter goes under the dash on the left side heading towards the front and disappears into a maze of
wires. 

Re: Adding a Jake brake

Reply #76 –
Well your coach must have a new hiding spot for that Allison ECM,  those two places is the only ones that I have dealt with. Redtractor may have some idea.

Mike

Re: Adding a Jake brake

Reply #77 –
Thanks Mike, luckily there is no hurry to find it.

Re: Adding a Jake brake

Reply #78 –
I finally found it and it is in the basement and it is tucked under a angled cover at the rear and beside a drawer. I will take a picture
of it tomorrow and post it. Does any one know if there are any spare wires from the dash to the basement area.

Re: Adding a Jake brake

Reply #79 –
Here are the pictures of the ECU and with out a light I might have not found it.