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My Bus is now home where the Buffalo Roam
Yes-Sir-Re-Bob, My bus is back home! But not yet ready for prime time…
I was maybe halfway home when my first hill of consequence arrived. As I was reaching over to downshift shift the ol tranny I remembered “Hey, Jeff fixed the Jake brake”! Reaching down to the dash I pushed the Jake button into position 1 and guess what? Nothin! No reason to panic I’m only going 95 with an S curve coming up. But not to worry I still have position 2 on the Jake and now going 125 into an S turn with a sign saying 20 mph I felt it a good time to kick it into motion. Guess what??? No Jake Brake 2 either!
There may be parts of the above story not exactly accurate, I never intended to downshift the tranny! But the bottom line is NO JAKE BRAKE ahhhhhhhh!
Since I’ve been back, based on what you guys told me on line and at the seminar. You convinced me I’m better off with an outside space with 50 amp power than in a garage without power for the winter. Today I made arrangements at the new RV park here in town for a space from November 1 through April with full power. It also has full hook-ups but I’ll just be using it as a storage space.
In the title I mentioned buffalo and I was just kidding about that. I know how some of you enjoy nothing better than Bison-Bashing!
Harry
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36 Replies
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Harry,
Glad to see that you will have electricity while you store your coach during the winter.
I can see you pulling a ‘Fred Flintstone’ trying to stop your coach in the curve!
Safe travels,
Mark
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That’s funny Mark, I’d forgotten about that!
I’ve been told many times how engaging the Jake is like throwing out an anchor! I look forward to having that experience.
Other than that the bus is running like a top!
Harry
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Harry,
If you don’t have the transmission downshift for you, you have no choice but to do it yourself. You have hardly any braking in 6th gear with the Jake on. Did it work at lower speeds?
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Hi Per,
Mine is a 5 speed and I know from conversations that the Jake shifts to a lower gear. I did not notice that, all I know is everyone has told me when the Jake is activated its like throwing out an anchor! Mine felt like throwing out a Jello mold! I felt no slowing other than what I normally feel when lifting off the peddle.
I spoke with Jeff earlier today and he told me the next time I drive the coach to open the drivers window, set the Jake to 1 or 2 and see if I hear the roar typical of the Jake actuating?
Harry
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Harry, the Jake won’t shift to a lower gear if it is not programmed that way. Many folks on PC prefer to not have the transmission downshift, so they have to manually downshift like manual transmission equipped trucks have to do to get any braking action out of the Jake. The lower the gear, the more braking you get out of the Jake. You should be able to hear the Jake when it engages, especially if you are next to a wall or in a tunnel.
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But shouldn’t I feel an obvious slowing and a pulling against forward movement? I go back to the old “throwing out an anchor” statements that I’ve heard so often. That means to me “you can’t miss the Jake has been actuated because it pulls you back like an anchor”, is that not right?
Harry
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There is not much braking effect in 5th or 6th gear. But you should hear the jake when you open the driver window. Shift into 4th or 3rd gear and try the jake again.
The jake also won’t come on if the electronic gas pedal does not completely retract. Make sure it is not hung up on carpets. Usually restarting the engine will recalibrate the pedal.
Gerald
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Harry,
The throwing out the anchor doesn’t happen until you get down to forth, third or second gear. Hardly any braking in top gear. Have you tried to manually downshift with the Jake on?
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Per,
Try not to confuse the issue by relating your Jake and the 6 speed because the Jake with a 5 speed is different.
Harry,
I know you like to use humor but it makes it difficult to understand if you have an issue, question or concern. I think you need to help us try to help you by being somewhat specific as to what is or is not happening such as the circumstances when you think the jake is not working and save the humor for a more appropriate time.
You may not understand its operating method but it is not like throwing out an anchor unless you drive it aggressively.
If your jake is “on” and in the high setting every time you lift from the accelerator the jake will engage at its maximum strength. That strength of engine braking however is dependent upon engine speed. Your jake may engage but it will not drop a gear because on your coach you have to do that manually.
In order for you to do that you have to know your speed and what gear at that speed will give you a safe engine speed high RPM. If you are in 5th for example at 1700 RPM the jake may offer some assistance, but if you downshift to fourth you may be at 2000 RPM and the jake is going to be much more effective. But it is not going to be as effective as a jake on later engines because yours only operates on half the cylinders whereas later engines all cylinders will function with the jake.
As your coach is set up you have the burden to manually control the jake and engine speeds via gear selection. You have to know what gear to be in based on your speed to get the max performance from a jake system that is only working on 4 of your 8 cylinders.
Do you have pyrometers? If they are working you can immediately determine if the jake works. When the jake is not engaged and your foot is off the gas pedal the pyrometers will read close to zero. Engage the low setting of the jake and one pyrometer will rise from the heat of compressing air in the cylinders, and engage the high setting and both pyrometers will show heat. On a long downhill with a high RPM you might see about a 300 degree reading on both pyros.
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Harry, On my coach, which is the same as yours, there is a definite tug on high when you hit them. I can hear them also if the TV or sound system isn’t on. Only time I paddle down shifter is when I need to stop in a hurry. If you have a Detroit Dealer close would have them look at it. Use mine all the time and have saved the brakes a ton.
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Harry
As others above have said, you must determine what your top rpm in each gear has. When motor attains that rpm or lower you can downshift transmission for max Jake. You DDEC II Jake is gas pedal activated. Only way I know how to describe it. Once in driver seat, motor running low idle, you can goose gas pedal quickly punching, then taking foot off it and hear Jake exhaust noise. Also, if coach is on fast idle, you can switch FI off and hear slight exhaust warble. Your two speed Jake brake offers you choice of Jake drag. Being a V-8, position one is one bank of four out of your eight cylinders. Position two gives both sides of your V-8. As I said above, unlike Series 60 engines, you can test your Jake by punching quickly your gas pedal without moving. Do it with driver window open or have you wife stand outside when quickly goosing gas pedal. Goose pedal with Jake switch off then again with switch on. Listen to hear more exhaust noise when it’s switched on. You may also see tach slow faster with Jake on. All this is done stationary
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My rear view Cam has audio. Turn up the volume knob and I can hear the Jake. As others have said , Try it with window open and passing some structure like an underpass or tall buildings. You should be able to feel it and hear it. Good to hear that You worked out storage with the park to have 50 A.
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Hi guys and thank you all for your response,
This is a lot to take in… I didn’t know you had to downshift when using a Jake brake. I’ve read that some coaches drop a gear automatically and some have had the computer changed so it drops two gears instead of one. But that was a computer situation, I didn’t know that Jake brakes like mine, required a manual shift of the transmission! I don’t like taking my eyes off the road to select the right gear but I’m sure I’ll eventually know the shift pattern by touch but I’m not there yet.
If I have this right, here are how things work… (I will listen to make sure I hear the Jake sound)
• Take your foot off the brake in 5th gear (remember I have a 5 speed) and little happens.
• Take your foot off the brake and shift to 4th gear and the Jake is more helpful.
• Take your foot off the brake and shit to 3rd gear and the Jake is even more helpful etc.
On my way home I did shift to a lower gear going down hills, but I don’t remember if I left the Jake on at that point? Once I determined it wasn’t working (or not working as I expected) I may well have turned it off. I’ll take my bus out for a run next week to see what it does? I’ll report back to you!
I’m really surprised with all the reading I’ve done here and on the plastic coach forums that I’ve not read a Jake requires a manual downshift. I thought you put on the Jake and everything else is automatic once you take your foot off the peddle? I’ve downshifted my SUV two gears on a hill all the time. But I didn’t have a Jake and thinking it would slow me down on its own. I’m glad you guys help straighten me out!
I hope that my lack of HUMOR on this post didn’t keep you from understanding my intent!
Harry
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Harry, Mine doesn’t require a manual downshift for jake brake to work. It pulls down and automatically downshifts and will until it hits bottom of gears. Just not as abrupt as pushing the buttons but stops good without using them. Definitely feel them pulling you down. Usually don’t leave um on in the hills around Central Texas as brake lights come on everytime you go down a hill with cruise on and they apply.
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Hi Gerald: Theres nothing around the peddle to obstruct, its all wood.
Hi Per: It’s funny because if there’s one expression I’ve always heard is “it’s like throwing out an anchor”! Now everyone says “no its not like an anchor”, funny!
Hi Jon: As I approached the downward part of the hill I was in 5th gear traveling at 63/65 mph and my RPM’s were right at 1700 as I remember, similar to what you mentioned in your post. When I kicked in the Jake I saw no change to the RPM’s. Thats kind of funny because I wouldn’t have remembered that had you not have mention it?
Hi Glens: I’m going to try the open window idea to find out if I can hear the transition? And when you say “Mine doesn’t require a manual downshift”, thats what I thought as well!
Hi Jim: I’ll try that “goose the peddle” idea, it seems like a straight forward way to find out? Thanks for all the help you’ve given me Jim!
Hi Rocky: Mine doesn’t have sound and I wish it did, its easier than using a walkie- talkie isn’t it?
One thing Jeff wasn’t able to fix is the cruise control. If I understood Jeff correctly, a special program for the computer is needed for that?
Harry
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