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Additional two stage jake brake questions

Yahoo Message Number: 97196
We finally have the CC Intrigue ready to head west to Seattle, We will be heading from Iowa to Salt Lake City to Portland and Eugene then to Seattle. On that drive I suspect I will need to utilize the jake brake. So far in Iowa I have tried it around town and on a few short but steep hills. When engaged (switch down/forward) the transmission drops to 4th gear and the speed appears to stabilize around 40 mph. Of course before it really can work I have reached the bottom of the hill and need to accelerate. So my question is what happens and what speed will the exhaust brake hold when placed in the switch down/rear position? I assume this will be more aggressive but do not know. Will this position drop the transmission to 2nd gear? When would it be appropriate to use this brake position? I really would rather not experiment on Interstate 80 as I head west! While I have traveled these highways with my 38' gasser pulling my jeep I have never had air brakes or a jake brake so I am struggling a bit. Any information you can provide will be much appreciated! Thanks for your time and help,

Glen Burgess

2004 Intrigue #11772

42' tag with 2013 Jeep Wrangler Unlimited

Re: Additional two stage jake brake questions

Reply #1 –
Yahoo Message Number: 97197
The grade of the hill determines the effectiveness of the brake. Some hills it will reduce speed, some it will maintain and some the coach will accelerate.
As far as dropping to 4th gear. That can be changed by Cummins to anything from 6th to 2nd. It is programmable. You can always select a lower gear on the keypad. The trans will not down shift until it knows all will be good. It will not over speed the engine.

Mikee

Re: Additional two stage jake brake questions

Reply #2 –
Yahoo Message Number: 97203
Hi Glen, I too am learning a new to me Intrigue Ovation 525.

I'm curious about the jake too. I have the three stage in mine and was wondering which position offers maximum braking and least braking. So far I've only used it in the center position.

Britt

2004 Intrigue 11836

www.cojobluegrass.com

Re: Additional two stage jake brake questions

Reply #3 –
Yahoo Message Number: 97204
A 3 stage brake operates like this 1st position is 2 cylinders, 2nd is 4 cylinders and 3rd is all 6 cylinders. or 33%, 66% and 100%.
The transmission can be programmed to down shift for 6th to 2nd. Depending on the setting. The lower the gear the more effective the brake is. It will not down shift until it is safe for the engine RPM wise.
You will get the "feel" of it pretty quick. Do not be afraid to experiment to get used to it. On Icy or real wet roads it is suggested not to use it. I have never had a problem on wet roads. I try to avoid icy or snowy roads...

Mikee

Re: Additional two stage jake brake questions

Reply #4 –
Yahoo Message Number: 97205
I recently completed a round trip maiden voyage from Denver to Oregon in my new-to-me '02 Intrigue and was able to get a good feel for descending hills using the Jake brake. With the switch down in the forward position the Jake is working with all 6 cylinders and when down in the rear position it works with just 3 cylinders. Either position will gear you into 4th, but the forward setting provides you more braking power which you will notice and appreciate on the more serious downhill runs.

What seemed best for me when at the top of the hill was to begin descending in 5th gear and selecting 4th gear when I knew it was needed. And then if more braking was required select either the rear switch position (3 cylinders) or forward (6). The Cummins manual describing the engine brake cautions to utilize the system at RPM 2300 or less, and just for short periods between 2300 to 2600 RPM, and above 2600 can cause engine damage. I found that by gearing into 4th myself at the top of a hill I could better monitor engine speed so that if and when I utilized the Jake I could thereby avoid the unknown of high RPMs when switching on the Jake in 6th gear and immediately gearing down into 4th. A few occasions when doing so I was uncomfortable at being near or above 2600 RPM.

I've read a few posts where people suggested reprogramming the transmission to hunt for 2nd or 3rd rather than 4th gear, but after having travelled some serious downhill grades in Colorado and Utah I don't believe I'd benefit from such a change. Having the Jake cause the transmission to hunt for 4th gear seems fine.

This is my first motorhome and now that I've experienced using a Jake I'd not by another MH without one.

John

'02 intrigue 11467 (or close to it- I don't have the # nearby)

Re: Additional two stage jake brake questions

Reply #5 –
Yahoo Message Number: 97208
Good comments! I will add my take, which comes from some experience and also the fact that living in Salt Lake City forces you to respect the hills!

Like Mikee says, don't be afraid of the jake brake. I have mine on 95% of the time. Slowing down on a freeway ramp exit? I use the jake. Slowing down for a light? I use the jake. Of course jake brakes are limited someplaces due to noise restrictions, but baring that mine is usually always on.

As far as descending grades, the engine/jake brake combination is designed to allow you to descend virtually any grade without using the service brakes. If you are doing it correctly (read: safely) then you shouldn't need to even touch the service brakes when descending.

The key to this is to pick the correct gear and use the jake for the whole descent. Do not start to go down the hill without the jake, then engage it when the coach is going too fast. This is a recipe for disaster. What will happen is that you will need to use the service brakes to slow you down enough for the tranny to downshift and engage the jake. This may be OK, but isn't needed if the jake is engaged and you select the right gear at the top of the hill. A often used rule of thumb is that you descend the hill in roughly the same gear that you used to ascend it. This generally works, but sometimes I'm able to use one higher gear.

For example, if you start down the hill in 4th gear with the jake on and still gain some speed, you should gear down to 3rd. You may need to briefly use your service brakes to slow down enough to allow it to shift to 3rd gear. If you do, don't ride the service brake, but apply them all at once to slow you down, then release them. This is sometimes called "stabbing" the brakes. It is used with gassers that don't have a jake.

I will generally stay in the same gear for the whole grade and use the high/low setting to fine tune my speed. If I am in high and am slowing down too much, I switch to low. If I am still too slow then I turn the jake off or upshift. Again don't be afraid to play with it.

I really love driving in the hills! I find it quite fun to fine tune the engine/tranny/jake and descend the hill and never touch my brakes! :-) The grade on I-80 westbound into SLC is 6% and fairly long. Not as steep or long as some others in the west, but enough to demand respect. The descent on I80 in the Sierras from Truckee into Sacramento is another fun one, as well as the one west of Denver on I-70.

There is an old truckers saying - "you can go down the mountain as many times as you want too slow, but you can only go down it once too fast". If you watch the savvy truckers you will find that they do just this, pick their speed and descend the hill slowly, but safely.

Good luck and safe descents! :-)
Dan

2006 Allure 430 with tag
#31344

Re: Additional two stage jake brake questions

Reply #6 –
Yahoo Message Number: 97210
Glen, good topic.

I think I have my coach set up different than others. Last fall we bought a 2000 Magna with a Cat 10 and I wasn't comfortable with the Jake setup. I had both the Alison and the Cat reprogrammed and I am very happy with the result. The Tranny no longer shifts to 4th as before and the Jake works whenever the throttle is closed. Now on the Highway, with the cruise set, the Jake will maintain the set speed downhill and I don't have to touch the brakes, I don't have to re-engage the cruise at the bottom of the hill and I'm not running up on the vehicle in front of me. With the cruise off, the transmission shifts down as the speed decreases, and I only use the service brakes to come to a complete stop, even in stop and go traffic. Of course, if the machine isn't slowing enough I can choose a lower gear with the push of the shift button and I also descend severe grades as described by others.
Regards

Ed Recknagle 2000 Magna 36, C10 Cat 5738
Ed Recknagle
2000 Magna 36  #5738
 

Re: Additional two stage jake brake questions

Reply #7 –
Yahoo Message Number: 97215
The Jake on my coach operates exactly as ed describes his. With the cruise on, the Jake gives about a 10 mph overage on long downhills before engagement.
Tom R

2006 Intrigue 12057
Cummins 400 ISL