Jake Brake help

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.

keithb

Active member
Joined
Apr 25, 2005
Posts
33
I need some help. I just purchased an 06 Newmar Mountainaire 4304 DP and it has a two stage jake brake. I can't seem to get it to work. I had an exhaust brake on my last coach and it was very simple to operate -- as I suppose the new one should be. Any help, before I call the company and make an idiot out of myself, would be appreciated. I am assuming that the concensus will be that it just doesn't work, but maybe I am overlooking something.

Thanks,
Keith
 

JerArdra

Well-known member
Joined
Mar 3, 2005
Posts
1,814
Keithb,

Call Newmar.  The most likely problem is a faulty electrical connection or a fuse.  Jake brakes just keep working and working.

JerryF
 

keithb

Active member
Joined
Apr 25, 2005
Posts
33
The only thing I can find is a switch on the left side armrest area with high/low and off settings. Maybe there is something else  -- I'm not sure.

P.S. salesman is absolutely no help and can't find any paperwork
 

PancakeBill

Well-known member
Joined
Apr 9, 2005
Posts
5,944
Location
Benson - Tucson, AZ. West Yellowstone,MT
Is the high, low and off switch labelled Jake Brake?  When on, and letting off the gas, does it do anything different? 

Salesman, the bane of ...  wait, I am a salesman....  Used to hate them, now I are one...

We don't carry Mountainaire so I don't have a library to check, but what chassis is it on?  I can ask around.

 

JerArdra

Well-known member
Joined
Mar 3, 2005
Posts
1,814
Keithb,

When there is ONLY a hi/lo switch that USUALLY means there is a foot pedal to activate the Jake Brake.  The pedal is on the left floor so you can press it with your left foot.

JerryF
 

keithb

Active member
Joined
Apr 25, 2005
Posts
33
Thank you sir for that information. I am a working man still but I can assure you I will ck that this evening as soon as I get home.

Thank you,
Keith
 

JerArdra

Well-known member
Joined
Mar 3, 2005
Posts
1,814
Keithb,

By the way,  if you do have a foot pedal it works just like your service brake pedal, e.g., when you press it the Jake brake is on and when you release it the Jake brake is off.

On the other hand, if do NOT have a floor pedal then you have an on/off switch PLUS a Hi/Lo switch.  In this case when the on/off switch is ON every time you let your foot off the accelerator pedal the Jake brake is turned on and is slowing you down.  This means if you do not want to slow down as fast as the Jake brake is slowing you, you must again press the accelerator pedal to stop the Jake brake or you must turn the Jake brake off with the on/off switch which requires constantly looking (eyes off road) and finding the on/off switch to keep moving it between on and off.  We did not like this especially in traffic and on down hill runs.

We have had both an on/off switch and a floor pedal.  We settled on a floor switch so now we just leave our Jake brake on the HI position.  We never have to look for a Hi/Lo or an On/Off switch so we can keep our eyes on the road.  Because we now have a floor pedal (no on/off switch) here is what we do.  When we are driving and want to stop accelerating, slow, or stop the coach we let off the  accelerator pedal.  This lets the diesel engine slow up the coach a very LITTLE bit (almost like coasting in a car).  If we want to slow faster we press the Jake brake floor switch to slow the coach at a faster rate.  And last, we press the service brake to stop or slow down at a much faster rate. 

If you have never used a Jake or Pac Brake pedal it DOES NOT require foot pressure like the service brake pedal.  It is a small flat box or circular pedal that is hinged at the top (upper portion) of the pedal.  By doing it this way you really do not have to press the pedal.  You just set the ball of your foot on the rear (bottom) of the pedal and the Jake brake goes on.  It DOES NOT require pushing pressure like a brake pedal does.  It almost like setting the weight of your foot on the pedal.

Going down mountains it's great because at the top of a hill we press the floor switch.  Then when there are less steep or flat spots on the long downhill run and the Jake brake is slowing you to much we just let off the pedal and again press the pedal when the incline gets steeper.  When we did not have a floor pedal we had to look over, find, and press the off switch and when the hill got steeper again we had to look for and press the ON switch again (imagine doing that in bumper to bumper traffic).  Or, on the other hand, instead of turning it the Jake brake OFF/ON we could have pressed the accelerator pedal to turn the Jake brake OFF but that meant if we pressed it a litle too much the engine started increasing the coaches speed which went against our instincts on a long downhill run where our objective was to control the downhill speed of the coach.  We weigh 44,000 lbs with our tow car and we do have brakes in the tow car.

Also, in stop and go city traffic we disliked the fact that every time we took our foot off the accelerator the Jake brake started slowing us.  In traffic we perfer the ability to coast (no power on), press the pedal to use the Jake brake, or use the service brake like we do in our car.  For example, in our car we press the gas pedal to go, let off the gas pedal to coast, sometimes downshift to slow the car at a faster rate if we want to (this is similar to the Jake brake in a MH), and press the brake pedal to stop.

Our Jake brake is set to automatically downshift all the way down to 2nd gear.  We like this because approximately 25% of the time we do not press the service brake pedal until the coach is going only 15 MPH.  15 MPH is the magic number because that is were the Jake brake turns off, that is, if it's set to downshift all the way down to second gear.  Sometime when you have the road to yourself press the downshift button (down arrow) on your Allison transmission so the target gear is 1st gear and you'll see that the Jake brake will work all the way down to about 7-1/2 MPH before you feel that slight pulse of it release and you're coasting.

JerryF
 

BernieD

Well-known member
Joined
Mar 1, 2005
Posts
5,877
Location
Goodyear, AZ
Keith

You probably have the Cummins ISL-400 engine and Spartan Mountain Master chassis, which is the same as I have. Mine is a couple  of years older, but should work excactly the same.

The brake is an engine compression brake manufactured by Cummins, it is not a Jake Brake which is a trade name of brakes produced by Jacobs Manufacturing but works similarly to the Jake Brakes on OTR trucks. The control rocker for the brake has 3 positions; high, low and off. Pulled down toward you is high, in the middle is off and the rocker pushed forward is low. When you are traveling above 40 miles an hour, the brake is in one of the on positions and you take your foot off the accelerator pedal, the brake will downshift the transmission seeking 4th gear, which works perfectly with this power package, and your transmission panel should show 4th gear. For the power of this engine and braking system, a 2nd gear seek is overkill.

If you are going slower than 40mph, in all probablility you won't feel much, if any impact, there isn't that much need for the brake. But you should see the transmission gear drop to 4th from 6th. If it doesn't do anything when you are traveling at 60mph and have the rocker in high, I would take the coach into a Cummins shop to have it checked out, it is under warranty and won't cost you anything.
 

keithb

Active member
Joined
Apr 25, 2005
Posts
33
Good morning to all,
 
        I checked last night and I can't find any other pedals or switches for the jake brake. I called my dealer's service department and it only took them about two seconds to blow me off to Spartan. Imagine that. I guess now that I have owned it for three weeks, I am not as special anymore as I was. I have had the coach upto 70+ mph with the switch activated and still nothing. I have come to the conclusion that I am not missing something. The brake just doesn't work. I thank all of you for your input and I will report back when I get the solution.

Thank you all so much,
Keith
 

PancakeBill

Well-known member
Joined
Apr 9, 2005
Posts
5,944
Location
Benson - Tucson, AZ. West Yellowstone,MT
Where did you buy the coach?  It might be that they do not have the mechanics qualified for the work and that if warranty Spartan will do the best job for you.  They may be doing you more of a favor than in having you come in. 
 

keithb

Active member
Joined
Apr 25, 2005
Posts
33
I am sure the c/control is off. As a matter of fact, I suppose I ought to test that also.
 

Terry A. Brewer

Well-known member
Joined
Mar 4, 2005
Posts
1,446
Keith

You say the Allison doesn't downshift when you take your foot off the accelerator with the Jake switch on high...Have you tried manually downshifting to 2nd or 4th with the Jake switch on?? The Jake may be activating & the Allison pad is not receiving he signal from the switch. I would try tracing the wire from the switch to the Allison pad, they are usually located in the same area.

 

keithb

Active member
Joined
Apr 25, 2005
Posts
33
No, I haven't tried downshifting manually to 2nd gear from 6th. My normal driving habits however, involve manually downshifing one gear at a time until I stop(never lower than 2nd gear). I have not knowingly had the jake on while doing that.

You are a good bunch of fellows for trying to help me through this. I really appreciate the assistance.

Thanks,
Keith
 

JerArdra

Well-known member
Joined
Mar 3, 2005
Posts
1,814
Keithb,

Allision Transmission are great!!!  I have attended half-a-dozen Allison seminars and one of the things they emphasize is that you can manually press the buttons to downshift  into 1st gear at 65 MPH and the transmission will NOT do it.  They even say if you accidentally manually shifted into reverse at 65 it would not do it.  The computer in the transmission makes it bulletproof.  Even though they say this, would you believe that I have not tried it in my coach.

JerryF
 

Terry A. Brewer

Well-known member
Joined
Mar 4, 2005
Posts
1,446
Jerry

>>The computer in the transmission makes it bulletproof.? Even though they say this, would you believe that I have not tried it in my coach.<<

I have hit reverse by accident several times & nothing happens....Thank God.<G>

 

magboiler

Member
Joined
Jan 22, 2006
Posts
14
Location
La Center, WA
70 miles an hour!  Jake brake will not work...need to get RPM's down, exhaust brake system on, an use regular brakes to point where rpm's will allow exhaust brake to work.

Asking questions of dealers and manufacturers is not stupid.  Not to do so is stupid.
 
Top Bottom