Exhaust Brake Use

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.

joesolo

Member
Joined
Sep 14, 2005
Posts
20
Location
Lakeland, TN
One more tech question....do yall leave the exhaust brake in the "on" position or toggle it only when needed? So far, I have toggled it when in traffic, exiting the freeway, or while having to brake hard. Otherwise, it is off. My personal issue with toggling it is that it is sometimes a handful to brake, hit the switch and steer all at the same time, especially if you need to stop kinda quick. So what do yall do?

BTW.....15 days til Florida and counting!

Thanks,

Joe
 

Ned

Moderator Emeritus
Joined
Feb 1, 2005
Posts
25,107
Location
USA
This is a matter of personal preference.  Some leave the exhaust brake on all the time, others turn it on only when needed.  Leaving it on means you don't have to remember to use it when you need, but the disadvantage is everytime you coast, it engages and turns off the cruise control.  You can prevent that behaviour by keeping a small fuel flow with the accelerator so it doesn't engage, but some find that inconvenient.

Generally, we keep it off when travelling fairly level roads, but turn it on when in hills or mountains.  It has no effect going uphill, and you usually need it coming down.

But, as I started out, it's a matter of personal preference.
 

BernieD

Well-known member
Joined
Mar 1, 2005
Posts
5,888
Location
Goodyear, AZ
joesolo said:
So far, I have toggled it when in traffic, exiting the freeway, or while having to brake hard. Otherwise, it is off.

Joe

Whichever way you wind up deciding, make you that when you first start your engine to turn on your exhaust brake and leave it on for at least 20 minutes. This is necessary to dry out the parts of any moisture to prevent binding in the future. After the 20 minutes, you can leave it on or off. I leave mine on unless I am on an Interstate with overpasses and hills. The kicking in of the brake when I don't expect it drives me bonkers.
 

Bob Zambenini

Well-known member
Joined
Mar 4, 2005
Posts
270
Location
Orange County California
joesolo said:
One more tech question....do yall leave the exhaust brake in the "on" position or toggle it only when needed? So far, I have toggled it when in traffic, exiting the freeway, or while having to brake hard. Otherwise, it is off. My personal issue with toggling it is that it is sometimes a handful to brake, hit the switch and steer all at the same time, especially if you need to stop kinda quick. So what do yall do?

BTW.....15 days til Florida and counting!

Thanks,

Joe

Joe, mine is  programmed to drop to 2nd gear so if I leave it on all the time and have cruise control on, I get a big jerk when it drops back to 2nd. So I don't leave it on all the time and only use when I need it.

Also, at an FMCA the 'expert' said leave it on all the way down a grade. So next trip I was going down the Grapevine toward Bakersfield and left it on. It was early in the day and sun was on my right. When I accelerated at the bottom I saw a lot of smoke from the rear via right mirror!  I quickly pulled over and went back and things were very hot back there to say the least!!!!!

So I shut down and started looking in my book for a Freightliner place in Bakersfield. Then started up and all the gauges were normal so I went about 30 miles up to a rest area and checked things over and all was normal back there. So went on to a rally in Lodi and talked to some of the diesel members. They all laughed and said sure it will heat up because its blocking your exhaust and all that heat has to go somewhere.

So now I used it only when needed coming down a grade by turning it on and off and watching my transmission temp.

Bob
 

Ron

Moderator Emeritus
Joined
Jan 29, 2005
Posts
18,082
Location
Home is where we park it
Our use of the exhaust brake is pretty much like Ned mentioned.  When topping a hill we usually slow down to what ever speed we think we want to go down at and have the exhaust brake engaged.  Remember whether your transmission is programed to select 4th or second when the exhaust brake engages the transmission only shifts down if your speed is slow enough to allow a downshift without overspeeding the engine.  In other words with exhaust brake on if you top the hill at say 65 MPH you will remain in 6th gear unless you use the brake to slow down enough for the transmission to shift down.
 

Jeff

Moderator Emeritus
Joined
Apr 8, 2005
Posts
8,965
Location
SD/AZ
Joe:

If your coach is on a Freightliner chassis there is a switch available that will allow you to arm the brake and then engage it by tapping the (air) brake. As soon as you use the accelerator it goes back to the arm position. If the switch is off your exhaust brake works as normal.

Great when using cruise as it will stay off until you tap the brakes.

Read for yourself. FCOC members get a 25% discount off the 79.95 price. http://www.brakeswitch.com/
 

Jim Dick

Moderator Emeritus
Joined
Feb 11, 2005
Posts
7,651
Location
Titusville, FL
Hi Joe,

Normally I leave my exhaust brake off until I need it. The switch is on a panel next to my left hand so it's easy to engage or disengage.

Sometimes I will turn it on when traversing a hilly section. I have it programmed with the Allison so it will operate when the speed gets 3mph above the setting for the cruise control. It will then slow me down until the speed is about 2mph below the set speed. It will then disengage until the coach speeds up. It sounds like it would cause the coach to jerk but it is very smooth and doesn't operate quickly. It makes driving hilly /mountainous roads a little easier. Of course, if the road is hilly and winding I'll do it manually.
 

Jim Godward

Well-known member
Joined
Mar 6, 2005
Posts
5,906
Location
Hillsboro, Oregon
Till we got the BrakeSwitch we used the Exhaust brake like most of the folks have mentioned.  My wife is the primary driver now and she loves it.  It works just as Jeff described and we both would not be without it.
 

Bob Zambenini

Well-known member
Joined
Mar 4, 2005
Posts
270
Location
Orange County California
James Godward said:
Till we got the BrakeSwitch we used the Exhaust brake like most of the folks have mentioned.  My wife is the primary driver now and she loves it.  It works just as Jeff described and we both would not be without it.

Jim,

I read their page but did not see anything about installing it. Did you do it yourself? Or do you need the dealer to install it?

Bob



 

Jim Godward

Well-known member
Joined
Mar 6, 2005
Posts
5,906
Location
Hillsboro, Oregon
Bob,

Ron is right, the manuals are there.  Yes, I did it myself after a few false starts.  G  It took a while but all the wiring is in the drivers area, I used the cable behind the switch and found a brake light signal in the steering column.  Once I did that it was easy.  VBG  It took all afternoon to find the wire and I needed a schematic.  Skip on Newmarowners posted them to that list files area.

You will like it.  Also do not forget IF you are a member of the Freightliners club, FCOC, there is a nice discount.

Good luck,
 

Tom

Administrator
Joined
Jan 13, 2005
Posts
49,534
Jeff /Washington said:
If your coach is on a Freightliner chassis there is a switch available that will allow you to arm the brake and then engage it by tapping the (air) brake.

Thanks for the link Jeff. Looks like it could also be used on the Roadmaster (Monaco) chassis. However, they show the following caution:

"As this information is based on feedback from other Motor Home owners and conversations with tech help at Roadmaster it should be considered as probable and NOT absolute Check your wiring diagrams."

Timing of seeing this is good for me because a few days ago I bought a "Pac brake floor switch" which I intended to use to replace the rocker switch at the side of the driver. However, when I called Monaco tech support today, they were somewhat vague about where/how to connect the switch since my rocker switch has 10 or more wires attached to it and the floor switch has only 2. The Brakeswitch you''ve pointed us to would appear to be a better alternative and simpler to install, if it will work on my chassis.
 

magboiler

Member
Joined
Jan 22, 2006
Posts
14
Location
La Center, WA
I never use exhaust brake when in cruise control, or when on wet roads, or in snow.  Read the manual and it will tell you what the safe operation of the exhaust brake...especially if you are using Freightliner and Allison transmission.

You need to know at what point (RPM's) the exhaust brake will kick in.  Reason:  to not exceed the max RPM's for the engine
 

Tom

Administrator
Joined
Jan 13, 2005
Posts
49,534
magboiler said:
I never use exhaust brake when in cruise control..

Good practice, or they'd be fighting each other. It's not possible anyway on our Monaco because, as soon as the exhaust brake switch is turned on, it kicks cruise control off.
 

Alaskansnowbirds

Site Team
Joined
Mar 11, 2005
Posts
3,033
Location
Camp Verde, AZ
magboiler said:
You need to know at what point (RPM's) the exhaust brake will kick in.  Reason:  to not exceed the max RPM's for the engine

Our exhaust brake (if turned on) kicks in as soon as you take your foot off the accelerator. Now the transmission will not downshift until it's safe. The exhaust brake by itself has no effect on the RPM.
 

Jim Dick

Moderator Emeritus
Joined
Feb 11, 2005
Posts
7,651
Location
Titusville, FL
magboiler said:
I never use exhaust brake when in cruise control, or when on wet roads, or in snow.  Read the manual and it will tell you what the safe operation of the exhaust brake...especially if you are using Freightliner and Allison transmission.

You need to know at what point (RPM's) the exhaust brake will kick in.  Reason:  to not exceed the max RPM's for the engine

The allison transmission is smarter than most humans. It will not downshift until the rpms are low enough to prevent over revving. The cruise and exhaust brake don't fight each other. The set points allow both to operate mutually. It's very handy in hilly country. It is programmable by anyone with the license for the software.

No, you should not use the exhaust brake in slippery conditions.
 

JerArdra

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

Here is something I wrote when I was commenting to KeithB.  It may help you with the problem regarding turning the exhaust brake switch ON and OFF in traffic.  Floor pedals are available for both Jake brakes and PAC brakes.

JerryF

DISCUSSION ON EXHAUST BRAKES:  JAKE BRAKE/PAC BRAKE

First, if you have a floor pedal on the left side of the floor it works just like your service brake pedal, e.g., when you press it the Jake/PAC brake is on and when you release it the Jake/PAC brake is off.  Usually when you have a pedal on the floor there is no On/Off switch to turn on or turn off the exhaust brake.  The floor pedal does it all.

On the other hand, with a Jake brake, if do NOT have a floor pedal then you have an On/Off switch PLUS a Hi/Lo switch. PAC brakes do not have an Hi/Lo switch, they only have an On/Off switch when they do NOT have a floor pedal.  In this case when the On/Off switch is ON, every time you let your foot off the accelerator pedal the Jake/PAC brake is turned on and the engine is slowing the coach.  This means if you do not want to slow down as fast as the Jake/PAC brake is slowing the coach, you must again press the accelerator pedal to turn off the Jake/PAC brake or you must turn the Jake/PAC brake off using the On/Off switch which requires constantly looking (eyes off road) and locating the On/Off switch so you can switch it between ON and OFF.  We did not like to turn the switch ON and OFF especially in traffic and on down hill runs.  We felt that a few seconds of looking at our side console to ensure we had the correct switch was too dangerous, especially on a downhill curve or in traffic.  By the way, if your Jake brake is slowing you more than you want you can, with a Jake brake, click the Hi/Lo switch to LO but this too requires that you look for (eyes off the road) the switch which we did not like to do..

We have had both an On/Off switch and a floor pedal.  We settled on a floor pedal 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 (Jake) or circular pedal (PAC) 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 lower portion of the pedal and the Jake/PAC brake goes on.  It DOES NOT require a pushing pressure like a service brake pedal does.  It is 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 too 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 or the Hi/Lo switch and when the hill got steeper again we had to look for and press the ON switch or Hi/Lo switch again (imagine doing that in bumper to bumper traffic).  Or, on the other hand, instead of turning 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 little 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 tow car 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 prefer the ability to coast (no power on), press the pedal to use the Jake brake (Pac is the same), 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 the transmission to slow the car at a faster rate (this is similar to the Jake/PAC brake in a motorhome), 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 before you feel that slight pulse where the exhaust brake release and you're coasting.  Targeting the transmission for 2nd gear works the same for a PAC brake too.

Another example is, if you're exiting a freeway or slowing for an intersection it's nice to let the Jake brake slow you as long as possible before using your service brakes and if you're not impeding traffic let it slow you to 15 MPH, which it will do if it's targeted for 2nd gear, before you must use your service brake.  This saves your brakes.

Because my transmission is targeted to downshift all the way down to 2nd gear, when I press the floor pedal, my Jake brake (same with my previous coach that had a PAC brake) downshifts at the following speeds:  at 65 MPH it downshifts into 5th gear, at 55 it downshifts into 4th, at 45 it downshifts into 3rd, at 35 it downshifts into 2nd, and at stays in 2nd gear until it finally releases itself (it quits) at 15 MPH. 

Another reason we like to have our transmission targeted to 2nd gear is that it's great in slow stop and go trafic where you may be downshifted to second gear by 35 MPH or less so it saves on the use of the service brakes.  By the way, our motto on long downhill runs is "keep 'em cool."
 

Jim Godward

Well-known member
Joined
Mar 6, 2005
Posts
5,906
Location
Hillsboro, Oregon
I'll add a different twist to the E-Brake. 

I installed a BrakeSwitch and both Pat and I like it.  If you turn on the "E-Brake and leave it on, the E_Brake only comes on IF you tap the brake pedal. Once you add a little fuel, the E-brake goes off till you tap the brake pedal again.  We leave it on in cruise etc. and never have it come on unless we want it to do so.

Check it out at www.brakeswitch.com.

It can be a bit of a bear to install but if you are handy and follow instructions it is doable.
 

Tom

Administrator
Joined
Jan 13, 2005
Posts
49,534
Jim,

The Brakeswitch looks like a good solution. I didn't buy one because of some doubt expressed on their web site about installation on a Roadmaster (Monaco) chassis. However, they show a schematic for installing on a Roadmaster. Do you know any Monaco owners who have installed it?
 

Forum statistics

Threads
123,314
Posts
1,250,482
Members
128,893
Latest member
dablingking
Top Bottom