Jake brake on or off driving on flats or small hills?

[holstein13]

One of the debates we had this week was whether you should drive with your Jake Brakes on or off while on flat land or small hills. Everyone agreed that you should use them in the mountains or steep grades.

But what about hills and flats? The tire and brake instructor said we should not use them because the brakes need a workout to prevent glazing and if you always use the Jake Brakes, you won't automatically adjust your slack adjusters.

The engine guy said that the latest evidence from Cummins suggested that the Jake Brakes helped keep the turbo chargers clean. He recommended leaving it on.

Do any of you have an opinion?

[WILDEBILL308]

This is true Glazing is more associated with over heating. I haven't heard of anyone wearing out their brakes on a diesel pusher.
Bill

[holstein13]

creeper wrote:

DSDP Don wrote:


Glazing.....One poster was surprised by a statement that an instructor warned against ALWAYS using engine power to slow down. Yes, it's I a bad thing to do. At slower speeds and in traffic, you should use the foot brake to keep the rotors/drums from glazing. Your brakes are going to go at least 80K, some occasional foot brake usage keeps them from squealing and certainly won't wear them out.

.

Brake glazing is caused by EXCESSIVE heat to the pads and rotors. Engine braking is to keep the brakes from heating up, thus preventing glazing and loss of braking power due to excessive heat. That's why you use engine braking in the mountains. If you don't your brakes will heat up, glaze and you will losing stopping power. Engine brakes prevent glazing, not cause it. I'm very familiar with brake glazing living in the mountains. All our cars had glazed brakes for many years and a pain to get off, done it MANY times.

Normal stop and go does not cause glazing. If anything using the engine brake/Transmission brake will help in not causing glazing. You can't stop only on jake brake/transmission braking.

I rolled from the top of the rockies to the bottom on transmission braking with very little brake usage and very little ATF heating. Thus, no glazing. You can't get brake glazing without over heating the braking system.

How exactly are you getting brake glazing not using your brakes? :h

So yes I was surprised.

Creeper, thank you for clearing this up. I had only vaguely heard the term glazing and didn't really understand what it was so I looked it up. I think it's one of those terms you are expected to know but nobody really explains it so everyone makes up their own definition.

From what I was able to learn through Google (surprisingly, there is very little authoritative information found) you are exactly correct. Looks like glazing is caused by excessive heat and in particular brake dust getting overheated and crystalizing. If that's the case, I would think that the use of the engine brake would prevent / minimize this.

I'm going to write back to the instructor to clarify this.

[WILDEBILL308]

FIRE UP wrote:

Kayteg1 wrote:
I do have transmission retarder as well, but that thing gets ATF very hot very fast.
Sure lack if any noise is nice.

That is specifically WHY we discontinued the option and use of them on the FD, early on. The Jake (compression system braking) is a far superior braking system without potential damage to any parts or components.
Scott

I don't find that to be true on my coach. Yes it may warm up the transmission temps 5-10 degrees in heavy use but it will cool right back down.
Bill

[creeper]

DSDP Don wrote:


Glazing.....One poster was surprised by a statement that an instructor warned against ALWAYS using engine power to slow down. Yes, it's I a bad thing to do. At slower speeds and in traffic, you should use the foot brake to keep the rotors/drums from glazing. Your brakes are going to go at least 80K, some occasional foot brake usage keeps them from squealing and certainly won't wear them out.

.

Brake glazing is caused by EXCESSIVE heat to the pads and rotors. Engine braking is to keep the brakes from heating up, thus preventing glazing and loss of braking power due to excessive heat. That's why you use engine braking in the mountains. If you don't your brakes will heat up, glaze and you will losing stopping power. Engine brakes prevent glazing, not cause it. I'm very familiar with brake glazing living in the mountains. All our cars had glazed brakes for many years and a pain to get off, done it MANY times.

Normal stop and go does not cause glazing. If anything using the engine brake/Transmission brake will help in not causing glazing. You can't stop only on jake brake/transmission braking.

I rolled from the top of the rockies to the bottom on transmission braking with very little brake usage and very little ATF heating. Thus, no glazing. You can't get brake glazing without over heating the braking system.

How exactly are you getting brake glazing not using your brakes? :h

So yes I was surprised.

[FIRE_UP]

Kayteg1 wrote:
I do have transmission retarder as well, but that thing gets ATF very hot very fast.
Sure lack if any noise is nice.

That is specifically WHY we discontinued the option and use of them on the FD, early on. The Jake (compression system braking) is a far superior braking system without potential damage to any parts or components.
Scott

[Sprink-Fitter]

Busskipper wrote:

holstein13 wrote:
One of the debates we had this week was whether you should drive with your Jake Brakes on or off while on flat land or small hills. Everyone agreed that you should use them in the mountains or steep grades.

But what about hills and flats? The tire and brake instructor said we should not use them because the brakes need a workout to prevent glazing and if you always use the Jake Brakes, you won't automatically adjust your slack adjusters.

Where did you get this info – Sounds like *S -

The engine guy said that the latest evidence from Cummins suggested that the Jake Brakes helped keep the turbo chargers clean. He recommended leaving it on.

Again your two “Instructors” should get together.

Do any of you have an opinion?

Being retired from the Heavy construction business we had a number of diesel trucks with engine/jake breaks so I can only speak from past experience, no one would leave the break on unless they were breaking or stopping – the engine/jake breaks, will, if working just not make for a smooth ride if left on.

If going down a long grade Yes not an issue unless you want to continue at speed or just drive without breaking.

My advice – leave off and just flip the switch when you want to break (which in most cases will be enough to clean the turbo and when you stop you will take the glaze off).

JMHO,

Brakes and Breaks are two different things.

[holstein13]

DSDP Don wrote:
Wow.....There sure are a lot of people driving completely different from others.

Coasting.....I love the setup on my new coach compared to my previous. When I descend a hill/grade, my engine brake allows my coach to gain from 3-5 mph (when the cruise control is on) before the engine brake engages. To me, it's smart and fuel efficient to let the coach coast and get a running start at the next hill/grade. If it's a hill I don't want to increase speed on, I just thumb down the cruise on Smart Wheel 3-5 times to maintain my speed. If it's still increasing, I switch to High on the engine brake.

Glazing.....One poster was surprised by a statement that an instructor warned against ALWAYS using engine power to slow down. Yes, it's I a bad thing to do. At slower speeds and in traffic, you should use the foot brake to keep the rotors/drums from glazing. Your brakes are going to go at least 80K, some occasional foot brake usage keeps them from squealing and certainly won't wear them out.

Emergency stops.....On my last coach, you couldn't have the exhaust brake switch turned on (switch only) because it would shut off the cruise control. On my new coach, I can have the engine brake switch on either high or low and still be able to use cruise. I think this is a huge advantage. In the event of an emergency stop, I won't have to be fumbling around to turn on the engine/exhaust brake while trying to stop and steer 40K of RV. If your coach is setup to allow the cruise to work while the engine/exhaust switch is on, why not just leave it on.

Exhaust noise.....On a modern coach, unless you've eliminated the exhaust system, they don't make enough noise to violate engine/exhaust brake rules. That rule was for trucks that ran straight exhausts and unmuffled engine brakes.

I think there are some important lessons to be learned from this post. I think many don't get a chance to put enough miles on a coach to really know how it works or how it can work. Many are also learning that you can have your Allison reprogrammed to do things differently (latching changes).

Lastly, I think the transmission and engine/exhaust brake programming has come a long ways in the past few years. If your coach is somewhere around 2004 or newer, there are some changes that can be done to change how your engine/exhaust brake function, making for a more enjoyable drive.

Great post, Don. On my coach, the OEM disabled the engine brake on cruise control. That's one thing I definitely want to change. I'd like it to use low engine braking at 3 mph over the set speed and go to high engine braking at 6 mph over the set speed.

I was reviewing the Cummins "Features and Parameters" that I can change on my engine but I'm not sure of all the changes that would make sense for my driving style. I'd love to hear your list of top features and also more about this "latching changes."

I'm embarrassed to admit this, but I thought latching had something to do with nursing a newborn child.

Any suggestions you could make would be appreciated.

[DSDP_Don]

Wow.....There sure are a lot of people driving completely different from others.

Coasting.....I love the setup on my new coach compared to my previous. When I descend a hill/grade, my engine brake allows my coach to gain from 3-5 mph (when the cruise control is on) before the engine brake engages. To me, it's smart and fuel efficient to let the coach coast and get a running start at the next hill/grade. If it's a hill I don't want to increase speed on, I just thumb down the cruise on Smart Wheel 3-5 times to maintain my speed. If it's still increasing, I switch to High on the engine brake.

Glazing.....One poster was surprised by a statement that an instructor warned against ALWAYS using engine power to slow down. Yes, it's I a bad thing to do. At slower speeds and in traffic, you should use the foot brake to keep the rotors/drums from glazing. Your brakes are going to go at least 80K, some occasional foot brake usage keeps them from squealing and certainly won't wear them out.

Emergency stops.....On my last coach, you couldn't have the exhaust brake switch turned on (switch only) because it would shut off the cruise control. On my new coach, I can have the engine brake switch on either high or low and still be able to use cruise. I think this is a huge advantage. In the event of an emergency stop, I won't have to be fumbling around to turn on the engine/exhaust brake while trying to stop and steer 40K of RV. If your coach is setup to allow the cruise to work while the engine/exhaust switch is on, why not just leave it on.

Exhaust noise.....On a modern coach, unless you've eliminated the exhaust system, they don't make enough noise to violate engine/exhaust brake rules. That rule was for trucks that ran straight exhausts and unmuffled engine brakes.

I think there are some important lessons to be learned from this post. I think many don't get a chance to put enough miles on a coach to really know how it works or how it can work. Many are also learning that you can have your Allison reprogrammed to do things differently (latching changes).

Lastly, I think the transmission and engine/exhaust brake programming has come a long ways in the past few years. If your coach is somewhere around 2004 or newer, there are some changes that can be done to change how your engine/exhaust brake function, making for a more enjoyable drive.

[Busskipper]

holstein13 wrote:
One of the debates we had this week was whether you should drive with your Jake Brakes on or off while on flat land or small hills. Everyone agreed that you should use them in the mountains or steep grades.

But what about hills and flats? The tire and brake instructor said we should not use them because the brakes need a workout to prevent glazing and if you always use the Jake Brakes, you won't automatically adjust your slack adjusters.

Where did you get this info – Sounds like *S -

The engine guy said that the latest evidence from Cummins suggested that the Jake Brakes helped keep the turbo chargers clean. He recommended leaving it on.

Again your two “Instructors” should get together.

Do any of you have an opinion?

Being retired from the Heavy construction business we had a number of diesel trucks with engine/jake brakes so I can only speak from past experience, no one would leave the brake on unless they were braking or stopping – the engine/jake brakes, will, if working just not make for a smooth ride if left on.

If going down a long grade Yes not an issue unless you want to continue at speed or just drive without braking.

My advice – leave off and just flip the switch when you want to brake (which in most cases will be enough to clean the turbo and when you stop you will take the glaze off).

JMHO,

[wolfe10]

box710 wrote:
... in fact it is good for your diesel engine cause it gets oil to your upper ringss so I'm told by a diesel mechanic

Boy, would sure like an explanation of that one.

[box710]

The only time I turn my jake off is in wet weather,otherwise its on all the time. in fact it is good for your diesel engine cause it gets oil to your upper ringss so I'm told by a diesel mechanic

[Kayteg1]

I do have transmission retarder as well, but that thing gets ATF very hot very fast.
Sure lack if any noise is nice.

[WILDEBILL308]

I know I have a integral output retarder in the transmission that will act to slow the coach.
Bill

[creeper]

holstein13 wrote:
The tire and brake instructor said we should not use them because the brakes need a workout to prevent glazing and if you always use the Jake Brakes, you won't automatically adjust your slack adjusters.

And and instructor said this? Yikes.

[Kayteg1]

New technology brings something every day, but I recall that when real Jake brake will give you >100% of braking power (comparing to engine HP), the exhaust brake will give you <40%