How do you use your engine brake?

[Rich W.]

First, for the uninitiated, it's important to understand what a Jake brake does. Its basically using the engine as a giant compressor (by manipulating valve timing), which takes a lot of horse power, by making it compress air in the absence of fuel. So they measure engine brake capability in braking horse power. Low, med, and high are 1/3, 2/3 and full horse power of braking, utilizing 2, 4, or 6 cylinders respectively. Also engine brake hp depends on engine speed, higher rpm delivering more hp of braking. So with the Jake on high, at 1500 rpm you’ll get around 450 brake hp out of your 600hp engine, but at 2100 you’ll get the full 600hp worth.

So the decision on where to set it should be based on the amount of braking horse power needed in a given situation - more grade, more engine brake. And while it certainly helps you when slowing down, the purpose isn't really to assist in sudden or unplanned stops in traffic - thats what the service brakes are for. The Jake was designed and intended to help moderate speed in traffic and on grades over longer periods where constant use of the serivce brakes would burn them up.

I just have a VGT engine brake on an ISB and it’s of so little help (very little braking HP for 34,000lbs) that I don’t rely on it for slowing but it does help a little on grades in conjunction with the service brakes - not much but some. When crusing on relatively flat terrain I shut it off so its not always decelerating and down-shifting when I let off the accelerator to coast, since its tied in with the transmission’s brain. I would imagine its the same with a Jake with an auto-trans. I’ve only driven trucks (mainly 10 wheel 4,000 gal tank trucks) with standard transmissions and Jakes so its a little different.

I also want to echo the point @Neal made about slippery roads - it’s easy to imaging the drive wheels locking up on a wet road when you suddenly apply 600 horsepower of braking to them - a situation that would most likely be unpleasant at best.

As to @DSD’s comment about glazing, I think what he’s getting at is that if you use the Jake all the time, you aren’t braking as hard or as often, so you aren’t burning off any glazing that may have occurred. Just a guess - I never thought about it before.

As to the brake light issue @Buly mentioned, I’m on the fence about disabling the brake lights when only the engine brake is on. Mine doesn't activate the toad brakes, but there are other pros and cons about it, the worst con being that if your brake lights have been on constantly while descending a grade and suddenly you have to stop for traffic or construction or whatever, the driver behind you won’t see any difference in your lights when you stand on the brakes.

 

[ARD]

I only use it when I’m driving in the mountains and/or steep grades. And never when it is raining.

 

[sheridany]

only use it when I’m driving in the mountains and/or steep grades. And never when it is raining.

Hi @ARD what do you do coming down a grade without the engine brake In the rain. I have read go slow and use your service brakes off on sparingly. Are you using a lower gear to retard speed?

 

[ARD]

Hi @ARD what do you do coming down a grade without the engine brake In the rain. I have read go slow and use your service brakes off on sparingly. Are you using a lower gear to retard speed?

Hi @sheridany! Happy 2023! The way I was taught is what I do which is exactly what you have read. I downshift as I go up and will downshift further as I go down if needed. When I start gathering too much speed, I apply the brakes to get back to a safe speed and release. I never want to ride my brakes, so I repeat the process of braking to get back to speed as needed. If it's a really steep grade and raining, I have tequila once I get to my campground.

 

[NWIP]

First I do not leave my engine brake on all the time. I was told when I attended Spartan Academy, use engine brake as you want but then they gave some pitfalls.
We will never wear out the brakes on these units, we don’t put enough miles on them. There was a 10 year old Dutchstar with over 130,000 miles and when they inspected the brakes there was 60% brake life left. They said use the brakes and use them hard to build up heat which will prevent glazing.
I did learn that using the motorhome brakes like I do in a car (smoothly) can cause problems. I was driving on a section of US 395 which goes thru town, 100* outside temps, lots of traffic lights and by the time I got to the RV park about 7-10 miles away I overheated the front brakes. I now will use the engine brake in town at times.
Going down grades is where engine brake is most useful with a combination of downshifting. My goal is to never touch the brakes and will switch between low/med/high as necessary.
In summary I don’t think there is a wrong way to use engine brake.

 

[Jim]

Knowing Bill, I was expecting him to say: "Brakes? Don't need no damn brakes!"

 

[NWIP]

I’m cheap so when I can get 500k out of a set, I start using them more

 

[Buly]

I’m cheap so when I can get 500k out of a set, I start using them more

Same here. Like to practice "energy management". Last car I sold had 110K miles and original brakes. The current SUV has 75K still original brake pads. My 40 YO step son in Nevada, has no clue how to drive on downgrades. Just steps on the brakes and holds as long as it takes . Had to give him a lesson.

 

[JRS]

I typically always use cruise control and like the advantage of coasting downhill. I always have mine off since it's easy to turn on with the 3 stage switch on my steering column. Use it on inclines and when rapid stops are needed.