When/how to use a Jake brake

[wildmandmc]

some models have a high speed an low speed exhaust brake, if u just have a low speed, i wouldnt advise using it on highway. if your going to be braking a lot in traffic i would use it. on highway i take it off.

[Snomas1]

I use mine all the time in town and when ever I have to stop to save wear and tear on the service brakes. I turn it off when on the freeway or don't have to stop for a long run. I hit the service brakes ocassionaly for a period of time to remove any glaze!

[DA_BUS]

I recommend you read your chassis manual as you will find a lot of information there. Don't go running around the mountains until you know how to use it properly....your manual should also give you some insight into when the brake kicks in (rpms), etc. My manual gave me a lot of insight on the braking system and how to use it.....for instance - depending on your brake type - you may be running to fast of rpm's to even get it to engage..then you have a problem.

[Dr4Film]

Originally Posted by jimbo2013

The data sheet from Monaco says its a retarder brake.

I only saw a switch, no pedal

I'm going to spend tomorrow going thru it all before a 120 mile trip home Tuesday or Wednesday.

When I demo'd it last Friday I didn't use the Jake, just wanted to keep it simple.

It's a 2000 38 HR Endeavor with a 330 HP - 3126

Monaco used the term retarder for a generic word that encompasses all types of engine brakes. That wouldn't be the first time that Monaco has screwed up in their literature supplied with the coach.

However, a true Engine Brake will NOT be found on an ISB or an ISC engine. It wasn't until the ISL came out where you will find Two Stage Engine Brakes on the Cummins engines.

Do a search up top and use the term PacBrake and you will get ALL of the information you will ever need regarding your Exhaust Brake.

Dr4Film ----- Richard

[jimbo2013]

Originally Posted by Steve Ownby

You have an exhaust brake aka PAC brake which is one major brand. It only has an on/off switch. When you start home turn the switch on & start the learning process.

I have a on/off switch no choice as to hi or low etc.

When I was going thru everything ready to leave I noticed the muffler was bad, so the dealer agreed to replace it in the morning, so I have to stay overnight.

We are in a beautiful CG (Myakka river state park)
about 23 miles drive from the dealer yesyterday.

So I hit the jake it goes into second, It was nice but at times downshifted too hard.
I read that the tranny can be reprogrammed to shift better into 3rd or 4th.

Any info on that?

Tomorrow I'll make the 120 mile trip home, next week FL -NY 1200 miles, then return 10 days later, so that will give me a 2500 mile shake down.

My first DP, sure beats towing a trailer...........

[coolhand108]

the more you use it the more comfortable you will feel I drove truck for forty years, was nice when they came out with the jake brakes. l leave mine on constantlyso I know when I lift the throttle it will come on. as mentioned be carefull using it on slippery roads, if it is strong enough it can actually make your rear aXLE TURN BACKWARDS, OTHER THAN THAT YOU SHOULD HAVE NO PROBLEMS WITH IT

[palehorse89]

Originally Posted by jimbo2013

I have a on/off switch no choice as to hi or low etc.

When I was going thru everything ready to leave I noticed the muffler was bad, so the dealer agreed to replace it in the morning, so I have to stay overnight.

We are in a beautiful CG (Myakka river state park)
about 23 miles drive from the dealer yesyterday.

So I hit the jake it goes into second, It was nice but at times downshifted too hard.
I read that the tranny can be reprogrammed to shift better into 3rd or 4th.

Any info on that?

Tomorrow I'll make the 120 mile trip home, next week FL -NY 1200 miles, then return 10 days later, so that will give me a 2500 mile shake down.

My first DP, sure beats towing a trailer...........

Simply put.....yes. You can have a dealer with the software and a laptop change the "factory default" setting to suit your needs as far as the gear it selects for the engine brake downshift.When it downshifts and you see 3rd on the screen it does not mean that it downshifted to 3rd, it is just pre-set to select 3rd,and at 60 mph downshifts to lets say 5th but the screen says 2nd. The TCM & ECM WILL NOT ALLOW YOU TO OVER-REV THE ENGINE. Also you can change how your cruise control works with your engine brake also(not sure how yours is set up now) I had mine re-programed to stay in 6th for the engine brake downshift (my presonal preferance) and the factory default use to be 4th.

[HD4Mark]

We had never driven anything with an exhaust brake until purchasing this coach. When test driving the dealer said "just leave it on all of the time". I thought OK but what is the point of having an on/off switch?

After driving it for a while I also discovered it is great in traffic but I turn it off for most highway use. If the cruise control is on and I start to come up on someone going a little slower all I want to do is hit the brake lightly to disengage the cruise and coast until I can pass or reset the cruise. At our exit I switch the exhaust brake and usually leave it on until getting back on the highway.

[Gearhead383]

Originally Posted by jimbo2013

I have a on/off switch no choice as to hi or low etc.

So I hit the jake it goes into second, It was nice but at times downshifted too hard.
I read that the tranny can be reprogrammed to shift better into 3rd or 4th.

Any info on that?

Jimbo2013, as stated earlier, you do not have a Jake brake. What you have is a Pac brake. Entirely two different braking systems. The Jake is an engine braking system while the Pac is an exhaust braking system. If you every need help with you Pac exhaust brake, as you do now, it would save a whole lot of confusion if everyone was on the same page.
If I were you, I would hold off on reprogramming the transmission. Get to know the coach first. I only use my Pac brake if the coach is gaining speed while going down hills or coming off the freeway onto an exit ramp. I think they do an excellent job slowing down the RV. I have never used it while driving in town although I'm sure some do. Good luck with your new RV

[palehorse89]

Originally Posted by Gearhead383

Jimbo2013, as stated earlier, you do not have a Jake brake. What you have is a Pac brake. Entirely two different braking systems. The Jake is an engine braking system while the Pac is an exhaust braking system. If you every need help with you Pac exhaust brake, as you do now, it would save a whole lot of confusion if everyone was on the same page.
If I were you, I would hold off on reprogramming the transmission. Get to know the coach first. I only use my Pac brake if the coach is gaining speed while going down hills or coming off the freeway onto an exit ramp. I think they do an excellent job slowing down the RV. I have never used it while driving in town although I'm sure some do. Good luck with your new RV

Same page, Compression braking and exhaust braking (proper names)

Difference Between Jake Brake and Exhaust Brake | Difference Between | Jake Brake vs Exhaust Brake

[Steve Ownby]

Originally Posted by jimbo2013

I have a on/off switch no choice as to hi or low etc. When I was going thru everything ready to leave I noticed the muffler was bad, so the dealer agreed to replace it in the morning, so I have to stay overnight. We are in a beautiful CG (Myakka river state park) about 23 miles drive from the dealer yesyterday. So I hit the jake it goes into second, It was nice but at times downshifted too hard. I read that the tranny can be reprogrammed to shift better into 3rd or 4th. Any info on that? Tomorrow I'll make the 120 mile trip home, next week FL -NY 1200 miles, then return 10 days later, so that will give me a 2500 mile shake down. My first DP, sure beats towing a trailer...........

We spend most winters in Fort Myers so know that area well. Great place to be right now. It's not a great place to learn the operating characteristics of an exhaust brake. The programming to shift to 2nd gives the widest operating range without any operator intervention other than allowing the throttle to close. The exhaust brake needs the engine to be up toward the top of its rpm range to be very effective and if it's turning fairly slowly when the brake comes on you might get an immediate downshift from 6th to 4th which will seem harsh. If you reprogrammed for 4th the harsh shift would still be there. My advise is to wait until after your 2500 round trip and you have more operating knowledge.

If you are interested in becoming a truly knowledgeable diesel owner/driver I recommend that you investigate Silverleaf products. Their real time engine/transmission data products let you see the operating parameters from the ECM. I'm sure they will have a booth at the Tampa Super Show in January.

Be careful if you encounter any slick road surfaces on your trip. Don't use the exhaust brake on those roads.

[Dr4Film]

I really don't think FLORIDA is the place to decide whether the Allison ECM needs to be reprogrammed to a higher gear.

Drive it over all different types of terrain and THEN make a decision.

I actually installed the upgraded PacBrake package. I am 36,000 lb's on the coach and 11,000 lb's on my trailer. Trust me, you want ALL the help you have available to you to keep the rig under control descending mountains.

If your rig is small and light and you don't tow then that would be a different scenario.

Dr4Film ----- Richard

[1985 Bounder]

Jimbo's, as stated before you need to know what you have. There are basically 4 types of brakes. There are your service brakes which we all have, there are drive line brakes which very few have due to expense and problems, engine brakes which are a physical part of the engine and the exhaust brake found in the exhaust pipe after the turbocharger. Jacobs was the first to make an engine brake and held the patent for many years which held off competition and hence the generic reference to engine brakes as "Jake brakes". An engine brake allowed the engine to create the high compression during the upstroke of the piston but releases it at or near top dead center so the built up compression will not force the piston back down. The ECM or a series of switches will only allow the engine brake to come on when the engine is in the no fuel condition. Engine brakes are now made by several manufacturers with Jacobs and PAC being the lions share of the market. Engine manufacturers such as Mercedes and Volvo now have built in they're own version of a brake directly as a part of the engine and not as a component that is put on the engine. The engine brake has very strong braking capabilities because of the use of the diesels high compression. The manufacturers recommend they be left on with the exceptions of wet/slick roads and where they are prohibited by noise ordinances, usually accompanied by a sign on the road to advise you to turn it off. Some later model vehicles also added an exhaust brake too, not so much to assist in braking but to muffle the loud noises created by the release of the high compression.

Exhaust brakes as stated above were made for those engines not conducive to the addition to an engine brake to the overhead of the engine. These brakes are sometimes confusingly referred to as "Jake brakes" but are not the same as the engine brake. An exhaust brake uses increased exhaust pressures against the engine to slow down the engine. The braking power of an exhaust brake is no where near that of an engine brake but still makes a good addition to the service brake. There are many manufacturers of exhaust brakes including Jacobs, PAC, Blue Ox, BD, and many others. They have been referred to as "potato brake" because they restrict the exhaust like jamming a potato into the exhaust, as once was a practice joke. These brakes are also recommended to be left on so there will be there when needed and so the flapper in the brake will actuate every time you drive to keep it from sticking due to exhaust residue. The newer electronic engines will use the exhaust brakes to assist in the warming up the engine by holding the heat in.

Some set ups have a simple on off switch, some a high/low switch and some a high/medium/low switch. As others have mentioned I would first know for certain what system you have. Then before changing anything drive the vehicle and see how it operates in different situations and then you will be able to tell your dealer what works for you and how you would like to have it work and they can let you know what how they can't week it for you.

[jimbo2013]

Well the trip went fine had the brake on for the trip, got used to it, I'll take a good look at it tomorrow working on several other things.

Before going to the muffler shop a jacks down lite pooped up, all jacks were up.

His shop tried pushing up on each one think a bad contact, that didn't work, anther mechanic came out and suggested checking the hydraulic fluid level.

He said there is a sensor in the tank that must see all the oil returned when jacks are up.

The fluid was down a few ounces, fill light went off.

Didn't get the muffler, the shop the dealer was using couldn't do it today, I had to leave. The dealer gave me the money it would have cost him, so we left.

.