Just Installed Pac Brake

[Wheaties]

Hey, this thing is awesome!!! I thought the Pac brake would help me to slow down, but I got off the highway and slowed to a crawl on the offramp without touching the brake pedal, just by downshifting! This is going to add miles and miles to the life of my brakes. I recently priced front rotors at $170 apiece from the dealer and they aren't even gold plate. Who are they kidding?



Do any of you get funny looks from passersby when you flip the switch?



Special thanks to TDews and MassDiesel for all their help! You guys are awesome!



Matt

 

[LBTRS]

I don't know how true this is but someone mentioned to me that it's much cheaper for brakes than the wear on my drivetrain from the exhaust brake. I was not knowledgeable enough to argue with them one way or the other so I just nodded like I knew what they were saying. I wonder how much truth there is to this?

 

[RHARVEY]

Been there,done that... Also the questions you get when they see this. .

The wires were not yet ran to the switch. This is a push pull 2 speed switch.



Rick

 

[JR2]

My Dad has a pac brake on his 98. 5. He now has over 60K on the current brakes and they have at least 50% life left on em... ... No drive line problems and the truck runs great.

 

[Blu-meanie]

Ray... If you ever lost your brakes towing a trailer, you wouldn't care about the wear on anything. It is beyond a sicking feeling in the pit of your stomach. Plus, you need to keep your cool with your wife next to you while you are white as a ghost.

It wasn't with this Dodge. It was a #@$%!ord.

 

[Wheaties]

Yes, I've heard the argument that a clutch is more expensive to replace than brake pads, and it didn't have anything to do with a diesel. I can't say I have conclusive evidence, but consider this: the seat of my pants feels milder forces than what I get accellerating. To me this translates into smaller forces in play than a full throttle acceleration and a lighter load than what the drivetrain experiences fairly frequently. Sixty pounds of back pressure is probably less than the pressures achieved by combustion. Can anyone verify this?



Commercial trucks use this braking method all the time. Are they designed with heavier drivetrains to handle heavier loads? Certainly. Are these drivetrains made with a greater engineered margin of safety? I don't know. But the principle is accepted as sound.



As for the argument that you're wearing the clutch out faster. I'd argue that a clutch only wears when it's slipping. When you're braking, the clutch is fully engaged and not slipping. You don't brake with the clutch.



Not using an exhaust brake, down a long hill, with a trailer in tow can lead to severe brake fade and damage to the drivetrain, the entire vehicle, and the occupants.



Matt

 

[Oxjockey]

I'd have to think there's some merit to them if DC recommends and sells them. I have 3 basic questions, however:



1) How do they work with electric brakes and a controller like the Jordan?



2) Isn't downshifting about the same, without the concern of over revving or chirping the tires?



3) Are there different brakes for 3" & 4" (and 5") exhausts?



Bryan

 

[LBTRS]

Blu-meanie,



I have no question about a exhaust brake being used while towing or in emergencies. My question is whether use during normal everyday driving (like pacbrake recommends) is doing more harm than good. Save the brakes at what expense to the driveline? Like I said, I don't know how hard it is on the driveline so I can't say for sure so I'm looking for others opinions.

 

[HEYBOSS]

Congrats Wheaties.



They are awesome and if anyone tows with them they never will be without them. I tow a 12k 5er and on long trips out to IN and Fl hardly ever used the truck's brakes, the exhaust brake does most of the job and Yes Oxjockey they work real nice with the Jordan controller. I use my exhaust brake every day and all the time, also they're awesome when some jack**ss is on your tail and you can slow down without hitting the brakes, it catches their attention



Now Wheaties, some bad news for you... ... ... ..... if you've gotten a Banks exhaust brake instead the Pac your fuel mileage would've increased 20%

 

[Wheaties]

Originally posted by Oxjockey

I'd have to think there's some merit to them if DC recommends and sells them. I have 3 basic questions, however:



1) How do they work with electric brakes and a controller like the Jordan?



I'd guess they are completely separate. I'd expect electric brakes are triggered by pressing on the brake pedal. The Pac brake is activated by getting off the go pedal and having the switch on.





2) Isn't downshifting about the same, without the concern of over revving or chirping the tires?



Downshifting a diesel produces almost no braking because there is no butterfly in the intake, therefore no vacuum to pull against the pistons. The exhaust brake puts a butterfly in the exhaust, providing back pressure to the pistons.



3) Are there different brakes for 3" & 4" (and 5") exhausts?



Not sure what you do for different size pipes. Most exhaust brakes ar in the elbow, just off the turbo, though there is one that mounts much farther downstream. How do you connect a 4" or 5" downpipe to the elbow?

 

[Wheaties]

Originally posted by HEYBOSS

Congrats Wheaties.



THANKS! It's great to hear from you.





Now Wheaties, some bad news for you... ... ... ..... if you've gotten a Banks exhaust brake instead the Pac your fuel mileage would've increased 20%

I'd forgotten about Banks! You know... I've heard that the guys who installed all and only the Banks gear actually have to stop from time to time and siphon fuel out of the tank. Their engines are so efficient, the tank keeps filling up by itself, but only if they keep their foot out of it.

 

[Roger Ledbetter]

Smoked my brakes only once

While towing my 5th wheel down from the mountains. And that was enough to convince me the benefit of an exhaust brake. Everyday driving I leave it off, going down hills with 18,000 gcvw she in on and saving the service brakes for stopping.

Not to mention the wife said she wouldn't ride along anymore if it happened again. I don't blame her.

 

[Snow man]

Congrats Wheaties, I told you it was awesome! I hardly use my brakes at all now,especially on the highway . I love to wind it up to 3400,then braaaaaappppppppppppppp ,especially going thru tunnels,or underpasses,people give me funny stares all the time when it kicks on. Mine is set on full automatic,with the DTT smart controller,and 2 5 pole double throw relays,it kicks on anytime above 17mph in 2nd,and above 25 mph in drive,and is on anytime the TC is in lockup. mine kicks back off at 17 mph,so i dont have to hear it hisssing at idle as i stop.

 

[Wheaties]

Snow man,



Sounds like a really nice arrangement! I'm discovering that I'm using the switch on the stick a lot more than I thought I would. Of course, I'm still getting a sense of how much distance I need to give myself to stop. I keep giving myself too much distance! Guess I better turn it off and coast a bit

 

[HEYBOSS]

Pac brake still works with 3" and 4" exhaust because it's mounted on the elbow and I believe it works with 5" exhaust because you need to use 4" down pipe for the 5" exhaust.

Where the Pac brake becomes obsolete is when you go into the Hx40 turbo because the mount now is different, someone can correct me if I'm wrong.



The Jordan brake controller works best with exhaust brakes because it acts like a true proportional brake controller. I believe that other controllers like the prodigy measure the rate of deceleration of the vehicle and then apply the trailer brakes proportional to it, therefore the Jordan works best because still has full brake effect on the trailer along with the exhaust brake. This was what I read some time ago here on brake controller discussion and if anyone interested can do a search, it seems to make sense.

 

[HEYBOSS]

Snow man; I've been kicking the idea for some time now on how to hook up the exhaust brake so it only comes on when the converter is locked up so you don't have it on at an idle. My idea was to run a relay that would get activated by the lock up wire from the smart controller so that every time the smart controller pulls ground off lock up it would shut off the exhaust brake. Would need a DPDT switch to keep exhaust brake on at an idle for winter warm up and pi** off some one behind you once in a while. I think it would work, when I get some time I'll fool with it.



Is that how you wired your's up?

 

[Snow man]

Yes, thats how i did it,but you need 2 relays,and one diode. Its not a big deal i found out that power feeds back everywhere on these things,that why you need to extra relay,and diode.

 

[Oxjockey]

Downshifting a diesel produces almost no braking because there is no butterfly in the intake, therefore no vacuum to pull against the pistons.

I have no problems downshifting for tolls. I actually chirped a tire this week with too fast a clutch/too many RPMs. I can see how the exhaust brake would help not to have to do any of that...



Bryan

 

[Wheaties]

Originally posted by Oxjockey





I have no problems downshifting for tolls. I actually chirped a tire this week with too fast a clutch/too many RPMs. I can see how the exhaust brake would help not to have to do any of that...



Bryan

I see what you're saying Bryan. You are right, you do get a minimal amount of braking by simply downshifting (without the brake) This is caused by accellerating the moving parts of the engine, especially the flywheel. Once that speed is matched however, this energy returns to the wheels. Think about a child's toy that you rub on the carpet and let go. You feel the resistance as you spin up the wheel under the toy, and it pushes the car along when you release it. The same thing is happening here.



Beyond that, to get any real braking, the engine needs to do work. On a gasoline engine, getting off the gas closes a butterfly valve in the intake, and the pistons pull against it to create vacuum.



If you remove this butterfly valve, then air can be easily pulled in through the intake and pushed just as easily out the exhaust. Aside from moving the mass of the air and overcoming the normal friction of the moving engine parts, very little work is done. Air is compressed during the compression stroke, but it behaves like a spring, returning that energy back to the piston on the down stroke.



But if you put a butterfly in the exhaust, the pistons have to compress the air to push it past the butterfly, up to the 60psi that the exhaust valves are rated for, work is done, and you get some real braking from the engine, up to about four times what you can get from a gasoline engine.



You may already understand this, I don't know if you do or don't. I hope I'm not offending you or anyone by explaining this. It certainly isn't my intent. There's bound to be someone who doesn't know how this works and will find this informative.



Matt

 

[Oxjockey]

You may already understand this, I don't know if you do or don't. I hope I'm not offending you or anyone by explaining this. It certainly isn't my intent. There's bound to be someone who doesn't know how this works and will find this informative.

Don't worry! Some day someone will be searching for this info and find it in this thread!



Bryan