Exhaust Brake ???

bullydogs1 wrote:
The exhaust brake over 65 mph will only drop you down into 5th and you won't feel it....at 65 it will then drop down to 4th and you will feel it kick in with the extra downshift....NORMAL....it is protecting the trans that way...

X 2

The exhaust brake over 65 mph will only drop you down into 5th and you won't feel it....at 65 it will then drop down to 4th and you will feel it kick in with the extra downshift....NORMAL....it is protecting the trans that way...

wolfe10 wrote:

lc0338 wrote:
I had an aftermarket pacbrake installed on my 01 Ram. It has an air pump. When I turn it on it takes a few minutes for the air pump to build up and the exhaust bake to be maximized. I supposed it has to build pressure to be able to close the baffle. Not sure any are made to work instantly. 18 wheelers take a few minutes to build up air. Maybe the factory brakes work electrically and don't need this air build time.

Why isn't the air compressor (and perhaps a storage tank) on all the time the ignition is on and controlled with a pressure switch? That way, the exhaust brake is available instantly. That is EXACTLY how I would wire it.

Why isn't it done from the factory like that? I just bought a 2014 RAM cab and chassis NEW and the exhaust is on a separate switch which can be turned on and off.

wolfe10 wrote:

lc0338 wrote:
I had an aftermarket pacbrake installed on my 01 Ram. It has an air pump. When I turn it on it takes a few minutes for the air pump to build up and the exhaust bake to be maximized. I supposed it has to build pressure to be able to close the baffle. Not sure any are made to work instantly. 18 wheelers take a few minutes to build up air. Maybe the factory brakes work electrically and don't need this air build time.

Why isn't the air compressor (and perhaps a storage tank) on all the time the ignition is on and controlled with a pressure switch? That way, the exhaust brake is available instantly. That is EXACTLY how I would wire it.

May be ok but the air is a benefit of the exhaust brake and not the intended function. Don't believe I would want to run all the time just to keep air tank full, if a tank was added. Anything is possible. The way it functions now is not a problem for me.

lc0338 wrote:
I had an aftermarket pacbrake installed on my 01 Ram. It has an air pump. When I turn it on it takes a few minutes for the air pump to build up and the exhaust bake to be maximized. I supposed it has to build pressure to be able to close the baffle. Not sure any are made to work instantly. 18 wheelers take a few minutes to build up air. Maybe the factory brakes work electrically and don't need this air build time.

Why isn't the air compressor (and perhaps a storage tank) on all the time the ignition is on and controlled with a pressure switch? That way, the exhaust brake is available instantly. That is EXACTLY how I would wire it.

I had an aftermarket pacbrake installed on my 01 Ram. It has an air pump. When I turn it on it takes a few minutes for the air pump to build up and the exhaust bake to be maximized. I supposed it has to build pressure to be able to close the baffle. Not sure any are made to work instantly. 18 wheelers take a few minutes to build up air. Maybe the factory brakes work electrically and don't need this air build time.

When you say "nothing happened", please be more specific:

Did the Allison shift pad go from "6" to your pre-select gear for the exhaust brake (normally 2nd or 4th, but can be anything)?

Did the transmission downshift (probably from 6th to 5th)? The 6-5 downshift should have occurred immediately, assuming that 5th gear at 65 would not overspeed the engine. If that 6-5 downshift would have overspeed the engine in 5th, it should have turned on the exhaust brake, but not downshifted until slowed enough that it would not overspeed the engine.

And BEST PRACTICE on a long downgrade is to find the combination of gear and exhaust brake that keeps you speed in EQUILIBRIUM. That is you are neither speed up nor slowing down without use of the brake pedal/service brakes. As a practical matter pure physics dictates that this speed is faster than a loaded 18 wheeler and slower than an empty one. If you are faster than all the trucks, YOU ARE GOING TOO FAST.

I don't think you will feel much effect from the EB until the trans downshifts and the engine RPMS increase. Increasing engine RPM increases backpressure which makes the EB effective. If your speed is too high the ECM will not allow the trans to downshift and over rev the engine, thus the service brake must be applied to slow the coach to a point that will allow the trans to down shift and provide full effect of the EB Don

Why didn't you have it on to begin with? EB is designed to be on all the time. Saves service brakes.