Allison Auto and exhaust brakes

[James3:13]

I have an Allison MD3500 behind a Cummins ISL8.9 engine.

It never had exhaust brakes fitted to it , Can anyone tell me if this can be done or is there a reason its not been fitted ?

Second question , If i lose brakes on long downhill runs or get brake fade , can i downshift using the shift selector to knock off speed or could this damage the transmission ?

I have owned manuals for many years so pardon my ignorance on the Autos.

 

[helloDog]

You should always downshift on a big downhill when towing so the engine assist in braking. Foolish to rely only on the brakes going down a mountain. I have gone down big hills in 2nd gear and 1st even on really steep parts (not interstate). Your transmission is made to shift gears, so as long as it is not revving super high then shift as needed.

Exhaust brakes are wonderful. They get attached to the exhaust pipe, not the transmission, so will have no effect on trans. Ex brakes basically make it hard for the piston to go in its upstroke by making backpressure that the piston has to compress, it would normally just push the air (burnt exhaust) out, but with ex brake the pipe is closed to nowhere for the exhaust to go and it just gets compressed - then released of course. This slows the engine which slows the truck.
It works great on manual trans.
It can work on an auto but not as good. The auto has a torque converter that allows the trans (wheels) to spin faster than the engine, so slowing the engine will not slow the wheels as much on auto as on a manual.
If your auto trans torque converter can stay locked up while ex braking then it works the same, but when it unlocks then is not as effective.
That said, yes, you can install on auto trans vehicle and yes it will provide benefit.
There is more to be said, but the short answer is, yes.