Exhaust Brake or Transmision Retarder

[Leo B]

Which is best a transmission retarder or exhaust brake? Will both work with cruise control? What are the advantages of each?

[Leo B]

Which is best a transmission retarder or exhaust brake? Will both work with cruise control? What are the advantages of each?

[Bikeboy57]

Trans retarder usually has five or six degrees of braking, most jakes have high and low.

Trans retarder in the rigs I have driven seems to kick in a little smoother.

Need to make sure the trannie has it's own cooler when using a retarder for mountain descents.

The exhaust brake and cruise control fought each other in both rigs I've owned.

[Leo B]

Thanks Richard!

[johned]

Leo,

From what I have learned the trans retarder is the least desired because it generates lots of heat for the engine radiator to get rid of. You should be at zero throttle when using it so the stock radiator "should" suffice. Still, I hear most recommending that an aux trans cooler/radiator/heat exchanger be added. Heating up the trans much over 220 will severely shorten the life of the trans.

The problem with Jakes is that they must be properly adjusted every couple years...like the valves. Is that a problem? They don't work much if not set properly but that doesn't hurt much. They make a ton of noise but most drivers seem to like it as it is a throaty growl. Communities bordering freeways and in deep valleys are sick of the racket and some hills have "NO JAKES" signs posted for noise abaitment. Those signs are ignored in favor of living thru the downhill.

The best ever is the Telma Retarder. Google that one. Almost standard equip in Europe and here on school buses.

Good luck.

John

[Leo B]

Thanks John!

[dbarton291]

Transmissions with output retarders should use a separate oil/water cooler of tube and shell design. Max temp to the cooler allowed is 300F. Retarders are allowed to go to 330F intermittently. The retarder cooling systems are tested with either a 0-30-0 cooling test until temps stabilize, or 0-40-0.

An exhaust brake (a jake is a compression brake) when used with an Allison six speed is normally interfaced with the trans ECU to request a preselect shift schedule to D4 when the exhaust brake is energized. This is because exhaust brakes need engine RPM to be efficient. The retarder absorbs much more engine HP than the exhaust brake, but it is expensive.

There's nothing wrong with the Telma either, if it's electrical connections are hooked up correctly and the driveline that contains it retains properly angularity and phasing after the Telma is installed.