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Information on the Allison Transmission and retarder can be found here by opening the PDF file.
http://www.allisontransmission.com/p...s/OM3349EN.jsp
Here are some highlights that may prove of interest. With a retarder service intervals are cut in half. If you use Dextron you need to change fluids every year or 12,000 miles instead of 25,000. Transynd is impacted similarly, but has longer oil change intervals, depending on some other factors such as flilter types.
The retarder force will be reduced if the fluid overheats. I mispoke earlier. It appears that the computer will eliminate the need to worry about temperatures.
Speaking of temperatures: they vary depending on where the temperature reading is taken. The sump oil temperature maximum is 250 degrees F. More details are available at the link above.
Instead of having to take the bus to Allison to deal with harsh shifting, it appears by using the correct inputs we can clear it so the transmission can reprogram (self teach) itself.
The file is 94 pages with lots of good information.
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Same experience here. Last two buses had jake brakes... two cycle detroit 8-92 engines. Current bus has retarder... four cycle detroit. I think the jake was idiot proof as far as operation. The retarder took a few trips over the Rockies before I was comfortable with it's operation. Today, I really don't have a preference.
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Transmission Retarder
On my way out to Santa Fe, it was brought to my attention that I was riding my brakes and black smoke kept poping from my exhaust. Well, it was the Trans. retarder. I had left it on and any time I let my foot of the gas, it would slow the Coach down and then I would apply the gas. So, you have to be more aware of what you are doing. I was told you could raise the temp up to 290 degrees no problem. But I can not remember who at POG II told me. It is great for slowing down coming off the freeway, or having to make a rapid deceleration. I have to watch it on long down hill slopes.
My Country Coach Lexa has a 3 stage Jake and I liked that a lot also.
Finally, I really like my Liberty . Gary
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RVbus01 The link did not come through for the Allison Tranny video, please send it to me again. From your information you apparently know your transmission, wow, great description of retarder action.
Gary
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That entire text on the retarder plus a whole lot more is on the link on my previous post. I learned a lot when I read it because it gives some good indepth information.
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While at DDA recently I was informed that the transmission temperature using the retarder can go as high as 280F to 290F but not for extended periods of time.
John
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Retarders and Jakes
I have owned both systems and favor the retarder. It gives you much more control over braking and temps are not an issue that people make them to be. Running Transynd solves the temp question and the noise that the Jake makes shake small town tempers.
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If they can number the Superbowl in Roman numerals surely we can handle them.
There is something classy about triple XXX.
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A quick review:
The bus is moving at some speed and you want to slow down. There are 3 common ways to do this:
A. The service brakes convert the kinetic energy to heat into the brake hardware by friction of the pads or shoes against the discs or drums.
B. A Jake brake uses the kinetic energy to compress air, which is then "wasted" out the exhaust system. No heat is generated.
C. A transmission retarder converts the kinetic energy to heat inside the transmission. The heat must then be removed by the transmission oil cooler. The cooler is a small "radiator" mounted in front of the big radiator and the transmission fluid needs to pass through here a time or two to cool off the transmission, which will take a few minutes or more depending on the outside temperatures and heat load on the transmission.
All three methods do slow down the bus. Method A and C will eventually reach the point where the heat added by slowing is greater than the heat dissipated by airflow. For a single stop in traffic all will work well. For lots of stops in traffic all will work well for a while, but eventually A and C will begin to reach their limits. For descending a long grade eventually A and C will overheat. B will just keep on working, leaving the service brakes fresh and cool.
For these reasons I prefer the Jake Brake. Especially if you live and travel mostly in the western states, almost anywhere you go you encounter mountain roads and passes. Knowing the Jake is ready to manage downhill speeds without needing the service brakes at all times is very comforting. You can select most any downhill speed by choosing the gear and setting the Jake on high or low. It is easy, effective, and the system has been trouble free.
Then there is the issue of some towns and their signs about compression brakes. I have noticed the wording of these signs varies from place to place. Some I have seen say "Unmuffled Compression Brakes Prohibited" , or " Jake Brakes Unlawful in city limits", "Use of Engine Brakes Prohibited" or some such.
I take the approach that in any kind of emergency, I will use all the braking systems I have no matter the signs in the area. Also, since the Prevost installation IS a muffled engine brake, it is not nearly so loud as what we typically heard on logging trucks, etc in the 1970's when the Jake Brakes came into common use and many of these signs sprang up. I have never heard of anyone getting stopped or ticketed for using the Jake Brake, but I would like to know if it has happened. Anyone?
Another interesting point, on my 94 the brake taillights come on when the jake brake is working, and when you step on the service brake pedal, the red light on the dash also comes on to indicate that. So, someone behind you might think you are riding the brakes all the way down a long hill when actually you might not have touched them at all. And if you are decelerating into a town that has several speed reductions as you come to the center, while the Jake is working any local policeman will see that you are slowing down and not ignoring his speed limit on purpose. SO far I have never been stopped for that either, and wear and tear on service brakes can be minimized.
One further note, I have driven both a Series 60 Detroit bus ( mine) and a 8V92 Detroit bus. The Jake effectiveness was noticably more in the Series 60 version when the setting on both was on High.
As always, comments welcome!
Peter vS
94 Marathon XLV
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Transyn Tranny Oil
IMHO The transyn may have helped the temps some, but not enough for the difference in the price. The temps have concerned me enough that I am on my second dose. I don't know that I will use it again although I have had one so called mechanic tell me - once you use it, you must stay with it. I have been BSed before. Any body else heard that?