Trip Coburg Or.To San Antonio Fl.

[Gary & Peggy Stevens]

Gary S, and Bruce, do you guys in fact have the Jake Brake, or do you have trans. retarders?
If it's the retarder I don't think the braking action is as great as with a full Jake set up.

J.C. I have the Jake not the Transmission Retarder for sure. No stick on the right hand side of the steering wheel to control the speeds of the TR.

Jim, I have to disagree with you on the braking capability of the Retarder vs the Jake. I drove a 99 Liberty two years ago when we first started looking, which had the actual Retarder, and man it really stopped the bus, and you could control how much it stopped you with the 6 speeds (?) on the retarder. Where as the Jake system slows you down, it is nothing IMO, to the stopping of the Retarder. I wish I had the retarder. I would feel much better about stopping this monster. But I am learning to handle it.

[JIM CHALOUPKA]

Thanks for the comments that's interesting.

[Kevin Erion]

I agree with Mango, I had a 99 Marathon with the transmission retarder and now an 01 Marathon with the engine brake. The retarder has more stopping power but you can easily overheat the transmission fluid if you are not careful, I will take the engine brake over the retarder all day long!

[0533]

I agree with Mango, I had a 99 Marathon with the transmission retarder and now an 01 Marathon with the engine brake. The retarder has more stopping power but you can easily overheat the transmission fluid if you are not careful, I will take the engine brake over the retarder all day long!

I have the jB. and when going down long steep grades I found myself shifting down manually at times to keep the coach from running beyond a comfortable speed even with the second click of the JB. button on. It works but it is not the best option for slowing down in my opinion.

[Jon Wehrenberg]

Just a few comments, some are opinions.

A Jake on an 8V92, as set up with 2 cylinders per bank has a maximum of 220 HP rquivalent braking. It is not equal to the force of a retarder.

However, in my opinion a Jake is a no cost effective means of slowing on a hill, and in my previous bus I could go down a steep grade and if the high setting slowed the bus too much, and the low setting not enough I could switch back and forth between the two to maintain the desired speed.

A Jake brake is most effective when the RPMs are higher, hence Orren's idea of downshifting makes perfect sense.

A retarder will heat the transmission fluid rapidly. It is taking the oil pasing through the transmission and making it work hydrauilically in the retarder section before entering the water to oil intercooler. The fluid temperature we see on our transmission temperature gauges is what we see immediately prior to the intercooler, or when it is at its hottest having done the work of retarding. This is not the temperature of the transmission fluid in the transmission.

However, while the transmission is not necessarily seeing overheated oil, those high temperatures do haven an impact on the life of the oil itself. The ATEC computer limits the discharge oil temperature to 300 degrees, and if it reaches or is about to exceed that value, the amount of retardation is diminished to maintain the fluid temperature at or below the 300 degree value.

It is my opinion both the Jake and the retarder require the driver to exercise control. The retarder however also requires the driver to try to limit the temperatures via whatever means is possible, and that is not only more work, but it requires a lot of attention in hilly or curvy roads.

The retarder switch can be left on, and the seven position stalk can be in the off position and the retarder will still engage proportional to the amount of braking force being used. The driver needs to monitor the transmission oil temperatures under hard braking even when the lever control is in the off position. The retarder has a significant impact on improving braking distances.

But I would take a Jake brake any day of the week.

[garyde]

Gary, Does your jake brake work when your cruise control is on? That might be a conflict.
Jon. My retarder works great and I've never had it higher than 228 . I can't see where replacing the trans oil sooner is any big deal. Instead of 50000 miles, replace at 25000 miles.
Kevin, how are you? How's those girls?
I wouldn't mind having both the retarder and the jake but I would not give up the trans retarder. It stops a 50k bus very quickly.

[Gary & Peggy Stevens]

Gary, Does your jake brake work when your cruise control is on? That might be a conflict.

GaryDe, you asked if my jake brake works when my cruise control is ON? Do you mean when the switch for the cruise is on, or when I am actually using the cruise to maintain speed going down the highway?

My reply, seems kind of silly when I read it again, BECAUSE, the Jake Brake is never actually on, IF, the cruise is on and set, cause I am going down the highway at a maintained speed.

GaryDe, clarify your question for me please. I really don't think my Jake is functioning? Maybe someone can jump in and take a test drive to verify what they think.

Is there an electrical connection for the Jake, or just mechanical. Maybe I pulled a Relay and shouldn't have?

[Ray Davis]

Gary,

Our coaches are similar in year, and I assume similar in function. I can definitely feel the jake, but as others have mentioned it's much more effective when used at higher RPMS.

ON my previous bus, after a DD service, it turns out my jake wires were not connected into the motor, and believe me, going down any hill without a jake is a scary thing.

If you can't find a hill to verify, try to find a tunnel, or concrete wall nearby that you can open your window and listen. You should definitely here AND feel the jake.

Ray

[Jon Wehrenberg]

Gary,

If you use Transynd AND YOU HAVE A RETARDER your fluid change interval is 75,000 miles or four years. Apparently Allison considers that harsh duty.

If you are using Dextron the interval is one year or 12,000 miles whichever comes first.

I am surprised at the temp. It bears some checking to learn if on the XLII shells the temperature is monitored at the retarder outlet side or some other location. Those of us that have a retarder and watch the gauge can see it literally sweep across the gauge if we are working the retarder or brakes. I take action by either turning off the retarder or dropping iits setting down a little to limit mine to a self imposed 230 degree limit, but I know for sure I can run the temps way past that point.

[Ray Davis]

If you are using Dextron the interval is one year or 12,000 miles whichever comes first.

Jon, do you mean that the fluid should be changed at one year, or simple checked and topped-off? I had just yesterday spoken to Prevost service guy in Dallas, and he's telling me 50,000 on Dextron, and up to 100,000 on Transynd. Didn't mention anything about interval.

Ray