Tranny Retarder switch/lever problem (Alli B500R)

[Dirtball]

1996 MCI DL3 Series 60 B500R .  Standard MCI dash toggle turns retarder on/off. Lever to my left next to the tranny keypad has about 5 "detent" positions. WIth TR turned on and the lever pushed to the forwardmost position, I get retarder engagement on brake pedal application only. Or , I can drive keeping the lever in the next position back and get retarder engagement upon lifting off the throttle. SO when I am coasting down a grade or on level road retarder engages without brake application when I lift off throttle. Maybe a nice concept for metro travel but I like to be more active with the TR lever and work it back and forth as tranny temp gauge tolerates. .....Current problem is I have lost the ablilty to have that first position stick in place. The one that gives me no retard on coasting. The lever ? may have come out of adjustment, it acts like it's the next rearward position, that gives me retard ever time I lift off throttle. I can push the lever forward to act like the old first postion but It won't stay put. SO if I want to coast down a long grade and build some speed for the next hill, I have to use my left hand and hold the lever forward in the first postion.
  Problem here is ^Tranny temps that are unnecessary, which will lead to ^ water temps. And wasting fuel and making me drive one handed.
  I will check tranny for codes, but is there a basic mechanical adjustment under the plastic console to "zero" the toggle lever?     thanks

[Busted Knuckle]

All I can say is if it were my B500 transmission I would not want to leave the retarder in the on position when not using it!

Our local allison tech told us even when you think it's not on it is and it causes higher trans temps and will fry your tranny if done much! (he said he didn't mind making repairing it, but would rather say me the $ up front and making his $ off me honestly!)

Now let me tell everybody I don't know how accurate it is, but I do as he recommends.
  BK 

[Joe Camper]

I have heard it suggested by many who have these retarders that the temp probe is located directly in the path of fluid exiting the main body of the trans at the hottest possible point that the fluid could be. That the actual temp of the fluid reentering the valve body is very much cooler than what the gauge is showing and that all is really OK

Has anyone here know of any of these trans that was burned up by using a retarder and absolutely know it for sure to be the reason for the failure

[Busted Knuckle]

I have been told more than once that the retarders cause overheating.

I know a guy that had several Van Hools that had constant transmission problems while still under warranty and Allison told him that it was because the drivers were leaving the retarders on and just lifting their foot off the accelerator to activate them.
He told them to unhook them so they couldn't be left on.
So they pulled the fuses. And he never had another problem at all with the transmissions until he traded them off! (this guy buys 3-4 new coaches runs them until the warranty runs out and trades them off, keeping new under warranty buses all the time. And is currently running Setra's!)

Also our dearly departed Sammy told me on more than one occasion that the retarders were killers. (said a transit drivers best braking tools & the mechanics worst enemies are retarders and curbs!)

My Allison shop tells me it's a fact that his shop replaces many retarder equipped transmissions than non-retarder ones.

I'm sure Clifford can get us the straight scoop from Cole or one of his other Allison guru's!
  BK 

[hargreaves]

Allison can reprogram the transmission module so that the retarder only comes on with brake apllication. they can also program how much retarder you get.    Gerry

[luvrbus]

You can have 6 levels of modulation with the B500 but only 3 if tied to the service brake, and to answer his question about adjustment of the lever I cannot find any adjustment in the book

good luck

[Joe Camper]

What a stupid way to change the way we assist braking when the jake brake is still alive and well.

[Dirtball]

I have 5 or 6 levels of modulation using the lever only ( no brake pedal actuation). I'll go count later and report back.   I guess I've now learned that if my hand is off the the lever and I use brake pedal only, the more I press the pedal the more retard I get. Obviously if the dash switch for TR is off I get NO retard with pedal or the lever. SO if I call the lever positions 0-1-2-3-4-5 , my current problem is I have lost the 0 position, so the retarder acts like I am in the 1 position all the time. Which is how some people drive. I had a 25 yr fulltime MCI veteran driver, drive me somewhere once, and she kept the lever in 1 or 2 position all the time. When I questioned her ,she said that what she's done for years. I always keep it in 0 position and use it when I want it or get retard with brake pedal actuation.  So back to my lever, I can gently PUSH it forward to act like it's in the 0 position so I can "coast" when I want to without retard. SO my old 0 position is now my 1 position. It seems like there must be a simple adjustment to the rear of the lever( some type of gimble assembly). I called my bus guru besides you guys and he says one of his 6 buses recently started doing the same thing.  ANyone have a microfiche blow up of that thing? .....thanks again.

[Joe Camper]

Dirtball. Compare the retarder to a jake.

Based on your experience if you could get the retarder to function correctly as you describe,do you think you get more performance from it or a Jake brake or less. Which would you rather have everything considered?

[Dirtball]

The retarder is in and paid for, just out of adjustment I hope. With me driving the bus I can keep it out of the redline, sometimes shutting off the bus-air in hot weather on a long grade. As owner/driver I watch the gauges, unlike the hired guns.  Search my old posts , I had a thread about adding a Jake to the TR and having both. The mechanic who had done that mod before,  moved away. If I had to pick one I'd take the Jake. I wouldn't want to be running down big mountain roads in August with the TR. I think they are more of a 55 passenger flat turnpike aid , that is silent and saves brakes and doesn't wake the passengers. The thought of having both was exciting. They should make a ( probably already do) ,  TR , that is a Regenerative battery charger for a hybrid bus. Why waste all that energy heating your tranny fluid, mine as well make some amperage with it.

[Zeroclearance]

If I was you I would try to pick up a set of JAKES for you Series 60.   My father retired from Denvers RTD and drove there latest MCI DL's and the Allisons were alway getting replaced.    I will ask him about the temperatures that the usually see coming down I-70 into Denver.    They believed that rebuilding Allisons vs brakes were a better alternative.    The perfect system would be Jakes and a retarder.   Using the retarder as the 3rd stage. 

[belfert]

What a stupid way to change the way we assist braking when the jake brake is still alive and well.

There are many areas were engine brakes are prohibited by ordinance due to the noise.  I doubt engine brakes would be a very good idea on an a bus used in transit service either due to the noise.

I80 going west in Salt Lake City prohibits engine brakes on a long downgrade coming into the metro area.  I use my Jake anyhow rather than risk overheating my service brakes.  I always smell burning brakes from other heavy vehicles on that downgrade.  One time the guys in the bus were yelling at me because they thought I was overheating the brakes and I hadn't even touched the brakes in over a minute.  (It was another vehicle.)

[Joe Camper]

With the risk of disagreement and in the name of the discussion and complete disclosure of info..........a differing view.


A good friend sent me this (this is with an XLII and possibly the prevos are wired differently but the temps sould be comparable)

here is what he sent me

I go to that site every day and I don't agree that a retarder is on if the handle is in the 0 position,the manual states that it will become activated with brake application if the dash switch is on,I have never seen temps over 224 and that was with a trailer and I was at 71,000 LBS. down Black Mountain.

[luvrbus]

Joe your friend didn't use much retardation if he only saw 224 those babies will get to 300 in a hurry with full retardation on long grades heat depends on the level used.

If he was using the pedal no way can he have full retardation unless he applies full brake pressure 

Allison does not want Jakes and the retarder used simultaneously that is the reason not to many buses with retarders have Jakes

good luck

[buswarrior]

Dirtball, I suspect that your retarder joystick may be broken.

When set up as originally intended, I prefer the retarder.

More steps than Jake, more "stopping" power, and no noise.

Coupled with appropriate use of the downshift button on the transmission keypad.

The cooling fans and the water pump run at engine speed....

Full retarder downhill while the engine is loafing in 5th or 6th gear, depending on programming....

Well, who has the marshmallows?

I do not agree with leaving the retarder, or the jake, turned on so it will engage with a simple lift throttle.

Activates expensive machinery when it may not be required, hurts fuel economy, encourages the accelerator to be left applied longer than it should for defensive driving reasons to inhibit the deceleration, and gives a poor quality ride to the passengers.

And makes unnecessary heat in a retarder equipped transmission.

happy coaching!
buswarrior