What exactly does mode do on B500 tranny?

[belfert]

Does hitting the mode button on a B500 tranny turn on economy mode?  What exactly does it do?  Does it just change the shifting pattern and not change anything on the open road?

I was over at a Detroit dealer getting some harsh shifting looked at and they recommended using the mode button.  It never shifted harshly for them and they didn't fix anything.  For some reason, the bus doesn't seem to accelerate as well now, even without mode on, but it might be my imagination.

Brian Elfert

[buswarrior]

Hello Brian.

I'm not impressed with that advice to "just use the Mode button" Less than knowledgeable responce, or they don't care about what you care about.

As for the "Mode" button, it depends which way the transmission is programmed.

Typically, there is a performance program, and an economy program, with variations within each.

The performance program downshifts earlier when climbing (at higher revs), and holds gears longer on acceleration (to higher RPM)

the economy holds gears longer(lower revs) when slowing on a climb, and shifts earlier on part throttle upshifts

Whichever is the default operates with "Mode" off, the other with "Mode" on.

On the seated coaches I drive, (not knowing which other adjustments may be programmed in) I prefer the economy setting, because on "performance", the transmission downshifts at the slightest provocation on the highway, for no real gain in performance, just a degradation of fuel economy, and another shift for a passenger to notice.

If I want a lower gear, I select it myself with the keypad, when I want it. No different than car manufacturers, the factory settings still leave a lot to be desired in some real world conditions...

happy coaching!
buswarrior

[prevosman]

I believe the default for the transmission is economy mode, and selecting the mode position (it shows on the display) it changes to a performance setting. The performance setting has harsher shifts.

buswarrior's comments were right on.

[H3Jim]

My Mode setting is for the economy setting.  the standard is the "performance" setting.  For mine, mode holds a gear longer before downshiftg, and upsifts sooner.  Better fuel economy they say, not that I can tell.

[belfert]

Hmm..  I wonder if they changed the default from performance to economy?  They did reprogram the DDEC so it doesn't hold the speed on cruise quite so ridgidly as it was upshifting and downshifting all the time to keep the speed constant when on cruise.

The good thing is they didn't charge me anything even though I expected to pay an hour or two for diagnosis.

The harsh shifting is occasionally when stopping when it shifts from 2nd to 1st and sometimes when shifting from drive to reverse and back.  This never happened during their test drives and they checked everything to no avail.

Brian Elfert

[H3Jim]

Occasionally mine shifts really rough too.  Most of the time its ok, but sometimes when it shifts it really slams.  Its been better since I changed the oil and put synthetic oil back in.  I have had the Prevost dealer look at it several times while its been in the shop, but there were no fault codes, so nothing to do but pray.  It also seems to do it more often when in Mode, after a long drive. 

We both better hope the tranny's last, as I guess they cost in the $15,000 to $25,000 range to rebuild.  That would be a big ouch.

[belfert]

We both better hope the tranny's last, as I guess they cost in the $15,000 to $25,000 range to rebuild.  That would be a big ouch.

MCI sells a reman B500 for $10,000 to $11,000.  With labor, it might be $15,000.  Somewhere on their website I saw something where they can put a ZF Astronic in instead of a reman B500 for the same price.  Doesn't help on a Prevost, but I have a Dina that is supported by MCI.

Brian Elfert

[buswarrior]

Rebuilt B500R was just sitting there beside the door when I was at MCI Newcastle last week....

If I had only brought a few strong friends and the truck....

They wouldn't miss it, would they?

I would strongly recommend you go drive a ZF Astronic with a knowledgeable person to demonstrate and coach you before you think about buying one.

If you are shown all that it can do for you, you might like it, or you might hate it.

No matter what you do, it does not accelerate as smartly as the Allison, lots of gear changes as it works to 10th gear, but the Allsion will cause massive fuel consumption to launch hard.

No free lunch, as they say!

happy coaching!
buswarrior

[Sammy]

Brian, did you get a chance to check the drivetrain - u joints,mounts,etc?
If you have a good tech that you know with a Pro-Link, ask them to activate"fast adaptive", then drive your bus.
This usually gets the trans to shift smoother.
Sammy 

[belfert]

Brian, did you get a chance to check the drivetrain - u joints,mounts,etc?
If you have a good tech that you know with a Pro-Link, ask them to activate"fast adaptive", then drive your bus.
This usually gets the trans to shift smoother.

Yes, all that stuff was checked by C&J Bus Repair.

Brian Elfert