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Author Topic: Model of differential  (Read 4088 times)
buswarrior
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'75 MC8 8V71 HT740




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« Reply #30 on: September 01, 2007, 07:40:32 AM »

The Ultrashift will skip the gears for you, as will the ZF ASTronic, the one MCI is using in the new coaches.

Under light throttle and light load, it jumps to whatever gear makes sence.

In a bus, the ASTronic 10 speed typically will start in 2 and go 4,6 8 9 10, depending on grade, headway being made, weight in the bus and your choice of throttle setting.

You may tap the control pad and ask for an early shift, or tap twice for a gear skip, or leave it alone, whatever your mood or desire.

I'm with Tom. Gear rowing, fun as it was in the beginning, is now just a chore.

These transmissions are beginning to be found in donor trucks, with everything you need to do a 4 stroke power upgrade swap at the same time. A bunch of younger tires attached, a couple of airride seats...and then sell what's left to a scrap yard with al your take-outs stuffed into and make some money back.

Or, the quicker route: Anyone have the winning lottery numbers for an upcoming draw?

happy coaching!
buswarrior
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Frozen North, Greater Toronto Area
prevost82
82 Prevost 8V92ta 6 speed
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82 Prevost Marathon XL




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« Reply #31 on: September 01, 2007, 09:22:57 AM »

Hey Tom ... I'm in the middle of nowhere right now (no cell service, only sat. internet) I will check the numbers when I get back to civilization. Prevost uses a dummy box up front and a cabover shift tower on the tranny and a drive shaft inbetween so that shouldn't be a problem ... just have to find a cabover tower for a 13 speed or maybe I will get lucky and this one will fit.

Ron
« Last Edit: September 01, 2007, 09:24:40 AM by prevost82 » Logged
TomC
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« Reply #32 on: September 01, 2007, 09:29:56 AM »

Actually on the 18spd and the high range of the 13spd where the overdrive splitter is working, you can skip shift manually up to four gears at a time-since with the splitter thats what it takes to actually skip a whole gear.  So example- on the 10 spd, if you want to go from 6 to 8th, you tap the up arrow twice-once onto 7th then again into 8th.  On the 13 or 18 speed if you want to go from 6th direct to 8th direct, you tap the up button once into 6th overdrive, again for 7th direct, again for 7th overdrive, then again for 8th direct.  The easiest is just to let the transmission do its' thing.  As long as you keep your foot off the accelerator and just use partial throttle during acceleration, the transmission will automatically skip shift.  During full throttle with for instance going up a hill and the rate of acceleration is low, the transmission will use all gears.

Ron- KW and Freightliner on their latest cabovers used a very successful 2 cable shifting method, one for the X shifting (side to side) and the other for the Y shifting (for and back).  You'd have to have for instance Johnston controls make some long cables for you, but then would be the easiest installation-rather than using and trying to align up a long driveshaft.  The other advantage to the cables is that you could install them to get a normal shift pattern up front, compared to the direct drive shaft that most likely would be backwards.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
prevost82
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« Reply #33 on: September 01, 2007, 09:56:25 AM »

Tom The way the dummy box up front work is it reverses the shift pattern to normal. I think I'll stick with the drive shafts for shifting, but thks for the suggesting.
Ron
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Sojourner
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« Reply #34 on: September 01, 2007, 06:04:49 PM »

TomC & Buswarrior...........Thanks you so much to update me. I can now go looking for a futrue wreck class 8 truck with the Ultrashift or ZF ASTronic with ISM or DD 12.7 which is more common than RV burnout Spartan Mountain equips motorhome with B500. I always prefer slider shift trans over sun-gear type trans. So this is well waiting for the right time to get the latest upgrade.

Thanks to all for good supports.

Sojourn for Christ, Jerry
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TomC
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« Reply #35 on: September 01, 2007, 10:32:00 PM »

Sojourner- Highly recommend you stay away from the ZF Astronic transmission.  While they are a good design, work well, shift smoothly, they use a very expensive 17" single plate clutch.  And if the transmission ever goofs up, they are so expensive to repair usually you just exchange it for a newly rebuilt one.  Personally-look for a truck with the Eaton Ultrashift in it-much easier to get service on it since the basic transmission is a standard truck transmission with electronic controls added, they use standard clutch linings, and they have been around long enough to be proven.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
belfert
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« Reply #36 on: September 01, 2007, 11:49:25 PM »

An interesting note is that MCI is offering to replace B500 trannies with a new ZF Astronic for the same cost as replacing a B500 with a rebuilt B500.  I am guessing this only applies to true MCI buses and not my Dina.  (Not that I ever intend to replace my B500.)

Posters here have reported that the ZF Astronic in new buses is not nearly as smooth for passengers due to the many shifts needed to get to highway speed compared to the B500.
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buswarrior
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« Reply #37 on: September 02, 2007, 07:08:04 AM »

On the ride quality issue:

Allsion is now heavily using this in their marketing. The clear detection and break in power delivery for every shift of the automated trannies, and the related complaints from little old ladies, and other discerning customers about their heads bobbing in the hands of a thug driver versus the seamless power delivery of a proper torque converter equipped Allision.

And in the city, in stop and go, the Allsion will be out of sight, the automated are much slower to get motivated down the road.

Not necessarily issues for a busnut, as the automated may be driven smoothly in the hands of a caring driver, just not at any great rate of acceleration without an increase in notice by the passengers.

happy coaching!
buswarrior
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TomC
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« Reply #38 on: September 02, 2007, 09:57:56 AM »

With proper driving techniques- meaning easing out of a signal and not just flooring it all the time (although it is alot of fun) the Allison will get very close to the Automated transmission in fuel mileage.  With the smoothness and great acceleration from a stop, and hill starting capabilities, I'm sold on Allison.  I drove a truck with 76,000lb with the wide ration Allison 4500RDS in it, and it was truly eye opening the acceleration it had compared to a stick transmission, or even an automated.  I firmly believe, for our use, the Allison is the best choice-anyone can drive it, it is smooth on acceleration, fast from a stop, and most any trans shop can work on them that are Allison trained-compared to the ZF that gets alot of head scratching.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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