Bus Conversions dot Com Bulletin Board
October 02, 2014, 09:48:51 AM *
Welcome, Guest. Please login or register.

Login with username, password and session length
News: If you had an E-Mag Subscription:  It will not get lost in the mail.
   Home   Help Forum Rules Search Calendar Login Register BCM Home Page Contact BCM  
Pages: 1 2 3 [4]   Go Down
  Print  
Author Topic: automatic vs 4spd  (Read 7699 times)
Happycampersrus
Full Member
***
Offline Offline

Posts: 120




Ignore
« Reply #45 on: March 26, 2010, 04:32:25 AM »

Was there ever a synchronized 4 or 5 speed that could be used behind a 92 or 71??

I've allways wondered. Smiley
Logged
lostagain
Hero Member
*****
Offline Offline

Posts: 1537


MC5C




Ignore
« Reply #46 on: March 26, 2010, 06:48:45 AM »

MCI Courier 96s have a 5 speed synchromesh Spicer behind the 4-71. (Except 1st gear). Probably not strong enough for a 92 though. I don't double clutch going up, but I do going down. And it is stiff, takes lots of effort to shift it. I remember they were all like that. 1st gear is really low, nice for starting.

JC
Logged

JC
Invermere, BC
1977 MC5C, 6V92/HT740
TomC
Hero Member
*****
Offline Offline

Posts: 6815





Ignore
« Reply #47 on: March 26, 2010, 07:56:59 AM »

The biggest synchronized transmission made is the Eaton Fuller 6spd overdrive rated at 860lb/ft torque.  In terms of engine-you could run a 8V-71N with up to 70 injectors, or a 8V-71T with up to 60 injectors, or a 6V-92TA with 75 injectors.

This has always been a real thorn in my side since all European truck manufacturers have been using synchronized transmissions for well over 15 years.  In 1998 went on a bus tour in Europe on a DAF (Dutch Automotive Fabrication) bus with a straight 8 spd-no splitter.  The bus driver only missed two shifts the entire 3 weeks.  Eaton Fuller's answer to this was to create the Autoshift (with a clutch pedal), the UltraShift (without a clutch pedal using a centrifugal clutch [which seems to only get about 100,000 miles of life-hence the next generation-]), the new UltraShift Plus that uses an electronically controlled standard clutch for more control (mainly you can creep with it at idle speeds), and much longer clutch life.  With talking to our transmission overhaulers and service managers, there are many different scenarios that will cause an Eaton Fuller Autoshift type transmission to break down that just doesn't exist in the Allison transmission. With the new programming that Allison has now, they are claiming only a 1-2% fuel mileage difference between the Allison and Autoshift.  When comparing a manual shift to Allison-the Allison wins most of the time (unless you are a very good shifter 100% of the time-which we all know doesn't happen.  I crunched gears many times-especially when tired).  Good Luck, TomC
Logged

Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
rv_safetyman
Hero Member
*****
Offline Offline

Posts: 2199


Jim Shepherd


WWW

Ignore
« Reply #48 on: March 26, 2010, 02:03:30 PM »

TomC, I would be interested in knowing what can go wrong with the AutoShift.  After all of my problems with the Series 60, I don't want to have any issues with the AutoShift.  I assume it is in the electronics.  I normally carry most of the electronic parts with me.

Jim
Logged

Jim Shepherd
Evergreen, CO
85 Eagle 10/Series 60/Eaton AutoShift 10 speed transmission
Somewhere between a tin tent and a finished product
Bus Project details: http://beltguy.com/Bus_Project/busproject.htm
Blog:  http://rvsafetyman.blogspot.com/
DaveG
Hero Member
*****
Offline Offline

Posts: 539




Ignore
« Reply #49 on: March 26, 2010, 06:07:22 PM »

Richard -

Square.


FWIW & HTH. . .

 Wink

RJ, I laughed so hard I almost fell off my chair!!!!!!!!
Logged
DaveG
Hero Member
*****
Offline Offline

Posts: 539




Ignore
« Reply #50 on: March 26, 2010, 06:09:46 PM »

On the RR facing backwards on a rear pusher, Eaton makes a reverse shifter that changes the shift pattern to make it seem correct at the driver's seat. 
I was once on a Dina bus in Mex and it had a 10 speed with reversed gear pattern and what they call a U shift overdrive.  I watched the driver drive the bus and obviously he'd been driving it for a while. But-it would definitely take a learning curve.  Here it is:

   4/9   3/8   1/6
     |      |      |
     |-----|----|
     |      |      |
   5/10  2/7   R

Tom, any more info or nomenclature on the reverse shifter for Eaton? Sounds like a great idea
Logged
TomC
Hero Member
*****
Offline Offline

Posts: 6815





Ignore
« Reply #51 on: March 26, 2010, 10:36:45 PM »

Dave- I believe Eaton calls the reverse shifter the "X Shifter". Just call their help line and tell them you have a rear engine bus and want to have the shifter work the standard way.

Jim- the big problem with the AutoShift compared to the Allison, is that the wiring for the AutoShift is on the outside of the transmission case compared to the Allison's internal wiring.  Hence, alot of connector, dirt, and vibration problems.  Also the X-Y motor shifters on top of the transmission should be changed every 300,000 miles, whether they need it or not.  The motors also can be affected by weather (mainly cold) changes.
The best thing you can do is to make sure your X-Y motor shifters are fairly recent, and make sure all your connection are tight and supported.  When the X-Y motor shifters get tired, they can present an in between gear shift that will present the transmission as though it is in neutral.  When changing the X-Y motor shifters, it is a good idea to open the top of the transmission to inspect the shifting forks for wear.

No transmission is perfect.  While you get maximum fuel economy from the AutoShift, you still have a clutch to operate when stopping and starting, the acceleration is slow and ponderous from the signal, and there are much more wiring problems (as discussed above).  While the Allison does not have the wiring problems, the torque converter does make for tremendous acceleration from the signal, but with fuel mileage hit since the clutches in the Allison do drag a bit-to the tune of about 20hp loss.  And even though the AutoShift has 10spds (the first 5 just to get it rolling-of which the torque converter in the Allison takes care of that) and those 10 spds are spaced just about equally, the Allison's gears are spaced wide apart in the lower gears, then bunched closer together near the top with 5th and 6th only about 200rpm apart from each other making for better freeway cruising.  But- you make you choice.  Good Luck, TomC
Logged

Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
rv_safetyman
Hero Member
*****
Offline Offline

Posts: 2199


Jim Shepherd


WWW

Ignore
« Reply #52 on: March 27, 2010, 06:59:54 AM »

TomC, your answer on the AutoShift is pretty much what I had suspected.  I have had some pretty significant issues with the electrical connections.  During all of my trials and tribulations with the replacement Series 60 (included several transmission fault codes), I completely rebuilt the harness.  Both large connectors on the transmission ECM are really not very robust (tend to come loose).  The tabs that lock the connections to the ECM tend to fail (on the Series 60 these size connections have a machine screw to secure the connection - much better).  I talked to the local Eaton rep and he said folks use strong wire ties to secure the connections.  I "remoted" the ECM to a location I can get to better and made a very robust wire tie "harness".

I had not heard about the motor shifters having problems, but I am not surprised.  I had corresponded with Boogiethecat quite a bit and his opinion was that the components were not all that robust.  I normally carry an extra set of motors as well as the two ECMs (transmission and tower), since I have an extra unit.  Don't have them on this trip {gulp} Shocked Shocked.

Jim
Logged

Jim Shepherd
Evergreen, CO
85 Eagle 10/Series 60/Eaton AutoShift 10 speed transmission
Somewhere between a tin tent and a finished product
Bus Project details: http://beltguy.com/Bus_Project/busproject.htm
Blog:  http://rvsafetyman.blogspot.com/
Pages: 1 2 3 [4]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.18 | SMF © 2013, Simple Machines Valid XHTML 1.0! Valid CSS!