Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×


Reply
 
Thread Tools Display Modes
 
Old 05-23-2018, 11:17 AM   #41
Skoolie
 
Mgulley82's Avatar
 
Join Date: Feb 2018
Location: Tennessee
Posts: 171
Year: 2004
Coachwork: Thomas
Chassis: 40' Saf-T-Liner MVP ER
Engine: CAT 3126 7.2L
Does anyone know what rear end ratio would render a 6th gear mostly useless?

Essentially: is there a max rear end ratio which becomes the limiting factor for top speed?

Currently my 04 Thomas 40í FE peaks at around 65 mph in 5th gear on level, 67 down hill, 62 uphill

Mgulley82 is offline   Reply With Quote
Old 05-23-2018, 12:02 PM   #42
Bus Geek
 
Join Date: May 2016
Location: Eastern WA
Posts: 6,400
Year: 2002
Coachwork: Bluebird
Chassis: All American RE (A3RE)
Engine: Cummins ISC (8.3)
Rated Cap: 72
Quote:
Originally Posted by Mgulley82 View Post
Does anyone know what rear end ratio would render a 6th gear mostly useless?

Essentially: is there a max rear end ratio which becomes the limiting factor for top speed?

Currently my 04 Thomas 40í FE peaks at around 65 mph in 5th gear on level, 67 down hill, 62 uphill
It depends on your tire size, engine and desired top speed(or cruising speed).

My Bluebird has 11r22.5 and , 8.3 Cummins and 5.38 rear gears. It goes fast enough in 5th (67+) but is wound up tight. I want 6th to reduce rpm at highway speeds.

If my rear gear was much taller at all I probably would not be looking to unlock 6th.

Personal preference : I think that 65mph is plenty fast in a 26k lb bus. Fuel mileage in my bus drops notably when I run 65mph Vs. 55mph. If I recall, drag increases with the square of speed and overcoming drag is the primary consumer of hp/fuel at highway speeds.
PNW_Steve is offline   Reply With Quote
Old 05-23-2018, 12:10 PM   #43
Bus Geek
 
Join Date: Sep 2017
Location: Owasso, OK
Posts: 2,627
Year: 1999
Coachwork: Thomas
Chassis: Saf-T-Liner MVP ER
Engine: Cummins 6CTA8.3 Mechanical MD3060
Rated Cap: 46 Coach Seats, 40 foot
Quote:
Originally Posted by PNW_Steve View Post
It depends on your tire size, engine and desired top speed(or cruising speed).

My Bluebird has 11r22.5 and , 8.3 Cummins and 5.38 rear gears. It goes fast enough in 5th (67+) but is wound up tight. I want 6th to reduce rpm at highway speeds.

If my rear gear was much taller at all I probably would not be looking to unlock 6th.

Personal preference : I think that 65mph is plenty fast in a 26k lb bus. Fuel mileage in my bus drops notably when I run 65mph Vs. 55mph. If I recall, drag increases with the square of speed and overcoming drag is the primary consumer of hp/fuel at highway speeds.
You have the same drivetrain as me.

I have a request in with Thomas, but as yet I haven't heard of them agreeing to the unlock with an FD higher than around 6.14.

I'm hoping they will agree. 6th would give our buses a top speed of around 75-77 mph, but more importantly reduce the cruising rpm and aid fuel economy.

FWIW, the 8.3 in standard trim can handle 3400 rpm before the valve springs need changing. That would increase the speed available, but cost fuel.
__________________
Steve Bracken

Build Thread
Twigg is offline   Reply With Quote
Old 05-23-2018, 02:59 PM   #44
Bus Crazy
 
Join Date: Feb 2012
Location: Salt Lake City Utah
Posts: 1,635
Year: 2000
Chassis: Blue Bird
Engine: ISC 8.3
My local Allison shop quoted me about $300 for calibration changes when I asked several years ago. Sending $400 to PCM, plus the work of removing and shipping the physical box, does cost more... but then again it's not fair to compare the price of getting it done to the theoretical price of "if we could.. but we can't." They sound like a pretty good deal.

I wonder whether the shift points for the other 5 gears change -- I've considered finding a vocational truck with an MD3060 and using it as a carrier to take my tranny computer to Allison for re-programming. Or just buy the computer out of a wrecked truck. But I'm concerned about whether its programming will be a good match to the tune of my engine and the characteristics of my bus. Have PCM reverse engineered this thing, or do they use a hack like putting the computer into an approved vehicle and using the existing Allison procedure?

To the earlier question about rear end ratio: I have one bus with the ISC8.3 with a B300R transmission (fundamentally the same as MD3060, I'm told) and 5.38 rear end. I have the same view as PNW_Steve: it goes as fast as I want it to, but I'd like to not have the engine bumping its rev limiter (2450 RPM?) at the same time.

I also have a bus with the ISC8.3, MD3060, and a 4.78 rear end. I'm hoping that one will be running in the next week or two, and maybe I'll do a race with the two buses so I can see which axle ratio I like most. I'm expecting this one will accelerate more slowly than the first, but that it'll cruise 70 MPH with a more agreeable engine speed.
family wagon is offline   Reply With Quote
Old 05-23-2018, 03:09 PM   #45
Bus Geek
 
EastCoastCB's Avatar
 
Join Date: Sep 2014
Location: Eustis FLORIDA
Posts: 23,673
Year: 1999
Coachwork: Thomas
Chassis: Freighliner FS65
Engine: Cat 3126
Rated Cap: 15
Quote:
Originally Posted by PNW_Steve View Post
It depends on your tire size, engine and desired top speed(or cruising speed).

My Bluebird has 11r22.5 and , 8.3 Cummins and 5.38 rear gears. It goes fast enough in 5th (67+) but is wound up tight. I want 6th to reduce rpm at highway speeds.

If my rear gear was much taller at all I probably would not be looking to unlock 6th.

Personal preference : I think that 65mph is plenty fast in a 26k lb bus. Fuel mileage in my bus drops notably when I run 65mph Vs. 55mph. If I recall, drag increases with the square of speed and overcoming drag is the primary consumer of hp/fuel at highway speeds.
I need a bus that can achieve 70-75 when needed. Won't need it much as I live deep in the "45mph" areas. But one trip through atlanta in a bus made me want one that could at least keep up when NEEDED.
My shorty is more or less capable of 80 with bigger tires on it. As with any school bus- its happiest at 55-60.
__________________
.
Wear A Mask- Stop the Spread!
EastCoastCB is offline   Reply With Quote
Old 05-23-2018, 03:38 PM   #46
Bus Geek
 
o1marc's Avatar
 
Join Date: Dec 2017
Location: Dawsonville, Ga.
Posts: 10,472
Year: 1999
Coachwork: Genesis
Chassis: International
Engine: DT466/3060
Rated Cap: 77
What other trans have an unlockable 6th gear or have a working 5th gear?
o1marc is offline   Reply With Quote
Old 05-23-2018, 03:39 PM   #47
Bus Geek
 
EastCoastCB's Avatar
 
Join Date: Sep 2014
Location: Eustis FLORIDA
Posts: 23,673
Year: 1999
Coachwork: Thomas
Chassis: Freighliner FS65
Engine: Cat 3126
Rated Cap: 15
Quote:
Originally Posted by o1marc View Post
What other trans have an unlockable 6th gear or have a working 5th gear?
I've been told later model 2000-series have a 6th gear. IDK anything about it, but Chris does.
__________________
.
Wear A Mask- Stop the Spread!
EastCoastCB is offline   Reply With Quote
Old 05-23-2018, 06:27 PM   #48
Bus Geek
 
Join Date: Sep 2017
Location: Owasso, OK
Posts: 2,627
Year: 1999
Coachwork: Thomas
Chassis: Saf-T-Liner MVP ER
Engine: Cummins 6CTA8.3 Mechanical MD3060
Rated Cap: 46 Coach Seats, 40 foot
Quote:
Originally Posted by EastCoastCB View Post
I've been told later model 2000-series have a 6th gear. IDK anything about it, but Chris does.
They do, but they also need extra hard parts to use 6th, it's not just software.
__________________
Steve Bracken

Build Thread
Twigg is offline   Reply With Quote
Old 05-23-2018, 07:47 PM   #49
Bus Geek
 
Join Date: May 2016
Location: Eastern WA
Posts: 6,400
Year: 2002
Coachwork: Bluebird
Chassis: All American RE (A3RE)
Engine: Cummins ISC (8.3)
Rated Cap: 72
I have read a bunch on the 2000 series but have never owned one.

My best understanding is that early versions were 5 speed only and could be upgraded to 6 speed by swapping hard parts & programming. Later models have the hardware and only need the appropriate programming.
PNW_Steve is offline   Reply With Quote
Old 05-23-2018, 10:35 PM   #50
Bus Geek
 
EastCoastCB's Avatar
 
Join Date: Sep 2014
Location: Eustis FLORIDA
Posts: 23,673
Year: 1999
Coachwork: Thomas
Chassis: Freighliner FS65
Engine: Cat 3126
Rated Cap: 15
Quote:
Originally Posted by PNW_Steve View Post
I have read a bunch on the 2000 series but have never owned one.

My best understanding is that early versions were 5 speed only and could be upgraded to 6 speed by swapping hard parts & programming. Later models have the hardware and only need the appropriate programming.
That's what Chris told me, IIRC.
__________________
.
Wear A Mask- Stop the Spread!
EastCoastCB is offline   Reply With Quote
Old 05-24-2018, 08:18 AM   #51
New Member
 
Join Date: Mar 2018
Location: Utah County, Utah
Posts: 9
Year: 2004
Coachwork: Blue Bird
Chassis: International 3800
Engine: DT466E
Rated Cap: 66
Quote:
Originally Posted by PNW_Steve View Post
I have read a bunch on the 2000 series but have never owned one.

My best understanding is that early versions were 5 speed only and could be upgraded to 6 speed by swapping hard parts & programming. Later models have the hardware and only need the appropriate programming.
If I may quote from the range increase PDF, "All 3000/4000 series transmissions have the ability to achieve 6 speeds; however, only 1000/2000 Series transmissions built after June 28, 2006 contain the necessary hardware to achieve 6 speeds."

I forgot that was in that letter, but I knew I had read it somewhere.
Panoman14 is offline   Reply With Quote
Old 05-24-2018, 08:31 AM   #52
Bus Geek
 
EastCoastCB's Avatar
 
Join Date: Sep 2014
Location: Eustis FLORIDA
Posts: 23,673
Year: 1999
Coachwork: Thomas
Chassis: Freighliner FS65
Engine: Cat 3126
Rated Cap: 15
Quote:
Originally Posted by Panoman14 View Post
If I may quote from the range increase PDF, "All 3000/4000 series transmissions have the ability to achieve 6 speeds; however, only 1000/2000 Series transmissions built after June 28, 2006 contain the necessary hardware to achieve 6 speeds."

I forgot that was in that letter, but I knew I had read it somewhere.
I wonder if the extra gear is the only difference.
If my 2000 ever goes out I'd gladly swap it for an extra OD gear.
__________________
.
Wear A Mask- Stop the Spread!
EastCoastCB is offline   Reply With Quote
Old 05-24-2018, 10:29 PM   #53
Bus Nut
 
Join Date: Feb 2018
Location: Pendleton Indiana
Posts: 342
Year: 2010
Coachwork: IC
Engine: MF DT466
Rated Cap: 81
Wondering how hard it would be with mine,dont think they would approve with the gearing. Probably go the secondary tuning programming.
Miles O Roads is offline   Reply With Quote
Old 05-25-2018, 10:36 PM   #54
Skoolie
 
Mgulley82's Avatar
 
Join Date: Feb 2018
Location: Tennessee
Posts: 171
Year: 2004
Coachwork: Thomas
Chassis: 40' Saf-T-Liner MVP ER
Engine: CAT 3126 7.2L
Thomas replied to my request with a ďIím forwarding this to my supervisorĒ email

Local Allison shop quoted me $175 to program once I have a letter from Thomas
Mgulley82 is offline   Reply With Quote
Old 05-26-2018, 12:12 PM   #55
Bus Nut
 
Join Date: Feb 2018
Location: Pendleton Indiana
Posts: 342
Year: 2010
Coachwork: IC
Engine: MF DT466
Rated Cap: 81
Quote:
Originally Posted by Mgulley82 View Post
Thomas replied to my request with a ďIím forwarding this to my supervisorĒ email

Local Allison shop quoted me $175 to program once I have a letter from Thomas

Good stuff. I may submit mine worst they can say is no.
Miles O Roads is offline   Reply With Quote
Old 05-26-2018, 01:21 PM   #56
Skoolie
 
Mgulley82's Avatar
 
Join Date: Feb 2018
Location: Tennessee
Posts: 171
Year: 2004
Coachwork: Thomas
Chassis: 40' Saf-T-Liner MVP ER
Engine: CAT 3126 7.2L
Quote:
Originally Posted by Miles O Roads View Post
Good stuff. I may submit mine worst they can say is no.


Better sooner than later

I have 2 months before I want to hit the road at this point so Iím in no rush
Mgulley82 is offline   Reply With Quote
Old 05-31-2018, 06:29 AM   #57
Skoolie
 
Mgulley82's Avatar
 
Join Date: Feb 2018
Location: Tennessee
Posts: 171
Year: 2004
Coachwork: Thomas
Chassis: 40' Saf-T-Liner MVP ER
Engine: CAT 3126 7.2L
Thomas informed me it would take several weeks to get approval for the modification request
Mgulley82 is offline   Reply With Quote
Old 06-02-2018, 10:55 PM   #58
Skoolie
 
Mgulley82's Avatar
 
Join Date: Feb 2018
Location: Tennessee
Posts: 171
Year: 2004
Coachwork: Thomas
Chassis: 40' Saf-T-Liner MVP ER
Engine: CAT 3126 7.2L
Received email that my modification order has been sent to engineering
Mgulley82 is offline   Reply With Quote
Old 06-03-2018, 04:59 AM   #59
Bus Geek
 
Join Date: May 2009
Location: Columbus Ohio
Posts: 17,363
Year: 1991
Coachwork: Carpenter
Chassis: International 3800
Engine: DTA360 / MT643
Rated Cap: 7 Row Handicap
Quote:
Originally Posted by EastCoastCB View Post
I wonder if the extra gear is the only difference.
If my 2000 ever goes out I'd gladly swap it for an extra OD gear.



the gears and clutches exist in the earlier 2000s. but the valve body and associated electronics are differences..


https://www.xtremediesel.com/sun-coa...eed-conversion


-Christopher
cadillackid is offline   Reply With Quote
Old 06-08-2018, 12:10 AM   #60
Almost There
 
concrete's Avatar
 
Join Date: Jun 2018
Location: Alaska
Posts: 78
Year: 1996
Coachwork: American Fire & Rescue
Chassis: IH 4900
Engine: DT466 250hp P-pump
Want 6th gear, Turned down by the OEM; plan B...

I have a 1996 IH 4900 (WHAT!?! On a skoolie forum!? Yes, heresy, I know. But this place has the best info on this subject anywhere Iíve foundóBy a wide margin.); dt466 250hp HT (mechanical injection), md3060 (close ratio), 5.38 rear, 11R 22.5, lever shifter (I think WTEC 2).
I tried (twice) through the OEM, but IH says they wonít approve anything older than ~2004. Apparently they donít keep records for stuff that old so the engineers donít have the numbers they need.
Plan B: get a donor with the same/similar power train and all 6 gears (anybody know of one?). Said donor could supply the TCM itself (assuming itís a salvage vehicle) OR THE NUMBERS ALLISON USES TO PROGRAM TCMís. From my research (I havenít done this yet, so please correct me if you know different) Allison needs 4#ís: vehicle VIN, transmission serial #, TCM/ECU #, and the CIN# (calibration #). With these numbers an Allison dealer will reprogram your TCM to the supplied specs for ~$130-150, according to phone calls Iíve made.
How similar does the power train need to be? I donít know. Presumably the tranny itself should be identical. Presumably the engine should have the same kind of communication with the tranny (i.e.ómechanical throttle sensor vs electronic style); perhaps dissimilar engines with similar tranny communication could be interchangeable? Rear gears and tire size would presumably affect speedo accuracy, but perhaps would still work well? Iíd rather have 6th gear and an incorrect speedo...
Lots of assumptions. I only know my own experience with IH and what Iíve read online; Iím counting on yíall to be my fact checkers. Shout-out to Cadillackid! I have really appreciated your posts on this and other threads. A couple other members as well, but I donít have their names handy...
If you have the same/similar power train I do, PLEASE contact me ASAP! I bought this truck online, am picking it up today-June 8 (Iíve been trying to post this for a while, but my account wasnít working correctly) in Ohio, and driving it to Alaska. 6 gears will make for a much happier road trip.
Again, if you have or know of a vehicle with the needed stuff, please let me know! Iím assuming a PM would be the best way to relay the info; though posting it all openly on the forum would be convenient for all interested parties.
LET THE ROAD TRIP BEGIN!! (Hopefully with 6 gears)
concrete is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 08:29 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2022, vBulletin Solutions, Inc.