Reply
 
Thread Tools Display Modes
 
Old 10-12-2018, 02:41 PM   #1
Skoolie
 
PeteinSF's Avatar
 
Join Date: Aug 2018
Location: San Francisco
Posts: 112
Year: 2006
Coachwork: IC
Chassis: IC FE 9 Window
Engine: DT466E
Rated Cap: 29850
Rear end ratio with Allison 2500

Hi All,


I discovered my new 10 window bus has a 6.17 rear end ratio and based on the 11r22.5 tires I calculated my engine speed to be 2130rpm = 60mph.


In looking at the engine torque/HP curves it seems to me that 1600-1800rpm would be the best freeway RPM for my 210HP DT466E.


My question to the group is "What rear ends seem to work well for 8-12 window sized buses with a A2500 transmission?"



I will be buying a used 3rd member and my initial guess would be a 4.66 to 1 (5th:1700rpm=63mph, 1st gear:1700rpm=13mph) but I am using that as just a starting point for discussion.



I would like to avoid changing the carrier twice.
PeteinSF is offline   Reply With Quote
Old 10-12-2018, 04:25 PM   #2
Skoolie
 
Pizote's Avatar
 
Join Date: Aug 2018
Location: Santa Rosa, CA
Posts: 226
Year: 2007
Coachwork: ICCORP
Chassis: CE300
Engine: DT466
Rated Cap: 16
Quote:
Originally Posted by PeteinSF View Post
Hi All,


I discovered my new 10 window bus has a 6.17 rear end ratio and based on the 11r22.5 tires I calculated my engine speed to be 2130rpm = 60mph.


In looking at the engine torque/HP curves it seems to me that 1600-1800rpm would be the best freeway RPM for my 210HP DT466E.


My question to the group is "What rear ends seem to work well for 8-12 window sized buses with a A2500 transmission?"



I will be buying a used 3rd member and my initial guess would be a 4.66 to 1 (5th:1700rpm=63mph, 1st gear:1700rpm=13mph) but I am using that as just a starting point for discussion.



I would like to avoid changing the carrier twice.
4.66 gets you there. But it's not the carrier that you change out, it's the Ring and Pinion gears you change. It's possible that you might have to change the carrier when dropping from the 6.17 down to a 4.66, but not likely. In either case, the carrier has to come out when you change gears. The ring gear is attached to the carrier and the pinion gear is attached to the differential housing/drive shaft - both internal to the differential.

If and when I decide to gear down, I will replace the carrier with an LS carrier - better control and less chances of getting stuck with power to both sides.
Pizote is offline   Reply With Quote
Old 10-12-2018, 05:09 PM   #3
Skoolie
 
PeteinSF's Avatar
 
Join Date: Aug 2018
Location: San Francisco
Posts: 112
Year: 2006
Coachwork: IC
Chassis: IC FE 9 Window
Engine: DT466E
Rated Cap: 29850
By carrier I mean a complete 3rd member (like a Ford 8 inch)
PeteinSF is offline   Reply With Quote
Old 10-12-2018, 05:57 PM   #4
Bus Nut
 
Join Date: May 2018
Location: topeka kansas
Posts: 586
Year: 1954
Coachwork: wayne
Chassis: old f500- new 2005 f-450
Engine: cummins 12 valve
Rated Cap: 20? five rows of 4?
peteinSF

I did what you are doing.... 4.88 rear gears in mine, but I went to 3.73 cost about $800 in my case. calculated for me 3.73 gears, 245 70 19.5 tires at 65 mph will put me at 1875 rpm... I think I used michelin data that has the tire I want to use doing 622 revolutions per mile. so at 65 mph I am at some thing like 674 to 677 revolutions per minute at 65 miles an hour and I have an over drive of around .73 In the end works out to around 1875 in 6th gear and 2525rpm in 5th gear at 65 mph

william
magnakansas is offline   Reply With Quote
Old 10-20-2018, 11:48 AM   #5
Skoolie
 
PeteinSF's Avatar
 
Join Date: Aug 2018
Location: San Francisco
Posts: 112
Year: 2006
Coachwork: IC
Chassis: IC FE 9 Window
Engine: DT466E
Rated Cap: 29850
My survey is clearly a flop...


I was hoping to see what range of axles were attached to 2500s out there.


The good news is that used Spicer 3rd members are generally < $500 so I guess I don't need to get it perfectly right.
PeteinSF is offline   Reply With Quote
Old 10-20-2018, 11:50 AM   #6
Bus Geek
 
EastCoastCB's Avatar
 
Join Date: Sep 2014
Location: Eustis FLORIDA
Posts: 18,719
Year: 1999
Coachwork: Thomas
Chassis: Freighliner FS65
Engine: Cat 3126
Rated Cap: 15
Quote:
Originally Posted by PeteinSF View Post
Hi All,


I discovered my new 10 window bus has a 6.17 rear end ratio and based on the 11r22.5 tires I calculated my engine speed to be 2130rpm = 60mph.


In looking at the engine torque/HP curves it seems to me that 1600-1800rpm would be the best freeway RPM for my 210HP DT466E.


My question to the group is "What rear ends seem to work well for 8-12 window sized buses with a A2500 transmission?"



I will be buying a used 3rd member and my initial guess would be a 4.66 to 1 (5th:1700rpm=63mph, 1st gear:1700rpm=13mph) but I am using that as just a starting point for discussion.



I would like to avoid changing the carrier twice.
5.29 is nice with that setup and full size tires.
__________________
.
Roll Your Own Build Thread
EastCoastCB is offline   Reply With Quote
Old 10-20-2018, 12:29 PM   #7
Bus Nut
 
Join Date: Feb 2015
Location: Cincinnati, Ohio
Posts: 859
Year: 2000
Coachwork: Blue Bird
Chassis: International
Engine: TE 444
Rated Cap: 12
Depending on what rear axle you have in your bus, you will find a bunch of carriers being sold with ratios in the high 4's (4.90, 4.73) from buses and trucks with direct drive transmissions,also 4.44 seems to be real common a couple of years ago when I was looking
Kubla is offline   Reply With Quote
Old 10-20-2018, 07:41 PM   #8
Bus Geek
 
Tango's Avatar
 
Join Date: Mar 2011
Location: Houston, Texas
Posts: 8,462
Year: 1946
Coachwork: Chevrolet/Wayne
Chassis: 1- 1/2 ton
Engine: Cummins 4BT
Rated Cap: 15
Best bet is to run all the numbers through a gear ratio calculator...like the one below.



Gotta know desired highway RPM, tire diameter, trans final drive ratio, etc., but it will tell you just where you need to be on the rear end.


Engine RPM Calculator


(the one at the bottom of the page is best for your calcs).
Tango is offline   Reply With Quote
Old 10-21-2018, 11:44 AM   #9
Skoolie
 
Join Date: Jan 2015
Posts: 140
Quote:
Originally Posted by PeteinSF View Post
Hi All,

I discovered my new 10 window bus has a 6.17 rear end ratio and based on the 11r22.5 tires I calculated my engine speed to be 2130rpm = 60mph.

In looking at the engine torque/HP curves it seems to me that 1600-1800rpm would be the best freeway RPM for my 210HP DT466E.

My question to the group is "What rear ends seem to work well for 8-12 window sized buses with a A2500 transmission?"

I will be buying a used 3rd member and my initial guess would be a 4.66 to 1 (5th:1700rpm=63mph, 1st gear:1700rpm=13mph) but I am using that as just a starting point for discussion.

I would like to avoid changing the carrier twice.
Gearing up to a higher ratio(lower number ) and getting it exactly right is not easy the first time.

Getting the RPM you want is So very easy. pick the gear, speed, and tire height and you have it.

you sound close on that 4.66 gear to me.

What RPM does that trans shift at WOT?
What is your governed speed now?

But a school bus is not a F250 pickup truck. The weight and Aerodynamics are NOT even close. Sometimes the area you will be in makes a difference if you will like your gears.
Are you going to be seeing:
Towing 5-9K lbs?
Mountain grades?

Both??

I went a little too far with my F700. however i have a 6sp manual trans so i only use 6th above 55MPH on highways.
Mekanic is offline   Reply With Quote
Old 10-21-2018, 05:22 PM   #10
Bus Geek
 
Join Date: May 2016
Location: Eastern WA
Posts: 5,258
Year: 2002
Coachwork: Bluebird
Chassis: All American RE (A3RE)
Engine: Cummins ISC (8.3)
Rated Cap: 72
Quote:
Originally Posted by Mekanic View Post
Gearing up to a higher ratio(lower number ) and getting it exactly right is not easy the first time.

Getting the RPM you want is So very easy. pick the gear, speed, and tire height and you have it.



I went a little too far with my F700. however i have a 6sp manual trans so i only use 6th above 55MPH on highways.
I have the same trouble.

I have 3.73's in my truck with a 5.9, 6speed and 22.5's.

Backing up trailers is a pain. Reverse is "too fast".

Most of my highway driving is in 60mph limits. That makes for a lot of 5th gear driving.

I also get my best fuel mileage in 5th gear.

4.11-4.66 gears would be a notable improvement.

Taller is not always better...
PNW_Steve is offline   Reply With Quote
Old 10-21-2018, 06:16 PM   #11
Skoolie
 
PeteinSF's Avatar
 
Join Date: Aug 2018
Location: San Francisco
Posts: 112
Year: 2006
Coachwork: IC
Chassis: IC FE 9 Window
Engine: DT466E
Rated Cap: 29850
I have not driven her yet as she is in Alabama and I am not. So no shifting info. That was sort of why I asked the question the way a did, I figured there must be a lot of mid sized busses with A2500s.

The dilemma is that I really canít attempt an AL>CA with 6.17 ratio so I have to just pick one and go.

The max torque peaks @ 1400 and pulls to 1800 so I figured 55 @ 1400 would be a good target for 5th gear.
PeteinSF is offline   Reply With Quote
Old 10-21-2018, 06:30 PM   #12
Bus Geek
 
EastCoastCB's Avatar
 
Join Date: Sep 2014
Location: Eustis FLORIDA
Posts: 18,719
Year: 1999
Coachwork: Thomas
Chassis: Freighliner FS65
Engine: Cat 3126
Rated Cap: 15
Quote:
Originally Posted by PNW_Steve View Post
I have the same trouble.

I have 3.73's in my truck with a 5.9, 6speed and 22.5's.

Backing up trailers is a pain. Reverse is "too fast".

Most of my highway driving is in 60mph limits. That makes for a lot of 5th gear driving.

I also get my best fuel mileage in 5th gear.

4.11-4.66 gears would be a notable improvement.

Taller is not always better...
With low pro's and a 466/2500 my bus is a screamer with 5.29 in the rear. With 11R's anything numerically lower than 4.88 would be too high, IMO.
4.11 is great if you don't have overdrive.
__________________
.
Roll Your Own Build Thread
EastCoastCB is offline   Reply With Quote
Old 10-22-2018, 10:34 AM   #13
Bus Geek
 
Join Date: May 2016
Location: Eastern WA
Posts: 5,258
Year: 2002
Coachwork: Bluebird
Chassis: All American RE (A3RE)
Engine: Cummins ISC (8.3)
Rated Cap: 72
Quote:
Originally Posted by EastCoastCB View Post
With low pro's and a 466/2500 my bus is a screamer with 5.29 in the rear. With 11R's anything numerically lower than 4.88 would be too high, IMO.
4.11 is great if you don't have overdrive.
I would have to agree with CB.

I have 5.29s in my Bluebird along with an 8.3, 11r22.5's & MD3060. I find it to be near ideal.

If I could get 6th unlocked I would call the 5.29's perfect.
PNW_Steve is offline   Reply With Quote
Old 10-22-2018, 12:53 PM   #14
Skoolie
 
Pizote's Avatar
 
Join Date: Aug 2018
Location: Santa Rosa, CA
Posts: 226
Year: 2007
Coachwork: ICCORP
Chassis: CE300
Engine: DT466
Rated Cap: 16
So I just got back from New Orleans (to Santa Rosa CA) with my new bus. It has a 6.17 R&P and a 5sp 2500 with 11x22.5 rims.

It cruised well at 65mph at an indicated 2450RPM. Over the 2400 miles, I got an average of 8.37MPG.

The impressive thing about this is that it was very comfortable at that speed - even going over mountain passes. It held the 65MPH uphill with only a couple of dips to 60MPH. Downhill, the torque converter and lockup on the transmission held it at whatever I set the cruise control for. Very impressive - I didn't have to hit the brakes at all but for traffic patterns.

I'll post pictures in the build thread an on my FB page @pizote.adventures
Pizote is offline   Reply With Quote
Old 10-22-2018, 12:54 PM   #15
Skoolie
 
Pizote's Avatar
 
Join Date: Aug 2018
Location: Santa Rosa, CA
Posts: 226
Year: 2007
Coachwork: ICCORP
Chassis: CE300
Engine: DT466
Rated Cap: 16
Oh - it also seems to be governed at either 69MPH or 2600RPM - not sure which. This is kind of a pain if you are passing a semi and need just that little bit of extra.
Pizote is offline   Reply With Quote
Old 10-22-2018, 01:26 PM   #16
Bus Geek
 
Join Date: May 2009
Location: Columbus Ohio
Posts: 11,946
Year: 1991
Coachwork: Carpenter
Chassis: International 3800
Engine: DTA360 / MT643
Rated Cap: 7 Row Handicap
DT466's are governed at 2600 RPM...



to answer Pete's question, there are MANY different rear ratios connected behind PTS-2500 transmissions.. these were options.. and there are lots of them.. school systems could spec one of many... these hus chassis are essentially medium duty trucks.. and many rear ratios are available on those..



Kubla has it right.. crawl under and see what type of axle you have.. S-150, S-110, S-175 etc.. then go shopping for a 3rd member with the correct gears.. common in school busses in the 4's were 4.44 and 4.78, ive found those in many busses.. you DT466 will like to run in the 1900-2100 RPM range at high cruise.. gear too low and you run into power issues. climbing hills and such.. if you plan to climb hills, build for what your 4th gear speeds will be as well. so when you are out of OD you have decent climbing torque and arent over-speeding. the DT466E peaks at 2300 RPM om the high side.. spinning it faster wont huert it but you arent making more power above 2300.



dont gear so high that you are always dropping out of OD just to maintain your desired cruise speed.. the transmission uses throttle position and engine loading data (a calculated parameter based on desired RPM via throttle and actual RPM.).. Hunting occurs when you lug it down and have to kick it.. the step down from 5 to 4 in an allison is significant.. build acordingly.
-Christopher
cadillackid is offline   Reply With Quote
Old 10-22-2018, 01:28 PM   #17
Bus Geek
 
Join Date: May 2009
Location: Columbus Ohio
Posts: 11,946
Year: 1991
Coachwork: Carpenter
Chassis: International 3800
Engine: DTA360 / MT643
Rated Cap: 7 Row Handicap
oh i should add that being a 2006 you may have an other option and that is opening up 6th gear.. 2006 and up 2000s had the components for 6th gear installed..
-Christopher
cadillackid is offline   Reply With Quote
Old 10-26-2018, 01:53 AM   #18
Skoolie
 
PeteinSF's Avatar
 
Join Date: Aug 2018
Location: San Francisco
Posts: 112
Year: 2006
Coachwork: IC
Chassis: IC FE 9 Window
Engine: DT466E
Rated Cap: 29850
The bus was built in the summer of 2005 with a 2004 DT466E. I suspect the transmission is a 2005 model but we will all find out when my plates arrive!


* * *


Pizote, I know my DT is set for a 69MPH limit (and a 2600RPM governor). The international dealer offered to set it to the tire max of 75MPH for $160.

Question, Did she stay in 5th gear going up all the hills even when slowed to 60? Did you get any downshifting to 4th (1:1)?
PeteinSF is offline   Reply With Quote
Old 10-26-2018, 09:32 AM   #19
Skoolie
 
Pizote's Avatar
 
Join Date: Aug 2018
Location: Santa Rosa, CA
Posts: 226
Year: 2007
Coachwork: ICCORP
Chassis: CE300
Engine: DT466
Rated Cap: 16
Good to know about the governor reset.

My bus did not drop into 4th. The RPM was always in line with the speed and never jumped.
__________________
Follow my build - and adventures at https://www.facebook.com/pizote.adventures
Pizote is offline   Reply With Quote
Old 10-26-2018, 12:51 PM   #20
Skoolie
 
PeteinSF's Avatar
 
Join Date: Aug 2018
Location: San Francisco
Posts: 112
Year: 2006
Coachwork: IC
Chassis: IC FE 9 Window
Engine: DT466E
Rated Cap: 29850
That is great news.


With that report I think the ratio selection will be easier. As cadillackid pointed out as a concept a few posts ago, use 4th for needed power and 5th for cruise.



If I select a ratio where 4th gear matches your 2450RPM=65MPH I will have all the hill climbing power needed in 4th and better economy and quieter in 5th.
PeteinSF 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 10:49 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
×