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05-25-2016, 11:29 AM
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#1
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Almost There
Join Date: Apr 2015
Location: Calgary
Posts: 74
Year: 2000
Coachwork: Bluebird
Chassis: TC2000
Engine: 5.9L Cummins
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Whats a good rear axle ratio for a TC2000 bluebird 5.9 cummins?
As the title states, I have read a lot here that the 5.9 is not ideal and underpowered. Whelp, I bought one.
So for highway use, whats a good rear axle ratio?
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05-25-2016, 11:33 AM
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#2
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Bus Geek
Join Date: Sep 2014
Location: Eustis FLORIDA
Posts: 23,764
Year: 1999
Coachwork: Thomas
Chassis: Freighliner FS65
Engine: Cat 3126
Rated Cap: 15
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Quote:
Originally Posted by -cycosis-
As the title states, I have read a lot here that the 5.9 is not ideal and underpowered. Whelp, I bought one.
So for highway use, whats a good rear axle ratio?
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4 something should be good. Lower 4's are better.
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05-25-2016, 11:41 AM
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#3
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Almost There
Join Date: Apr 2015
Location: Calgary
Posts: 74
Year: 2000
Coachwork: Bluebird
Chassis: TC2000
Engine: 5.9L Cummins
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SO Im alright with a 4.44?
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05-25-2016, 11:46 AM
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#4
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Bus Geek
Join Date: Sep 2014
Location: Eustis FLORIDA
Posts: 23,764
Year: 1999
Coachwork: Thomas
Chassis: Freighliner FS65
Engine: Cat 3126
Rated Cap: 15
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Quote:
Originally Posted by -cycosis-
SO Im alright with a 4.44?
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Oh, absolutely. I don't have the cummins, but that's the axle ratio I'm running with my 195 hp/520 tq engine.
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05-25-2016, 11:52 AM
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#5
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Bus Nut
Join Date: Dec 2014
Posts: 447
Year: 1988
Coachwork: Ward
Chassis: International
Engine: Navistar 5.9 Diesel
Rated Cap: A butt-load...
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Besides calculations, is there a way to figure out rear diff. ration?
Should it be on the diff. itself, maybe on a plate somewhere?
Haven't really looked, yet....
Where/how did you figure yours out?
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05-25-2016, 11:56 AM
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#6
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Bus Geek
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
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Run some numbers here...
Engine RPM Calculator
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05-25-2016, 12:01 PM
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#7
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Bus Nut
Join Date: Dec 2014
Posts: 447
Year: 1988
Coachwork: Ward
Chassis: International
Engine: Navistar 5.9 Diesel
Rated Cap: A butt-load...
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Quote:
Originally Posted by Tango
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thanks, Tango!
I've see this calculator from other posts, was just wondering if anyone from the top of his/her head recalls if there is a plaque/note of rear gearing anywhere...
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05-25-2016, 12:29 PM
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#8
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Bus Geek
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
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On most units there is a plaque...somewhere. And it usually states the axle ratio but then, it could have been changed out.
Another way to find out what you actually have is to put it in neutral...jack up the driver side rear tires...align a mark on the tire and ground...and, put a mark on the driveshaft. Rotate the tire one full rev...and count how many turns the shaft makes. That will be your ratio or at least get you close enough to look up what is/was avail on your rig and get a match. I had to do that on mine and discovered the rear end was NOT what was indicated.
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05-25-2016, 12:33 PM
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#9
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Mini-Skoolie
Join Date: Mar 2015
Posts: 40
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Quote:
Originally Posted by skoolie_n00bie
Besides calculations, is there a way to figure out rear diff. ration?
Should it be on the diff. itself, maybe on a plate somewhere?
Haven't really looked, yet....
Where/how did you figure yours out?
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There are usually two metal information plates attached above the driver's seat/windshield area. One of them will have the rear axle ratio.
There also may be a tag on the axle itself.
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05-25-2016, 12:43 PM
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#10
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Mini-Skoolie
Join Date: Mar 2015
Posts: 40
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Quote:
Originally Posted by -cycosis-
As the title states, I have read a lot here that the 5.9 is not ideal and underpowered. Whelp, I bought one.
So for highway use, whats a good rear axle ratio?
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The 5.9 Cummins came in Dodge pickups. This engine is an industrial engine - very heavy duty. There are many inexpensive ways to increase performance on the 5.9 - it's no big deal.
Your 4.44 rear axle ratio is pretty good. The lower the number, the better for highway cruising. The higher the number, the better for acceleration.
We could tell you more if we knew what transmission you have!
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05-25-2016, 01:24 PM
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#11
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Bus Crazy
Join Date: Apr 2013
Location: Colorado
Posts: 2,359
Year: 1993
Coachwork: bluebird
Engine: 5.9 Cummins, Allison AT1545
Rated Cap: 2
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i have a cummins 5.9, at545, and a 4.7 rear. the math on the calculator works out perfectly. top speed of 67mph at 2500rpm
a 4.4 would be ideal imo
that should get close to 75mph
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05-25-2016, 02:09 PM
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#12
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Bus Geek
Join Date: Feb 2016
Location: Willamina, Oregon
Posts: 6,409
Coachwork: 97 Bluebird TC1000 5.9
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This special needs bus has a 3.54, but that's apparently to make up for my small tires.
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05-25-2016, 02:16 PM
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#13
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Bus Geek
Join Date: May 2009
Location: Columbus Ohio
Posts: 18,830
Year: 1991
Coachwork: Carpenter
Chassis: International 3800
Engine: DTA360 / MT643
Rated Cap: 7 Row Handicap
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yeah thats another thing to look at is not just axle and transmission its also tire sizes.. like robnin mentioned some handicap busses have smaller rear tires so it can have a flat floor inside..
like a VAN
-Christopher
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05-25-2016, 04:18 PM
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#14
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Bus Geek
Join Date: Feb 2016
Location: Willamina, Oregon
Posts: 6,409
Coachwork: 97 Bluebird TC1000 5.9
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Not LIKE a van. It's a van. Yes, I may have an inferiority complex about my little wheels.
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05-25-2016, 04:24 PM
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#15
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Bus Nut
Join Date: Feb 2015
Location: North carolina
Posts: 651
Year: 1986
Coachwork: Thomas
Chassis: Ford
Engine: Detroit 8.2
Rated Cap: 60 bodies
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Quote:
Originally Posted by Robin97396
Not LIKE a van. It's a van. Yes, I may have an inferiority complex about my little wheels.
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Your little wheels are fine. They get the job done. Just not as quick as bigger ones.
Just messin around.
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05-25-2016, 05:35 PM
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#16
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Bus Crazy
Join Date: Oct 2015
Location: Spring Valley AZ
Posts: 1,343
Year: 2000
Coachwork: Bluebird
Engine: 5.9 Cummins
Rated Cap: 2 elderly children, 1 cat
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Quote:
Originally Posted by Robin97396
This special needs bus has a 3.54, but that's apparently to make up for my smallish tires.
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Same here but a 4.10 would be ideal for my driving style plus I live in hill country.
My bus will do way past it's stability capabilities not to mention tire speed limits.
Fixed it for you Robin!
__________________
Don, Mary and Spooky the cat.
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05-25-2016, 06:57 PM
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#17
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Bus Geek
Join Date: Feb 2016
Location: Willamina, Oregon
Posts: 6,409
Coachwork: 97 Bluebird TC1000 5.9
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Yes, smallish sounds much better. It's the "ish" that neutralizes the sting. As long as they keep getting me to the grocery store I'm ok.
Wow, a 4.10. And I have so much trouble climbing hills. If I put on air bags I could increase to big boy wheels, but that would give me less power. Everything seems to center around this darn 545.
Gimme back my stick shift. But yeah, in traffic during rush hour when my leg gets tired on that clutch somebody is likely to get rear ended. I've got to remind myself to not fix things that don't need fixing.
I'm not sure if these tires are smallish or RVish.
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05-25-2016, 09:26 PM
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#18
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Moderator
Join Date: Feb 2007
Location: NUNYA
Posts: 4,236
Year: 1995
Coachwork: Thomas
Chassis: 3800
Engine: DT408, AT545
Rated Cap: 23 500 gvw
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It's all about the sweet spot for your engine. It is a very specialized technical term and should not be used loosely. You don't want to be driving down the freeway at 2700 rpm just because that is where the governor stops you. In case you didn't know, that's not good. My 1995 International has a DT408, AT545 trans, 9R22.5 tiresand a 4.78 rearend ratio. I'm at 2500 rpm @ 55mph. It kills me to drive with the engine turning that fast so I drive about 45-50 mph. The world goes by really slow at that speed.
What am I going to do about this? In this order, I will
1. Go to a larger tire size. Probably 11R22.5..
2. Swap my trans to a lockup trans. I have an AT1545 out of a 2 1/2 ton military truck.
These two things should drop rpm to about 2100 @ 55mph. If that is not enough, I will swap the 4.78 to a 4.44 rearend. I want to be at 2000 or a little under.
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05-26-2016, 12:56 AM
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#19
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Bus Geek
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
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Cal's got figger'd out. You have to take it all into consideration and aim for that sweet spot unless you want to burn a motor and suck way too much fuel doing it.
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05-26-2016, 08:46 AM
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#20
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Bus Crazy
Join Date: Apr 2013
Location: Colorado
Posts: 2,359
Year: 1993
Coachwork: bluebird
Engine: 5.9 Cummins, Allison AT1545
Rated Cap: 2
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ive heard about that sweet spot, but never found it.
plenty of peeps on the interweb say that you can run the cummins 5.9 pegged to the redline all day.
on the interstate, mine sure is. if i swapped to a 4.3 and got 75mph, i'd still peg it on the freeway for 75mph.
you'd need to gear it for max speed of 85mph before you got the sweet spot in a cruising speed. i honestly dont think the cummins 5.9 makes the kind of power to push that gearing. not at my weight of 20k lbs+. i can barely go uphill now.
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