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Old 07-09-2024, 07:16 AM   #21
Bus Geek
 
Join Date: May 2009
Location: Columbus Ohio
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Year: 1991
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Engine: DTA360 / MT643
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I forgot to mention, thats my intention to get a 3rd member and swap the whole chunk, its not a bad job to do on these.



floating axles make it easy, dont even have to take the wheels off..



on my 1978 SUperior, the pinion gear Nuked so on that one I had the chunk rebuilt, and thats an RA39 which is a much less common axle..



S135/S150 are pretty commonplace..

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Old 07-09-2024, 10:52 AM   #22
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OK lets have spme more fun.. I really probably should have the mods create me a new thread with these last few posts in it... im really just going through my own calculations and not the OP's... bit it is gear ratio related.. does that count?


anyway I took the bus out into the big parking lot at the uhaul where i keep it and stretched a 100 foot tape measure out.. I used a space with a slight incline.. so if I drive past a little.. Its real easy to just coast back a little..



first I lined the tire up so that one tread was dead center and noted that total of 3 treads are fully on the ground.. so i hash marked all 3 and took a measuremnent at the center hash.


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then I looked at my left front wheel, surmising that I really have no idea in the driver seat when I roll off a whole turn.. so I marked a hash on the shiny wheel cover.. (you can sort of see it to the inside of the hand hole.. that gave me a rough idea when id be close..



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then I turned the Air conditioning on Max as i knew id be jumping out and out of the seat and back in a whole bunch..


sometimes rolling back a little to get the marks lined up was as simple as keeping foot on the brake, release and reset the park brake.. which simple took off the driveshaft slack and the bus would go backwards an inch or so... (you know how hard it is to line those marks up?)


using 3 marks I ended up being amazingly consistent on my readings...


Start 1 ft 1.5
2. 9 ft 3.5 - 8 ft 2" - 98"

3. 17 ft 5.5 - 8 ft 2" - 98"

4. 25 ft 7.5 - 8 ft 2" - 98"

5. 33 ft 9.25 - 8 ft 1.75" - 97.75"

6. 41 ft 11.5 - 8 ft 1.75" - 97.75"

7. 50 ft 1.5 - 8 ft 2" - 98"

8. 58 ft 3.5 - 8 ft 2" - 98"

9. 66 ft 6 - 8 ft 2.5" - 98.5" - is this one an omen?
10. 74 ft 7.5 - 8 ft 1.5" - 97.5"

11.. 82 ft 9.5 - 8 ft 2" - 98"



so add it all up and divide by 10 (I did 10 revs.. per Magnakansas suggestion).



total of readings. 979.5 / 10 = 97.95" rolling circumference.


divide that by pi to get diameter.


97.95 / 3.14159 = 31.178", (this is my tire height).. def not the 31.5" the books list for a 225/70R19.5.


** OR ** I have worn 2" of an inch off my tires in ther 5 years they have been on.. remember tire height is a measurement of distance from the bottom to the top.. so if think about it you wear .2" off the "bottom" its also going to be gone off the "top" if measuring the height of a tire for a calculator..



so now armed with my real tire height I can go back to an RPM calculator and see how close it is to my dashboard..



still off by a little as 65 in 6th gear comes back to about 1515 RPM..

if I swap to a 4.10 rear gear...


I would be at 1752 in 6th gear at 65. and would be at 2040 in 5th gear.. about a 240 RPM change in 5th gear, is it enough??


lets say I go to a 4.44 gear. (the next easily available ratio in my S135 carrier..


and in 5th gear at 65 im at 2200 and 1900 in 6th gear...


if I want to drive 70 with a 4.44. will it make heat and noise?
about 2050 in 6th gear and about 2400 in 5th gear


Maximum speed 76.5 in 5th gear and 89 in 6th..


the more i think about it this is where i want to be... it makes 6th gear useable in many more situations than it was previously.. 1900 at 65 is not going to make a ton of noise and heat.. downshifting to 5th puts it in a good Power band.. the top horsepower rating for this engine is in the 2200-2400 range.. 4.44 allows me to use the power wisely if / when i need it...



thanks for the insight to look at this rather than just the 4.10
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Old 07-09-2024, 01:56 PM   #23
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and even more fun..



I took the bus out for a drive.. to see with my new tire measurements.. how close is my dashboard to the calculators.. I drove till the digital dash just tripped from the numeral before and onto the number.. and even flicker back n forth... it doesnt round up according to navistar, so 49.7 displays as 49 not 50.



in 5th gear
dashboard 60 MPH RPM 1650. calculators 60.9
Dashboard 65 MPH RPM 1785. calculators 65.88
dashboard 70 MPH RPM 1930. Calculators 71.23


6th gear.


Dashboard 70 MPH RPM 1650. Calculators 70.88


interesting in the difference at 70... prob a resolution thing.. I*think* the tach resolution is not to the 1. at least not through the J1939 interface.. it has a formula and its not unlimited...
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Old 07-09-2024, 10:21 PM   #24
Skoolie
 
Join Date: Jul 2023
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Year: 2010
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Engine: Cummins 6.7 ISB Allison 2500
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Quote:
Originally Posted by cadillackid View Post
get the true rolling circumference of a tire. you lay out a tape measure, chalk the tire, and drive next to it.. measuring the number of inches you go to make a complete revolution.



you of course use a rear tire and drive straight. Jacking up the vehicle and measuring the a tape is NOT accurate as the rubber does get a bit compressed from the weight so its best to actually drive off the distance.



william way is better as any error you make(ie is the mark exactly one revolution or are you back for forward a little) is divided by 10, ill get a 100 foot tape measure and do it this way..


ultimately it can also be used to program the speedometer in your dashboard as well, at least on International and freightliner (CAT based busses).



Allison transmissions output typically 16 or 40 pulses per driveshaft revolution.


so lets say for kicks that my tires are in fact 31.5" in diameter... to get the inches rolled by calculation.. I would do Pi (I use 3.14159) X D (diameter). (I know math purists say its 2 pi R).


so it comes to 98.960085 inches rolled per tire rev.


1 mile is 63,360 inches.


divide your tire inches rolled into your inches per mile. 63,360 / 98.960085
so that is 640.25814 tire revolutions per mile. an interesting tidbit is if you are driving 60 MPH, thats the RPM of your wheel


in the current setup my gear ratio is 3.54:1, meaning my driveshaft spins 3.54 times every time the wheel goes round once.



so multiply my tire revs per mile by 3.54 to get the driveshaft revs per mile. 640.25814 X 3.54 = 2266.51382



now in most factory Allison configurations you get 16 pulses per driveshaft rev. so multiply the driveshaft revs by 16 to get the number of sensor pulses per mile.


2266.51382 X 16 = 36264.2211



round up or down whichever you like and program your computer with the whole number in the "pulses per mile" parameter and thats how your speedometer is calibrated.. I tend to round up as over time the number of pulses per mile will increase as your tires wear down..



on the older internationals there are dip switches on the gauge cluster that can be set. ( i have the book with those.. i posted some it someplace here)..



these forumulas above can also be uses similarly to compute your speeds and engine RPMs as well as driveshaft RPMs..



this is the bus i am working with on the rear gear project.


its an 00 Bluebird CV with an IH 3800 chassis. was used as the "pregnant teenage mothers" bus at a district in Houston area.. it was built with a top speed of 70 on its original drivetrain. other than some interior paint and the digital dashboard, its all original fully seated. hydraulic ABS disc brakes but has factory air compressor for air ride rear and air seat. factory Air-Conditioning as well



it originally had an AT545 (1:1 top ratio) and i swapped in an allison 1000 (a performance built one by suncoast) 7 years ago.. it has a 0.71:1 5th gear and a 0.61:1 6th gear. it has its 6th gear open.



the engine is a T444E (think powerstroke 7.3), with stage 1 injectors, adrenaline HPOP, lines, and Orion tuner. I run my orion on stage 4 out of 7 and can still pass about anything I need to getting on freeway ramps.



Attachment 78217
Oh yeah, all that gets complicated. I just use tire size calculator to find out tire height based on the tire size. Then a gear ratio/rpm/tire size/speed calculator to figure all that stuff out. You put in 3 of the 4 paramters and it tells you what the 4th parameter is. Rocky Road used to have a real good one, but they revamped their page and it's gone now. But there are others.

That's a nice looking bus. Sure does have some small wheels and tires though. For sure I'd want 6th unlocked with them cute little wheels. Step in height has to be nice. With my back ailments, that's becoming an important factor too. Not to mention smaller tires and lower to the ground should mean less wind drag as well as smaller tires not being as wide will also mean less friction to the pavement and should also net better mpg.

Since I didn't get the pusher bus, I'm back to my 2010 Vision with the 6.7ISB and 2500PTS. I wanted to go with 11R wheels and install rear wheel wells. Now I think I'm just going to leave the little Prius tires, 255 70R22.5, but open up 6th gear and that'll put me where I'm happy with the 5.29 rear gears.

I was told you had to also get a valve body and solenoid pack swap along with the TCM flash on a 2500PTS. So by accident, I found a thread on here today from 2019-2022. It was saying you do have to change that hardward if it's 2005 and older. But if it's 2006 and newer, you can open up 6th with just a TCM flash. So I need to find that guy who has the Allison DOC software and mail him my TCM and let him open itup for $200 and ship it back to me. There's another guy who does it for $400. Both are cheaper than Allison and they don't require permission from Blue Bird like Allison does. So I'm looking for that guy and going to keep my 2010 Vision, and the Wittle Prius Tires on it too to keep the flat floor without wheel wells and the lower step in height.
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Old 07-10-2024, 06:41 AM   #25
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Join Date: May 2009
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Engine: DTA360 / MT643
Rated Cap: 7 Row Handicap
yep you shopuld be able to turn 6th gear on with your 2010, that will take you from a 0.74 overdrive to a 0.64 in 6th gear..



my stepwell height is low.. i would never consider taking that bus off road as id probably have clearance issues .. I notice a huge difference getitng in my DEV bus which is a really tall bus.. its built on a super big chassis for its size.. 7 window busses with a GVWR of 27,500 (the DEV bus).. and a tall step height,,



the red one is much easier to get in and out of.. the red one's design was for pregnant teenage mothers and also once they had their babies to take their kids with them to school.. it has a few regular bus seats and some seats with build in kid-seats.. it is seated as a 5 row even though its 6 window.. so theres more room between seats.. its really a fun little bus to drive.. with the small wheels it can Easily out-turn my Dodge ram extended cab pickup.. easy to parallel park..



I get 11-14 MPG running at 65.. that number goes down running 70.. while the bus is more than capable of running 75 i dont drive it at that.. bus is for relaxed travel.


if I need to get someplace in a sort-of hurry there my dodge ram with a HEMI.. if i need to get someplace in a big-hurry theres delta airlines...





your tires are bigger than mine.. where you saw my circumference is in the 98.5" range.. your tire size is in the 114" range , this seems like a perfect setup with 6th gear turned on.. and you get to keep your flat for inside which is nice for the build,


a lot of people curse the wheel wells..



I did these calculations as tire sizes vary even though the "posted size" is the same..



granted in my case its entirely possible ive worn a couple thenths off my tires.. although they still look pretty new.. I do know my rear ones are smaller than the front as the front tire I chalked when making my drive-off didnt roll as much.. the marks stopped short by a decent amount.. my front tires are different brand than my rears and newer..



I swapped in my allison transmission 7 years ago.. so I boight one and the associated computers for it with 6 speeds already.. i went a step further and got a TCM that allows me to reprogram the shifting patterns and lockup behaviour.. so I built my own shift curves to help with the fact my gears are too tall in the rear...



once i regear ill likely be rebuilding my shift patterns all over again , ill drop them as the bus will have more torque at lower RPMs I can crowd it a bit in lower gears and not cause a lug condition.
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Old Yesterday, 02:52 AM   #26
Skoolie
 
Join Date: Jul 2023
Location: OKC, OK
Posts: 151
Year: 2010
Chassis: Bluebird Vision
Engine: Cummins 6.7 ISB Allison 2500
Rated Cap: ADA Lift Bus Lift Removed
Quote:
Originally Posted by cadillackid View Post
yep you shopuld be able to turn 6th gear on with your 2010, that will take you from a 0.74 overdrive to a 0.64 in 6th gear..



my stepwell height is low.. i would never consider taking that bus off road as id probably have clearance issues .. I notice a huge difference getitng in my DEV bus which is a really tall bus.. its built on a super big chassis for its size.. 7 window busses with a GVWR of 27,500 (the DEV bus).. and a tall step height,,



the red one is much easier to get in and out of.. the red one's design was for pregnant teenage mothers and also once they had their babies to take their kids with them to school.. it has a few regular bus seats and some seats with build in kid-seats.. it is seated as a 5 row even though its 6 window.. so theres more room between seats.. its really a fun little bus to drive.. with the small wheels it can Easily out-turn my Dodge ram extended cab pickup.. easy to parallel park..



I get 11-14 MPG running at 65.. that number goes down running 70.. while the bus is more than capable of running 75 i dont drive it at that.. bus is for relaxed travel.


if I need to get someplace in a sort-of hurry there my dodge ram with a HEMI.. if i need to get someplace in a big-hurry theres delta airlines...





your tires are bigger than mine.. where you saw my circumference is in the 98.5" range.. your tire size is in the 114" range , this seems like a perfect setup with 6th gear turned on.. and you get to keep your flat for inside which is nice for the build,


a lot of people curse the wheel wells..



I did these calculations as tire sizes vary even though the "posted size" is the same..



granted in my case its entirely possible ive worn a couple thenths off my tires.. although they still look pretty new.. I do know my rear ones are smaller than the front as the front tire I chalked when making my drive-off didnt roll as much.. the marks stopped short by a decent amount.. my front tires are different brand than my rears and newer..



I swapped in my allison transmission 7 years ago.. so I boight one and the associated computers for it with 6 speeds already.. i went a step further and got a TCM that allows me to reprogram the shifting patterns and lockup behaviour.. so I built my own shift curves to help with the fact my gears are too tall in the rear...



once i regear ill likely be rebuilding my shift patterns all over again , ill drop them as the bus will have more torque at lower RPMs I can crowd it a bit in lower gears and not cause a lug condition.
You're marroom bus seems to be a very cool weeked stroller, no pun intended on the stroller, but going on a weekend stroll. LOL It looks nice, MPG even sounds good for what it is so when diesel fuel is reasonable is the time to fill it up so it's ready to go for a ride. My grandkids love love love riding in the bus. Even though one of them rides a school bus, she says it's better when Papa is driving it and she can sit whereever she wants and can chew gum. LOL, Gotta love kids and their perspective. I guess no gum is allowed on the school bus she rides so she likes my bus better and they like riding the lift up and down to get on the bus. That's all coming out to build it though. I need a name for that bus tool. If it was as easy as yours, I'd name it Knocked Up. LMAO, I'm sure a few would be offended but hey, that's what the bus's intention was for. Carry all them knocked up girls.

Yes, I was real happy to see with my 2500PTS being after 2006, I can unlock it. The .10 does make a difference when you're running them little tires, so I'll keep them little tires and it's advantages and now I will pursue the 6th unlock which I blew off. It wasn't that big of a deal to unlock it to me, and I'd have rather just gone with the 11R tire swap and my 2005 Blue Bird Vison is a long bus with no Handy door and it has 11R tires. I think I'll be keeping that bus too. Everyone needs 2 buses right? Well, I'll actually 3 but 1 don't count since it's coach is coming off the chassis to be permanent anchored like a sall studio being it's a 6 window. Wheel wells dont' bother me. I'll incorporate those into the build. Closets or Pantry space no big deal. I can see how the flat nose bus buys get bothered having 4 wheel wells, but even then, the front 2 can build under your face to face sofa and pull out bed. Though I've not cared for that layout either. If someone has it pulled out and sleeping, and I want to get up to go outside for a smoke or a leak, then I have jump over somoene. Not much into that.

Yep, you'll want to retune the shift behavior after a regear. See, you get all these freaks about all mechanical. That's not me. Electronic don't scare me a bit. Sure it's more parts to go wrong, but most of them parts are non moving parts and they can last forever and ever. For the ones that do fail occasionally, there's many benefits to the electronics so I'll sure take the bad with all the good, cuz the bad really isn't all that bad. Just like Emissions, if you want a bus with OD and lock up, chances are you're going to have electronics, and possibly even some emissions. My 2005 Vision, CAT C7 has no emissions, and does have OD and Luck Up with a 2000 Series Allsion. Not sure which one it is, maybe just 2000. The 2010 does have EGR and Cooler. EGR can be taken off and cleaned. Probably time to flush the cooling system and refill with good RED antifreeze to keep the cooler from clogging up and so long as I don't overheat it, the EGR cooler shouldn't crack which is somewhat of a common issue if you don't maintain your cooling system. Just like HEUI pump is somewhat common failure on the early C7's if you don't maintain your engine oil and keep it clean. Now DPF issues can be bad, and DEF issues can be bad. Naww, I prefer to stay away from those when I can. My 2010 might even have DPF, but I don't think so, all I see is a biggo muffler and when I seen a 2012 and the DPF system, I certainly do not have all that BS.

I take it your DEV bus is more like a tour bus???
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Old Yesterday, 02:58 AM   #27
Skoolie
 
Join Date: Jul 2023
Location: OKC, OK
Posts: 151
Year: 2010
Chassis: Bluebird Vision
Engine: Cummins 6.7 ISB Allison 2500
Rated Cap: ADA Lift Bus Lift Removed
Quote:
Originally Posted by cadillackid View Post
yep you shopuld be able to turn 6th gear on with your 2010, that will take you from a 0.74 overdrive to a 0.64 in 6th gear..



my stepwell height is low.. i would never consider taking that bus off road as id probably have clearance issues .. I notice a huge difference getitng in my DEV bus which is a really tall bus.. its built on a super big chassis for its size.. 7 window busses with a GVWR of 27,500 (the DEV bus).. and a tall step height,,



the red one is much easier to get in and out of.. the red one's design was for pregnant teenage mothers and also once they had their babies to take their kids with them to school.. it has a few regular bus seats and some seats with build in kid-seats.. it is seated as a 5 row even though its 6 window.. so theres more room between seats.. its really a fun little bus to drive.. with the small wheels it can Easily out-turn my Dodge ram extended cab pickup.. easy to parallel park..



I get 11-14 MPG running at 65.. that number goes down running 70.. while the bus is more than capable of running 75 i dont drive it at that.. bus is for relaxed travel.


if I need to get someplace in a sort-of hurry there my dodge ram with a HEMI.. if i need to get someplace in a big-hurry theres delta airlines...





your tires are bigger than mine.. where you saw my circumference is in the 98.5" range.. your tire size is in the 114" range , this seems like a perfect setup with 6th gear turned on.. and you get to keep your flat for inside which is nice for the build,


a lot of people curse the wheel wells..



I did these calculations as tire sizes vary even though the "posted size" is the same..



granted in my case its entirely possible ive worn a couple thenths off my tires.. although they still look pretty new.. I do know my rear ones are smaller than the front as the front tire I chalked when making my drive-off didnt roll as much.. the marks stopped short by a decent amount.. my front tires are different brand than my rears and newer..



I swapped in my allison transmission 7 years ago.. so I boight one and the associated computers for it with 6 speeds already.. i went a step further and got a TCM that allows me to reprogram the shifting patterns and lockup behaviour.. so I built my own shift curves to help with the fact my gears are too tall in the rear...



once i regear ill likely be rebuilding my shift patterns all over again , ill drop them as the bus will have more torque at lower RPMs I can crowd it a bit in lower gears and not cause a lug condition.
I said all that about the tires and forgot to mention, I don't know how much a 16 ply tire can expand, but one thing about radials, the tend to grow taller and skinnier with centrifical force, so doing tire runouts on paper, or speed and rpm calculators based on tire height, those figures can be a bit better in our favor at freeway speeds. Granted, it's minimal but every little bit helps. Just like a lock up converter, it's only 200-300rpm drop, but if that put you in your sweet spot for mpg or power band holding cruise control speed, then so be it, we'll take it. IMO, the biggest gain to a lock up converter is, the cooler transmission temp adding years of life to your transmission clutches.
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Old Yesterday, 07:53 AM   #28
Bus Geek
 
Join Date: May 2009
Location: Columbus Ohio
Posts: 19,127
Year: 1991
Coachwork: Carpenter
Chassis: International 3800
Engine: DTA360 / MT643
Rated Cap: 7 Row Handicap
Quote:
Originally Posted by Hooker View Post
I said all that about the tires and forgot to mention, I don't know how much a 16 ply tire can expand, but one thing about radials, the tend to grow taller and skinnier with centrifical force, so doing tire runouts on paper, or speed and rpm calculators based on tire height, those figures can be a bit better in our favor at freeway speeds. Granted, it's minimal but every little bit helps. Just like a lock up converter, it's only 200-300rpm drop, but if that put you in your sweet spot for mpg or power band holding cruise control speed, then so be it, we'll take it. IMO, the biggest gain to a lock up converter is, the cooler transmission temp adding years of life to your transmission clutches.



the DEV bus is a 7 window School bus.. 1990 chassis.. funny you mention all mechanical.. it is all mechanical, DTA360 engine with an MT643 (4 speed lockup, no overdrive) transmission.. it had an AT545 and I blew it up so changed to a MT643.. I love electronics but I dont care for the way the allison electroniuc tranmissions act behind a mechanical engine.. so I stayed mechanical.. (and got a dry reman trans CHEAP)..



interesting on centrifigual force.. something I hadnt thought about but the 16 ply and the radial bands definitely have ewnough weight to somewhat change the dynamic.. esp at the 640-650 RPM the 19.5" tires spin...



Lockup advantage is a couole-fold,


1. definitely the heat factor in keeping the fluid temp cooler.. but also with no slip, that power which was lost making heat is now going to the wheels so it does make a MPG difference.. somewhere in this forum was me doing a comparison with MPG in the red bus from where i had calulated it when I had the AT545, vs running my 1000 in non-OD (but locked up) mode and there was a solid 1 MPG gain just adding lockup.. something ive also seen true in my DEV bus now that it has the MT643 vs the AT545..



Most all school busses with 2000 "series" have the 2500-PTS. it was a vocation designed by allison for school busses.. (PTS - Pupil Transport Service).


while 4th and 5th and 6th gear are all the same amongst the vocations.. the 2500 PTS has a wider ratio 1-3 so it was better for stop N go.. a lower first and a little taller 3rd.. cant remember but I think 2nd was a little shorter than standard also..



the 1000 / 2000 are essentially the same transmission.. the way I was told was the 1000 was deisgned to be an off-the shelf solution,with certain options.. like (what type of bell, SAE3, GMC),(parking pawl or not).. but all would have the same ratios .


and the 2000 series were SPEC'd and programmed to each OEM that contracted allison to build their transmisisons.. so they got more custom programming.. for instance a 2200MH is a motorhome spec with narrow range gears and a Parking pawl (you have a 'P' on the shifter). they made a 2400 wide ratio with a PTO to be used for Boom / Bucket trucks..



the original vocation for the 1000 series was in 2001 GMC duramaxx pickups.. ford was talking about a 5 speed to replace the 4R100.. GMC beat them with the 5 speed allison 1000 .. which later became a 6 speed.. (the gears and clutches for 6 gears was there all along.. taking o na simialr design to the 3000 series).. ill never understand why it was not released as a 6 speed..



the electronic "world" series (better known as 3000 series, MD3060) had been out since 93/94 and were succesful in the bigger vehicles .. but were a really pricey option..



the SAE3 bell 2000 series was conveniently designed to bolt right up exactly where an AT545 mightve precviously been Spec'd.. same shifter cable and pattern design, same converter bolt pattern and converter offset, same mounting technique and bracketry.. with J1939 data links pretty much on all electronic engines by year 2000 using standard parameters it was an easy integration for allison to release these to the likes of International, Freightliner, GMC for bus chassis use..
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Old Today, 12:49 AM   #29
Skoolie
 
Join Date: Jul 2023
Location: OKC, OK
Posts: 151
Year: 2010
Chassis: Bluebird Vision
Engine: Cummins 6.7 ISB Allison 2500
Rated Cap: ADA Lift Bus Lift Removed
Quote:
Originally Posted by cadillackid View Post
the DEV bus is a 7 window School bus.. 1990 chassis.. funny you mention all mechanical.. it is all mechanical, DTA360 engine with an MT643 (4 speed lockup, no overdrive) transmission.. it had an AT545 and I blew it up so changed to a MT643.. I love electronics but I dont care for the way the allison electroniuc tranmissions act behind a mechanical engine.. so I stayed mechanical.. (and got a dry reman trans CHEAP)..



interesting on centrifigual force.. something I hadnt thought about but the 16 ply and the radial bands definitely have ewnough weight to somewhat change the dynamic.. esp at the 640-650 RPM the 19.5" tires spin...



Lockup advantage is a couole-fold,


1. definitely the heat factor in keeping the fluid temp cooler.. but also with no slip, that power which was lost making heat is now going to the wheels so it does make a MPG difference.. somewhere in this forum was me doing a comparison with MPG in the red bus from where i had calulated it when I had the AT545, vs running my 1000 in non-OD (but locked up) mode and there was a solid 1 MPG gain just adding lockup.. something ive also seen true in my DEV bus now that it has the MT643 vs the AT545..



Most all school busses with 2000 "series" have the 2500-PTS. it was a vocation designed by allison for school busses.. (PTS - Pupil Transport Service).


while 4th and 5th and 6th gear are all the same amongst the vocations.. the 2500 PTS has a wider ratio 1-3 so it was better for stop N go.. a lower first and a little taller 3rd.. cant remember but I think 2nd was a little shorter than standard also..



the 1000 / 2000 are essentially the same transmission.. the way I was told was the 1000 was deisgned to be an off-the shelf solution,with certain options.. like (what type of bell, SAE3, GMC),(parking pawl or not).. but all would have the same ratios .


and the 2000 series were SPEC'd and programmed to each OEM that contracted allison to build their transmisisons.. so they got more custom programming.. for instance a 2200MH is a motorhome spec with narrow range gears and a Parking pawl (you have a 'P' on the shifter). they made a 2400 wide ratio with a PTO to be used for Boom / Bucket trucks..



the original vocation for the 1000 series was in 2001 GMC duramaxx pickups.. ford was talking about a 5 speed to replace the 4R100.. GMC beat them with the 5 speed allison 1000 .. which later became a 6 speed.. (the gears and clutches for 6 gears was there all along.. taking o na simialr design to the 3000 series).. ill never understand why it was not released as a 6 speed..



the electronic "world" series (better known as 3000 series, MD3060) had been out since 93/94 and were succesful in the bigger vehicles .. but were a really pricey option..



the SAE3 bell 2000 series was conveniently designed to bolt right up exactly where an AT545 mightve precviously been Spec'd.. same shifter cable and pattern design, same converter bolt pattern and converter offset, same mounting technique and bracketry.. with J1939 data links pretty much on all electronic engines by year 2000 using standard parameters it was an easy integration for allison to release these to the likes of International, Freightliner, GMC for bus chassis use..

Yep, Allisons have pretty much done it right. And you have to for an automatic in Medium and Heavy Duty. Where a 10,13 and 18 speed manuals, they can make up what their purpose is by how they're driven so they can be cookie cutter and the driver drives it accordingly. Not so true on an Auto. Auto means Auto and the driver doesn't get to decide much, so Allisson does all that work in their builds. Like The PTS and features you mention. They have many other series too. Our Medium Duty trucks seem to have RDS (Rugged Duty Series) and also some HS (Highway Series) in Paccar (KW and Pete) and Freightliners. All depends on who the builder.upfitter of the truck is. We've got 2 Freightliner M2 trucks that are about the same age, 2022 and 2023, built by different builders. Though they look like twins, far from it. Same engines and same style Allissons. One is an RDS transmission, one is a HS transmission. The RDS truck also has an electronic rear locker and does it ever come in handy doing those recoveries out in fields for burned out stolen vehicles. The engine tunes are a bit different too, but both those truck have totally different attitudes. One seems like a work horse, one seems like a street princess. Both are governed at 75mph since 2021 was last year for 85. Truck manufactures now govern them to match the T Spec speed rating on the tire. You can get it without the 75 moh, but you have to order the truck with upgraded tires and most employers consider 75 safe enough. This is why when I was offerend the new 2023 truck, I opted to take the low mileage used 2021 truck. I did like the bed better, but that truck would run 85 and me being the night driver 6pm to 6am, many 2, 3 and 4 am calls I'd have to run way out, there;s ZERO traffic and I could run out there at 85mph and let the dayshift boys have them slower trucks. They're usually hung up in some traffic anyway.

For sure Lock up will save some mpg. Sometimes lucky enough to save even more than 1mpg as you mention that parasitic loss of powerto the ground is part of it. But if yuo get that rpm into a sweet spot where it might not have been before, you can probably expect another mpg also. But for sure, I personally feel the biggest advantage of the lock up, is losing that heat generation from all the slipping and friction in the converter. The lack of heat helps with longevity immensely. I'd say the difference in the heat alone can mean at least another 30% gain in longevity since heat is the #1 Killer of Auto transmissions.
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Old Today, 04:56 AM   #30
Skoolie
 
Join Date: Jul 2023
Location: OKC, OK
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Year: 2010
Chassis: Bluebird Vision
Engine: Cummins 6.7 ISB Allison 2500
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Quote:
Originally Posted by cadillackid View Post
get the true rolling circumference of a tire. you lay out a tape measure, chalk the tire, and drive next to it.. measuring the number of inches you go to make a complete revolution.



you of course use a rear tire and drive straight. Jacking up the vehicle and measuring the a tape is NOT accurate as the rubber does get a bit compressed from the weight so its best to actually drive off the distance.



william way is better as any error you make(ie is the mark exactly one revolution or are you back for forward a little) is divided by 10, ill get a 100 foot tape measure and do it this way..


ultimately it can also be used to program the speedometer in your dashboard as well, at least on International and freightliner (CAT based busses).



Allison transmissions output typically 16 or 40 pulses per driveshaft revolution.


so lets say for kicks that my tires are in fact 31.5" in diameter... to get the inches rolled by calculation.. I would do Pi (I use 3.14159) X D (diameter). (I know math purists say its 2 pi R).


so it comes to 98.960085 inches rolled per tire rev.


1 mile is 63,360 inches.


divide your tire inches rolled into your inches per mile. 63,360 / 98.960085
so that is 640.25814 tire revolutions per mile. an interesting tidbit is if you are driving 60 MPH, thats the RPM of your wheel


in the current setup my gear ratio is 3.54:1, meaning my driveshaft spins 3.54 times every time the wheel goes round once.



so multiply my tire revs per mile by 3.54 to get the driveshaft revs per mile. 640.25814 X 3.54 = 2266.51382



now in most factory Allison configurations you get 16 pulses per driveshaft rev. so multiply the driveshaft revs by 16 to get the number of sensor pulses per mile.


2266.51382 X 16 = 36264.2211



round up or down whichever you like and program your computer with the whole number in the "pulses per mile" parameter and thats how your speedometer is calibrated.. I tend to round up as over time the number of pulses per mile will increase as your tires wear down..



on the older internationals there are dip switches on the gauge cluster that can be set. ( i have the book with those.. i posted some it someplace here)..



these forumulas above can also be uses similarly to compute your speeds and engine RPMs as well as driveshaft RPMs..



this is the bus i am working with on the rear gear project.


its an 00 Bluebird CV with an IH 3800 chassis. was used as the "pregnant teenage mothers" bus at a district in Houston area.. it was built with a top speed of 70 on its original drivetrain. other than some interior paint and the digital dashboard, its all original fully seated. hydraulic ABS disc brakes but has factory air compressor for air ride rear and air seat. factory Air-Conditioning as well



it originally had an AT545 (1:1 top ratio) and i swapped in an allison 1000 (a performance built one by suncoast) 7 years ago.. it has a 0.71:1 5th gear and a 0.61:1 6th gear. it has its 6th gear open.



the engine is a T444E (think powerstroke 7.3), with stage 1 injectors, adrenaline HPOP, lines, and Orion tuner. I run my orion on stage 4 out of 7 and can still pass about anything I need to getting on freeway ramps.



Attachment 78217
Man, not sure why I didn't think of this earlier. I was getting ready to list a drop out 3rd member from one of my buses. It might be exactly what you'll be looking for. It's a 2002 IIRC, IH Blue Bird short bus with 9r-22.5 tires. I can't remember now, I'll have to look to make sure, I know it's in the 4's, but I think it's 4.33 rear gear ratio. If it's the same rear axle that's in yours, this one should fit your bus and do that math, I think you'll be happy with the 4.33 ratio. I can't confirm it, but I was told this was a 110,000 miles bus. The guy I got it from bought it for the engine and transmission for his rollback, and he took a few other parts too like the instument cluster so no odo.
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Old Today, 07:45 AM   #31
Bus Geek
 
Join Date: May 2009
Location: Columbus Ohio
Posts: 19,127
Year: 1991
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Chassis: International 3800
Engine: DTA360 / MT643
Rated Cap: 7 Row Handicap
awesome little bus.. Spec a bit higher than mine.. dual instead of single A/C and the bigger axle.. mine is an S135/S150, ill bet yours is an N or J series axle.



the S135/S150 wasnt made with a 4.33 ratio..



what are you replacing the 4.33 with? that bus is probably a good runner with a 4.33 in it..
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