Help with Gear Ratios

[cowlitzcoach]

Quite interesting remarks regarding transmissions and gear ratios. I bought my bus a year ago with a two-year deadline (by wife) to convert. It has been sitting in my backyard unconverted but worked on for almost a year. Yesterday after reading the discussion in this thread I contacted the manufacturer (or assembler) Wolfington and got a response right away. I have a Wolfington Bus Company production with coachwork by ATC (American Transportation Company) and an International chassis, 11 windows, 54 passenger capacity. It was built 10/2001, titled as 2002. Miles: 114K. The engine is T444E and now I have learned the transmission is Allison 2400 and gear ratio 5.57. What can you say about this combination?

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The Allison 2400 is a newer style transmission with at least one OD gear. With 5.57 rear gears you will get an 5th OD of about .74 which would put your final gearing effectively about the same as direct with 4.11 rear gears. Top speed would be about 70-75 MPH at 2600 RPM.

How many HP the engine is rated will determine how much of that OD gear you can use. 180 HP is going to have to work really hard to maintain 60+ MPH. 210 HP will maintain 65 MPH. But you are going to need well in excess of 250 HP if you want to maintain 75 MPH.

 

[1olfart]

Don't want to hijack anyone's thread, but 1 quick question..

Any one know what ratio might be in a mid 80's S1700 with the 'beloved' 545

Thanks in advance

 

[brokedown-SKO]

Rear end could be anything really. 4.78 anecdotally seems to be the most common.

 

[1olfart]

That's about what I was thinking, but I hope I can find one around 4. I'm sure they are out there.

Thanks

 

[Tango-SKO]

Definitely need to confirm what you have before shopping new gears. If necessary, pull the cover and count the teeth. Many are also stamped on the ring gear. Or...do the old jack it up and rotate the wheel routine while you count the revs on the driveshaft.

 

[cadillackid]

hey turf.. luckily i didnt blow up the nice allison 1000 I put in the red bus a year ago... the DEV bus has a DTA360 and an AT545.. I found a sweet deal on 643s REMAN.. so thats the route im taking..



that bus has a 4.78 rear.. the 2 i see the most in busses in many states is 4.78 and 4.44 (wwatch out for NC busses.. busses out of that state are often 1:1 trans with gears in the 5s or 6s.. of course tire sizes affect ratios.. 11R22.5s on most full size busses.. but a myriad of tire sizes exist on shorter busses..

-Christopher

 

[turf]

the 643 is the obvious choice, cost and durability. sorry to hear you toasted the 545.
just my opinion, but my disappointment with my trans swap was there was little noticeable improvement. a 4 speed for a 4 speed. no new mph's, just exactly the same. only its much more crisp in shifting than the old trans.

like the thread title or the OP, i think excitement will come from a shiney new 4.11 ring.

just a question, but how come rear engine buses are 5 something rear ends? i know ive seen a cummins 8.3 FE with a 4.11. never a pusher though

 

[cadillackid]

The RE were the first to get overdrive generally or at least where the 3000 series trans was used most widely in a school bus, other thing is while tallercgears make your max calculated speed higher they hurt your 100 foot time. Going to need more power or more time to get up to speed .. school buses, most of them, spent their time pulling out into traffic vs running the highway.. RE busses atcone time were the biggest and heaviest.

As for me and my 535 to 643, that bus is a DT360 which isn’t a powerhouse. Having overdrive would lower my rpm if I. Oils actually use it .. the bus top speed is 68 but it hums along perfect at 55-60,where I like to run it. The lockup will lower my heat production and also give me the ability to turn up the smoke on that DT if I want.

The Allison overdrives are all electronic. While you can run then on a purely mechanical motor .. many people do.. they really come to life when you have an electronic engine and can run them with an active data link.

Christopher

 

[Potkoff]

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The Allison 2400 is a newer style transmission with at least one OD gear. With 5.57 rear gears you will get an 5th OD of about .74 which would put your final gearing effectively about the same as direct with 4.11 rear gears. Top speed would be about 70-75 MPH at 2600 RPM.

How many HP the engine is rated will determine how much of that OD gear you can use. 180 HP is going to have to work really hard to maintain 60+ MPH. 210 HP will maintain 65 MPH. But you are going to need well in excess of 250 HP if you want to maintain 75 MPH.

Cowlitzcoach big thanks for the thoughts. I just sent an email to Wolfington about the HP. I thought all T444Es were equal... When we picked up the bus in Cape May, NJ I was assured it was in good shape, just finished carrying students, serviced like a month earlier. We embarked on a trip to Florida without even lifting the hood. I admit I am naïve and stupid. Still no surprises. I was driving steady 65 mph, sometimes more downhill, but I understand the speed is capped and I will still have to get to it. I don't think I will ever want to drive faster but if I have to it would be nice to have the capacity.
Richard

 

[cadillackid]

the mosdt common T-444E horsepower is 175, you can look at the tag on the driver side valve cover and it will be stamped with your Horsepower rating.. there are a few members here lucky enough to have the 210s.. mine is a 190.. in a short bus I can run 70 all day long wiothout issues.. but I wouldnt want to be a 175 in a full size trying to do that..

 

[Potkoff]

the mosdt common T-444E horsepower is 175, you can look at the tag on the driver side valve cover and it will be stamped with your Horsepower rating.. there are a few members here lucky enough to have the 210s.. mine is a 190.. in a short bus I can run 70 all day long wiothout issues.. but I wouldnt want to be a 175 in a full size trying to do that..

My engine is 195HP, confirmed by the manufacturer and stamped on the label on the valve cover. Thanks for the answer.
Richard