ISM Cummin

[busme66]

What allison transmission goes with a Cummin ISM and the best
way to find one inexpensively.

[luvrbus]

you have a problem with the gearing on a Eagle a 3:36 rear gear and the 700 series works good if not you can spend the bucks and go with the world Allison and use it as a 5 speed with the 3:73 gears or a Auto shift Eaton lot of Eagle guys run the 740 behind the ISM,M 11 and series 60 Detroit with 3:36 gears.
Jim here on the board runs the Eaton behind his series 60 works good for him in his Eagle I think he has 3:73 gears cost a bundle to change gear ratios on a Eagle and very limited on the ratios, 3:33, 3:36,3:38 3:73 or if you are lucky maybe a 4:10 then the cage has to be changed for the 4:10 gear


good luck

[busme66]

I have 373 rear end thought might have a few more options.
                                                       Thanks.

[Brian Diehl]

I have the 3.33 gears in my MCI 96A3.  This works great with the Eaton Autoshift I put behind my ISM.  I'm very happy with this combination and find overdrive (.74) useful down to about 58 mph.

[Boomer]

I have an Eagle with ISM 450 and HD4560P World Trans.  Drop box diff with 3:36 gears.  It runs perfectly fine in 5th gear and delivers excellant fuel economy.  For all the high ballers out there, if you want to drive 90 mph that still leaves one more gear, LOL.

[Boomer]

I saw a S60 and B500 for sale on E place a day or two ago.  Out of burned bus, no fire in engine compartment.  Reasonable price.

[busme66]

Whats a S60? and this will work?

[luvrbus]

A series 60 is a Detroit engine the number 1 truck engine lots of Eagles have those also on the Eagle board little more hard to install than the ISM but a better engine sorry Cummins guys you need to raise the floor in the rear as the 60 series is taller and most put the bed over that section to install a 60 series you don't need to raise the floor for a ISM fwiw you can install about any manufactures engine in a Eagle with out much of a problem except gearing raising the floor is not that big of a deal 



good luck

[busme66]

Interior is already in this is a repower so have to go with the cummins and it
sounds like this is the easist way to go.

[luvrbus]

The guy Hal on the Eagles board that answered your post knows how to make a Eagle work he has a 625 hp series 60 and gets around 10mpg not to shabby huh then Boomer get 9+ with his ISM in his Eagle

good luck

[rv_safetyman]

Per my reply on eaglesinternational.net:

Kevin (had to go to your profile to dig that one up), I wrote a 3 part article for Bus Conversion Magazine on the subject. Not so much a how to do, but what to consider. If you are serious about doing an engine swap, then you should probably get the copies.

There are lots of considerations when considering a engine swap. You have hit on the main one: gearing. Four-stroke engines are designed to operate in an RPM range that is about 30% slower than a two-stroke. They have the same 2100 governed speed,but they don't like to run at the higher RPMs for long periods of time and their efficiency goes way down at those RPM.

Your Eagle with 3.73 gears can do about 72 MPH at full governed speed (2100). The only taller gear is 3.36. That helps, but does not put the engine in the sweet spot at speeds you want to travel.

Your transmission is a either an Allison or Voith both of which have a 1.0 to one top gear. You need an overdrive or the 3.36 gears (over $2K). I went with the Eaton AutoShift with a .73 overdrive. Really puts the engine at a sweet spot at 70 MPH.

The World has a .73 fifth gear and something like a .63 sixth gear. Some have 6th locked out. The fifth would give you a great combination.

As has been pointed out, your are on the heavy side. Mine weighs about 46K with the service truck and my Series 60 does not run away from some of the big trucks on big hills.

The World and the Eaton AutoShift will bolt up to the ISM

Just some random thoughts.

Jim

Jim

[TomC]

The ISM Cummins is just about the perfect bus engine.  It is smaller in size from the Series 60 and puts out almost the same power-with a bit less fuel mileage.  You could run the Allison HT740 four speed with a 3.36 or 3.08 gear ratio.  Or keep the same rear end and use the Allison B500 with its' .74 and .64 overdrives.  But-the World transmission will be twice the money, and you would have to run about 300,000 miles to recoup the cost with fuel mileage savings and run all the electronics.  I replaced my 13spd manual with the HT740.  With 3.55 gears and 11R-24.5's and the Caterpillar 3406B 400hp-which would run at about the same RPM as the ISM, my speeds in 4th gear will be- 55mph @ 1550rpm (really good fuel mileage), 60mph @ 1690rpm (still good fuel mileage), 65mph @ 1830rpm (about the top of the fuel mileage curve), 70mph @ 1971rpm, 75mph @ 2112rpm (the highest I'd want to run continuously), 80mph @ 2253rpm, 85mph @ 2394rpm (just for a short time).  So personally-I'm satisfied with the Allison HT740-and especially since it is a very reliable mechanically controlled transmission.  Both my engine and transmission are non electronic-just the way I like it.  Good Luck, TomC

[Hal]

Using an ISM with anything other than an electronic trans seems to be a step in the wrong direction. The 740's are cheaper but you will have a hard time making one work well with the ISM's electrical. There are electronic 700 series trannies out there but they won't be any easier to install than the worlds and won't offer the advantages. With your 46,000lb weight and not knowing the specs on the ISM (400,450,500hp, 1400-1550 tq ?) its really hard to get a handle on your requirements. Running 75mph at 1300 rpm with this load can also create heating issues. These motors are easier to cool because of their better efficiency but there is no 'free lunch'.  There is a reason factory built buses ran 4.56 gea rsets-it helped with power cooling and stopping (Jake's). Like I mentioned before, its all a matter of a balanced combination that makes these motors economical. Hal