Possible gearing change

[Flying I 365]

Got a strange question, perhaps some advice is in order.

Bus is a 2006 IC CE200 (VT365, Allison 2500PTS) at 143K miles (Sabrina is her name)

A bit of info to fill in the blanks. After going to the International dealer close to my place, I was able to get my rear gear ratio, and it’s at 6.17 on 11R22.5 tires. The engine runs at 2100-2200RPM (somewhere around that range) with the bus currently governed electronically at 60MPH. My question is this, could a different gear ratio be used in the rear end to bring down the engine RPM while increasing the speed? (After the governor is removed)

I’m hoping to get better speed out of the bus without having the VT365 screaming like crazy, or guzzling fuel like no tomorrow (at current diesel fuel prices in my area)

[TJones]

Yes a gearing change should be possible. Depending on what differential you have a shop should be able to remove the differential carrier and either replace the ring and pinion gear or replace the entire carrier. You will need to get the model number for your differential to see if gear can be changed and what ratios are available.

A couple years ago I was quoted $2500 to install a new ring and pinion. This was with me removing the carrier myself and bringing it to the shop. If you have the ring and pinion changed make sure you find an expirenced mechanic as adjusting the gears correctly is important.

Ted

[La Camioneta]

https://spicerparts.com/calculators/...rpm-calculator

From what you posted you're in 5th, and possibly have a 6th gear that can be unlocked.

Someone more knowledgeable will be along shortly. Meanwhile search for '6th gear unlock' for the tech info.

Use the calculator to play with possible ratios, my B700 has 4.88 on 11/22.4 42" tall and fifth gear says 90+. 5th is OD1 @ .71 and 6th is OD2@ .61 https://www.dieselhub.com/trans/allison-1000.html

[Flying I 365]

The bus spec sheet I was given shows the Allison 2500PTS equipped being 5 gears, no 6th equipped. (Paper shows Allison 2500PTS 5-SP L/PTO L/RETR (Whatever that means)) 5th gear is at 0.74:1 on the transmission. Rear end is shown to be a Dana/Spicer 19060S configured for leaf springs and disc brakes. (sheet shows 19.8K 190 WE DANA 19060S) Not sure what ratios would be available for that kind of differential, or if they were changed to something lower, what engine damage could possibly result to the VT365. I know a few things about the older IC CE series buses (06-12) but I don’t know everything.

Any idea what ratios were available for that kind of differential? And what might be a good ratio option to lower the RPMs and increase the speed?

[Booyah45828]

L/pto and L/retr mean less pto and retarder.

Here is your axle spec sheet. 2nd page shows available ratios.

https://media.spicerparts.com/cfs/fi...store=original

With a 6.17 you could drop to a 5.xx something easily, gain the mph you're after, and lose very little acceleration. Don't get too carried away though, as too fast of gears will make a real pooch on mountains. Also, there's a good chance you'll lose mpg if you try and utilize the additional speed capability that you've gained. If efficiency is your goal, slower speed must be in the recipe. At 60 mph in direct, don't have your rpm lower then peak torque rpm.

[Dbacks2k4]

Originally Posted by Flying I 365

The bus spec sheet I was given shows the Allison 2500PTS equipped being 5 gears, no 6th equipped. (Paper shows Allison 2500PTS 5-SP L/PTO L/RETR (Whatever that means))

2006 was a transition year for the 2500PTS. The ones manuafacturered after June I believe have the necessary hardware for 6th and can be unlocked by re-flashing the TCM. Prior to June required hardware changes in addition to the TCM re-program.

[Flying I 365]

Looks to be a lot of choices for the rear axle according to the axle spec sheet. Efficiency is what I’m after yes, but the other thing is that I do not want to overheat and possibly damage and destroy the VT365 while running at highway speeds (I have been told a few of the bits in the oil filter housing are made of plastic and can melt at high oil temperatures) and the engine itself is 15-16 years old and is well worn in after years of school usage so it’s a bit sluggish already.

I do not think Sabrina will ever see any mountain passes. As for her build date, I think (and I’ll need to check the body tag on the bus for the actual date) it was sometime in Oct of 2005

[Dbacks2k4]

Originally Posted by Flying I 365

Efficiency is what I’m after yes, but the other thing is that I do not want to overheat and possibly damage and destroy the VT365 while running at highway speeds

If your bus is a 2006 "title year" and built in '05 then enabling 6th will definitely require the hardware changes.

The VT365 is a trouble-prone engine to start with as I'm sure you're already aware. I would do as much bulletproofing and prevent-maintenance on it as possible. Heat management and frequent clean oil changes are musts on those.

[Flying I 365]

Yeah, I think so. Though it is unknown if the transmission even had 6th gear built in.

I do know the VT365 engine is troublesome at best, and I know I would have been running into mechanical issues when I bought Sabrina upon her retirement from school service. The original engine is well worn in and in need of a rebuild. It starts (barely) and runs (not all too well) despite smoking coolant badly (from a blown EGR) and lack of compression on a few cylinders (Guessing Ether was used heavily while still in service) however it has to be real hot out (and oil put down the cylinders) before the engine can even fire at all.

[Miles O Roads]

To bad,will have a 4.88 rear forsale but has air brakes.

[Flying I 365]

I think all I’d need is the carrier (if the rear axle is a Dana 19060S) to replace the 6.17 gears. Begs the question though, if the rear ratio was changed, would there need to be alterations to the computer to reflect the change to get the Speedo to read right?

[musigenesis]

Speaking of ether start: my bus has an ether start button, and although I have no plans of ever using it I wonder how you actually start a bus with it. Do you hold the button down and then turn the key to start, or do you start it cranking and then press the button?

[Flying I 365]

Not exactly sure. My bus wasn’t equipped with such a button. To start mine with ether (which I do not recommend with the VT365 that’s in it) one person had to be on the key while the other was outside with the spray can at the intake. I’ve never heard of a bus being equipped with a button for ether.

[Miles O Roads]

A lot of older dozens and equipment have this. We always use a can if need be. Don't trust how functional some of that stuff still works.

[Flying I 365]

Ether does work in a pinch, but not recommended for regular use on diesels (as I’ve been told and have also experienced with the lack of compression now in my engine) I have however heard that brake cleaner is a softer starting aid than ether, but I’ve never tried it on my bus.

[Booyah45828]

Originally Posted by Miles O Roads

To bad,will have a 4.88 rear forsale but has air brakes.

What axle and hubs?

I've been looking, but what I'm finding is either sold by someone clueless and too lazy to figure out what they have, located halfway across the country, or they want 5k for something that's trash.

[Booyah45828]

Originally Posted by Flying I 365

I think all I’d need is the carrier (if the rear axle is a Dana 19060S) to replace the 6.17 gears. Begs the question though, if the rear ratio was changed, would there need to be alterations to the computer to reflect the change to get the Speedo to read right?

Yes, you'd have to change stuff in the computer after the gear change. You're going to have to do that anyways if you want the 60mph speed limiter removed. You also might have to change stuff on the back of the speedometer, depending on how your bus is setup.

[Booyah45828]

Originally Posted by musigenesis

Speaking of ether start: my bus has an ether start button, and although I have no plans of ever using it I wonder how you actually start a bus with it. Do you hold the button down and then turn the key to start, or do you start it cranking and then press the button?

Always crank then spray. Start with a small amount first then progressively more. You definitely don't want too much, as too much is damaging.

If it's an installed system, it likely injects it near the intake of the engine. All too often do guys spray on the air filter, which has a long path through the turbo, intercooler, and piping before it gets to the engine. Sometimes that ether can pool in the bottom of the intercooler, which can be sucked in in one big gulp, bending rods and breaking pistons in the process.

[Flying I 365]

Originally Posted by Booyah45828

Yes, you'd have to change stuff in the computer after the gear change. You're going to have to do that anyways if you want the 60mph speed limiter removed. You also might have to change stuff on the back of the speedometer, depending on how your bus is setup.

The bus is a 2nd gen CE from 2006 with the gages originally equipped. I’m not sure what would need to be changed with the speedometer (I don’t think it’s mechanically driven) but I do know alterations would need to be made to the computer to remove the limiter (I haven’t tried yet nor do I have the computer necessary to remove the limiter from the bus computer)

[Flying I 365]

Originally Posted by Booyah45828

What axle and hubs?

I've been looking, but what I'm finding is either sold by someone clueless and too lazy to figure out what they have, located halfway across the country, or they want 5k for something that's trash.

Even I’d have to ask the same question (in case the axle splines are different because from what I’ve seen so far, the Dana 19060S has been used on a fair amount of heavy on-road equipment and not just buses)

I know my rear axle itself is 8 bolt (like photos shown below) (photos are reference only)



(Wheels on Sabrina are 10 lug standard 11R22.5 on disc brakes.)