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Old 06-24-2013, 02:56 PM   #1
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MD 3060 transmission 6th gear

My bus comes with the MD 3060 5 speed. I have read that it can be programed with another OD making it a 6 speed.

Anyone do this and is it worth it? The bus manager says the bus makes 65 mph easily. I did not know if the extra OD would help with gas milage.
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Old 06-27-2013, 02:40 PM   #2
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Re: MD 3060 transmission 6th gear

If it were me, I would want the 2nd overdrive. You gain the ability to cruise at a lower rpm and can always downshift if needed. I would think you would gain some economy. Also, just checked out your blog. Good luck with the auctions...exciting!!!
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Old 06-27-2013, 03:26 PM   #3
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Re: MD 3060 transmission 6th gear

Thanks JakeC,

I'm hunting down an Allison Certified mech in the area to see what it would require and cost.

Edit

Just talked to an Allison Certified Mechanic and they said that the transmission is setup and geared for the weight of the bus, matched to the engine and cannot be changed. I think they ment should not be changed. I have been told it can be if you can find someone willing to do it.

Maybe it is better left alone.
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Old 06-27-2013, 03:34 PM   #4
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Re: MD 3060 transmission 6th gear

My last Diesel pusher, 40 ft motorhome with slideout, loaded to the max only got 9-10 MPG on the highway......
It was an MD 3060 six speed. while it will help it won't be a big enough improvement to pay for the upgrade unless you stay on the road.
I have nno idea what you get now....... but just saying...
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Old 06-27-2013, 03:45 PM   #5
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Re: MD 3060 transmission 6th gear

My B300R is similar in that the equipment has a 2nd overdrive ratio, but the control is programmed for only 5-speed operation. With 11R22.5 rubber and 5.38 axle my engine turns around 2500 RPM at 75 MPH. According to The Internet, yours and mine probably have the same OD ratios (0.75 5th and 0.65 6th). My gut feel at the throttle pedal is that my engine may have enough grunt to hold 65+ MPH, at least on flat highway, even in the 2nd OD. With my gearing I'd see ~2170 RPM at 75 MPH or ~1900 RPM at 65 MPH. That would surely pay dividends at the fuel pump!

Per my Allison dealer (Smith Power Products) it's an Allison policy their dealers must not make such changes without written approval from the OEM. I worked through my Blue Bird dealer and made contact with a support engineer (just a week ago) at Blue Bird who incidentally did power train engineering for BB in the past.. Anyway, he couldn't locate any matching already-engineered combination for me (looking for Cummins ISC 8.3, 5.38 axle, B300R 6-speed) and so couldn't give approval.

So.. I guess I'm stuck for now. Maybe some day I'll pursue getting Allison to let me assume the risk and just make the change. Smith told me that, assuming approval could be found, they'd be in the $150 range to change the programming.

Last trip out I did about 9.3 MPG over 220 miles including climbing from 4500 ft to 9650 ft elevation and back down again. More is always welcome of course, but I guess this isn't terrible either. Glad I didn't get a DD 8V92 engine with its estimated 5-6 MPG!
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Old 06-27-2013, 03:53 PM   #6
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Re: MD 3060 transmission 6th gear

Quote:
Originally Posted by wmkbailey
Thanks JakeC,

I'm hunting down an Allison Certified mech in the area to see what it would require and cost.

Edit

Just talked to an Allison Certified Mechanic and they said that the transmission is setup and geared for the weight of the bus, matched to the engine and cannot be changed. I think they ment should not be changed. I have been told it can be if you can find someone willing to do it.

Maybe it is better left alone.
Yeah, some things just aren't worth the hassle, and if Grey Eagle is correct, it may not be that big of a benefit anyway. I wouldn't think about it too much until you've gotten the bus and have a feel for it.
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Old 06-27-2013, 04:02 PM   #7
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Re: MD 3060 transmission 6th gear

Thanks family wagon,

I have the same OD ratios (0.75 5th and 0.65 6th). The school maintenance manager said these buses are averaging about 10 mpg. We will see how it goes.

I'm not sure what my top end will be, he said they are governed to 2400 rpms, so maybe 70 mph. I know at 60 mph it is at 2000 rpms, that would put me at 71.5 mph at 2400.
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Old 07-29-2013, 09:43 PM   #8
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Re: MD 3060 transmission 6th gear

Quote:
Originally Posted by family wagon
My B300R is similar in that the equipment has a 2nd overdrive ratio, but the control is programmed for only 5-speed operation. With 11R22.5 rubber and 5.38 axle my engine turns around 2500 RPM at 75 MPH. According to The Internet, yours and mine probably have the same OD ratios (0.75 5th and 0.65 6th). My gut feel at the throttle pedal is that my engine may have enough grunt to hold 65+ MPH, at least on flat highway, even in the 2nd OD. With my gearing I'd see ~2170 RPM at 75 MPH or ~1900 RPM at 65 MPH. That would surely pay dividends at the fuel pump!

Per my Allison dealer (Smith Power Products) it's an Allison policy their dealers must not make such changes without written approval from the OEM. I worked through my Blue Bird dealer and made contact with a support engineer (just a week ago) at Blue Bird who incidentally did power train engineering for BB in the past.. Anyway, he couldn't locate any matching already-engineered combination for me (looking for Cummins ISC 8.3, 5.38 axle, B300R 6-speed) and so couldn't give approval.

So.. I guess I'm stuck for now. Maybe some day I'll pursue getting Allison to let me assume the risk and just make the change. Smith told me that, assuming approval could be found, they'd be in the $150 range to change the programming.

Last trip out I did about 9.3 MPG over 220 miles including climbing from 4500 ft to 9650 ft elevation and back down again. More is always welcome of course, but I guess this isn't terrible either. Glad I didn't get a DD 8V92 engine with its estimated 5-6 MPG!

Wow, that bus is geared for the city! 2500 for an 8.3 Cummins is SCREAMING! Isn't it GOVERNED around there?! You would DEFINITELY benefit from the second OD!

My Genesis has an MT643 (non-OD) and 4.11's...1900RPM at 60.
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Old 07-29-2013, 11:10 PM   #9
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Re: MD 3060 transmission 6th gear

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Wow, that bus is geared for the city! 2500 for an 8.3 Cummins is SCREAMING! Isn't it GOVERNED around there?!
Mine is governed at 2600. I would terrified at the speed I would be doing at that rpm! Mine is the same as yours, about 62@2000
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Old 07-30-2013, 06:42 AM   #10
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Re: MD 3060 transmission 6th gear


I think 75 is a little too fast in a bus...have fun stopping in a hurry; it always scares me on interstate seeing big class A's running 70+ 20 feet off the bumper in front of them
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