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Old 07-12-2018, 12:32 PM   #1
Mini-Skoolie
 
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Mountain driving - which engine/transmission

Howdy,



I am searching for a bus to fit my needs and am curious if any of the knowledgeable folks here can point me in the right direction.

I'm looking to full time in the bus, and will be in the mountains for a majority of the time, as well as put in a lot of miles on the interstate traveling between destinations. I'm leaning more towards a shorty, as I feel many mountain roads will be too twisty for me to comfortably or safely drive a full size bus.


Basically wondering which types of engines or transmissions I should be looking towards, and any that I should steer away from. I appreciate any feedback or tips! Thanks
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Old 07-12-2018, 01:14 PM   #2
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Are you thinking of "mountain roads" as in unimproved logging roads, forest service roads, or paved two-lane county and state roads?
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Old 07-12-2018, 01:25 PM   #3
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Short answer: you do NOT want an Allison AT545 transmission - it freewheels down hills and overheats going up.
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Old 07-12-2018, 03:14 PM   #4
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Quote:
Originally Posted by family wagon View Post
Are you thinking of "mountain roads" as in unimproved logging roads, forest service roads, or paved two-lane county and state roads?

When the term mountain road comes to mind, the paved two lane roads were what I was referencing. I'll probably have a bike as well, and love hiking, but something that could tackle the steeper grades is my main concern. I'd love to hear any suggestions for the unimproved roads as well, as I do foresee many of those in my future.


Dapplecreek - Thank you for the information! Does the term freewheel reference the fact that the transmission will not hold you back and help to moderate speed?
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Old 07-12-2018, 04:46 PM   #5
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Exactly! The AT545 does NOT have a lockup torque converter, so there is no mechanical connection to the engine, only a fluid coupling. Very minimal engine braking, with lots of slip and wasted energy going up hills.
An MT643 is a good solid 4-speed, the 1000 and 2000 series are solid overdrive 5&6-speed trannys and the MD3060 is a very solid 6-speed transmission. *However* if you want to use the full capabilities of them, make sure 6th gear is unlocked as some of them have it locked out.

My dream setup would be a 250+HP DT466 or a Cummins 8.3 mated to an MD3060 transmission with around a 4.11-4.38 geared rear end!

John
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Old 07-12-2018, 05:26 PM   #6
Mini-Skoolie
 
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Quote:
Originally Posted by johnbloem1974 View Post
Exactly! The AT545 does NOT have a lockup torque converter, so there is no mechanical connection to the engine, only a fluid coupling. Very minimal engine braking, with lots of slip and wasted energy going up hills.
An MT643 is a good solid 4-speed, the 1000 and 2000 series are solid overdrive 5&6-speed trannys and the MD3060 is a very solid 6-speed transmission. *However* if you want to use the full capabilities of them, make sure 6th gear is unlocked as some of them have it locked out.

My dream setup would be a 250+HP DT466 or a Cummins 8.3 mated to an MD3060 transmission with around a 4.11-4.38 geared rear end!

John

Thanks for the info John! It is going to help greatly in my research and search for a bus! Can't wait to get in the mountains!
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Old 07-12-2018, 07:18 PM   #7
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Quote:
Originally Posted by johnbloem1974 View Post
Exactly! The AT545 does NOT have a lockup torque converter, so there is no mechanical connection to the engine, only a fluid coupling. Very minimal engine braking, with lots of slip and wasted energy going up hills.
An MT643 is a good solid 4-speed, the 1000 and 2000 series are solid overdrive 5&6-speed trannys and the MD3060 is a very solid 6-speed transmission. *However* if you want to use the full capabilities of them, make sure 6th gear is unlocked as some of them have it locked out.

My dream setup would be a 250+HP DT466 or a Cummins 8.3 mated to an MD3060 transmission with around a 4.11-4.38 geared rear end!

John
Hummmm, I have the 8.3 with a MT647 & 4.10 rearend, What do I need to know about that setup?
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Old 07-12-2018, 08:24 PM   #8
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Originally Posted by Stu & Filo. T View Post
Hummmm, I have the 8.3 with a MT647 & 4.10 rearend, What do I need to know about that setup?
As far as I know, the 647 is pretty similar to the 643, making it -in my mind- a pretty solid setup. I have an MT643 in my bus, and I am happy with it. Paired to an 8.3 makes that a real nice setup.
I'm assuming you probably are able to cruise at 65-70 with a nice low RPM?

John
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Old 07-13-2018, 09:34 AM   #9
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Quote:
Originally Posted by johnbloem1974 View Post
As far as I know, the 647 is pretty similar to the 643, making it -in my mind- a pretty solid setup. I have an MT643 in my bus, and I am happy with it. Paired to an 8.3 makes that a real nice setup.
I'm assuming you probably are able to cruise at 65-70 with a nice low RPM?

John
When I drove it home at WOT top speed was 67mph BUT the tach was reading 4500 rpm,, I Think it's a little off . Even at idle it reads 1200 rpm & I've tried another tack so thats brings up the next question, Where does the tach take its reading on the eng? I think I read off the alt but haven't really dug into it yet.
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Old 07-13-2018, 11:08 PM   #10
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4500!!?? Ya...you really need to check that tach. My old 6v53 Detroit "Screamer" only ran about 3300 at that speed and it was one of the highest winding (and loudest) diesels ever built.


Most factory diesels explode around 4000.


You might check out a little device called the "Tiny Tach". Brick simple and very accurate.
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