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Author Topic: 13 speed  (Read 1587 times)
harpold700 3
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« on: November 20, 2017, 04:24:54 PM »

any one retro fit a 13 speed into an mc7. transmission swap is simple, what about the shifter modification? Had read somewhere of a modification to the shifter, although it may have to be backwards. Not a real problem for the benefit of the 13 speed.  Any info will be greatly appreciated. thanks.
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B_K
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« Reply #1 on: November 20, 2017, 05:00:24 PM »

I don't know any details but I do know it's been done before more than once.
Grin  BK  Grin
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HB of CJ
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« Reply #2 on: November 20, 2017, 07:06:37 PM »

An overdrive 9 speed would also probably work, (power to weight ratio) and would be about 3.5 inches shorter?  May or may not make any difference with the drive shaft length.  Also that over drive would be slightly taller at about .73 or so?

My old Crown Supercoach had the RTO910.  One shift rod. Many grease zerts on the pillow bearings and a couple of U-joints.  Either the 13 or 9 would give you a high reverse necessary for those high speed reverse "boot legger 180's".
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chessie4905
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« Reply #3 on: November 21, 2017, 04:24:21 AM »

They also make a remote manual shifter for these. A master unit at driver's area and a slave unit at tranny. Connects with two Morse cables. Fits all Roadrangers. Also if you use an RTO 9509 with the overdrive 13 speed rear section, you get a double overdrive with .63, .74, and .80. top three ratios.
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GMC h8h 649#028 (4905)
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« Reply #4 on: November 21, 2017, 06:15:12 AM »

You will need to convert the clutch and flywheel over to make it work on a MCI the Roadranger transmission used a pull type double disk clutch they don't work right with the push type Long clutch MCI used.A simple shiftier is find a old White 7000 cab over with the air shiftier then you have no linkage 
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Life is short drink the good wine first
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« Reply #5 on: November 21, 2017, 07:48:35 AM »

Do air shifters default to neutral if you lose air pressure?  Or ... do you stay in the gear you were in?  I dunno.  A mechanical linkage like already said, (cable or shift rod) still lets you use your Jake. 

Which can bring you to a complete stop.

Nothing wrong with the single shift rod with pillow bearings and U-joints.  The Crown Supercoach has the pancake engine in the middle.  When greased up the shifting is very smooth, quick and easy.

More like shifting a dirt bike than a big 10 speed.  About one inch of shifter movement.  About 3-5 pounds of effort needed.  Very easy to "lay" against a gear and feel where you are.  Kid easy to use.
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luvrbus
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« Reply #6 on: November 21, 2017, 07:53:45 AM »

Yep the ones I been around would default to neutral only draw back was if you accidentally grasped one entering the cab they would shift into gear   
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TomC
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« Reply #7 on: November 21, 2017, 08:00:28 AM »

Most recent cabover trucks used a cable shifter (my '85 Kenworth did). Then all you need is mount the shifter in the front and have long control cables made back to the transmission. You can hook them up so it does shift the normal way-commonly called the X and Y shifter.
I had a 13spd single overdrive in my truck (RTO-14613A) for nearly 1.2 million miles of commercial driving. The transmission was rebuilt at 330,000 miles, and the clutch was never replaced when I switched to the Allison HT740. I just wished I had the Allison HT740 when I was driving. Personally-the only transmission swap I would do is to change it to an Allison automatic. Changing from the 4spd to a 9 or 13spd is a big job. Yes you'll get better low gears, but ultimately going up a hill is determined by the torque output of your engine. Yes you might get 2-5 mph better going up a hill because of more gear selection, but driveability wise, there's nothing that can replace the Allison. Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
luvrbus
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« Reply #8 on: November 21, 2017, 08:06:00 AM »

Yep Allison is the way to go and so easy on the drive train too 
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harpold700 3
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« Reply #9 on: November 21, 2017, 01:38:59 PM »

Allison would require a cooler. Could I use a remote cooler?, read don't need, cant take any more heat to the cooling system.
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RJ
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« Reply #10 on: November 21, 2017, 05:02:26 PM »

Allison would require a cooler. Could I use a remote cooler?

Yes, you can use a remote cooler, it just has to have the capacity to handle the heat load.

Since you've got an MC-7, you can easily mount one on your louvered side access doors. 

CAVEAT:

The engine cooling blowers pump a LOT of air into the engine compartment.  You'll need a really strong fan system on the remote cooler to overcome the engine blowers.

FWIW & HTH. . .

 Wink
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RJ Long
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« Reply #11 on: November 21, 2017, 05:28:47 PM »

RJ and harpold, have the fan in the side engine door blowing from inside to outside so it goes with the flow, instead of fighting the squirrel cage fans.

JC
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JC
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1977 MC5C, 6V92/HT740
chessie4905
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« Reply #12 on: November 22, 2017, 04:13:45 AM »

Just clean fins periodically as grease and, oil, and dirt is going to collect on it. You can use an aftermarket automotive radiator cooling fan.
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GMC h8h 649#028 (4905)
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bevans6
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« Reply #13 on: November 22, 2017, 06:31:46 AM »

RJ and harpold, have the fan in the side engine door blowing from inside to outside so it goes with the flow, instead of fighting the squirrel cage fans.

JC

Can work but difficult.  The rear side of the bus is a quite high pressure area at speed, the inside of the engine bay is a low pressure area.  Fans blowing air from a low pressure area to a high pressure area have to work pretty hard.  If the cooler was at the rear doors, the back of the bus is a low pressure area and that could work pretty well.  You need a fairly sizable cooler.  The one I used (MT647) had a core that was 22" by 25", three inches thick, and overall height of close to 30".  Around 125,000 btu.  I mounted it fairly vertically beside the engine, standing upright on the old AC compressor mounting frame.
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
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harpold700 3
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« Reply #14 on: November 22, 2017, 04:46:39 PM »

How about a six speed , will my shifter gate move for 2 more holes? Or do I need a new shifter?
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