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Author Topic: 10spd in my MC7?  (Read 3174 times)
MC7S50
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73 MC7 with Series 50 and 10 speed




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« Reply #15 on: October 14, 2006, 08:30:50 AM »

We used a Fuller-Eaton 10 spd from a Peterbilt cabover truck that was being parted out.  The cabover setup has a shifter tower on the top of the transmission that adapts to the bus configuration nicely in that it includes a rod that will adapt to using one of the two existing shifter rods already installed in your MC7.  The 2 shifter rods were used to shift the original Spicer 4 spd.  The 10spd only requires one of the rods.  We used the outboard one because it aligned with the shift tower better. The 10spd shifter rod twists as well as moves back and forth, so be sure the joints in the shifter rod are very tight or are tack welded together.  Otherwise, the joints will slip, and the twisting motion will be lost.  The front shifter box from the cabover was adapted to the same location where the Spicer box was.  It only required fabrication of a mounting bracket from angle stock.  The output shaft of the shifter box was connected to the outboard shifter rod using a small universal joint.  A universal joint was also used on the other end of the rod where it connects to the single shifter rod on the transmission.  The length of the rod at the transmission must be custom fitted to the installation, but was difficult to do.  This configuration results in a shift pattern that is not the same as it was in the truck.  It is upside down and backwards.  That means that 10th is outboard and forward, and reverse is inboard and back.  The air splitter switch operates normally.  This sounds like a big deal at first, but both my wife and I adapted to it very quickly.  We made a shift pattern diagram that we put on the dash for a while until we got used to it.  It is no big deal now. We now routinely shift without using the clutch most of the time.

There are 2 bellhousing configurations.  The 10spd required a different bellhousing than the Spicer because of the bolt pattern and the clutch.  The original clutch configuration was a 2 plate push type clutch.  This was scrapped in favor of a single plate pull type clutch that is the common type found in class 8 trucks.  The stock clutch rod was used, but it had to be adapted to the pull type clutch. 

If you do this, I suggest you use an RTO 10 spd, because it adapts much better to any of the low-rpm 4-stroke engines that you may want to install later on.  While using the 10spd with the 2 stroke you will probably not use 10th because your engine will turn too slowly.  Just use 9th as your top gear, because it is 1:1 direct, the same as 4th on your Spicer.

Hope this helps.

John
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kyle4501
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PD4501 South Carolina




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« Reply #16 on: October 14, 2006, 08:36:08 AM »

Thanks for cutting thru the fog John. That's the best explaination I've seen so far.
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I know you believe you understand what you think I said, but I am not sure you realize that what you heard is not what I meant. (R.M. Nixon)
boogiethecat
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« Reply #17 on: October 14, 2006, 02:31:09 PM »

My two cents, if you do get a 10 speed and it's an overdrive model, make SURE it's an RTX version.  The "X" means that they've rearranged the internal stuff to keep the shift pattern "normal".  Reason: when they turn a 9 or 10sp into an overdrive, it's actually gear #8 or #9 that is the overdrive. So you'd have to shift 1-2-3-4-5-6-7-8-10-9
But the "X" version fixes that, so it appears to be a normal shift pattern to the driver.

I'm surprised at John's comments about the 2 plate clutch.  When I stuck an RTX on my Crown, I was advised to dump the single plate clutch and get a ceramic-puck style two plate unit made by Lipe. I did so and it's been the most amazing clutch I've ever had in any vehicle...super easy to push and no way it'll slip, and it's rated for a lot more weight than my bus will ever be...

All that said, now that I have two busses and the second one has an automatic, I'm TOTALLY rethinking why I am so stubbornly attached to my 9 speed. That auto absolutely makes driving MUCH more pleasant, the wife WILL drive it, and with it's lockup feature it doesn't apparently eat that much more fuel than a stick (which I never believed until I had this one).  I'm SERIOUSLY thinking of how to change the Crown over to an automatic.... anyone have an allison 647 they don't need? (I've been told that's the only one that will fit up with the Crown's pancake bellhousing)

Cheers
Gary
« Last Edit: October 14, 2006, 08:11:40 PM by boogiethecat » Logged

1962 Crown
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ol713
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« Reply #18 on: October 16, 2006, 08:50:03 AM »

In reality, torque is torque and the 8V-71N with 65 injectors only puts out 800lb/ft.  No matter how many gears you have, you're going to slow down on the grades.  What a 10 speed will do is allow you to select from more gears to go up the hill, but at best may increase your hill climbing by 5-10 mph (and that's being very optimistic).  What would serve you better would be to either turbo your engine (more or less a complete overhaul for full turboing) or install a 6V-92TA with 350hp and 1050lb/ft of torque.  That 4 speed is rated at a minimum of 1200lb/ft capacity.

I am most likely going to have Don Fairchild in Bakersfield install a smoke turbo with a one injector increase from 65 to 70's.  What we're going to do is I am going to have a custom air to air intercooler made (13" of space in front of the radiator), Don will pull the two piece pistons and replace the rings with turbo style rings (but keeping the same two piece pistons at the higher 18.7 to one compression ratio), install a waste gated turbo and keep the boost around 6-8 lbs (instead of 25-28 lbs on a full turbo). I figure this will increase my power from 318hp to about 350hp and the torque from 800lb/ft to about 1000lb/ft.  But most importantly will maintain that power in high altitudes without smoking (the politically correct thing to do) since any black smoke is fuel wasted rather than turned into power.  Besides, how many hills have you gone up with the bus slowly loosing speed (just doesn't fall on its' face right away-compared to trucks that slow down quickly to grind up the hill) to find yourself having to go up with the trucks about half way up? Personally I know just a little more power would maintain the speed.  Will keep you posted, but not going to do this till the end of the year when it is cooler in Bakersfield.  Good Luck, TomC


Tom;   Can you glive me a phone number or business name for Don Fairchild?  I have not located my oil leak forward side of the blower yet,
          but if it gets serious, I may need some place to take my coach.     Thanks,  Merle.    (MC-7)     I live in Lancaster
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