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Author Topic: Single rear axle MCI  (Read 5046 times)
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« Reply #15 on: January 13, 2011, 11:23:28 AM »

Personally, I still think the 4106 was one of the best-looking 35' coaches ever built.  Sort of an "evolutionary" design between the rounded shapes of the post-WWII workhorses and the more modern 40'-footers with their shiny stainless and boxy sides.

  I agree with ya there, those are one of my favorites along with the 04. Too bad its so hard to upgrade the brakes to readily available (and affordable) parts and make it climb a hill. Or am I sticking my foot in my mouth again?
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lostagain
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« Reply #16 on: January 13, 2011, 12:05:02 PM »

My comments about the larger turning radius of the tri-axle 40 footers was based from my experience 35 years ago with the MC7 and 8s.

When I think of it, the 102D3 of the hockey team's does turn really tight, due to the front wheels turning so sharp.

And about tag tires, they wear out fast from scuffing on those tight turns, unless you have a steering axle.

JC
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JC
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1977 MC5C, 6V92/HT740
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« Reply #17 on: January 13, 2011, 07:08:29 PM »

Well we have one of the older GM's, a stepchild to the Silversides which i think is one of the best looking, i think the same designer as the Scenicruiser. The MCI 6 is an awesome looking bus. The 4104 are my favorite, the 06 close behind then the MCI 5 series. But i have always loved  the look of the Eagles. My wife hates the "bug eyed look" of the Eagle. And as for brakes, we now have MCI drums and brakes on the rear axle and holy $#!% do they stop the bus. As in right away. Like whoa! Might upgrade to a shoulder belt.
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we love our buses!!! NE Pa or LI NY, or somewhere in between!
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« Reply #18 on: January 13, 2011, 07:11:13 PM »

Art -

Or am I sticking my foot in my mouth again?


Yes!   Grin


A 4106 with good stock linings and drums, adjusted properly and with no moisture in the system, will throw the front seat passengers thru the windshield if you stand on the brakes hard.  Driver better have his seat belt on, too!  They won't quite match the phenomenal brakes on a 10-wheel Crown, but they'll come close.  BTDT.  However, if you insist on upgrading, you can use the axles out of a 96" RTS, providing you can find one of the rare 4.10:1 gear sets.

As for hill-climbing, we've been over this before, several times.  There isn't a bus out there with a normal stock powertrain that will climb 6% grades at 65 - 70 mph, especially at altitude.  They're just too plain heavy.  Some of those new Prevost conversions with all the glitz, glamor and granite, pushed along by a 500 hp Series-60, will still only climb a 6% grade at about 40 mph since they weigh close to 50K.  Power to weight ratio is what we're dealing with here.

Bob Sheaves, an automotive engineer who used to post on the old MAK board (back in the days when it crashed a lot), has a program on his laptop that can instantly tell you how much HP you'll need to climb whatever percent grade you want to plug in, at what road speed, based on the weight of your rig.  And since his expertise is cooling systems, he'll also be able to tell you how big a radiator you're gonna need to keep that beast of a motor cool.  Sorry, he doesn't post on the boards anymore, nor will he share his program.  But it sure was fun playing will all the numbers a couple of years ago at BusinUSA in Rickreall, OR.

Now, some simple math for you.  Take an MC-9 with a 350 hp 6V92TA bolted to an HT-740 automatic, loaded to it's GVW, which is 36,600.  Compare that to a 4106 loaded to it's GVW of 32,000 with the same 350 hp 6V92TA and a V-730.  Guess which one's gonna go up the mountain faster?  Duh

In reality, buses are slow in the mountains (at least going uphill).  It's hard for non-professionals to wrap their heads around that fact, but it's true.  I've seen it time and time again.  If you think your bus is going to be a BMW on the Grapevine, you're going to be sadly disappointed.  Deal with it, sit back and enjoy the scenery and let everyone else figure out how to get around you.

FWIW & HTH. . .

 Wink
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RJ Long
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« Reply #19 on: January 13, 2011, 08:36:23 PM »

  Now now, its not little 6% hills I'm worried about, its my billy goat driveway I need to climb. And for that I need a granny low 1st gear. If I thought a GM could get up here with a manual, or if there was an economical way to make it work, I would keep looking. But I gave up as I slowly realised the difficulty. "Maybe it will" or "it might" arent good enough answers to make a decision about which Bus to buy. The 5 speed with 7:1 in first, even in a -9, will make it up here without any question.
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« Reply #20 on: January 13, 2011, 09:00:19 PM »

Yep RJ;

 Even though I own a 5C Saudi I think the roof cap is a little weird from the 8 transition should have been a bump up as in the Buffalo would have looked better but I do like the newer looking front. Also think it would look better with the SS siding all the way to bottom of windows like the 5 A & B.
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« Reply #21 on: January 14, 2011, 05:41:30 AM »

I have the 40 foot single axle eagle model 10S, and love it. Have an extra bay to stick stuff. But I am not a heavy conversion right at 30,000 pounds.
Tom Hamrick
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Tom Hamrick
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« Reply #22 on: January 14, 2011, 07:42:34 AM »

  "if" a guy were to put an auto in a 4104 or 06, what kind of a mileage hit would it be? This HT740 y'all mention, is it mechanical, or computer controlled? I dont want any computers or electronics.
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« Reply #23 on: January 14, 2011, 08:29:34 AM »

Art,

The HT740 is a mechanical transmission, but it won't fit in a 4106 or 4104. The v-drive in the 4106 limits you to the v730, which is a 3 speed(won't fit in the 4104). The general consensus as to the MPG hit, is, I believe, 1-3 mpg. Depends, of course, on where and how you drive it.

I have heard that a few nuts have converted some GMs to a t-drive, but involves changing all of the running gear and extending the rear of the bus. Seems like a lot of work.

Bob
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« Reply #24 on: January 14, 2011, 10:48:40 AM »

  It all makes you wonder what the perfect setup would be. On flat level ground at steady speed, weight shouldnt have much effect of fuel economy. It does add to rolling resistance, but when your comparing vehicles weighing between 20k and 30K pounds rolling on big slow turning tires, rolling resistance probably isnt changed much by weight.

  The biggest factor on level road then, is air resistance, how big a hole your punching through the air, and how hard your punching through it.

  The second biggest factor then, is engine and driveline efficiency. At steady speed on level road, engine HP makes little difference, the Bus takes a certain amount of power to run that speed, and no more. Whether you have a 250 HP engine, or a 1500 HP engine, makes no difference to the amount of energy required to push the bus down the road at steady speed. So in every case, the same amount of effort needs to be put to the wheels.

  HP takes fuel. I read somewhere that a 4104 uses about 125 HP to punch through the air at 65 mph. Dont quote me on that, besides, it really doesnt matter. The point is that you can start from that figure and move up or down. Slow down, and the Bus needs less power. Speed up and you need more. Raise the roof and you need more power. Drive a cooling fan with 30 HP, your burning extra fuel. Drive a large AC compressor and your burning extra fuel. have an automatic thats sucking 30 HP in pump and clutch drag losses and your burning extra fuel.

  Then you have the engine itself. Is it efficient? How wide is its power band? Does it have reserve power? Can it be kept in its sweet spot? I recall the Turbo Formula One cars, and how they rapidly became so so fast and powerful, with some developing as much as 1500 HP from tiny 1500 cc engines. Initial efforts to slow them down were to cut boost, which was reaching over 100 psi at the intake manifold. But it did not stop the increase. In a last ditch effort the FIA investigated cutting displacement to 1200 cc. But it was found that by dropping to a 3 cylinder engine, they would actually have gained even more power by reduction of pumping losses. So obviously, less cyclinders should be more efficient than more.

  So a lil 4-71 would do the job in almost any Bus on level road. But when you hit the hills or jack rabbit from a stop light in that 30K pound rig dragging your car along, all bets are off. Start cranking that fan, the auto trans pump, power steering pump, slipping clutches, and driving the AC compressor, and there's no power left to drive the Bus.

  So where do we go? I was trying to research turbo diesel vs non turbo diesel efficiency. Specifically, is a small diesel running at constant power on boost, lets say developing 100 HP, more efficient than a non turbo diesel producing the same power? Or in a Bus application, could a turbo aftercooled 4-71, have any hope of pushing a lightened Bus around and making better economy?
 

 
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« Reply #25 on: January 14, 2011, 11:00:55 AM »

What do you think a 190 hp 4-71 with 525 lbs of torque would do at the first hill ? bike riders in their funny shorts and caps will pass you



good luck
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« Reply #26 on: January 14, 2011, 11:48:52 AM »

What do you think a 190 hp 4-71 with 525 lbs of torque would do at the first hill ? bike riders in their funny shorts and caps will pass you



good luck

  No doubt. I run out of poop on hills with the bounder with only 190 HP. But then it only has 4 gears. But what I was asking is if a turbo diesel operating with full boost, would burn more or less fuel per HP/hr, than a non turbo engine making the same amount of HP.
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« Reply #27 on: January 14, 2011, 11:57:51 AM »

On the detroit diesel Yahoo forum there was a post the other day about a guy who had a 6V52T aluminium block/head engine built for the Military in 2002.  Apparently they wanted it back, which was kind of funny.  Anyway, it made 350 hp and could be programmed to 400.  Probably needed a lake to cool it and would last about a week, but that would be awesome in a pickup truck!

Brian
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« Reply #28 on: January 14, 2011, 01:10:16 PM »




     The v-drive in the 4106 limits you to the v730, which is a 3 speed(won't fit in the 4104).

        "never say never".

uncle ned
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« Reply #29 on: January 14, 2011, 01:25:47 PM »

  Now now, its not little 6% hills I'm worried about, its my billy goat driveway I need to climb. And for that I need a granny low 1st gear. If I thought a GM could get up here with a manual, or if there was an economical way to make it work, I would keep looking. But I gave up as I slowly realised the difficulty. "Maybe it will" or "it might" arent good enough answers to make a decision about which Bus to buy. The 5 speed with 7:1 in first, even in a -9, will make it up here without any question.

Art... I have one of those billy goat driveways.. Mine is so steep that I have to use 4wd in my truck climbing it so I won't spin out the gravel. I climb it on a regular basis with my MC9 with 8V71T and HT740. Granted that I do have enough room (aprox 100 ft) to get up some speed before hitting the hill. I just pull her down in low and floor it.. I've never not made it yet.

Jimmy
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