I was going to resurect an older thread, but maybe it is better to just start over. Ive come across an MCI-7 not to far away. As many of you know, I had settled on finding a 4104 as the best compromise for my needs. One of those needs is trying to get up my bloody driveway. I think I already know the answer here, but thought I would at least ask in case I dont have the right information. IIRC, an MC7 shell is around 27,000 pounds, with most conversions running around 33-35,000 pounds. Is this correct? Im thinking the possibility of out climbing a 4104 is rediculous, but again, just checking. I might look at it anyway, maybe I could just park it somewhere else. It appears its geared more for interstate than it was two lane back roads?
I found these gear ratios in another thread, but believe these are for an MC9, and im checking to see if these apply to an MC7;
1st - 4.30
2nd - 2.33
3rd - 1.36
4th - 1.00
rev - 6.00
differential - 3.70
MC7s are geared quite high, especially if it still has the 4 speed. I used to drive them back when they were new, and we liked how they handled compared to the 35 foot MCIs, but with the 8V71, they were underpowered. Same power train as an MC5, but 10 000 lbs heavier... Not nice for steep hills, otherwise a nice coach.
JC
Wellllllll you know how it is, the bigger better tighter sweater thing. I just came across the Bus in a search, and went "hey, looky that". And then I went nahhhh, that sucker aint EVER coming up here unless its got a D9 cat in front it. But it never hurts to ask.
Those look like Spicer 4 speed gear ratios. If they are, reverse is actually 4.28 even though the manuals say 6.00, just so you don't think of trying to go up backwards in a very low gear. Reverse is a tad higher than first, in other words. I have an open Spicer 8844 in my shop and on a slow day I went out and counted the teeth on all the reverse gears and worked out the actual ratio. But I lost the piece of paper with all the teeth counts on it...
Your thought is pretty much correct. First gear start-ability of an MCI with a spicer sucks. The heavier, the worser. If you want to get up that driveway in an MCI, a MC-5C with a 6V92 and a 740 is the best bet. Having a 3.7 diff does help, obviously, and there may be a transit/low top speed diff ratio you could think about.
My thoughts are that a skooli is the 4 wheel drive back roads kinda bus and an RTS is a sports car kinda bus and a Prevost is a cadillac kind..... the MCI is more for the practicle type of person. The skoolis are the only one I am familiar with that are specifically made for going on dirt roads to pick up rural kids and stuff.....
Now that you're talking a T drive, rather then the V drive on the 4104, you have some options on transmissions. I would yank that 4 spd out and install a 7spd Eaton/Spicer transmission with overdrive. The 7spd overdrive has a 9.24 1st with a .75 overdrive. You'll be able to get up your driveway with that. With 3.7 gears and 485 rpm 12R-22.5 tires, your first gear top speed would be 7.6 mph @ 2100rpm-of which I'm confident you could get up to full governor speed at the bottom-even start up on the hill. You're startability with the regular 8V-71N with this 7spd overdrive (based on 35,000lbs) would be 26.5%-that's pretty steep! You're climbing with full torque in 1st would be (getting a running start) 35% grade.
The nice thing about the 7spd, is that it doesn't have any air operated splitters and it is a fairly short transmission (about 3 inches longer then the 4spd). Good Luck, TomC
I wonder what would happen if you shortened the drive shaft on a MC-5C by 3 inches? Any thoughts on that? How does the shift linkage/mechanism on a 7 speed work?
Brian
Quote from: TomC on September 14, 2010, 12:55:07 PM
Now that you're talking a T drive, you have some options on transmissions. I would yank that 4 spd out and install a 7spd Eaton/Spicer transmission with overdrive. (about 3 inches longer then the 4spd). Good Luck, TomC
Hmmmmm. I was really trying to get talked out of this, not get in deeper. How hard is it to put that gearbox in, and how hard ($$$) are they to find??
And very seriously, what kind of fuel economy can be expected with that gearbox (overdrive) if I keep the speed down??
Paul~
I met people once with a MC7. They had put in a DD S50 in it with a 10 speed manual. Sweet.
JC
Two methods of shifting either the 7spd or any of the Roadranger transmissions. You can have a single shaft that goes the entire length of the bus that both twists and goes fore and aft. Or you can have a two shaft or two cable system that one takes care of side to side and the other fore and aft shifting. Good Luck, TomC
Tom, any advice on those last two questions??
Quote from: happycamperbrat on September 14, 2010, 11:53:39 AM
My thoughts are that a skooli is the 4 wheel drive back roads kinda bus and an RTS is a sports car kinda bus and a Prevost is a cadillac kind..... the MCI is more for the practicle type of person. The skoolis are the only one I am familiar with that are specifically made for going on dirt roads to pick up rural kids and stuff.....
Yeah but if ya want top class then ya get a SETRA which in Germany is a step above a Mercedes! ;)
I own a MCI 7 with the spicer 4 speed. TOTALLY empty shell was almost 23k lbs. Super light conversion with water and generator could be as low as 27k lbs. I need to weigh mine since I've done that kind of conversion. First gear is a little tall, reverse is VERY tall! I thinks Tom C has the right idea for trans. The 871N does a fine job, at least here in flatland Michigan and as far away as Duluth MN. Good lines, not bad interior height, well built. I've been told they used more stainless steel in the construction than in the 8's and 9's, but I don't know that for a fact. Anyone else have definitive knowledge about that?
Glenn
Quote from: Tenor on September 14, 2010, 06:07:47 PM
I own a MCI 7 with the spicer 4 speed. TOTALLY empty shell was almost 23k lbs. Super light conversion with water and generator could be as low as 27k lbs. I thinks Tom C has the right idea for trans.
Glenn
Thats actually pretty light considering its a 40 foot bus with a tag and all that stainless. Tom's gearbox idea is a real eye opener. Tom, I read a post you wrote a while back on the other board regarding another MC7, saying the 7 speed sucked because it was non synco and to run a 10 speed? Is the 10 speed easier to shift without clutching? Is there even enough room for an 871 with a 10 speed in an MC7? What about a 6V71? Probably a bit slow but yould have plenty of gears to play with???
I guess I need more schooling on these. I really hadnt looked at them because they just seemed too large and heavy. I didnt want to get involved in a repower either, but if its easy enough and affordable, why not?
on the 7 pick up the tags and back up the hill..rev is by far the lowest gear..Bob
Bob, in an MC-7 reverse is actually taller than first gear. The manual has the gear ratio wrong, it is not 6:1, it is actually 4.28:1
edit: I just counted teeth again ( I was out there anyway, and putting off starting an obnoxious job I have to do) and reverse is actually 4.2:1 in the spicer, which if that isn't useless trivia I don't know what is...
Brian
was just going off what he posted in beginning..6 to 1..I have backed up hills before I couldn't climb in foward..happy bussing Bob
Quote from: artvonne on September 15, 2010, 04:26:46 AM
Tom, I read a post you wrote a while back on the other board regarding another MC7, saying the 7 speed sucked because it was non synco and to run a 10 speed? Is the 10 speed easier to shift without clutching? Is there even enough room for an 871 with a 10 speed in an MC7? What about a 6V71? Probably a bit slow but yould have plenty of gears to play with???
I don't think any heavy truck / bus transmissions in North America are syncronized. Even if there're are, it'll be pretty rare.
If you want to float shift (clutcheless), then definitely get an un-syncronized transmission, or you'll ruin the syncros pretty quick. I find on a coach, float shifting is a little harder, as the stick is not directly mounted on the tranny, and thus don't have the "feel" as on a rig. But with practice, it's certainly do-able.
I wouldn't go with a 6V71 on a thriple axle coach. I've got one on my 35' Prevost, probably as high a hp tune as they come in the NA form - 4V heads, N70 injectors, A timing, 2500 rpm limiter. Even then, I'd describe the power as only "adequate".
I have been "float shifting" (both up and down) the 4 speed in my 4104 more often than shifting with the clutch, for me it works better than double clutching......
Rick
Blame Rick, but after being around his bus and toolin around in it, im still really hooked on a 4104. An MC7 is a very nice ride, there is no doubt, but im asking myself why I need 15 tons of 40 foot of bus with 8 tires and 33% more engine. Does any of this make any sense? The only real benefit I see with the 7 is the ability for an extra bedroom, and more cargo space to carry more gear we probably dont need. Im not so sure I want to drive 4 hours to look at something I'm not interested in. Why is my interest waning?
Oh well, at least we have choices and the freedom to own a bus. Life could be worse.
The big difference is a 4104 is 50-57 years old with a V drive that while it is reliable, you have no options in gearing except to go with an Allison automatic. The MC7 was built in the 70's, so 10-20 years newer, has an inline T drive that has almost limitless possibilities as to engine and transmission choices. While the 4104 is nice, I would choose a 4106 (better and stronger transmission and engine) or even a 4107 or 4109 if you want to stay with a 35ft'r. I have a 40ft'r, and it really isn't that big of a deal to drive, but then again it is a transit that turns sharper then a normal bus. If I were doing another bus, my choice would be a MCI 102C3. My bus is a 102" wide, and that extra 6" is really noticeable for inside space. Good Luck, TomC
I know the 7 is about as good as they come, I was just trying to talk myself out of it. Never heard an 871 V drive was tougher than a inline 671 V drive before, thought it was the opposite way around, ya learn something new every day dont ya.