1986 BLUEBIRD FLATNOSE 30FT: AXEL RATIO

[mokibrabrant]

I have a 30ft Bluebird FE........It is powered by a Chevy 427 "tall deck" mated to an Allison MT 643.......running on 22.5 inch rims. Current rear axel ratio is 6.83. I would like to change the Axel ratio, as to have a Coach that maxes out in terms of a comfortable highway speed. I understand there are always trade-offs when this is done. Climbing, towing, capabilities are diminished. This Bus will remain very close to it's "unladen weight".......and wil not be used for towing in anyway..........Sowering facilities will be designed to be used outside, as well as Kitchen...........Stove, Fridge, wil be designed to be done outside as well, incorporating the wheel chair lift.......at the rear....the concept I am going for with this little bird is the Rolling Hotel Room........Living Room. I have owned several buses before..............and did a Ground Up restoration of a 1962 Western Flyer...My principle thrust, with this Bus is to have an eminently nice handling driving "Baby Coach"...I'm simply wondering, since it is a Gas Puller, and highwayspeed is my primary objective, I can suffer the Grades, what axel ratio would be best suited with the torque curve of this engine, to obrain my objective? Thanks in advance.............Loved reading the thread on Vanguy vs The Church Guy.........Too bad Vanguy walked away from that Carpenter..............Probably more about the bad taste, and the taint, of such an unpleaseant transaction. Probably reasonable to have "no confidence" in any other representations the "Church Guy might have made with regard the Bus.....Prior to purchasing my Bus I checked into this guy's site...........Glad i stayed away........Oil Analysis....a great lesson there.........

[mokibrabrant]

Well, Vanguy, I hope your right. This /engine/tranny/differential/axle ratio........question I think falls into some "esoteric" zone that has not been easily answered. I have gone directly to Allison with my question, and awaiting reply from them as I write this. I would like to put this to rest, and get it done.
I have owned five Buses and the Western Flyer I did the ground up on, was one of the coolest buses I ever owned. It was one of 18 custom built for the Canadian Army: It had a International harvester RD550, and Allison 6spd with an "Electric Clutch", positive ground, where the alternator, by a flick of the switch became an AC generator,.........was designed to be broken down and repaired in "the field". For the first year, it was simply a workshop, where I hand tooled all the diaphrams for the air, hand built all the gaskets, topped off at the end by hand fabricating out of copper the Head Gaskets. Sandblasted it in my front yard, caused a Sensation, cops, code enforcement etc....tried to bluff me out of the work with some "fake" zoning ordinance, entirely inapplicable: By the time they got back from City Hall........Sand blasting was complete. Spent the next week taping it off, did all the graphic design on my computer; Drove it off to a Home depot Parking Lot at about 3:30 am, and painted the whole thing, running my paint gun off the compressor tank for the brakes, idling at 800 rpm. By 4:45 A.M. The deed was Done........Used lots of Hardner, crashed out, woke up in time to get some fittings at the "depot: to finish off some of the work on the "heat exchanger" that was made by Kholer..........and on my way.

Anyway, that's a short blurb there.........I would like this "little bird" to be as close to a giant porsche as possible. I love Buses what can I say. I love that they are designed from the ground up to be what the become, I love them when they are unladen, with basic creature comforts, I love the way they corner, I love sitting above the fray and seeing for miles, I like changing lanes when I need to change lanes, and the reticence of others to "play chicken"...Just generally a great vibe. And most importantly you don't leave anyone cold. You never know the heart and character of another human, until your standing next to them and you tell them "yeah that's my bus over there". The immediate expression on their face becomes an expose on their soul....

So I'm out for the time being..............still with the unresolved axle quest........Personalized Plates for my Magic Bus............HOWIROLL

[sportyrick]

my 427 pulls best at or above 3400 rpm and that relates to a speed of about 65mph, 3600 is 70mph, 4000 is like 75 and ready to blow up. If I drop down below 3000 it loses a lot of power so it's best to have a run at a hill to keep the rpms up and my foot down it's throat. I have a 6.83 rearend ratio also but my bus is 38' long instead of your 30 and weights in at 23,000. You should be able to figure this all out by goggling something about tire diameter vrs rpm vrs rear end ratio. I wouldn't go much lower than 6.5 or you won't climb any hills. I would think yours would be fast enough on the highway considering you probably are 5000# lighter than me. I have been reading a lot about diesels in buses and it looks like we aren't that much out of line on torque and power. A 427 tall deck is rated a conservative 260HP and a realistic 400# torque. This makes the HP higher than most of the diesels but lower on torque. I just went on a float trip last weekend and the bus did pretty good, averaged around 60MPH, down to 30 on a couple of steep long pulls, 72 on some down hills. I think I could say I run 65 on the flats if I am not trying to save fuel costs but the rpm's have to stay in the 3400 area to do that. You won't get a schoolie to run down the highway like a greyhound style bus, they're just too underpowered. Look at the specs on most of the diesels in a bus, LOW powered medium duty truck motors. I have a friend with a dodge pu truck and he has it turned up to 425 HP and that is a dyno#. I guess you could do that to one of them and see how long it lasts. We need torque in the 650-800# range to get more road speed. I read somewhere there was a guy that put turbo's on motorhomes with gas motors and had great success, looks like something worth looking into. Aftermarket fuel injection is another option, I don't see running a turbo with a carburetor though, fuel injection would be mandatory with a turbo. sportyrick ps I just did the math and it says you want a 6.07 to run 70mph at 3400 rpm on 41 inch tires.

[mokibrabrant]

Thanks very much Sporty Rick: I like that Real World stuff......A guy that runs the same power plant. I realize torque curves are radically different from "gassers" to diesel. And I did do a lot of "googling" and used the "conversion tables" afforded there, and came up with all kinds of varying specs.
This is one of the reasons I posted here: I've already considered going to a diesel conversion, and spent a great deal of time and energy.. It winds up being a pretty expensive proposition, and the return, other than longevity of the engine, doesn't seem that great to warrant it. I mean if this engine gets tired or fails, it's fairly inexpensive proposition do drop in another crate engine. I could probably put in three new gassers, in what it would cost to do the diesel conversion. I know that the Banks System, frequently done on motor homes is an option, ram air induction, running performance headers in to straight 3" dual exhaust, and apparently there is a chip, or mechanical linkage used to alter the "shift points", this is usually located on the tranny. I thank you very much for your input, and it sets my mind at ease that I won't be driving around at 48 mph. If I can get to where I want to go at 68 mph, and take my hotel room with me, then, I guess worse things could happen to a human. I've also been looking into Getting an old International Red Diamond (Straight Six) It had incredible torque, and used to pull my 36' Western flyer at 80+..........at about 3800 rpm.......I might have to shorten the drive shaft, elongate and modify the dog house, and do some custom motor mount work: but if one desires driving a giant Porsche one should have to work for it..........thanks again mokibrabrant

[sportyrick]

mokibrabrant: Ya you have to change the whole drive line to go to diesel. I thought maybe if you are in the right place at the right time you might be able to get a whole bus and steal the driveline out of it an put into ours but the reality is that we aren't that bad off with our gas gobblers over a diesel. Pay at the pump or pay in the garage you aren't going to drive your motel room around for nothing. Looks like most of the diesels don't get much better mileage then us and it's more expensive to buy. Remember that if things go to hell in a hand bag diesel will be the first thing in real short supply. Trains, trucking, trash haulers will get it first then everybody else later. Also I don't want to go to Dayton wheels, I have gone to to much trouble to have polished alloy wheels to lose them this far along in the game. We (my main squeeze Joan) and I are going to go to the Memphis Blues Festival in a few weeks with the bus and the Harleys inside for local transportation. We took it on a float trip last weekend, we use it 7 or 8 times a year and especially for the xmas trips to Salina, 3 so far and we had 18 in the bus this last xmas. Worked out great and fuel prices were down pretty low too. A couple of things I have learned with the 427. It likes a little Lucas fuel conditioner, it just runs better. Also I put some factory 454 headers on it and it seemed to help. I welded the injector bungs shut, actually I plasma cut them off and patched in some more SS then wrapped them in header wrap. Some time when you are motivating down the highway with someone driving that is cool open the doghouse and look at your exhaust manifolds, you will **** your drawers. them suckers are red hot. Your glorified air pump is pumping it's heart out. Also those sodium filled exhaust valves are good for about 100,000 miles or so then they like to drop their head off, especially #1 cylinder. So if you are getting a lot of miles on that engine you might do a valve job and replace all the exhaust valve, don't just grind them, replace them or you will have to replace the whole engine like I did. Internationals are renowned for it also. I did do a little to it while it was down, I couldn't resist my HP greed. Bored +.040, balanced, blueprinted, +.100 larger SS intake valves, inconel off shore racing boat exhaust valves that can run 1800 degrees and not get hurt, stellite seats, heads flowed on a flow bench, matched ports, Eagle rods, high lift short duration cam (.500), roller rockers, high flow oil pump (my oil pressure runs about 100 psi which is a little too high, the cam gear will wear a groove in the front of the block, tough), but the compression is stock 8.5 to 1 so I can still run junk gas. It did help motivate the bus a little better, I think it hurt gas mileage, I am sorry we didn't dyno it though. sportyrick

[mokibrabrant]

SportyRick: Obviously you saved the best for last. Melting valves and radiating exhaust headers that resemble the elements in a Kiln I guess if I'm cruising around Ohio in the winter, I won't need a heater, just open the doghouse and hook up an electric fan. As with the diesel conversion, there al kinds of engines available, on line, fairly inexpensively. If I got serious I would simply sell this little bird, and get another already equipped. I'm pretty sure I would always get what I paid for it....There's a "special activity" Bird that's 28 feet, and it is all set to go with the cummings 5.9...........saw a pretty nice one for about 3K so that is an option. Big picture is I want to get one of these to Hawaii, but the shipping is deadly......about 8K...I've been in contact with this guy Doug at Allison in texas. He is crunching all the numbers for me, with regard a change in this rear end, coupled with the Mt643....We finally got it together, this evening, with all the particulars, rear end manufacturer, rim spec's and type of Rubber I'm running...He is very knowledgeable with regard power curves, especially with this specific tranny in mind. He still hasn't gotten the final numbers together, but he's suggested 70 mph at about 3200 rpm...we haven't discussed all the trade-offs, towing, climbing, city driveing accelerating around town and that jazz; but I'm liking what I'm hearing so far. Keep in mind, and I think this is fairly significant, I'm 8 ft shorter, and will be very close to the unladen weight for this Coach. If I ever look back through my rear view, and see eighteen humans and a couple of Harley's, well, I an only assume that reality has far exeeded my imaginings........Lone Wolf that's HOWIROLL.

I checked out a lot of engines on ebay last night, 4-bolts that would drop right in and mate up with the Allison. Saw some pretty sweet FI Vortec's though I hear they suck in terms of fuel consumption. Saw some tricked out Mopar 440's weighing in at 480 hp, and 600 ft lbs torque at 3600. So I haven't foreclosed on anything, I figure if I'm going to have a "little coach" what I lose in over-all "space" it's my obligation to make up for in performance. Whatever i do, whereever I go with this, I will err on the side of the overbuild.........Just want whatever powers me, to do so comfortably...in my mind this will be the key to the longevity of this drive train...don't need to be burning valves, turning exhaust headers into pourous clay. I do however appreciate that you appreciate your "ride" and after all that is the true test of the experiment. Men and their Machines. I had an FMC motorcoach/rv, pusher, 440 industrial. Four wheel independant suspension, built from the ground up to be what it became. 19 1/2 inch Alcoas, 9' 3" at it's highest point there are a lot of brilliant "build" aspects of this Coach....and of course there's funky stuff too. Only 1050 copies ever made, between 73 and 76.........I believe it still holds the Land Speed record for an RV.....Stock....just shy or a bit over 120mph.......What a pain to work on.........5 belts on this thing, that need to be harmonically balanced like a watch. One belt goes.............they all go........Four Wheel drum Brakes with two brake cylinders per wheel each one about the size of a can of beer.........bottom line to all this I'm looking to the simplicity of the "Bird" something I can crawl under, lay down, spinning wrenches..............If you got a spin......laying down is the best..............mokibra...................

[paul iossi]

think about manual transmissions, 2 speed rear axles or over/underdrive units.
the faster you go the more power it takes to push the wind, optimize your gear ratio's to keep the engine in the sweet spot (between torque and HP peaks).

now for the "old fart advice" back when i rode the bus to school gas engines with 4 or 5 speed and 2 speed axles were king
look for a 2 speed axle that will give you about a .8 overdrive effect

[mokibrabrant]

I suppose where there is a will there's a way. I can only just imagine, how I would set up a shift configuration (standard) with that "doghouse" there. I suppose I could mount a couple feet back, and custom fabricate a gear shift that would reach with a couple of bends to hit the pattern.........Then comes the problem associated with a "clutch Pedal". So unless I could get one of those old Allison transmissions they use to use for "tractors" with an "electric clutch" It seems the logistics of space available might limit the thought of going manual. I'm not suggesting we don't have the technology, however, bringing in Nasa to configure might be a little more than even I would go for this............thanks ..............everything else is right..........

[paul iossi]

IIRC, 2 speed axles are electric shift, run the tranny thru the gears, flip the switch, back off of the accelerator the axle shifts and get back on the pedal, to downshift it flip the switch back off the pedal and then stand on it, its all about unloading the driveline so that the axle can shift itself.

their are lots of cab forward or cabover trucks in existance, look at the linkage that some of them use.

just about everything in the car world is using either hydraulec or cable clutch linkage.

what part of ohio do you run in?

[mokibrabrant]

Thanks again Paul: obviously your knowledge extends beyond mine in this matter: I do like your thoughts. I did have a Western Flyer, that had an electric clutch, and an Allison tranny. I would depress the button on the shifter, shift the pattern, let off on the button, and in would "torque convert" smoothly into gear. It was a beautiful set-up. It is the only vehicle I ever owned so equipped. I did hear, that in the "early" days, Jaguars, the big Saloon type had this type of transmission, as did some of the "Limey" vehicles, Riley, and Rolls. I'm not sure of the need for a split axle, in such a small vehicle, but a six speed allison with an electric clutch would surely get it done. As said before, I had a 550 cu in International Harvester Red diamond, in this 36ft Coach, and I could get close to 90 mph in conjunction with this set-up at about 4000 rpm..........too much I now but it was a Western Flyer, and I do love to fly........I don't run in Ohio, I simply store my coach there because it's cheap...under roof for about $15.00 a month. I actually live in Hawaii, use the coach for about 6 weeks a year. Play the national indoors in Seattle, fly to Ohio from there, drive the coach to Long island, Play the National Grass courts, then Head down to Georgia for the National clay Courts...................back to Ohio...........Store...........fly to the West coast and Home........Like I said, a rolling hotel room..........mokibra

[paul iossi]

think of a 2 speed axle as an overdrive/underdrive and or another gear in the trans with a lot less hassle than changing the trans and working out clutch and shift linkages.