Author Topic: Convert(ed-ing) Coach (and other stuff)  (Read 6571 times)

Offline Savantster

  • Newbie
  • *
  • Posts: 10
Convert(ed-ing) Coach (and other stuff)
« on: August 13, 2006, 09:40:25 PM »
Ok.. so I'm gonna do something pretty silly and try to convert a bus into an RV. Here are some questions that I hope can be answered by the various wisdoms here at

I understand that "metro busses" are likely to have lower top speeds because they aren't set up to run down the highways (normally).. But, say a bus is "governed" at 65 MPH, is that something you can change if there is still RPM available? That is, is there a way to change the governed limit? Also, I'm thinking for fuel economy, 55 - 60 is where I should be trying to keep the bus anyway, otherwise we start dropping in efficiency pretty fast (right?). I've also heard you can "change the axle gears" to a lower ratio.. what kind of impact does that have on starting out from a stop, and/or towing? Say, going from a 3.7 to a 3.4 rear-end? And speaking of towing, how hard is it to get a receiver hitch on a bus and would a metro/highway bus be able to tow a small/medium trailer (holding an S10 blazer and maybe a 450 lb bike)?

Storage is also going to be a problem, as I understand it.. but the question I have is.. Is there room under a "metro" that is just covered by solid skins? Do they still mostly have storage bays, just not finished? Would there be room to "build my own" under the bus? I realize that it has a lot to do with the type/make of the bus.. what I'm looking at for a purchase from a municiple auction is going to be a 40' Gillig Phantom (1994), and those don't look like they would have the same "under spaces" that say an RTS might have. But, the other question is, just how important is the storage space anyway? Would I be able to build tank suspension systems under there? is there room under the Gillig to put in plumbing/generator/etc? Actual "storage" won't be much of a problem for me because I don't have anything (really) to bring with me that can't be stowed in cupboards/cabinets or in the bedroom while driving..

Forgiving getting the Gillig, what types of busses make the best (decent) conversions? Prevost and MCI aside (pretty much any highway coach "should" be good). Looks like RTS might be a good bet (heard/read they have the undercarriage storage, just have to add doors?).

Been wondering some about diesel engines.. What is "fast idle" for? is it a cooling thing for when the engine is running but not being driven? Is it something pretty much all "highway/metro busses" would have? and be missing on (some) school busses?

Would there be anything specific I should look out for when looking to get a bus for conversion, as in, on the Gilligs.. I understand that you can have different air bag configurations, and the 4 bags/axle is the smoothest ride while 2 up front and 2 in back cause a lot of bucking on rough roads..? Are there some other things to look for like solid front axle (not sure what the Gilligs have for configurations... seems the '87 and later RTS busses probably have solid fronts... etc?).

Sorry to be anoying with this. I am just trying to get something "class A-ish" for as little money as I can spend to see if I even like RV-ing.. been camping tons and love it, and using a pop-up was heaven.. Just not sure how a Class A would be "over time" and figure if I can get one built for a few grand (I'm pretty handy and would do all the work myself, and try to salvage camper parts from salvage yards.. pretty isn't as important to me as function). I have no idea how hard it would be to put on leveling jacks, for example.. would I be able to just bolt/weld them on to a Metro or Highway coach? etc etc..


PS.. Oh, and does anyone know a good place to get decomissioned busses, like from Greyhound.. or any decent way to find out where auctions around the country might be that would have RTS or highway coaches?

Offline Ross

  • Sr. Member
  • ****
  • Posts: 406
Re: Convert(ed-ing) Coach (and other stuff)
« Reply #1 on: August 14, 2006, 06:00:41 AM »
Just my opinion, but if you're looking for highway speeds (65+), don't bother with a transit.  You might save a little money over a highway coach, but you'll spend that... plus...trying to get highway speeds out of it.  You'll have to either change rear end gears or do something with the transmission.  I don't think you can just make an adjustment to increase the engines max RPM.  Not sure, but I also don't think these things are really "governed"  They have a max RPM that they will reach, but that is based on the amount of air and fuel that goes into the engine. 

Storage....Again, if you want something where you can take months worth of stuff along, just buy a highway coach.  You can add bays to a transit, but again, you're spending money and time to do it.

I met a guy about a year ago that had an old RTS is pretty rough shape.  It wasn't raod worthy.  He stole it for $4000.  When I saw it, he had changed the gears, done some engine work, built bays....basically done everything to turn it into a highway coach.  He had around $15000 in it, still had a rust bucket that wasn't raod worthy and hadn't even started the conversion.  He was trying to sell it, which is why I stopped to look at it.

You can find a decent MC9 in the 10-15K range.  That's about the most economical bus to convert right now.  If you can find a little more cash, the MCI 102's are strating to come within reach also. 

Leveling jacks....These buses are heavy. Jacks would have to be pretty stout.  I looked at building a set and figured I'd have about $1000 in hydraulics.  Air leveling was more economical.

Fast idle...Not sure what the text book definition is, but generally it's not good to let these engines idle for long at low oil pressure.  Fast idle brings up the oil pressure.  School buses are not running the same Detroit engines, which is why they don't have fast idle.

I can understand wanting to spend as little as possible, but most of the time saving in one area costs you in another.  If you end up buying/building a bus that does not suit your needs, you will not enjoy it, however, if you thought a popup was heaven, you can probably get by with just about anything. :)   Personally, I HATE camping, that's why I built a bus.


Offline Savantster

  • Newbie
  • *
  • Posts: 10
Re: Convert(ed-ing) Coach (and other stuff)
« Reply #2 on: August 14, 2006, 06:48:12 AM »
Some notes (and another question).

For storage, I don't plan on being on the road for more than, say, a week or so at a time (for now). That's why I was wondering if I'd really need the storage right away (and building bays over time for plumbing and storage could be drug out over a year or more).

The question about governed was because someone said they have a bus that runs at 65 mph all day, goverened, and would run up hills at 65 as well.. kind of implied there was RPMs available, just not access to speeds over 65.. which kin of makes sense for public safety on a public transit, I'd think. If there was an easy way to modify that (without going over safe RPMs, of course) then that particular coach would seem to be all set up for highway..

Fast Idle makes sense now.. I wasn't sure if it was to move more coolant or what, but keeping up the oil pressure makes sense.

new questions..

Detroit 6V92TA Diesel ... that's the non-computer, non-ddec.. right? And aren't those able to have bigger injectors and bigger turbos and the like put on to make them produce more HPs?

Allison HTB748 Is that considered a good transmission? anyone have more info on this one? I'll run a web search later on it as well..

(that engine/trans is in a 1992 Orion with 197k miles on it.. looks kind of retro, and much nicer than the 92/94 Gilligs that will be up for auction..I hate the recessed driver's window on the Phantoms)

What about the series 50 Detroit Diesel? how does that stack up to a 6v92TA (and the ddec.. isn't that ~350 hp?)

Oh, and does anyone have more info on what's involved with swapping rear end gears? How much, etc? Or does that come based on the specific axle with a huge swing in potential costs (which would help limit my search as well)..

TIA, again :)
« Last Edit: August 14, 2006, 07:04:04 AM by Savantster »

Offline pvcces

  • Hero Member
  • *****
  • Posts: 803
Re: Convert(ed-ing) Coach (and other stuff)
« Reply #3 on: August 14, 2006, 09:47:16 PM »
Savantster, just reading between the lines, it seems to me you ought to be looking at partially converted and converted GMs from the 60s and maybe the 70s. They have the features that you want, and a lot of the time, they can be bought very little money. And a good many of them will do 80 mph, no problem.

For those coaches, if they have the standard shift, there isn't much economy to be gained by driving them under 06 mph. They have respectable sized bays, but no frame, because they are built a lot like an aircraft. They are light, for a bus, running around 20,000 lbs. stripped, which can give good economy and performance. Our conversion runs just under 27,000 lbs.

They are a fairly inexpensive way to learn if the converted coach suits you.

Good luck on your search.

Tom Caffrey
Ketchikan, Alaska
Tom Caffrey PD4106-2576
Ketchikan, Alaska

Offline TomC

  • Hero Member
  • *****
  • Posts: 8725
Re: Convert(ed-ing) Coach (and other stuff)
« Reply #4 on: August 15, 2006, 03:02:47 AM »
I have a '77 AMGeneral transit 10240B.  It has a 8V-71N and V730-which is a sideways mounted engine with the driveshaft going at an angle to the rear axle in a "V" shape.  The Allison V730 is only a three speed transmission which is going to be a compromise on starting and top speed.  I have the 4.625 rear axle ratio (sometimes called the 4 & 5/8) with 11R-24.5 tires is geared for 65mph at 2100rpm.  Go with 4.11, and that changes to 65mph at 1870rpm.  This ratio should only be used with turbo'ed engines, which I'm in the process of doing to mine.  Top rpm is around 23-2400rpm, with ideal cruising rpm in the 16-1800rpm range for the 2 stroke Detroits.

I used the transit because of the low price.  I got mine for $4000, and put in another $5500 to change the rear end gear ratio (originally had the 5.57 ratio for a top governed speed of 60mph-to slow for me), changed the front axle bearings from greased to oil, increased the injectors from 55mm to 65mm (basically from 270hp and 680lb/ft torque to 305hp and 800lb/ft torque. My soft turboing will increased this to 345hp and 1050lb/ft torque-but more importantly will keep it from smoking in high altitudes), installed Jake brakes, and changed the wheels from the 12R-22.5 hub piloted to 11R-24.5 nut piloted aluminum wheels.  The V-drive drive train is basically the same as Flex transits, RTS transit, GMC 4106, 4107, 4109, 4907 and 4909.  Gillig phantom has a T drive that is like a normal truck but mounted in back, so a minimum of a 4 speed auto, with a 6spd auto now being used.  The Gillig has straight sides that will give much more room inside and not present the building challenges that the RTS will with its' very curved walls.

The main reason I used the transit was because of the low initial price.  But, it is alot more work since you have to create the mountings for the tanks and storage under neath.  Mine has 22" between the bottom of the floor and the bottom of the body skirt.  First, I removed the heating/A/C system to make room for the tanks, etc.  In the space under the floor, I mounted an 85gal gray water tank, 45 gal black water tank, 20gal propane tank, 2-8D deep cycle batteries, 10kw Diesel gen mounted next to the driver's seat like a front engine (have to access it from inside the bus), made a 99"w x 22"h x 66"l storage compartment behind the front axle (which stores alot of stuff with room left over), and a smaller 30"w x 22"h x 18"l storage compartment on the right right behind the rear axle.  Inside under the bed in back I have the 130gal fresh water tank, two 10gal elec water heaters plumbed one into the next with the final water heater wired through the inverter for hot water going down the road (tremendously cheaper than the Diesel fired AquaHot system), two water pumps, hot and cold individual fixture ball valve manifold system.  I have just about everything any other bus has with the exception of the larger storage bays-which I haven't found to be a problem since I don't full time.

On suspensions-most air suspensions will be fine, with the Eagles rubber torsilastic suspension being the argueably the best in ride quality.  The advantage to air suspension is that you can have manually controlled leveling valves (I also still have the automatic valves for driving) that make leveling at camp a less than one minute affair.

While transits are quite a bit less expensive than the highway type buses initially, they do require alot of work underneath-I spent the first year with the bus on blocks and me on my back.  While I now have a very usuable converted bus, it did cost about $75,000 to convert and I'm still changing things.  The turboing will be a minimum of $5,000 more.  For my next bus in about 10 years, the one I like is the MCI 102C3 that is 102" wide with 6'10" headroom, BIG windows, straight sides, and lots of under storage. Can get a decent one for about $35,000, but your converting time will be about half that of a transit.

There is no perfect bus made. All have advantages and disadvantages.  Whichever model you choose to make it work for you will be the proper one.  Just remember that these are commercial vehicles.  And while they are tremendously reliable and long lasting, the repair parts are expensive (6 new tires for $2,900) to maintain and repair.  If you don't have the money to do this, then an older sticks and staples might be the better choice.  But all of us agree that sticks and staples motorhomes are not a choice.  From my 21 years of over the road truck driving, I've seen sticks and staples motorhomes in crashes, and that's why I have a very stout transit bus for my motorhome (transits are the strongest made buses to with stand the very punishing day in and day out driving service they have to survive-plus the crash standards they are made to compared to a highway bus).  Just remember to do it your way!  Good Luck, TomC
Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.

Offline Jeremy

  • Hero Member
  • *****
  • Posts: 2228
  • 1987 Bedford Plaxton
    • Magazine Exchange
Re: Convert(ed-ing) Coach (and other stuff)
« Reply #5 on: August 15, 2006, 04:21:31 AM »
Regarding the question about governors - coaches in Europe (I can't speak for the US) are all govened to either 60kph, 80kph or 100kph depending upon the country. We call these devices speed limters - a governor is strictly speaking a mechanical device that prevents an engine overspeeding - a speed limiter is electrical and needs to be tested and certificated by the authorities every year for vehicles in PSV use, but can easily and legally be disconnected if the coach goes into private ownership. I haven't got around to disconnecting mine yet, as it is helps the fuel economy, and thus far it seems more satisficatory to run at the same speed as trucks and HGVs rather than be constantly pulling out to overtake them anyway.

Obviously the speed limiter described above is a device fitted to long-distance coaches to limit the speed on the open road. I doubt our buses (what you call transits) have any kind of speed or rev-limiting device at all, as there would be no need for it. In fact, until a few years ago coaches didn't have them either, and it was quite normal for coaches to be geared for 90mph+ (seriously) and spend all day bouncing sports cars out of the fast lane of the motorway.

A shameless plug for my business - visit for back issue magazines - thousands of titles covering cars, motorbikes, aircraft, railways, boats, modelling etc. You'll find lots of interest, although not much covering American buses sadly.

Offline mdainsd

  • Newbie
  • *
  • Posts: 19
Re: Convert(ed-ing) Coach (and other stuff)
« Reply #6 on: August 15, 2006, 10:18:31 AM »
Im so thankfull for this forum. By reading the threads I have gained some great insight. Insight before I got started to boot!

I have done fabrication most of my life, and one fact I have come to realize, is the one garaunteed way to make a job more expensive and time consuming is to rework something already built as opposed to starting with a clean slate.

Now as I apply this to my upcoming bus adventure, I personally would not concider buying a non over the road bus and going to all that trouble to make it into one. I know a bunch of us are on tight budgets, but it doesn't take too many modifications to take your 4000 dollar great buy, and run it up to the point where you could have gotten an over the road model for LESS!!!. I know some love the challenge, but for myself, I know there will be challenge aplenty just doing the work on the conversion parts. I wouldn't have the time or energy for the "corrections".

Im not trying to be critical either, was not intended that way. And I understand that everyone here has different reasons and gets different satisfactions out of their projects.

I am about ready to start my hunt in ernest now. Im not going to rush, I dont have a time limit on the hunt. Reading the board, I have decided on a Prevost. I would of course prefer the later design engines, but will settle for a 8V92T, and hope to find one with a 5 or 6 speed trans, manulal or auto. My runner up was Eagle.
"The difference between stupidity and genius, is that genius has it's limits" - Albert Einstein