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Old 12-23-2021, 08:40 PM   #21
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Originally Posted by jimmythomas View Post
I rode a Greyhound from Spokane to Missoula in January 1977. Lookout Pass was awesome, solid ice all the way up and that driver was was drifting that big old bus like a pro, and it was even a 4 speed! At the top the State Patrol was making everybody chain up -- and they waved the Dog right on thru. I'll never forget that sound of the Detroit !

A few years ago a friend bought an old stripped out GM coach for $500 and put the tires on his dump truck. He got the 6-71 running but had clutch/shift issues - the 35 foot long shift linkage must weigh 300 lbs. Every moving part in that shift linkage was worn out. Eventually he got it stuck in first gear and the clutch working sort of.
That bus was sold very soon after.
Haha picturing that drifting 35 bus actually sounds kinda fun. That linkage story sounds about like id imagine. Even though these buses could put multi million miles on them they were turning a profit while doing it and could afford to keep all these things maintained meticulously. Or I guess couldnt afford not to. I could picture myself buying one and being lazy and having a serious failure somewhere down the road.

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Originally Posted by Tejon7 View Post
I haven't done Lookout pass in a bus, but I have driven I-90 from Missoula to Billings about ten years ago (my bus trips are normally North-South). That bus had an underpowered gas engine and a 5-speed. I got down to 10 mph at times, but it was fine. That's a worst case scenario, but you might have to change your expectations for speed if you're used to zooming through the mountains in a Sprinter-type van
Im ok with going slow through the mountains. Going slow through texas not so much. Anyone have an idea on the top speed for this era bus in this configuration. Some things I was reading were saying 45-55! Im starting to sound like I want to have my cake and eat it too.

As much as I hate towing, I wonder if having a diesel truck and building an old airstream is the way to go for my situation.

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Old 12-23-2021, 09:00 PM   #22
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I have two GM 4104 coaches with 4-speed manual transmissions and Detroit 6-71 engines. They're definitely retro and something you need to love/want to drive. And cruise speed is about 65, tops. We also have a bus with a 5-speed and a Detroit 8V71, which definitely has more pep. All 3 of these are rear engine configurations so the shifting isn't super tight, but even with the age I'm impressed by how well all 3 shift.

These coaches are fun and I love the manual transmissions, personally, but you ought to be willing to learn lots of mechanical stuff and do your own maintenance and repairs. If you prefer to just get in, start it up, and go...then you might want something less "vintagy" (I made that word up).
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Old 12-23-2021, 10:09 PM   #23
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Originally Posted by Victor Monsanto View Post
You prefer a manual because of the flexibility of choosing the gear or reliability/longevity?

Actually both, plus an automatic tends to make a lot of heat, which a manual does not. Another thing the manual gives is better holding back on down grades



I have a 5 speed plus two speed rear in my bus, that gives 10 speeds when needed. Typical driving I just use 4 speeds. Rear in high range, and start in 2nd.



I did see Ross mentioned needing to like vintage buses and be willing to learn about how to take care of it, they are a different beast, take his words to heart.
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Old 12-23-2021, 10:49 PM   #24
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Originally Posted by rossvtaylor View Post
I have two GM 4104 coaches with 4-speed manual transmissions and Detroit 6-71 engines. They're definitely retro and something you need to love/want to drive. And cruise speed is about 65, tops. We also have a bus with a 5-speed and a Detroit 8V71, which definitely has more pep. All 3 of these are rear engine configurations so the shifting isn't super tight, but even with the age I'm impressed by how well all 3 shift.

These coaches are fun and I love the manual transmissions, personally, but you ought to be willing to learn lots of mechanical stuff and do your own maintenance and repairs. If you prefer to just get in, start it up, and go...then you might want something less "vintagy" (I made that word up).
Needing to love and want to drive kind of reminds me of my vw or sprinters. Theyre good platforms but you really need to love to work on them to have them work for you. I have a degree in automotive and diesel technologies but got really burnt out on it in school and never pursued it as a profession. Its been great to be able to fix my own stuff but I hate doing it. I appreciate your input, experience is invaluable.

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Actually both, plus an automatic tends to make a lot of heat, which a manual does not. Another thing the manual gives is better holding back on down grades



I have a 5 speed plus two speed rear in my bus, that gives 10 speeds when needed. Typical driving I just use 4 speeds. Rear in high range, and start in 2nd.



I did see Ross mentioned needing to like vintage buses and be willing to learn about how to take care of it, they are a different beast, take his words to heart.
True. And from what ive heard two stroke diesels make quite a bit of heat as it is. I like the idea of a 2 speed rear, is that the second shift lever I see in some trucks/buses? Do they make one that is like an overdrive? It sounds like yours is geared for climbing.
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Old 12-24-2021, 07:17 AM   #25
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Two strokes do not make any more heat then any other engine of the same power. I have repowered and not found any need for more cooling, as long as I was in the same horsepower range.


A two speed rear gives you in high range a nice cruising speed, in low good climbing, and off road. The shifter is normally a red knob on the main gearshift, and is electrically shifted, or sometimes vacuum shift, as my Dad's old GMC trucks were. I have always favored International and they usually have electric shift. My comfortable cruising speed is 65-70. I must say I have not heard of a motor coach having a two speed rear, you would have to check into that.


As for the second gearshift you see in trucks mostly older ones this is a brownie box, or properly called an auxiliary transmission. It serves the same function as a two speed rear in that it allows you to split gears. I had one in one of my trucks, it takes some practice to get good at twin stick shifting. Look it up on youtube. Better get good at the 4 speed first, besides I do not think there would be room to put one in on a bus( motor coach) Motor coaches are a whole different animal.


Looking at a conventional dognose school bus it is the same chassis as a medium duty truck, and all the power train I have is common to medium duty trucks of my vintage.


A motor coach shares engines with class 8 trucks, but most else is unique to them.
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Old 12-24-2021, 06:15 PM   #26
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My initial comment for folks that consider buying any coach with no prior experience in buses is very simple.....

If you have to Ask then you shouldn't be doing it. Most especially a GM coach, for lots and lots of expensive reasons.

Be afraid, be VERY afraid.

I don't want to sound too negative, but I really should say that for someone who doesn't yet have any experiences with all the stuff that comes up when buying, driving, maintaining, and converting any kind of large vehicle, bus, box-truck, mini, anything really, I can't stress enough just how much hell you're bringing on yourself when getting involved in any Coach.

All Coaches are designed to be run hard and maintained regularly, and very expensively, to remain in revenue service which was needed to pay for all that maintenance and parts. Without the income stream they are unbelievable money pits. If you are very well off and money isn't much of an issue then Coaches can be a consideration, but if you're like most everybody else a Coach is one of the fastest ways to lose everything you have. I place them in the same category as Airplane, Boat, Race cars, Divorce, take your pick. You really should consider starting off easy with some kind of a common, simple, school bus that has some support still for parts and mechanics to work on it. Then you'll see what I'm talking about.

The engine isn't even the worst part. Working on and getting parts for the Coach itself can, and might, drive a man to drink. Everything is specific to that GM 4108 and nothing else will fit. There are some things to be found from other GM models, but that takes lots of time and research to find the common parts, and even then they are extremely rare to find. We're talking about a Vintage vehicle here and all things about it are a Restoration type challenge. Definitely not something a new guy with no idea what he's getting into, or with the Very deep pockets, should be attempting. I'd take a cold shower and keep looking for a nice, simple, relatively recent school bus to start with. You'll thank me later, I'm sure.

Among the Coaches GM's are considered the hardest to keep up and on the road today since they are way out of production and the numbers are dwindling for the good ones. I'd strongly suggest that you check out the forum site: busconversionmagazine.com . There are several guys there who own and drive successfully GM Coach conversions.... BUT they all have had previous experience with them as conversions and have learned through the school of hard knocks what to expect and how to get the most from their Coaches, and for them it's a good experience. But they also have had troubles with getting them into tight situations and again have learned the limits of what they can do with the bus. Plus they have learned where to find the precious parts they need for their Vintage Bus.

That's a 4108, not sure of year the change was made but the tip off is the dash setup with the switches on the sides vertically like the 4104. The 4107 had all the switches across bottom and they were all the hated rocker switches. The dash on those was a rounded affair where the gauges were mounted. From the outside you can tell by the shape of the dash what it is. That one is square and higher, thus it's a 4108.

The 4108 was a very slight upgrade to the 4107 with mostly some small cosmetic changes and improvements to some interior lighting and parcel rack supports, and other upgrades to vehicle systems I'm not aware of. The re-design of the dash was a much more usable and historic echo from the 4104 and Scenicruiser dash designs and added A/C outlets on the sides for the driver to get more direct cooling on him.

And yes I do have extensive experience driving all manner of GM Coaches through the years in Charter and Tour Service, including these 4107s. I will say at the outset that they are NOT for the faint of heart to drive and get down the road.

At the time they were new and when we all were used to driving 4-spd transmissions, the 4107s were notorious for being a bus you had to be very precise in your shifting or they would make a fool out of you. You always needed to be on your game with them

I would say that for someone with little or no experience in shifting a manual transmission, the very last thing you should try to do is learn or try to teach yourself how to drive a GM coach, especially a 4107. You'll end up tearing it up while you try to learn and you may also have an accident when you blow a shift and forget to drive the bus. Trust me, it's not something I would encourage a new guy to try doing by himself.

Back in the day when we all drove them the 4107's were nasty. Cold in the morning they were almost impossible to shift, once they warmed up they could be really nice, but you still had to stay sharp, if you started getting tired the first thing that went away was your smooth shifting and ability to drive it well, and then you started missing shifts, and on hills and around town in traffic that could get you into some serious trouble.

They were designed, as were all the GM Coaches, for FLAT land highway service and are definitely not good at all on steep inclines and even moderate off highway conditions. An experienced driver CAN take one on difficult hills and in and out of driveways, which is where the real problems are, but he has to exercise good judgement and excellent technique to keep from getting either high centered or stuck where he can't get back out due to the high first gear ratio. There isn't a single thing you can do to improve or modify the transmission gear ratios, or the rear-end ratio, Period. It is what it is and that's what you must live with. The only thing that you could do is to convert it to a V730 automatic transmission, which some have done, but that's a rich man's game and isn't worth it if the rest of the coach isn't in good enough condition to warrant it.

There were several times I had to make the passengers get out and walk to the top of the hill or driveway so I could take the empty bus up, or out. These were cases I would have made them walk in as well if I'd known in advance. I made it a practice to get out myself and walk the situation and check it out before attempting to take the bus in.

As long as you are on a highway and can keep the bus moving and not let it stop on a steep grade you can usually do OK. But if you get stopped you may find you can't get it going again. I've seen this happen and had it almost happen to me a few times. The Clutch is the one that takes the beating if you do manage to get it moving again.

One other nasty little surprise is the Reverse Gear electric solenoid operation. You need to hit a switch in order to get it into Reverse, and we were taught to NEVER let yourself get into a situation where you HAD to use reverse to get going again. Always park so you can pull straight ahead to get out. When the Reverse fails you are so SOL it's not even funny. GM was so well designed that there was a manual override method on the transmissions where you push an extension on the reverse lever with your foot while the driver pulled it into gear. A hassle, but at least you could get out of a jam...... sometimes.

As to the whole question about 2-strokes, and yes that's 318 hp naturally aspirated which was the standard engine at the time, 8V-71. It's mounted cross-wise in a V-Drive configuration unique to GM and at the time the best thing going. When parts were available they were easy to keep repaired and on the road. The entire engine and transmission are mounted on a removable cradle that can be removed very quickly and replaced so the coach stays on the road in revenue service. A real advantage for any Bus Company. Today it's very difficult to find mechanics to work on the engine and even the coach itself. Good parts for repair and most everything on them are all GM proprietary and custom designs so keeping it maintained, even if you do most of the work yourself, will be a never ending challenge. They are also a 24 Volt system so even the lights can be hard and expensive to get. The engine also turns backwards in what is called a left handed engine. All GM's with the V-drive are left handed engines and some parts for them are particular and unique, and harder to find today.

Coaches are by definition and design much more complicated in all ways and require many more items to be watched and taken care of. All manner of systems on Coaches that are not usually put on school buses. Full Air-ride suspension, A/C, 24 volt electrical, complicated and proprietary parts and systems forcing you to go to the manufacturer, and for the older buses like GM's today the need to find sources that still might have parts available. It's getting harder and harder though.

As much as I really love the GM coaches and consider them a blast to drive and take on the road. They can be a true joy to drive,.... if it's well maintained, otherwise they can be a real pain in the ass. I still wouldn't have one today as a conversion because of the built-in problem with the high first gear ratio. Too many problems getting into and out of camps and driveways. Road speed is fine, they all will do an honest 70-75mph with the usual gearing that was put out at the time. There was an optional rear-end ratio for hilly terrain with a slightly lower top end speed but it wasn't much and even then they could to 65mph.

I'd only plan on getting a GM for the restoration and preservation of the seated bus as a living example of the great era of GM Highway Coaches. At one time they Ruled the Roads of America and were ubiquitous and literally everywhere both in Transit buses and Highway buses going cross country. And they were all powered by the Mighty 2-stoke Detroit Diesel in it's many different configurations and sizes. Truly an engineering marvel to behold.
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Old 12-24-2021, 07:08 PM   #27
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Great write up Crown_Guy, thanks for that. I figured we had some folks here with the kind of experience you described.

Of all the points you made the one that would stop me from buying one to use as a conversion is limited ground clearance. I intend to get as far away from the bustling crowd ad I can and that would never happen in one of those coaches.
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Old 12-24-2021, 09:02 PM   #28
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I have seen that interesting v drive, a friend of mine had one. He did mention parts are getting rare for them .
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Old 12-27-2021, 02:04 PM   #29
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Two strokes do not make any more heat then any other engine of the same power. I have repowered and not found any need for more cooling, as long as I was in the same horsepower range.
Oh, if only that were true! I wish that cooling was not the biggest influence in where and how I drive my bus. My bus had worsening overheat issues, so a few years ago I completely rebuilt its entire cooling system, and even after doing all that I still wish the temperatures were slightly lower. Climbing long 6% grades in 90-plus heat requires very careful driving while watching the turbo boost gauge and temperature gauge.

When some MC12s were reengined with Detroit Series 50 four-strokes of similar power, one of their two original radiators was no longer needed, so an intercooler was installed in its place. A four-stroke dumps a lot less heat into its coolant than a two-stroke. I sometimes wish I could install an intercooler for my engine, but there's no space left; the original aftercooler unfortunately dumps its heat into the coolant.

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Old 12-27-2021, 06:35 PM   #30
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These non synchro 4 speeds aren't for everyone.
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Old 12-27-2021, 08:10 PM   #31
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My initial comment for folks that consider buying any coach with no prior experience in buses is very simple.....

.
Thank you for the very thorough and very sobering review. I think it's easy for a guy like me to read a couple of very simplified "What bus is best for me" articles and decide on a coach, and then find an old cool looking one for a good price and think "Bingo!".

Im glad I asked for some real world opinions before getting in too deep. I think ultimately I could do it, but restoring an antique for long distance and occasional offroad travel doesnt sound like its a good fit for me at the moment. Not to mention the low clearance, high first gear and overall cost.
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Old 12-29-2021, 04:22 PM   #32
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…..

Not sure about the 318 part??? I was under the impression that size bus had either a Detroit Diesel 2 stroke 8V-71 (8x71-568 cu.in.) or at the least a 6-71 (6x71=426 cu.in.) ……

Those buses go down the road quite well if they're in good condition. ……

I'm sure others will chime in who have more direct knowledge of the comparison you're looking for.

https://www.youtube.com/c/BusGreaseMonkey

I’m not 1000% sure but i think a Detroit 318 is a 6-71 in-line six. The 318 referring to the HP setting.
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Old 12-29-2021, 04:50 PM   #33
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318 does refer to hp, but it's the 8v71 that was commonly spec'd with 318 hp back in the day. When they turbocharged them, went to silver engines, and went to electric controls the HP all changed.
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Old 12-29-2021, 08:00 PM   #34
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If you want OLD go out and buy a late 1970's early/mid 1980's Bluebird Conversion Bus/RV to rebuild.

Not much "Mo Money" these days to purchase than a old worn out Skoolie.

House/RV conversion was factory built with all the basics there waiting for your upgrades/remodel.

A Bluebird RV most likely will already have a Detroit 2 Cycle engine or a Cat engine in it already if old skool diesel is what your really want.

Will drive much better than a old worn out Greyhound bus from the 60's.

May have a "Stick" in it for a transmission IF you buy one old enough.

Since most of these old Bluebird Bus RV's SAT much more than they ever drove on the road mileage will be MUCH LOWER than any Skoolie you will ever buy.

The BEST PART is you won't have to start from scratch with your Skoolie conversion!

Just remember that starting any rebuild process is EASY! It's that "Putting It Back Together" parts that causes so many unfinished bus projects to go UP FOR SALE by an owner who has lost all interest!
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Old 12-29-2021, 08:46 PM   #35
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318hp was the standard for most of the GM vehicles with the 8V-71 naturally aspirated. There wasn't any room to install a turbo and no need at the time. Some customers ordered the 8V-71's with a slightly smaller HP rating of about 285HP in an attempt to save fuel. It didn't usually work out so well. They were even bigger dogs on hills and such than the rip roaring 318. 318 was a standard in Tractors, Buses, Stationary apps, and all manner of other uses since it was a good balance of power/weight/size in many installations as well as massive parts commonality making them relatively inexpensive for parts and repair compared to other engine brands.

When the MCI MC7's started getting popular with Greyhound they were able to start playing around with the Turbocharged 350hp 8V and found it worked out rather well, except for the added load on the already undersized cooling system, which required modifications. Ultimately they didn't use 8V-71T's in the MC7 since the cooling system just wasn't able to handle the extra heat.

In point of fact MCI is a Canadian Company and they were designed for operation in the Canadian Climate. When the 35ft MC5 with the 8V-71NA was introduced it was a hit with operators. Then they introduced the 40ft MC7 with essentially the same 8V-71NA and 4spd Spicer transmission. They were fine in the Canadian Great White North, but down here in the States, especially in the Western States the cooling system and radiator surface area was woefully inadequate. They were notorious for overheating under normal conditions in desert heat and passenger loads. Never mind climbing hills, they were always alarming and on the verge of shutting down, even after gearing down to try keeping them cool.

That's why you see all manner of customized modifications to the radiator area. Ever noticed the "Elephant Ears" usually rubber mounted at the back of the side radiators in an attempt to ram more air through them. Or how about the water misters that some operators installed to help keep them cool. It all wasn't much help since there just wasn't enough cooling surface to dissipate the heat. That's why nobody in their right mind ever tried to put an 8V-71T into an MC7.

Greyhound had just introduced at the time the paradigm busting MC6 which was the first production 40ft long 102" wide bus. They only ordered and built 100 of these units with which they intended to force the States and the Feds to increase the legal allowed width to 102" for highway buses. It was already legal in the Transit buses in cities, but not on the highways and Interstates. Go figure how that ever made sense.

Anyway, the MC6 was equipped with a 12V-71 NA Detroit with a 4-spd manual transmission. They tended to eat clutches and Greyhound finally got tired of the clutch issue and low fuel economy of the 12V so they experimented by putting in the then brand new at the time 8V-71 with the new water below the ports block and turbocharger kit putting out 350HP. They ended up replacing all the MC6 12V's with the 8V-71T's and Allison Automatics, which were also just getting to the point of being reliable and strong enough to take on the job in highway Coaches. The Allison automatics certainly weren't cheap to buy or fix, but they were better than the accumulated parts, labor, and lost revenue due to down-time of the previous 12V/4spd installation.

A turbocharged Detroit requires many new parts in order to not burn the damn thing up. New Cross-head Pistons, lower compression ratio, re-design of the engine block to provide coolant below the intake ports, thus the new and ongoing "water below the ports" engine block still in use today. Different blower speeds and all manner of things with timing and injector designs. When it's all done correctly you end up with a very solid and reliable turbocharged engine capable of either putting out lots more power/HP or tuned to give the same power and use less fuel. Very good engineering and flexibility to the users requirements.

The In-line 6-71 non-turbo was usually in the 238hp range when tuned with "A" timing and N65 injectors. That was a very common setup for Truck and Bus installs. I worked at a charter company that ran Crowns exclusively that were all 238hp engines.

They also ran a large fleet of GM 4104's which had the exact same engine 6-71 mounted sideways in the rear with the patented GM V-drive configuration. Most of the coaches were not overly powerful and the 6-71 was typically in the 195-215hp range which was very factory stock for GM at that time. A few of the 4104's this charter company owned were upgraded to the full 238hp, N65's, "A" timing when it came time to overhaul them. They were then some truly awesome coaches to drive. Again there were no turbocharged 6-71's in any of them for the simple reason there wasn't any such thing yet as the water below the ports block, plus there just wasn't any spare room in the engine compt. for all the new piping or to mount a turbo without cutting a hole in the rear door.

There isn't any 6-71 with a 318hp rating in any common use, period. Never was. Usual range was 195 to 238HP depending on injector sizes and the timing of the camshaft. Until new water cooled blocks and cross-head pistons (with lower compression) came along there wasn't much you could do to the Naturally Aspirated DD's except put in larger injectors.

I do know that you CAN boost a 6-71 to those kinds of HP levels but you end up shortening the engines' life by many orders of magnitude. Usually these would be for Military applications and vehicles, civilian and military Boats, military Tanks and such. I'm aware that the venerable M113 tracked APC from the Vietnam War era uses an 8V-53 Aluminum Block, Twin-turbo'd variant that puts out about 400HP I think, for a rated engine life of about 250 hours. These are STILL in production today if you can believe it. The Military still likes them their Detroit Diesel 2-strokes.

Sorry if this comes across as a Rant, not my intention, merely got a little carried away with the interesting historical aspects of what and how certain Detroit engines and configurations ended up in various Coaches and some school buses, (Crowns and Gilligs mostly).

The history of engine developments and how they influenced all manner of vehicle designs is a fascinating subject. The 8V wasn't even available until about 1960 or so which is when GMC introduced the 8V-71 powered 4106 to replace the venerable 4104. Greyhound also re-powered the Scenicruiser from it's original twin-pack of two side-by-side inline 4-71's to the new 8V-71NA and the rest is history.
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Old 12-31-2021, 12:03 PM   #36
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With respect to any old(er) manual transmissions: When I was driving for Grayline in and around Boston, MA we had some pretty old equipment, almost all had manual transmissions. I was taught to ALWAYS shift using "square corners" in the shift pattern; NEVER apply sideways pressure until the shift lever was in the neutral position, so that the shift lever always travels in a straight line horizontally or vertically as you look down upon the pattern. Doing that, I never had any problem with the linkages hanging up. Because of that I never learned what had to be done to "unhook" the linkage.

A second point: Find the largest, flattest parking lot to practice shifting. My first attempt to shift a standard was when I bought my first car. The sales staff must have been laughing treir asses off — I stall the car 7-8 times before even getting out of their parking lot. >>
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Old 12-31-2021, 12:42 PM   #37
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I can't give you any comparison information but I can suggest you drop in on the Bus Grease Monkey channel on YouTube where you'll see a lot about the old touring buses.

If I were interested in driving around in a 35' or 40' bus that has limited ground clearance I'd have bought one of those, problems be dammed.

Not sure about the 318 part??? I was under the impression that size bus had either a Detroit Diesel 2 stroke 8V-71 (8x71-568 cu.in.) or at the least a 6-71 (6x71=426 cu.in.) but don't hold me to that I'm certainly no expert on those.

In terms of shifting the tranny, I believe it's non-synchronized which means you'll be double clutching. In the last millennium I actually drove a GMC 410? for a summer on a route and it had the 4 speed with a floor mounted shifter and I enjoyed driving it and found it quite easy.

Those buses go down the road quite well if they're in good condition.

I wouldn't want to drive any bus through a high mountain pass in bad weather. I'd go the southern route and call it a day. It's not as though you have a schedule to keep that you'd risk your life, limb and property to save time.

I'm sure others will chime in who have more direct knowledge of the comparison you're looking for.

https://www.youtube.com/c/BusGreaseMonkey

my fishbowl has the non synchro 4 speed.. with a DD 2 cycle its easy to float the gears.. you only use the clutch when you stop
cadillackid is offline   Reply With Quote
Old 01-04-2022, 10:46 PM   #38
Mini-Skoolie
 
Join Date: Dec 2019
Location: Union Bridge Maryland
Posts: 33
Year: 2002
The motor is a 871N Detroit. The gear box will be a Spicer which unfortunately is unsynchronized. I have one in a MCI 9. You have to double clutch, which some old timer needs to teach you. Or you tube. An Allison 840 are cheap,readily available and automatic. People have been driving them thru mountains for years. It does take time to learn it. Good luck
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