we have a mci9. it has a manual transmission that works poorly. if we looked for an automatic whwt wood we look for? is there different rotation on a ht740?
An Allison HT740 is an excellent choice for a bus.
All HT740s in buses are RH rotation. Same as an OTR truck. A rule of thumb is that "T" drive coaches are all RH, and transverse mounted engines (V drive) in buses are mostly LH...maybe. Transverse DD S-50s are RH rotation.
Engines from Prevost, Eagle, MCI, Dina, and most modern coaches are all RH.
2 strokes in GM and Flxible are LH. No problem with the transverse trans...they used "V" drive transmissions...there's no mistaking V series with HT series transmissions.
You'll need a good bit of parts in addition to the transmission. Bell housing, flex plate, transmission, shift tower, cable (or air shifter), modulator components, remote oil filter and lines, oil cooler and piping(coolant and oil lines), and driveshaft. Maybe a speedo VSS if your speedo drives off the transmission. Might be a LH front wheel excited unit.
An MC9 transmission 'hangs' in the engine room, so your motor mounts (TTBOMK) are OK.
You may wish to contact US Coach, Nimco Bus, or Sam Caylor for a takeout retrofit package.
Or look around locally for a trashed MC9, 86 and down church bus. Might be cheaper!
79 and 80 year models had 8V71/HT740 for the most.
The change over will be a good bit of work, but it isn't overly technical. Just a lot of work.
If you can remove the engine cradle, you have the hard part done.
You'll also want to change out the rear main seal and wear ring while the engine is out of the bus....and the bell housing's off.
As stated, this is going to be a good bit of work, but the results will be worth the effort.
You may find buying a 'donor' is less expensive than buying all the individual parts to convert to automatic. In most buses, an HT740 is the last thing to fail. The engine could be totally worn out, but the transmission will have a lot of miles left.
A good take out HT is usually in the $3K range. Total parts used...maybe $4 to $5K? They can be bought for much less occasionally. Just gotta look around. Once all the components are bolted on the engine, changing just the transmission isn't too tough.
Another less expensive way to gain a good transmission would be to keep your bus a manual and install a truck 9 or 10 speed transmission with a dual shift pattern. You would have an ideal gear for every condition. Mileage would be improved, starts and low speed maneuvering would be at an easy crawl (no throttle needed). Easy campground maneuvering...maybe not quite as easy as an automatic.
Some mods to the shift linkage and driveshaft would be necessary. And you may end up with a reversed shift pattern. This isn't a showstopper.
If this concept interests you, I'd recommend staying away from the Auto Shift and electronic transmissions (same for ATEC Allison HT741 or 748). A truck style Fuller Roadranger would be ideal, not too expensive, and super dependable.
If, on the other hand, your clutch and shift linkage is worn out, clutch assist cylinder is screwed, and your clutch is impossible...and you ain't a truck driver at heart, go with the automatic. The automatic will add value to your bus. And, it'll be too easy to drive.
JR
I think your Detroit turns the normal direction, RH, which is the same as a heavy truck. I do NOT believe Allision made the 740 to turn either direction, but could be very wrong tooss. Also, maybe the smaller 640 series 4 speed Allision auto of the proper model would work with the 8V71N.
Or...you could swap out your worn manual tranny for something as good....or much better. Do not know how much driveline length you have...maybe a RTO-910 Roadranger 10 speed manual will fit. This truck tranny was practically designed for the 8V71. I have the RTO-910 in my Crown. Also, Fuller made a TX14507 7 speed which would...
...be almost perfect for your MCI and is about 2 inches shorter or sooss than the 10 speed. Available used for $1000.00. Perhaps even your stock manual shifter rod may work. About a 34% overdrive, sooss do the math and you can go much faster. Six road gears. Plus the 7 speed has a very low granny gear/reverse which normally would not be needed..
...but would be cool if you have to creep your coach forward and backwards like when setting up at a campground. Steep starting grades would also become no problemo. Anyway, just some ideas other than swapping in an Allision. The 7 speed Fuller MAY be practically a bolt in. :) :) :)
Quote from: berrybus on December 26, 2007, 06:04:08 PM
we have a mci9. it has a manual transmission that works poorly. if we looked for an automatic whwt wood we look for? is there different rotation on a ht740?
Berry -Please explain what you mean by
"it has a manual transmission that works poorly." More intelligent answers to your questions can be forthcoming based on a better explanation.
FWIW & HTH. . .
;)
If you do go with a multi-speed transmission do NOT use the 7 spd transmission. It is non synchronized and shifts are hard. Better to use the 9spd. Personally though, nothing beats the Allison HT740. It is bullet proof and there are alot of them around even though it isn't made anymore. The HT754CR 5 spd isn't as strongly built and usually won't last as long as the HT740. Once you have the Allison in and drive it a couple of times, you'll be kicking yourself for not doing it sooner. It is worth the hit in fuel mileage for the convenience and drivablility of the Allison automatic. And this from an old truck driver that drove nothing but 13 speeds for 21 years. Good Luck, TomC
having all autos in the 4 bus fleet now I miss the manual......
russ every time we take it out it for a drive it lodges in 3rd at some point and it takes a lot of bad words to get it out of gear. then theres reverse . very hard to get in gear then it seems to be geared very high. thanks jim.
Hanging up in third is pretty common and usually caused by trying to shift out of third without releasing the gear load from the trans.
It is also commonly caused by poor shift linkage adjustment or sloppy fit of the shift arm/linkage at the trans.
Worn out pins and clevises are common, both of mine were almost completely worn through at the firewall bellcrank. If your shift linkage connections are worn it can never be adjusted properly.
It can also be caused by simply not having the shifter slides at the shift lever bottom properly greased.
Quote from: berrybus on December 28, 2007, 06:11:19 PM
russ every time we take it out it for a drive it lodges in 3rd at some point and it takes a lot of bad words to get it out of gear. then theres reverse . very hard to get in gear then it seems to be geared very high. thanks jim.
Jim -Ah, now it makes sense.
Gus is on the right track - at least if you don't want to spend a bunch of bucks right now to swap in an automatic. Chances are very good that there's a LOT of slop in the linkage, both shifter and clutch. Time to get out "DA BOOKS" (Shop manual and parts books) and start your PM program. I think you'll find that with all the linkages in good condition, it will shift really nice. Also, running the transmission right up to the governor in each gear is highly recommended. More info on this can be found here:
http://www.busnut.com/bbs/messages/12262/16204.html?1167073154
As for reverse, remember that these things were designed to basically back out of a stall at the local bus station, not wiggle into some campground. Reverse is taller than first and lower than second, but I'll be one of the first to agree that it's too high for busnut use. Takes a lot of gentle clutch work to back smoothly, something that just comes with a LOT of practice. As for getting it into reverse, be sure to start from a dead stop, make sure the gearbox is in neutral, then hold the "Reverse" switch on while you pull the lever into 2nd. Sometimes you have to do it the GM way, which is to put it into 1st first, then hold the switch while you pull into second. One of these two will work for you, you just have to experiment a little. All bets are off, however, with worn-out linkage!
If you do decide to go the automatic route, as mentioned by others, the four-speed HT-740 is virtually bulletproof. It's cousin, the five-speed HT-754CR, is almost the same, especially in RV service, altho it's slightly longer. NIMCO or Caylor Supply are good sources for them, as they'll often supply everything needed, as they're used to parting them out. (Side note: The HT-754CR is often found in garbage trucks, so a local truck boneyard might have some. But beware - you DON'T want an HT-754
DR - that's got an extra-low granny first gear - way, way, way too low for a bus application.)
FWIW & HTH. . .
:)
FWIW & HTH. . .
thanks for the help everyone. my wife likes the idea of the ht740. i wonder about the electric shifter. i found a ht740 is low milage but it has a short control cable. the electric shifter might be easier to install. where can i find it and whats the cost? thanks jim.
Do you mean that you've found an electric over air shift? Or does the transmission have a touch pad with an Allison logo embossed on it? Be sure that you know the model of what transmission you're looking at. As long as it's an Ht740, it wouldn't matter, but the bus length harness will be unobtainium. And you would have to have a bus length harness.
ing at. A short harness may indicate the trans was removed from a truck (garbage truck?).
If it's an Allison touch pad, you're looking at an ATEC unit. Some were designed to operate as 'stand alone' (HT741) units...other ATECs were programmed to interface with a DDEC engine control system.
The only installation difference between an Allison HT electric shift and Morse cable shift is pulling the cable.
Add to the install work wiring up a coach electrical interface with the ATEC and the ATEC ECM electronics. Be very careful with ATEC units....if that's what you're looking at?
You don't have a DDEC, so the transmission you're looking at would have to be reprogrammed, probably, to function. I'd avoid all electronic HTs (HT 748/741).
Unless you know an Allison dealer, you're going to get into 'issues' with the ATEC.
An HT740 is a bolt-in conversion. No wiring or harness required.
You're correct, that pulling the shift cable will be a bit of work. Still isn't technically challenging...just a lot of work. The whole transmission conversion from manual to auto is going to be a lot of work. The conversion may cost more than your bus is worth if you must pay a shop to do the change. Hope you can do some of the work yourself. I'd definitely try to find a drivable donor. Maybe a wreck or rustout that still operates. HT740s are found in almost all automatic MC9s year model 86 and down. Any 6V92TA or 8V71 will work.
You'll enjoy the automatic, but it'll cost a lot more than repairing your manual....probably.
Your OEM manual, no matter how well it works, won't be suitable for backing into campsites..or noodling around at slow speeds.
There are also manual/electric (ie: Eaton AutoShift) transmissions that you may wish to consider. They would be less work to install compared to an automatic changeover, but plenty enough in any event. AutoShifts, I would guess, would be quite expensive to buy.
What drive axle ratio do you have in your 9?
JR
Hey berrybus...yeah, it now sounds like you just may have a linkage/wear/old age problem with your existing tranny LINKAGE and the gearbox itself may be ok. Also this cold time of year, for whatever it is worth, has an effect/affect on moving parts. Kinda like my no-longer-new body. He he he.
However....since it now looks like you may at least be addressing/fixing the potential shift linkage problem, you will still, however, be faced with the end product still being a 4 speed manual. I do NOT know what manufacture of tranny you have now. May be a Spicer?
If sossss, then I also do not know what kind of shift linkage set up you may have. With my Crown, the RTO-910 10-speed Roadranger is shifted by only ONE shift rod running all the way from the floor shifter by the drivers seat all the way to the rear/middle of the bus. Has about a million grease zerks.
Anyway, the coach shifted hard and clunky until The Crown guy rocket scientist boogiethecat told me to "grease them zerks dude". Sooos I did. Wow, what a D-I-F-F-E-R-E-N-C-E ! ! ! Nothing else done. Now my tranny shifts like a dirt bike like I have saids before. Maybe all you need is a lube job? Dunno.
Anyway again, perhaps this can save you time and money which is good. Or...perhaps your coach will need some TLC and $parts$ to fix your rough tranny. Dunno again. But....if you are still considering a tranny change, you can move up to (in my opinion, for whatever it is worth) to an appropriate 4 speed
Allision automatic (and all the hassle) ors you can update your MCI with a different manual tranny. Putting a Fuller in your coach may be very easy or it could be very difficult. We need to find out what exact tranny you have now and what kind of shifter linkage you have.
The final point of all this babble is that if you have to fix the linkage at some time and expense, then consider spending more $money$ and ugrade to either the Allision or a better manual, which would be some sort of Fuller. With a manual tranny there is a difference, the type of upgrade/change decision is up to you...
...however, again in my opinion, the RTO-910 is the only way to go, with the Fuller 7 speed being a close second choice. ANY 9 speed with your existing power may be a mistake. However, with lots of power it would work OK. Why would the 9 speed be a poor choice? (In my opinion)
Because the 9 speed was/is designed as a heavy truck tranny intended to start/pull very heavy loads, both up a grade and from a loading dock. The 9 speed in some versions was also used in on-off road trucks. This means that the granny gear, plus 1st and sometimes 2nd are just toos low to be practical in a coach.
You would never use them. Also to get 9 gears to do many jobs, the splits are very wide, which with your 8V71N would force the mill to ALMOST lug in the top 4 gears, unless you ran the Detroit all the way to the governor for upshifts. Even if the top side worked fine, you would be paying for, but never employing, about 3 of the available gears. Toos low.
With the Detroit series 60, no problem. That mill lugs well and works with the 9 speed. A 8V71N? Nope. Sorry. If you want to swap out to a manual, about the only real choice (if it will fit) would be the famous (infamous?) RTO-910 Roadranger. Ten gears very close together. 26% and a 22% split. Very cool starting up or going up grades.
The only problem with the overdrive TO-905/1105 5 speed trannys is that with an overdrive, your first gear would not be low enough for slow speed work. A 6 speed TO-906 would work and the forementioned TX-14507 would work better. The 5 and 6 speeds are now getting hard to find.
The 7 speeds are much newer, stronger and are available for around $1000 used. Chump change. Finally, a rebuilt RTO-910 close ratio, non scynkro, over drive 10 speed can be had with some warrantee for around $2000.00 and used ones for around #1000.00. Reason is they toos are older stuff with...
....no real present day applications except for....older coaches like we have and enjoy. You have lots of choices. I love a good plan. Best bet would be first to fix your linkage, then drive and enjoy the coach. If you want to upgrade, fine. Allisions are sooss cool, but Roadrangers rule the grades. Happy New Year. :) :) :)
thanks fellows. ive bought a ht740d allison. iwonder what to do aout a oil cooler? there is a company that has electric shift kits for these autos . stone benett is the company. just wondered if any one has tried one?
Berrybus, contact United Transmission Exchange a Allison dealer at 800-527-1627 or look at the web site www.utxchange.com they sell the Stone Bennett ,oil coolers and filters and are great to deal with.You will love the shifter I have had 2 buses with them just install a filter in the supply line to keep clean air and it will not give you any problems.One other point if you have a aluminum bell housing you need some support on the rear of the transmission on a cast iron bell housing you don,t need any this Allison not me .I could never understand this because the b500 Allison on a 60 series is mounted on a aluminum housing with no support and weighs 275# more. good luck and enjoy your Allison
No problem with hanging the transmission on the bell housing. An HT740 is designed to 'hang' on an aluminum bell housing in buses. No good way to add motor mounts to the rear of the transmission without imparting unwanted stress to areas that cannot handle such.
All MC9/HT740 uses bell housing mounts for transmisson mounts. This includes an HT740R which weighs a good bit more than an HT740. Most bus bell housings are aluminum.
You'll want to locate a used oil cooler and all the other parts you'll need. May I suggest that you'll need a right tidy pile of parts. Using OEM components will help you avoid fabricating expensive mounts that may be failure prone.
Try Caylor's Supply 7785 878 3405, or Nimco Bus @ www.nimcobus.com 800 526 8055.
Luke at US Coach occasionally parts out MC9s and may have what you need..856 767 4848
Not sure if still listed, but believe Tom Hall was (is) offering Stone Bennett shifters. Check at
http://users.cwnet.com/~thall/index.htm
There may be others, but these guys know what is involved in swapping an MC9 from manual to auto.
I highly recommend using OEM DD/Allison (especially oil coolers) components.
Good luck, JR
No contest here Jr just passing on information in the book for the 740 Allisons on 8v Detroits
I've had to eat crow before, and I'd rather eat it now than mislead BerryBus. ???
I'd be interested in what the book says. I've never seen an HT740 in an MC9 with a transmission motor mount. I'm aware that the transmission has provisions for side mounts, and have no idea why they are not used on MC9s. May narrow the footprint and allow too much engine movement? I'd have to look, but I don't believe the cradle has provisions for mounting transmission mounts.
I've got an MC9 with an HT748R, and have worked on several others. All have the transmission hanging on the bell housing.
An 8V71N makes less HP than a 6V92TA, so that wouldn't be the issue.
Perhaps there's a year model change or something that alters the later units from earlier?
Whilest thinking about Berrybus' plight...the most simple conversion would be to slide a complete powertrain (cradle with engine and transmission) and use the whole unit.
Maybe find a 6V92TA MUI too. Be a better overall system and bolt-in conversion.
Regards, JR
JR, sorry about misleading you and Barry the spec appiles to a 8v92 over 385hp so I will eat the crow
Quote from: makemineatwostroke on January 01, 2008, 09:59:23 AM
JR, sorry about misleading you and Barry the spec appiles to a 8v92 over 385hp so I will eat the crow
No problemo dude! My positions are occasionally...shall we say..."improved" upon?
Generally, any time I venture an opinion on other than 6V92 powered MC9s, I'm wrong...sometimes...well..really wrong! And electricity. I don't discuss electricity anymore. ;)
Hey, that never stops me from offering up SWAGs! ;D
While not a bus mechanic, I am a mechanic, and bring a mechanic's perspective to many things.
If your Yamaha, Suzuki, or Kawasaki won't run...I can help you with that! 8)
Best, JR