I have a 89 MCI 102c3 with a 6v92TA with a Allison 740 and a 3.36 rear end. I have perhaps an opportunity to purchase a salvaged RV with a 450 HP Cummins ISM with a Allison HD4060. It salvaged RV has the full drive train intact so I can strip everything from the RV to aid in the swap. This includes the gauges, wiring harness, gas pedal, etc. What I would like to know is would I need to change the gearing (3.36) in my bus for that powertrain? Does anyone know what the rpm and speed would be for that engine/Trans combo? Would this be a good swap?
You need to measure the ISM with the 4060 Allison is long combo you may not have enough room and the 3:36 is going to be to tall of a ratio 4:11 is what you need or block out 6th gear
I thought that might be the case with the gearing. Unfortunately the RV is in another state and I don't have access to measure the drive train. Perhaps, I can have them measure. Does anyone have that engine combo in an MCI?
Quote from: luvrbus on March 13, 2019, 03:25:46 PM
You need to measure the ISM with the 4060 Allison is long combo you may not have enough room and the 3:36 is going to be to tall of a ratio 4:11 is what you need or block out 6th gear
Get the specs on length of ism and specs on length of transmission and add them up. Info on both sould be available with some Googling.
Nothing is impossible...
The engine room may also have height issues, not insurmountable, but you might not fit it under the rear seat or the fan compartment, and have room to take the cover off to adjust the overhead.
The length issue is likely the bigger challenge.
There are quite a few coaches out there that have had their rear ends loosened off, pulled back, and filler skins hide the evidence. Engine support lengthened, more radiator room, a little more rear bedroom room...
What vintage ISM? Rear gear with a World was often 4.56 before the downspeeding really took hold.
As luvrbus says, you just don't use 6th gear.
If you don't use that drivetrain, someone else on here will pay you a finders fee, fer shure!
Happy coaching!
Buswarrior
It's a 1999 out of a gulfstream tourmaster motorhome. I was able to easily find the dimensions of the ISM but haven't found the dimensions of the HD4060. Has anyone swapped their rear gear in a MCI? How much trouble is that?
34.1 inches
I changed the rear in my 102C3, should have gone lower to about a 4:45. The gear change was about $2000.00 with parts and labor. I used a 4:10 and have to be over 63 to get in 6 gear.
Jack
Blue Goose
Do you have that engine and Trans in your coach?
Quote from: blue_goose on March 14, 2019, 05:38:03 AM
I changed the rear in my 102C3, should have gone lower to about a 4:45. The gear change was about $2000.00 with parts and labor. I used a 4:10 and have to be over 63 to get in 6 gear.
Jack
So Chessie said the HD4060 is 34.1 inches, correct? The Cummins ISM is 50.78 inches. That would make the Cummins/Allison combo 84.88 inches total. So is 84.88 inches to long to work in a MCI 102c3? I believe from what I found on the internet that the DD 6v92 is 41 inches long and the Allison HT740 is 37.4 inches. So the engine/Trans that I have currently is 78.4 inches. That's a difference of 6.48 inches. Does anyone know if that would work? I assume I would need to shorten my drive shaft or have another one made but 6.48 inches doesn't seem out of the realm of possibility.
ote author=chessie4905 link=topic=33833.msg387543#msg387543 date=1552563304]
34.1 inches
[/quote]
Check the overall height of the 6-92 compared to the ISM. Make sure it has sufficient overhead space to accomodate the extra length.
Driveshaft on the stock install is already perilously short.
MCI took full advantage of the small size of the Detroit V motors, both height and length.
Dramatic changes were required to put inline 6 cylinder engines into the MCI chassis.
Note the significant difference in the distance from drive axle to rear bumper between the different generations.
Nothing stopping you from making it work. Consult with the U-joint manufacturer tech people on the limits, and extend the rear to get the rest?
Have you read about the shorter Series 50 successes of other busnuts?
Happy coaching
Buswarrior
It looks like the height of the 6v92 is around 50 inches and the Cummins ISM is 45 inches. I am not sure about the height of the ISM with jakes. I know when Brian D did his repower he had to adapt the bedroom floor to make his ISM with jakes fit. However, Brian has a MCI9. I am not sure if the MCI9 has a lower floor than the MCI102c3.
96uote author=chessie4905 link=topic=33833.msg387571#msg387571 date=1552693836]
Check the overall height of the 6-92 compared to the ISM. Make sure it has sufficient overhead space to accomodate the extra length.
[/quote]
I haven't looked into a series 50. Would that be an easier swap? I heard they have vibration issues.
Quote from: buswarrior on March 15, 2019, 05:04:58 PM
Driveshaft on the stock install is already perilously short.
MCI took full advantage of the small size of the Detroit V motors, both height and length.
Dramatic changes were required to put inline 6 cylinder engines into the MCI chassis.
Note the significant difference in the distance from drive axle to rear bumper between the different generations.
Nothing stopping you from making it work. Consult with the U-joint manufacturer tech people on the limits, and extend the rear to get the rest?
Have you read about the shorter Series 50 successes of other busnuts?
Happy coaching
Buswarrior
I just read that the 6v92TA is 44 inches long not 41 inches. So that would make the 6v92TA/HD740 combo 81.4 inches. That would be a difference of 3.48 inches. That sounds better to me. I wonder why the 6v92ta is longer.
Something wrong in these numbers.
6 cylinders in a row vs 3 cylinders in a row...
Confirm sources over and over, the internet is total $#!% when it comes to this info...
When I type $#!%, I'd like it to say $HIT...
happy coaching!
buswarrior
Is there a site that has these specs that is trust worthy? I don't have a manual with me so the internet is all i have at the moment.
Quote from: buswarrior on March 15, 2019, 05:39:47 PM
Something wrong in these numbers.
6 cylinders in a row vs 3 cylinders in a row...
Confirm sources over and over, the internet is total $#!% when it comes to this info...
When I type $#!%, I'd like it to say $HIT...
happy coaching!
buswarrior
At least you can verify your coach with a tape measure. Also the listed length from the attachment on the transmission supplied may or may not include the additional length of an output shaft flange or yoke for driveshaft attachment. Personally, I'd go somewhere to actually measure one before going ahead on the purchase. Also you need the center to center measurement of u-joint caps on your driveshaft to get an accurate length. Also check if you will have any room to shift new engine closer to rear bumper, if necessary.
I know a couple of bus people with this combo in the 102C3 and it works great! The nice thing about the HD4060 is the first four gears are just about identical ratio wise to the HT740. And the fact that the ISM can put out more torque than the 6V-92TA (1550lb/ft in RV form), I don't believe you'd have to switch out the rear end ratio.
For sake of discussion-if you have 12R-22.5 that's a 485rpm tire. So with your 3.36 rear end, at 60 you'll turn 1629rpm. At 70 you'll be at 1901rpm and at 75 you'll be at 2037rpm. 5th gear is a .74 overdrive. At 60 you'll turn 1205, at 70 you'll be at 1409, and 75 at 1507. You want to be somewhere between 1400 and 1800 cruising with the Cummins ISM-so nothing wrong with using 3.36-you'll just not be able to drop into 6th till 80. At 2100 in 6th (.64 overdrive) you'll be going 121mph (you won't have enough horsepower to go that fast). But at 80 in 6th you'll be at 1390-probably again not enough horsepower. But there is nothing wrong with blocking 6th gear out-it's just a programming issue. Good Luck, TomC
Tom, would one even need to bother locking out 6th in this scenario?
Conditions for an upshift would likely never be met, so just ignore it? Save a dollar?
Happy coaching!
Buswarrior
Tom, would you recomend I do this repower or should I have my 6v92ta rebuilt?
Quote from: TomC on March 16, 2019, 05:58:03 AM
I know a couple of bus people with this combo in the 102C3 and it works great! The nice thing about the HD4060 is the first four gears are just about identical ratio wise to the HT740. And the fact that the ISM can put out more torque than the 6V-92TA (1550lb/ft in RV form), I don't believe you'd have to switch out the rear end ratio.
For sake of discussion-if you have 12R-22.5 that's a 485rpm tire. So with your 3.36 rear end, at 60 you'll turn 1629rpm. At 70 you'll be at 1901rpm and at 75 you'll be at 2037rpm. 5th gear is a .74 overdrive. At 60 you'll turn 1205, at 70 you'll be at 1409, and 75 at 1507. You want to be somewhere between 1400 and 1800 cruising with the Cummins ISM-so nothing wrong with using 3.36-you'll just not be able to drop into 6th till 80. At 2100 in 6th (.64 overdrive) you'll be going 121mph (you won't have enough horsepower to go that fast). But at 80 in 6th you'll be at 1390-probably again not enough horsepower. But there is nothing wrong with blocking 6th gear out-it's just a programming issue. Good Luck, TomC
I have a 6V92TA with HT740 in my bus now. 9G90 injectors, TV 7512 turbo, 3.36 rear, 24.5 tires. That gives me 350 HP and 1050 lb/ft of torque. It goes down the road quite nicely. It is a very reliable engine. Doesn't leak, doesn't burn oil. Has taken us from coast to coast, and Mex to Canada, and everywhere in between, without a hiccup. If and when it shits the bed, I would probably rebuild it and get another life out of it. Simple to work on, parts still available, mechanical without electronics. A repower with a different engine/transmission would be an enormous amount of work and more money than rebuilding the 6V92.
JC
If the transmission is already programmed for 6 speeds, then nothing else needs to be done. The transmission will only shift into 6th when appropriate, and will down shift as necessary. If you get a hunting situation between 5th and 6th, simply push the down arrow to hold it into 5th-done!
I would also just rebuild the 6V-92TA. Parts are going to be around for a long time-only thing is finding suitable mechanics that can work on them. Good Luck, TomC
That setup from the Gulfstream was using 4:56 gears some were as low as 5:30 using a 3:33 or 3:36 gear you lock out 5 gear too all of that is explained in the Principals of Operation Manual go the World Transmissions surely I am not the only person on this board with the Principal of Operation Manual for Allison.The 6v92TA is 41 inches long they are measured 2 ways the 44 inches is a fan to fly wheel measurement,the 6v92TA is 1 inch longer than a 6v71 which is 40 inches long.You need to check the ratio on the transmission it comes in a close ratio and a wide ratio Allison can do that for you with the model and serial number don't bank on it being the same as your 740 in the first 4 gears
If you lockout 5 th and 6 th, not much point on that transmission unless you add the gear change to the mix...more$$$. Might as well go with the 740 you already have.
I was worried that parts won't be available and that mechanics would soon be hard to find. I am also worried about the cooling issues. If I do a rebuild I would probably upgrade the radiators. If I rebuild the 6v92TA MUI what can I do to get the most power?
Quote from: TomC on March 16, 2019, 01:28:33 PM
If the transmission is already programmed for 6 speeds, then nothing else needs to be done. The transmission will only shift into 6th when appropriate, and will down shift as necessary. If you get a hunting situation between 5th and 6th, simply push the down arrow to hold it into 5th-done!
I would also just rebuild the 6V-92TA. Parts are going to be around for a long time-only thing is finding suitable mechanics that can work on them. Good Luck, TomC
Every Tom, Dick and Harry weren't too good with the Detroits years ago... Nothing changed there.
All those youngsters who were trained by the US military to maintain that fleet of EMP proof vehicles still have lots of life left in them.
Lots of boats, generators and pumps being run by Detroits, and plan to be for a long time.
We may have to look harder for a mechanic, and no doubt, the parts aren't likely to be priced at clearance, but once you have your Detroit up to snuff, when are you ever going to need anything again?
The decision is about your desires, your hobby, what YOU want to do with your coach.
It doesn't have to make sense, it just has to make you happy.
Building a strong 6V92 is just as fun as swapping in an ISM.
Pick yer fun?
Happy coaching!
Buswarrior
It's just the shops that don't want to work on a 2 stroke they are geared for the electronic 4 strokes ,the 2 stroke era for hiway use ended in 1997 that was 22 years ago
Interstate in Milwaukee has a few techs trained on 2-strokes. They are also continuing to train apprentices to work on them and last year purchased a few dozen used engines for parts. I imagine that having Lake Michigan next door means that they do quite a bit of marine work, and there are lots of these engines in marine use. In all the times they've worked on my two buses they've never not been able to find what they need through their usual supply chain, and they've never not had qualified techs to work on it whether first or second shift. There is another shop in town that has offered to work on the bus when needed as well. I know that this is just one anecdotal piece of the puzzle, but like has been said with the number of military mechanics and marine mechanics trained on these things I'm not worried.
My only problem has been when I accidentally hit the engine shut down on my first trip home in the bus after buying it. I was at a Flying J and got stuck right in the middle of the main lane - couldn't figure out how to reset the flapper. Clearly my own fault, and if I had read the manual I would have known. I went to the service bay to see if there was someone that could help - someone did finally offer to try and help, but it was clear that they had no 2-stroke people on site.
So, Luvrbus may be correct in that there are some shops that don't have the necessary people on hand, especially those that focus mainly on the trucking industry. But, fortunately there are still many shops around that do.
My FD still has 3 pumpers with 6V92 engines, of course they are Ddec. They run great and have never given us any trouble. Everything else is Series 60, we have 1 that lost a valve 3 months ago and is still not back in service.
I put a series 50 in my mci 9 about 2 years ago and so far I'm sure glad I went that way. I had it turned up to 375hp, and I pull my 2500hd crew cap pickup truck with a golfcart in the bed, so i'm loaded down pretty good and it does fine. 6th gear is locked out but I don't think with the rearend gearing I have I would never go fast enough to get into 6th. Plus only needing one radiator and not worrying about overheating was worth the engine swap. As far as being rough at idle I really don't think it is to bad, and going down the road it is much quieter than the 8V was. Jason
I had my 6v92ta rebuilt out of frame by Leids diesel in Pa. and they did a great job. for $ 10 k back in 2010 . But after it was rebuilt I had them set it up to 350 hp and it was great . No more drips !! and it did not smoke !! but there was still not enough power on the hills :-[ .
I could not find a local shop that I trusted to work on it so I would drive to Leids when I wanted something done . ( 12 hr drive each way )
That is the reason for the 3406e cat . ( all land is now flat )
If you are qualified to do the engine and transmission swap and the price is not outrages that is what I would do , or look for a coach that already is set up this way for probably less money and hopefully all the quarks have been ironed out
It is kind of boring now as all I do to the cat is feed it less fuel then the 6v92ta and change the oil and drive in cruise control
my 2 cents worth
dave
Leid diesel is great place. They turboed our 4104. It ran like an 8v-71 then.
Here's the thing. We have an 8v92 TA in our 102C3 with the 500hp setting on the ECM. And it's been turned up a little beyond that too. So I'm runnig over 500hp and I can tell you that my coach goes...I've finally got it running right now and even though I'm almost 50,000lbs fully loaded gross including toad, I can keep up with traffic at stop lights etc. if you're two stroke is kept up, it will work perfectly for you. My 6v92 in my last bus never overheated ever. It was mechanical and it just worked. The only way I'd recommend a repower is a few specific conditions:
1. Your engine is blown. If you are needing a $20,000 rebuild, that's the time to consider a repower because you're already into a rebuild 20k might as well explore other options
2. You have plenty of money and really just want to modify your bus out of sheer joy.
Repowering a coach with a 4 stroke when your two stroke is running good is just throwing money down a hole. People think it's going to make their coach more reliable like a car or give them 20mpg. It's just not like that. Sure, you'll gain a few mpgs, and yes you might be able to get parts a little easier etc, but neither of those little conveniences will even come close to outweighing the mods you have to do and the money you'll have to spend on a repower. Even though you're getting this drive train for free, you have a ton of modifications to do to make this work. And fitting it into the engine bay is just one of the puzzle pieces. So again, if it's a hobby and you're enjoying the process and have the money and time, go for it. But I have seen these swap attempts go bad before with people losing interest half way through and struggling to get all the pieces to work and they end up with a Frankenbus that is just kind of a mess. I have a guy I know in Texas who did a Cummins swap into his MCI9. He never ever worked out all the kinks with th modified cooling system and other issues he was having and got cancer so his bus is just sitting now. It's pretty, but it's not a good solid runner.
All of the comments have been great. I think the best plan is to have the 6v92ta refreshed and keep the original drive train. I just worry that I will get to the point where I can't find any good mechanics that can work on the 2 strokes. However, I should worry about that when I need to and not before. This forum is great for helping me make decisions.
Great insight Scott. One questions about your bus. How did you reroute your turbo inlet and what filter are you using? I see your inlet is a straight into the turbo from the passenger side engine compartment but how do you have your filter setup? Scott, could take some pics and post them for me?
Quote from: Scott & Heather on March 19, 2019, 04:59:27 AM
Here's the thing. We have an 8v92 TA in our 102C3 with the 500hp setting on the ECM. And it's been turned up a little beyond that too. So I'm runnig over 500hp and I can tell you that my coach goes...I've finally got it running right now and even though I'm almost 50,000lbs fully loaded gross including toad, I can keep up with traffic at stop lights etc. if you're two stroke is kept up, it will work perfectly for you. My 6v92 in my last bus never overheated ever. It was mechanical and it just worked. The only way I'd recommend a repower is a few specific conditions:
1. Your engine is blown. If you are needing a $20,000 rebuild, that's the time to consider a repower because you're already into a rebuild 20k might as well explore other options
2. You have plenty of money and really just want to modify your bus out of sheer joy.
Repowering a coach with a 4 stroke when your two stroke is running good is just throwing money down a hole. People think it's going to make their coach more reliable like a car or give them 20mpg. It's just not like that. Sure, you'll gain a few mpgs, and yes you might be able to get parts a little easier etc, but neither of those little conveniences will even come close to outweighing the mods you have to do and the money you'll have to spend on a repower. Even though you're getting this drive train for free, you have a ton of modifications to do to make this work. And fitting it into the engine bay is just one of the puzzle pieces. So again, if it's a hobby and you're enjoying the process and have the money and time, go for it. But I have seen these swap attempts go bad before with people losing interest half way through and struggling to get all the pieces to work and they end up with a Frankenbus that is just kind of a mess. I have a guy I know in Texas who did a Cummins swap into his MCI9. He never ever worked out all the kinks with th modified cooling system and other issues he was having and got cancer so his bus is just sitting now. It's pretty, but it's not a good solid runner.