| Author |
Message |
Duane Kaler (Duane)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 03, 2006 - 6:37 pm: | |
This is a repost of my question from another thread, sorry for any confusion.
OK, heres the deal. I currently have an MC7 with an 871 with a 4 sp manual. I dont have a tachometer in the bus. I drove the bus home about 1200 miles. I got around 9 miles a gallon. I ran about 60-65 mph. As I am not used to the 2 strokes she realy sounded like she was screaming along. I had to put new tires on before the trip home and I chose to go with 1200-22.5. The diff ratio is 3.70. Now I dont know what is a good rpm for these engines to run at all day long. I would like to be able to cruise at 70 on the flats. I do plan to build a heavy coach and pull a load in the 6000-7000 pound range. My plan is to go with an auto trans in the beginning but I want to go to a bigger engine down the road. I am thinking 8v92 0r the 12.7 four stroke. So the question is can I install an auto trans that woud work for now and any changes down the road. I would also like the pros and cons on a 10spd roadranger.
Thanks for any advise, Duane |
Greg Peterson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 03, 2006 - 7:44 pm: | |
Duane here is some advice from what I have learned from playing in this hobby.
First you are looking at a huge amount of work to change everything that you’re talking about on the bus. I had this same idea buy an old bus cheap and then upgrade everything.
I decided to buy a MCI parts manual for one of the models that offered an 8v-71,6v-92ta, and 8v=92ta option. I learned from reading the parts manual that many parts are different for each of these options. There are obvious things like drive shaft length and engine cradle to less obvious things like radiator size and exhaust pipe diameter. The bus manufacturer is just like the car guys in that they charge more money for bigger engines. Therefore, if you have an 8v-71 the radiators and other things are going to be minimized in cost so that it just works for that engine. You would be better off buying the bus with the engine and tranny you want already in it. After you add all this expense you will not get much more for your MCI 7. Now let us assume that your hobby is to upgrade the engine in the bus. You have fun doing this and we will not worry about logic.
In this scenario I would go with the B500 tranny and a 4-stroke engine. Try and buy all the parts at once from a wreck. You need both engine and tranny computers. You may need to have a different rear end and axel in order to take the extra torque of the 4 stoke and the 4.63 rear end ratio. (I will talk about this in my other post) The transmission controller can tell the engine to limit the torque at different gears and speeds. You will have to get an Allison master distributor to do the more complex computer reprograms.
They are not to friendly with doing this and I have a long story I will skip about that.
Try and get the wiring for the whole mess because this is a big pain to do on your own.
Just getting the pin out wiring schematics for everything is not easy.
If you could get the whole engine, tranny, rear end, radiators, fans, air-to-air cooler etc. that might be the best. May be hard to find all this stuff.
Good luck with the project |
Jim Shepherd (Rv_safetyman)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, June 04, 2006 - 11:14 am: | |
Duane, you might want to re-think your transmission options.
You might want to consider a 9 or 10 speed truck transmission. That would give you lots of gear options plus the overdrive you would need if you decide to go to a 4 stroke engine.
Most folks do not want to think about sifting, but with the truck transmission it will be much easier to make your shifts. Folks get good enough with them that they only use the clutch to start and stop and then simply make the shifts by synching the engine as they go to the next gear.
I have not made that transmission conversion (I took a different route with the AutoShift), but many folks have made this conversion and I think they were able to use the existing shift linkage and add a range change switch on the shift lever. If you can use the existing linkage, the conversion would be very simple.
The world transmission would be a good choice, but it is still very expensive and the truck transmissions are fairly cheap and very reliable.
Just food for thought.
Jim Shepherd
Evergreen, CO
’85 Eagle 10/Series 60/Eaton AutoShift 10 speed transmission
Bus Project details: http://www.rvsafetysystems.com/busproject.htm (updated 2/9/06) |
Duane Kaler (Duane)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, June 04, 2006 - 1:20 pm: | |
Thanks Jim, I have considered the 10 spd. I would like to here from somebody that has put one in there bus. I recall reading something about needing to deal with reversing the shift pattern. Can someone tell me what they had to do to make this conversion?
Thanks, Duane |
Larry Baird (Airhog)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, June 05, 2006 - 10:29 am: | |
I am almost done with a 8V71T and RTO conversion in my MC-7, but if I was getting 9MPG with the old setup I think I would have stayed with it. With the 4 speed and 11R24.5 tires at 65MPH I was about 2100 RPM and about 6.5 MPG the bus is around 33,000 lbs. The RTO will put me at about 1500 RPM so I will need to kick it up a notch. The new motor made 343 HP on the dyno Yor are limited because the more HP you make the more heat you make. I have added two radators with misters and a dry filter. The shift pater is no big deal, just backwards. |
Duane Kaler (Duane)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, June 05, 2006 - 12:03 pm: | |
Thanks Larry, I have wanted to hear from someone who has done this. Just to be clearer, I got 9mpg on the trip home in a totally stripped bus. Were you able to use the stock shift linkage? Which model RTO did you use? What dose your shift pattern look like now? Sorry for all the questions, this is all quite new for me but I sure am having fun with it!
Thanks again for your help with this, Duane.
(Message edited by Duane on June 05, 2006) |
Larry Baird (Airhog)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, June 05, 2006 - 12:38 pm: | |
I have a 10 speed RTO so I will have around .8 in 9th and 1:1 in 10th. Sounds funny but thats the way it works. I also looked for help when I started and what I found out was that you will need a shift tower (5 speed) from a cabover truck. If you do a search you can find out the correct model. You can use the stock rod but weld any joints in the rod and add support on the back end. You will need to cut it off and add a swivel (2). You need two 1/8" air lines and a valve on the tower or I guess you could use a electric valve and wires. This combo will give you a 100 MPH bus or if you change to a 4 stroke then nice gearing. |
Buswarrior (Buswarrior)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, June 05, 2006 - 1:43 pm: | |
Hello Duane.
With an MC7, you need to be careful. The original rads were sized to take care of the engine only, not an automatic transmission. The Allison HT 740 started being available at the end of the MC7 run, and they had cooling trouble. MCI tried to make it better in the MC8, and finally got the rad size right with the MC9.
If you are choosing a 10 speed, I'd recommend that you do a bunch of paper exercises first!!
There are a lot of diffent sets of ratios available, both direct and overdrive at the top end, various deep and deeper ratios at the bottom end, and a variety of ratio steps in between.
And then there are the power curves of your motor and your differential ratio, and the eventual weight of your coach to consider.
Be careful! Many people have geared their ride wrong and been VERY UNHAPPY with the driveability. Good to talk to the engine folks and listen to their recommendations.
For ratios, I'd look for a tranny with as close to equal steps between the ratios as you can find, so that the shift points for each gear is at the same RPM. For instance, Eaton/Fuller "B" ratios typically are pretty close.
I would also consider a "Super 10" as well as the more popular Roadranger. A Super 10 lets you only move the shift lever 5 times from neutral to 10, and each gear is split. The Roadranger has to move the lever 10 times to get from neutral to 10. Also seems to be easier for those without the experience to skip gears, which would be often in a bus.
If you haven't had a chance at one, a Super 10 works like a typical 13 does in the top half of the box. Starting in Neutral with split in low, Shift to 1, split high to 2, split low & shift to 3, split high to 4, split low & shift to 5, split high to 6, etc. Range shift happens automatically, activated by the shift linkage as you pass across between 6 and 7.
You skip gears by just leaving the splitter alone, and running the engine RPM higher/letting RPM drop off further for the shift, from bottom to top, like a typical 5 speed.
happy coaching!
buswarrior |
Steve (Steve)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, June 06, 2006 - 7:57 am: | |
Get A 10 speed auto shift from a truck. With this transmision you start by pushing in on the clutch flip the little lever to D and let out on the clutch and it shifts 10 speeds up and 10 speeds down. Most all trucks now have this type of auto shift transmissions from 9 to 18 speeds double overdrives. RTLO13 doubleover autoshift.I drove a truck with the 10 speed auto shift. I could flip the lever when I wanted to shift also. If my bus was set up for a manual with a clutch I would be installing this type of transmission. 10/4! |
Jim Shepherd (Rv_safetyman)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, June 06, 2006 - 11:06 am: | |
Steve, as you say, the AutoShift is a great transmission to drive (have one in my Eagle).
However, we need to be careful here. The AutoShift needs to talk to an electronic engine to work the way you described. Specifically, it needs to communicate with the J1939 “port” of an engine ECM. If the engine is a Detroit, it must be a DDEC IV (supposedly some DDEC IIIs could activated the J1939 port – mine could not). Duane’s application would not have that capability since it is a mechanical injection engine (non-electronic)
Eaton made what is called an AutoSelect transmission that can be used with a non-electronic engine. Without going into a huge discussion on technical issues, the AutoSelect is really an AutoShift that does not have the wiring for the J1939 connection to the engine (all of the components are the same). Indeed, an AutoShift will revert to an AutoSelect if the J1939 port fails or is not connected.
The AutoSelect will do all of the shifting, but the driver must break the torque by removing pressure from the throttle and then coordinate the throttle position/engine speed with the transmission speed via gauge on the dash that tells him whether the engine speed goes needs to go up or down. I have not driven one of these transmissions, but it should be pretty easy to get the hang of the engine/transmission speed relationship and only need to use the gauge sparingly.
If Duane considers this option, he should get an AutoShift (going now for about 4-6K if you can find them) with ALL of the components including the shifting tower (over 4K new). He could then use it as an AutoSelect now and then connect the J1939 wiring when/if he converts to an electronic 4 stroke.
Bottom line, the AutoSelect would work well for his present application and eliminate the need for any shift linkage modifications.
Jim Shepherd
Evergreen, CO
’85 Eagle 10/Series 60/Eaton AutoShift 10 speed transmission
Bus Project details: http://www.rvsafetysystems.com/busproject.htm (updated 2/9/06) |
Duane Kaler (Duane)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, June 06, 2006 - 1:16 pm: | |
Jim, once again I tip my hat to you. Do I understand you right in that the “auto Shift” will work with a mechanical engine, just requiring a little more involvement on my part during the shift process? This sounds very interesting. Can you tell me more about this? It seems to me that it would still need a minimal amount of signals from the engine like speed sensor not sure on a TPS. Any info would be greatly appreciated as this option sounds like a definite possibility.
Thanks again for all your help, Duane |
Jim Shepherd (Rv_safetyman)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, June 06, 2006 - 2:18 pm: | |
Hi Duane. Eaton Roadranger is very good about posting all of their manuals on their website - just a little hard to find.
Go to www.roadrange.com and look under litterature tab, then heavy duty automated transmission and you can find what you are looking for. To make it easier, you need two documents:
TRIG-0050 which is the installation manual and it is the BIBLE!!!
TRDR-0040 which is the operator manual that tells you how to operate the AutoSelect.
You can do a search by entering the above numbers. The returned items look like the search went bad, but if you look at the whole listing you will see that the items you want are there.
The only two signals that the AutoSelect needs (I think) are the input and tailshaft RPM. I believe that both of those sensors are within the transmission, so you don't need any additional transducers. You do not need a TPS as the transmission will know that you broke torque and will know the RPMs.
Take a look at the downloads and let me know if you have more questions. The wrecking yard in Denver had a transmission a few months ago.
If you decide to go this route, I would make the harness (from shift tower ECM to the transmission ECM)for the autoshift and have it available for later if you need it. I can help walk you through it.
Jim |
Duane Kaler (Duane)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, June 06, 2006 - 7:06 pm: | |
Thanks Jim, I have alot of info to go over. I will let you know what I deside to do. If I have any questions with this set up can I just E-mail you direct?
Thanks again for all your help with this, Duane |
Jim Shepherd (Rv_safetyman)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, June 07, 2006 - 10:10 am: | |
Duane, feel free to contanct me off-line.
The email address is jim at (xxx) rvsafetysystems dot com (change as needed)
Probably the best phone contact would be my cell phone
Three "Oh" three 478.3501
Jim |
|