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Author Topic: 10spd in my MC7?  (Read 3278 times)
DuaneMC7
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« on: June 04, 2006, 12:46:26 PM »

 I am just getting started on my MC7, now I know I want to get rid of that 4 spd gear grinder and install something that will get the most out of the current 8v71 and be a good match for a possible engine up grade later on down the line. Would like to hear from anyone that has done this swap and find out what needs to be done.

Thanks for any help with this, Duane
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Remember, anythingís possible itís just iron, well, almost.
NCbob
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« Reply #1 on: June 04, 2006, 03:44:30 PM »

I'm sure it's been done...and you sure make my mouth water at the thought of it... Grin  but inasmuch as I own an MC5A (a great bus) it ain't in my future.   Oh! (dreaming) Lord , give me just 4 more holes!!!!!!  Roll Eyes Roll Eyes Roll Eyes Roll Eyes Roll Eyes Roll Eyes Roll Eyes Roll Eyes Roll Eyes Roll Eyes Roll Eyes Roll Eyes Roll Eyes Roll Eyes Roll Eyes Roll Eyes

Ncbob
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TomC
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« Reply #2 on: June 05, 2006, 08:43:18 AM »

In reality, torque is torque and the 8V-71N with 65 injectors only puts out 800lb/ft.  No matter how many gears you have, you're going to slow down on the grades.  What a 10 speed will do is allow you to select from more gears to go up the hill, but at best may increase your hill climbing by 5-10 mph (and that's being very optimistic).  What would serve you better would be to either turbo your engine (more or less a complete overhaul for full turboing) or install a 6V-92TA with 350hp and 1050lb/ft of torque.  That 4 speed is rated at a minimum of 1200lb/ft capacity.

I am most likely going to have Don Fairchild in Bakersfield install a smoke turbo with a one injector increase from 65 to 70's.  What we're going to do is I am going to have a custom air to air intercooler made (13" of space in front of the radiator), Don will pull the two piece pistons and replace the rings with turbo style rings (but keeping the same two piece pistons at the higher 18.7 to one compression ratio), install a waste gated turbo and keep the boost around 6-8 lbs (instead of 25-28 lbs on a full turbo). I figure this will increase my power from 318hp to about 350hp and the torque from 800lb/ft to about 1000lb/ft.  But most importantly will maintain that power in high altitudes without smoking (the politically correct thing to do) since any black smoke is fuel wasted rather than turned into power.  Besides, how many hills have you gone up with the bus slowly loosing speed (just doesn't fall on its' face right away-compared to trucks that slow down quickly to grind up the hill) to find yourself having to go up with the trucks about half way up? Personally I know just a little more power would maintain the speed.  Will keep you posted, but not going to do this till the end of the year when it is cooler in Bakersfield.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #3 on: June 05, 2006, 08:48:32 AM »

A follow up- if you want to really increase your performance, have an Allison HT740 installed.  While it won't increase the speed going up the hills, the acceleration on the flats is second to none.  The pleasure of driving is outstanding (this coming from a truck driver that drove nothing but 13 speeds [still a great transmission-over the 10speed anyday] for 21 years and 1.3 million miles worth) and then anyone can drive your bus in a pinch.  If you don't believe me, drive a bus that is similar to yours with the
automatic in it.  Granted you mileage might go down a bit, but just how many miles will you put on it over the entire time you're owning it?  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
DrivingMissLazy
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« Reply #4 on: June 05, 2006, 09:55:18 AM »

Is there such a thing as a heavy duty 740? When I had my 6V switched to an 8V, the shop dong the work  informed me, after they had installed the larger engine that they were going to have to install a heavy duty 740 because of the increased hp. Since they screwed over me so bad on other things, I am just wondering if they screwed me on this also?
Richard


A follow up- if you want to really increase your performance, have an Allison HT740 installed.
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« Reply #5 on: June 05, 2006, 04:55:22 PM »

Richard- the HT740 had a heavy duty version called the HT748-mainly for the transit and trash trucks that were making hundreds of starts and stops a day.  They had a hardened input shaft and tuffer material on the clutches, but if I remember right was just about all they did to the trans.  Your standard HT740 was rated to around 1,400lb/ft for continuous use.  I could see them having to install a different torque converter with a lower numerically stall ratio since the 8V puts out much more torque than the 6V and the torque converter will only transmit a finite amount of torque before blowing.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #6 on: June 05, 2006, 05:39:05 PM »

Thanks, Tom. I was just curious. Probably another screwing. I went in with an $8,000 estimate to switch out and everything needed and it ended up over $25,000 before I got out of there.
Richard
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Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body. But rather to skid in sideways, chocolate in one hand, a good Reisling in the other, body thoroughly used up, totally worn out and screaming:  WOO HOO, what a ride
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« Reply #7 on: June 06, 2006, 07:38:26 AM »

I think Duane posted a few more details on the BNO board.  One of his goals was to select a transmission for a future change to a four stoke engine. 

The HT740 is recognized as one of the most durable automatics ever produced.  It has been used in some large truck applications for loads up to 80K.  However, it has a 1:1 high gear.

If a person is going to go to a four stroke they really should have an overdrive transmission (cruise at 1500 for a four stroke vs. 2100 for a two stroke).  Generally the gearing can't be accomplished by rear end ratio and has to be done with the transmission.

On BNO I had suggested that Duane consider a truck overdrive transmission to replace his 4 speed.  Lots of gears, easier to shift and he would have the overdrive.  He did not get much response over there, so made this posting on MAK to see if he could round up a person who has done this conversion.

Bottom line, I agree that the HT740 would be great for his present bus.  It would be a fairly expensive conversion  (maybe 4K?).  It would not be the ideal transmission for the later four stoke conversion and he was looking for options for only one transmission conversion.
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Jim Shepherd
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DuaneMC7
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« Reply #8 on: June 06, 2006, 09:25:52 AM »

Thanks Jim, nicely† put. Cool Cool
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TomC
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« Reply #9 on: June 06, 2006, 01:23:08 PM »

Just to give you an idea on the realistic use of a HT740 with a 4 stroke engine, I believe you can get a 3.08 rear ratio drive for the axle.  If you have 11R-24.5's (478rpm), you'll have a 65 mph rpm of 1595; 70mph @ 1717rpm and 75mph @ 1840rpm, which is not to high considering all big gensets run at 1,800rpm.  If you have an engine that is putting out 1,450lb/ft of torque, based on a weight of 45,000lb, then your startability will be- 32%!  At Freghtliner, we want the turnpike startability to be 14%, on road 16%, on/off road 20%, and off road to be 25%.  So you'll be fine
For some of you that want to play around with startability, here's the formula.  First, take what you think is the heaviest your bus will ever be in pounds and multiply that figure by 10.7 and put that figure into memory.  Then take the starting torque of the engine (with automatics it is pretty much full rated torque since the torque converter can pump up to 12-1400rpm on starting), multiply by first gear, multiply by torque converter ratio, multiply by rear end ratio, multiplty by tire rpm and divide by the figure in memory and that's your maximum startability in percent of grade. So in this case it'll look like this:
1450 X 3.692 X 2.0 (torque converter) X 3.08 X 478 Diivide by 481,500 = 32.74%.  Good Luck,TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
coachcrazy
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« Reply #10 on: June 06, 2006, 03:18:51 PM »

kinda on the same subject( i didnt want to start a new thread) with all this talk about different trannies, engines and what not.  I was wondering is it in common practice to upgrade turbos and add  "twin" turbo or more setups and run propane injection on buses?  i ask this only because an aquantance of mine works at a deisel shop and they do these type of upgrades all the time to full size pick up and ocasionally tractor trailer rigs.  Deisel motors love working hard and are capable to tremendous amouts of prower with little effort, im surprised to see that more "busnuts" aren't taking advantage of the raw power hidden within the powerplants in your coaches. 
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MC7S50
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« Reply #11 on: October 13, 2006, 08:36:35 PM »

Duane

I have a 10 spd in my MC-7.  The first one was a RTD (direct top gear), and the current one is a RTO (overdrive top gear).  I can give you details if you want. 

John
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oldmansax
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« Reply #12 on: October 14, 2006, 05:04:34 AM »

John,

Please publish or send the details. I have a 7 & am thinking about the swap also.

Thanks, TOM
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belfert
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« Reply #13 on: October 14, 2006, 05:16:08 AM »

70 MPH at over 1700 RPM in a 4 stroke is really going to suck down the fuel.† They like to run a lot closer to 1,500 RPM for best fuel sipping.

Edit: My Series 60/B500 will run at 1650 RPM at 70 MPH.  I wish the RPMs at that speed could be a little lower.  For some reason, Dina speced the B500 as a 5 speed and had the second overdrive locked out.  I talked to a Dina engineer (now employed by MCI) and he claims it was done because the RPMs are too low with the second overdrive.  I don't understand it,  but I wonder if this was done due to lower driving speeds in Mexico or something.

Brian Elfert
« Last Edit: October 14, 2006, 04:07:16 PM by belfert » Logged
kyle4501
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« Reply #14 on: October 14, 2006, 05:41:34 AM »

The estimates I have gotten to swap my 4spd to 740 auto have started at over $5000 in parts only!

Where do I go for the $4000 install?
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MC7S50
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« Reply #15 on: October 14, 2006, 08:30:50 AM »

We used a Fuller-Eaton 10 spd from a Peterbilt cabover truck that was being parted out.  The cabover setup has a shifter tower on the top of the transmission that adapts to the bus configuration nicely in that it includes a rod that will adapt to using one of the two existing shifter rods already installed in your MC7.  The 2 shifter rods were used to shift the original Spicer 4 spd.  The 10spd only requires one of the rods.  We used the outboard one because it aligned with the shift tower better. The 10spd shifter rod twists as well as moves back and forth, so be sure the joints in the shifter rod are very tight or are tack welded together.  Otherwise, the joints will slip, and the twisting motion will be lost.  The front shifter box from the cabover was adapted to the same location where the Spicer box was.  It only required fabrication of a mounting bracket from angle stock.  The output shaft of the shifter box was connected to the outboard shifter rod using a small universal joint.  A universal joint was also used on the other end of the rod where it connects to the single shifter rod on the transmission.  The length of the rod at the transmission must be custom fitted to the installation, but was difficult to do.  This configuration results in a shift pattern that is not the same as it was in the truck.  It is upside down and backwards.  That means that 10th is outboard and forward, and reverse is inboard and back.  The air splitter switch operates normally.  This sounds like a big deal at first, but both my wife and I adapted to it very quickly.  We made a shift pattern diagram that we put on the dash for a while until we got used to it.  It is no big deal now. We now routinely shift without using the clutch most of the time.

There are 2 bellhousing configurations.  The 10spd required a different bellhousing than the Spicer because of the bolt pattern and the clutch.  The original clutch configuration was a 2 plate push type clutch.  This was scrapped in favor of a single plate pull type clutch that is the common type found in class 8 trucks.  The stock clutch rod was used, but it had to be adapted to the pull type clutch. 

If you do this, I suggest you use an RTO 10 spd, because it adapts much better to any of the low-rpm 4-stroke engines that you may want to install later on.  While using the 10spd with the 2 stroke you will probably not use 10th because your engine will turn too slowly.  Just use 9th as your top gear, because it is 1:1 direct, the same as 4th on your Spicer.

Hope this helps.

John
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kyle4501
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« Reply #16 on: October 14, 2006, 08:36:08 AM »

Thanks for cutting thru the fog John. That's the best explaination I've seen so far.
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« Reply #17 on: October 14, 2006, 02:31:09 PM »

My two cents, if you do get a 10 speed and it's an overdrive model, make SURE it's an RTX version.  The "X" means that they've rearranged the internal stuff to keep the shift pattern "normal".  Reason: when they turn a 9 or 10sp into an overdrive, it's actually gear #8 or #9 that is the overdrive. So you'd have to shift 1-2-3-4-5-6-7-8-10-9
But the "X" version fixes that, so it appears to be a normal shift pattern to the driver.

I'm surprised at John's comments about the 2 plate clutch.  When I stuck an RTX on my Crown, I was advised to dump the single plate clutch and get a ceramic-puck style two plate unit made by Lipe. I did so and it's been the most amazing clutch I've ever had in any vehicle...super easy to push and no way it'll slip, and it's rated for a lot more weight than my bus will ever be...

All that said, now that I have two busses and the second one has an automatic, I'm TOTALLY rethinking why I am so stubbornly attached to my 9 speed. That auto absolutely makes driving MUCH more pleasant, the wife WILL drive it, and with it's lockup feature it doesn't apparently eat that much more fuel than a stick (which I never believed until I had this one).  I'm SERIOUSLY thinking of how to change the Crown over to an automatic.... anyone have an allison 647 they don't need? (I've been told that's the only one that will fit up with the Crown's pancake bellhousing)

Cheers
Gary
« Last Edit: October 14, 2006, 08:11:40 PM by boogiethecat » Logged

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ol713
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« Reply #18 on: October 16, 2006, 08:50:03 AM »

In reality, torque is torque and the 8V-71N with 65 injectors only puts out 800lb/ft.† No matter how many gears you have, you're going to slow down on the grades.† What a 10 speed will do is allow you to select from more gears to go up the hill, but at best may increase your hill climbing by 5-10 mph (and that's being very optimistic).† What would serve you better would be to either turbo your engine (more or less a complete overhaul for full turboing) or install a 6V-92TA with 350hp and 1050lb/ft of torque.† That 4 speed is rated at a minimum of 1200lb/ft capacity.

I am most likely going to have Don Fairchild in Bakersfield install a smoke turbo with a one injector increase from 65 to 70's.† What we're going to do is I am going to have a custom air to air intercooler made (13" of space in front of the radiator), Don will pull the two piece pistons and replace the rings with turbo style rings (but keeping the same two piece pistons at the higher 18.7 to one compression ratio), install a waste gated turbo and keep the boost around 6-8 lbs (instead of 25-28 lbs on a full turbo). I figure this will increase my power from 318hp to about 350hp and the torque from 800lb/ft to about 1000lb/ft.† But most importantly will maintain that power in high altitudes without smoking (the politically correct thing to do) since any black smoke is fuel wasted rather than turned into power.† Besides, how many hills have you gone up with the bus slowly loosing speed (just doesn't fall on its' face right away-compared to trucks that slow down quickly to grind up the hill) to find yourself having to go up with the trucks about half way up? Personally I know just a little more power would maintain the speed.† Will keep you posted, but not going to do this till the end of the year when it is cooler in Bakersfield.† Good Luck, TomC


Tom;   Can you glive me a phone number or business name for Don Fairchild?  I have not located my oil leak forward side of the blower yet,
          but if it gets serious, I may need some place to take my coach.     Thanks,  Merle.    (MC-7)     I live in Lancaster
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