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Author Topic: 4104 engine/tranny combo  (Read 3795 times)
RnMAdventures
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« on: April 01, 2011, 05:29:28 PM »

I am in the process of looking for another bus. I have a local one in mind, but I am also looking around at other options. I considered a Prevost or Eagle, but I like the old GM coach's better, specifically the 4104/06.

In another post I saw a 4104 with an interesting engine/tranny combination. It has a Cummins Diesel LTA 10-Bus (270)with a Voith automatic transmission with three stage tranny brake. I know nothing about that engine/transmission combo. The frame was modified to accomodate the engine/tranny. Does anyone have any experience with this setup? Pros/Con's? It is supposed to get 10 mpg.

Any info would be greatly appeciated.
« Last Edit: April 01, 2011, 05:34:28 PM by mike4104tx » Logged

Mike & Rosemarie
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« Reply #1 on: April 02, 2011, 03:19:23 PM »

Mike,

That is not an easy modification since the 4104 does not have a frame. There has to be a lot of body cutting or the engine has to stick out at the rear quite a bit to make all that stuff fit.

You need to look at this mod very carefully. If you can get someone very familiar with 4104s so much the better.  I have a 4104 for sale since I just bought a 4107 with AT & PS but if I were buying new right now I would look for a 4106 with an AT and Sheppard PS conversion because the 8V71 DD is much better with an AT. The 671 DD is great if you like to shift but I don't think it can be reasonably converted to an AT.

Also, I agree with you about the older buses. My favorite is actually the 3751 Silverside, that is one cool machine, especially the shift on the steering column and the art deco rear doors.  Prevosts are big and expensive, so are Eagles, but it is pretty much a personal preference thing. The old GMs are my favorites and the more original looking the better.
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PD4107-152
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luvrbus
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« Reply #2 on: April 02, 2011, 03:42:32 PM »

I don't think much modifications would be needed except for the transmission the L10 and 6L71 are about the same in size,I have helped a few friends install the DDEC 6L71 set at 330 hp makes a hot rod out of the 4104 and they average 10 to 12 mpg,now the Voith when in good shape are a good transmission but expect to pay around 10 grand for rebuild if it goes,lots of v drive transit buses used that setup without problems


good luck
« Last Edit: April 02, 2011, 03:54:10 PM by luvrbus » Logged

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RnMAdventures
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« Reply #3 on: April 02, 2011, 09:11:05 PM »

Gus,

When I referred to the “modified frame” I was using the owner’s words. I assumed he was referring to the engine cradle, but he could have meant the fuselage. I owned a 4104 a few years back and was never an expert on it, but I was learning. I didn’t think he was referring to the unibody, but I know nothing about the combo, so he very well could have. 

I love the old 3751 SS’s… the old Flxible VisaCoach is cool as well.

Thanks for the reply  Smiley
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Mike & Rosemarie
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RnMAdventures
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« Reply #4 on: April 02, 2011, 09:17:10 PM »

Luvrbus,

Thanks  for the info. An automatic transmission is convenient, but the spicer is a workhorse. Is the Alison V730 a better choice for an automatic? My wife wants a bus she can drive as well... she could handle the standard, but I think she would enjoy the automatic much more.

Thanks for the reply.
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Mike & Rosemarie
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TomC
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« Reply #5 on: April 02, 2011, 11:03:55 PM »

If you want a hot rod 4104, then quite simply find a transit with a 6V-92TA and V730 in it (there were thousands made), and swap out the whole drive train.  The 6V-92TA is a very compact engine, weighs less then the 6-71 and produces way more power (238hp and 600lb/ft torque, compared to 335hp and 1000lb/ft torque).  Lots of work, but it will be a sweet ride.  Good Luck, TomC
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« Reply #6 on: April 02, 2011, 11:24:58 PM »

There is a Knut on here that put a Cum L10 in a 4106 and he converted the coach to a "T" drive.  I remember his words when questioned about not posting:  He said something to the effect" I just got really tired of people telling me this engine conversion would not work and would kill lots of innocent folk.  I understand about "MONOCOCH" and what all that means.  Fact remains that my bus has been going strong for 100K(?) and hasn't broken a single thing.  The bus is 3 feet longer but if you aren't a 4106 savvy guy you won't know that.  Bus gets 14MPG."  That was a sad post to read.  Why wasn't everybody and his wife lined up to learn HOW YOU DO THAT?  Clearly the MPG was worth reaching for and that was at 70 or some such.  He is still here somewhere.  Clifford must certainly know...he knows what was on the menu at the last supper.  That is a comment on knowledge...not age. Tongue Lips Sealed

Pulling that off with a 4905 seems interesting but at what cost?

John

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« Reply #7 on: April 03, 2011, 11:29:59 AM »

I know that physically it is a much bigger engine, but how much sooss?  Didn't they at one time offer that mill in a pleasure boat TA version that was rated at 400hp?  Dunno.  HB of CJ (old coot)
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« Reply #8 on: April 03, 2011, 03:00:28 PM »

Mike,

I just assumed the Cummins had to go in fore and aft, but it appears from other posts that that is not the case, so my comments are not correct.

In the past I've had a few suggestions to install a 6V71 with AT from a transit but never got around to doing it. It sounds like a good fit and since the 6V71 is a lot shorter and approx the same power as a 671 it should work great.

That is really all the power a 4104 needs unless you are in a big hurry. I agree with TomC but my concern is all the extra heat from the 6V92 and more fuel consumption. A 6V92 certainly would make it move out but I'm more into casual touring than dragging!!

Instead of doing all that converting I just went ahead and bought the Hicks' 4107 but the 4104 was a lot of fun and I kind of miss it. Even with the 8V71 I find the 4107 is no quicker than the 4104 because of the extra weight but it sure is nice not worrying about having to stop on an incline with the 4-SP. The too-high first and reverse gears on the Spicer are a real pain, otherwise it is cool shifting it.
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« Reply #9 on: April 03, 2011, 03:36:57 PM »

It's just that a T-drive opens up so many good repower options.


I sort of remember seeing a very detailed T-drive conversion thread several years ago, but I don't recall the details or site. I don't believe it was here.

I measured a 4104 to size it up for T-drive conversion, but it looked too complicated to be worth pursuing and I forgot about it.

Ted
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« Reply #10 on: April 03, 2011, 03:48:32 PM »

Ted,

I think it has been done by either hanging the engine pretty far past the original setup by using a greatly modified rear cover.

I'm a great Cummins fan for trucks but prefer the DD in a bus because it is so much smoother. The great low rpm torque of a Cummins is nice, but otherwise it is really rough compared to a DD. Nothing else sounds as good as a wound DD either!!
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« Reply #11 on: April 03, 2011, 04:33:32 PM »

The big problem was driveshaft angle. I considered reversing the axle housing to front-mount and then going past the differential and sending powering back via drop box, or possibly a remote-mount transmission. But then you're back the the inefficiency and losses of  V-drive's extra gears. Maybe Crown style "belly-drive" would be the way to go? But... now with so many cheap powerful bus options available, it'd hardly be worth the fight.

Of course even the NA 6-71 would be much more tolerable with a few more cogs.

I have a solid CA '04 shell, but I keep thinking that I won't be happy with the 6-71's "steam" and will end up burying myself in a complex repower that I don't need in my life right now, or then, so I'm dragging my feet on the conversion and continue to bus shop.

Ted
« Last Edit: April 03, 2011, 04:35:33 PM by TedsBUSted » Logged

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« Reply #12 on: April 03, 2011, 04:44:51 PM »

TomC,
I am not looking for a hotrod, but this bus is out there and the engine/tranny is unique to the bus. When it comes to the turtle and the hare, I definitely prefer the turtle… slow, steady, and reliable. (heavy on the reliable)

JohnEd,
I remember the guy you are talking about with the 4106. Did he ever post pic’s? I wonder how he is doing now? It would be interesting to see how his setup is working today.

Gus,
The only issue I have with the 4104 is the mountains. I never drove it in the mountains, but I know a lot of folks have. Sent you a PM.
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Mike & Rosemarie
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« Reply #13 on: April 03, 2011, 05:03:39 PM »

They are getting harder to find, but there were transit buses built with 6-71TA's and V730's.  You need the rear end out of a 4106 to get the right diveline angle but if you want more power without a lot of fab work that is the ticket. 

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Geoff
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« Reply #14 on: April 03, 2011, 05:09:49 PM »

If you use an Allison V730 you will have to use a differential from 4106 up. I think that would go for any V drive transmission made after about 1960. If I remember correctly the Allison is 65 degrees and the original 4104 and back is 57 Degrees. If you use a 6V92 / v730 from a transit bus the 15 degree bell housing is the only one that will work without modifying the bulkhead or tailgate. Deans  coach did several 4104 repowers where they completely removed the first bulkhead and hung everything on the second. I think it was a little cleaner setup allowing plenty of room for an over sized radiator (which you will need) and the muffler. My old 04 is in Tuscon and Uncle Ned is in NC, both have the 6V92 / V730 setup. It's not much more trouble to install a Series 50 / VR731 setup from a transit bus. The only disadvantage I can think of with the Series 50 setup is that it wasn't designed to run at 2100 RPM and gearing selection is limited with a V drive unless you want to go the trouble to custom build a 4 speed 730.

I just was not satisfied with the power of the 671 and the manual transmission in my 04. It had a Hydra-Shift transmission, a 4 speed with a splitter giving 8 forwards and 2 reverses. The hydra-Shift was supposed to be the hot setup. No one could shift it but me and sometimes I would grind. The 6V92 / V730 was so much better. Great power and no grinding.
I don't see that much would be gained with a 6V71 swap.


Any engine swap is a big job.

Ken
« Last Edit: April 03, 2011, 05:11:28 PM by Hard Headed Ken » Logged

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« Reply #15 on: April 03, 2011, 05:15:24 PM »

But wasn't 4106 tough on the differential and now that's about the toughest to find?
Or is it the same carrier as an ‘04, with just a different offset to the housing?

By the way, with the T-drive conversion driveshaft angle problem, I of course meant when changing to a conventional carrier, but you all knew that.

I agree that any conversion is tough. There has to be a lot to gain to make it worthwhile.

Ted
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« Reply #16 on: April 03, 2011, 05:27:46 PM »

The City of Los Angeles Flxible Metros V drive buses had the LTA 10 Cummins and DDEC 6L71 other cities had the same setup the DDEC 6/71 is a smooth set up in a 4104


good luck
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« Reply #17 on: April 03, 2011, 05:40:46 PM »

The City of Los Angeles Flxible Metros V drive buses had the LTA 10 Cummins and DDEC 6L71 other cities had the same setup the DDEC 6/71 is a smooth set up in a 4104


good luck

Those sound like a good and workable plan.

Luvrbus - Do you suppose the swaps would require an axle  housing change to keep shaft alignment with the carrier?

If so, would the somewhat "fast" '04 pig fit the "city" or other housing?
Or is the '04 diff already close to its max torque limits anyway?  Huh

I guess the devil's in the details, huh?

Ted

« Last Edit: April 03, 2011, 05:43:35 PM by TedsBUSted » Logged

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« Reply #18 on: April 03, 2011, 05:52:31 PM »

Ted I have no idea where the 2 found the rear gear ratio but both have a 3:53 rear ratio some guys say that was never a option for the 4104 and people in the know (who really know) say it was a factory option so you knows both will move down the road for sure and both are set at 330 hp and average 10 to 13 mpg 


good luck
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« Reply #19 on: April 03, 2011, 06:16:16 PM »

Wow! Push-start turnpike cogs.  Grin

I heard of a fast "mystery cog" from a traveling vendor who used an ‘04 for years and seemed familiar enough with ‘em. I've recently seen 3:70s advertised, but I sort of wrote it off as a mistake.

3:50 is so tall I can't imagine how the old arrangement would pull it, unless the diff started out in some oddball planetary hub application, or Hall-Scott 1100 RPM package.  Wink (That's a joke, future reader)

To be clear, I personally don't know for fact about any ratio options and I've seen stranger things, so I can't say.

But the big problem seems to be that the carrier location changed sides starting with the ‘06, making driveshaft alignment difficult when moving inboard from the original '04 location.

Ted
« Last Edit: April 03, 2011, 06:18:00 PM by TedsBUSted » Logged

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« Reply #20 on: April 03, 2011, 06:40:32 PM »

I used the differential from a 4106. It was 8 teeth on the pinon and 33 on the ring gear, 4.125. I have heard of something like a 3.80 is out there. Even the 4.125 was a little high when taking off on a steep uphill so I don't know if a 3.80 would be a good ideal even if it exists. I used my original housing, the center member is in the correct location for the 6V92 / 730 but you will have grind the opening of the housing to allow extra clearance for the larger ring gear.

Ken
« Last Edit: April 04, 2011, 10:23:17 AM by Hard Headed Ken » Logged

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« Reply #21 on: April 03, 2011, 06:56:47 PM »

So, Hard Headed Ken,

Did you use the 4106 carrier to get the ratio, or for some other reason, such as driveshaft fit?
Did the side gears and axle splines match?

Ted
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« Reply #22 on: April 03, 2011, 07:13:42 PM »

So, Hard Headed Ken,

Did you use the 4106 carrier to get the ratio, or for some other reason, such as driveshaft fit?
Did the side gears and axle splines match?

Ted

I used the 4106 pumpkin, carrier, center member (it's know by many names) to get the correct angle and it just happen to have the ratio I needed. The 4104 has the same axle splines.

Ken
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« Reply #23 on: April 03, 2011, 07:18:48 PM »

I used the 4106 pumpkin, carrier, center member (it's know by many names) to get the correct angle and it just happen to have the ratio I needed. The 4104 has the same axle splines.

Ken

Thanks for the info.
So a 4106 pig is key.
I'll keep the '06 pumpkin in mind as I continue to mentally (at least first) repower an '04.

Ted
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« Reply #24 on: April 03, 2011, 07:38:24 PM »

I was told that the 4106, 4107, 4905 pretty much anything after 1961 used the same pumpkin. I just happened to find a 4106 first.

Ken

What I should have said is that anything from the 4106 up should work. I can't remember what year that was, 1962 I think.
« Last Edit: April 04, 2011, 10:22:21 AM by Hard Headed Ken » Logged

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« Reply #25 on: April 03, 2011, 09:51:57 PM »


JohnEd,
I remember the guy you are talking about with the 4106. Did he ever post pic’s? I wonder how he is doing now? It would be interesting to see how his setup is working today.

Mike,

I recall seeing a pic and the rear end was longer after the drive wheels.  Not a great deal....maybe a few feet...butg longer.  The bus looked good andnhe had racked up a lot of miles and was content with his creation.

Now Clifford has thrown another fly in the ointment.  His post says that a 6l71 can be had in some reasonably stock version where the DD gets 330 HP and 12 or 13 MPG.  If I could do that I wouldn't dream of going to the trouble of a "conversion".  330 is enuf!  In a 4106 or 4 anyway.  And I have a sneaky suspicion that there is more power to be had without much trouble/cost if the 330 was sanctioned by DD.  Converting the engine is a monumental undertaking and I have only heard of folks doing it to get more power and better MPG.  What I seem to have gathered over these years is that a "fresh" DD is pretty economical and even in power boosted trim they do OK in the HP/MPG category.  If that 671 got 330 from a turbo and such then what is the problem with lowering the compression another bump and jacking up the turbo boost?  I am learning that the engine stays together but needs overhauled more often at shorter intervals.  Haven't heard an interval that I will live to see expire, however.

The 4106 comes with the 8V71 and Don's answer, when I asked what the max power figure he knows about for the engine might be, was that I could make a wish.  He saw the only problem as getting rid of the heat.  I asked about the 750 HP 8V71s in tanks was that they had a radiator that covered the entire rear of the tank and that it wouldn't work in a abus.  OK, but it seems that with the cooling that can be had from the friggen ocean, they do boost the things to unreal power levels in boats.  What I heard, anyway.

I can tell you this without blinking......I rode with Tom PVCCSS in his 4106 and that thing was a genuine hot rod.  If you are not getting any power or MPG you should think "overhaul" or at least fix the thing.

John
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« Reply #26 on: April 03, 2011, 10:28:09 PM »

The thing about a 6V-71 compared to a 6V-92 is that they are exactly the same from the outside.  In fact, you can't tell the difference between the two except for the cast in 92 at the front of the block and if you open the valve cover, the wider stance of the lower of the 4 valves per cylinder.  This is why I suggest the 6V-92TA.  You most likely won't use much more fuel (especially if you drive it slowly) and then you have the extra power (which is REALLY nice) when you need it.

As to the ISM Cummins, it is still made to this day as a industrial and marine engine with ratings all the way up to 715hp-but remember boats have the ocean to cool them.  Nothing wrong with running a 4 stroke engine at 2100rpm all day-just will burn a bit more fuel, and many times are run that fast in boats all day also.  Good Luck, TomC
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