C8.3 4L80E NP205 swap

[Artanisman]

Hello, I have been browsing steelsoliders for a few weeks and I must say I am impressed with the wealth of knowlage available here.

Anyway, I am thinking of purchasing an m35a2 and modding it to meet my needs a bit better. I plan on using the truck as my around town daily driver and my weekend trail rig. I already own a nearly new Cummins C8.3 260hp engine which I would like to swap in. I work for a cummins/cat/detroit dealer and the engine fell off the forklift when being offloaded. The crate broke and the oil pan was mangled. The customer was going to purchase it for a camper project but backed out after the engine incident. So I bought it for half price and changed the pan.

I was thinking about using a 4l80e transmission and an np205 TC. I'd like to fab up a shifter base like one from the m35a3. and use a winters shifter.

Do any of you guys see the first gear of the 4l80e being too high even for road use? Any input would be appriciated.

--Kevin
----------
2LT KB Coleman

 

[Stretch44875]

Why the 205, and not the stock transfer case?

 

[Artanisman]

Re: RE: C8.3 4L80E NP205 swap

Why the 205, and not the stock transfer case?

Primarily because the "low max" np205 has 3:1 low ratio and theoreticly would help counteract the borderline "too high" 1st gear ratio of the 4L80E. But also because I know how strong it is and I am certain it will work with the 4L80E.



--Kevin

 

[Artanisman]

RE: Re: RE: C8.3 4L80E NP205 swap

The main thing im looking for input on is the 4L80E's 2.48:1 first gear and if it's too high for the deuce.

-----
Kevin

 

[gringeltaube]

I would definitely keep the stock TC, better if it's the T-136-27 air shift.
First, because of driveline geometry. Second, the NP205 doesn't have that nice synchro for easy up or down shifts. Third, I doubt it will live long enough between that full grown engine and over13k pounds of heavy metall (empty)!

Ahh, and 4th..... are you sure that 8.3 fits under the deuce hood?

Welcome to this great site, Kevin!

Gerhard

 

[Stretch44875]

RE: Re: RE: C8.3 4L80E NP205 swap

Well, it helps that the axles are 6.72 ratio. I think it would work, but may not for heavier towing. First gear is 6.00, second gear in the stock tranny is 3.31, and 3rd is 1.89.

Can you get a different gearset for your tranny? Would have to pay attention to the torque curve of the 8.3, and see how far apart the shifts are.

The larger 5 -tons had 8.3's with auto's in them, and 5 or 6 gears. (900 series 5-ton)

 

[Artanisman]

I would definitely keep the stock TC, better if it's the T-136-27 air shift.
First, because of driveline geometry. Second, the NP205 doesn't have that nice synchro for easy up or down shifts. Third, I doubt it will live long enough between that full grown engine and over13k pounds of heavy metall (empty)!

Ahh, and 4th..... are you sure that 8.3 fits under the deuce hood?

Welcome to this great site, Kevin!

Gerhard

It sounds like the stock t case would be the best bet, I'm completly new to commercial sized AWD vehicles.

Thanks for the warm welcome.

I've read about folks swapping the cummins 5.9 (b series). Here are the specs of the B5.9 and the C8.3 compared. (Dirrect from Cummins)

B5.9
ADVERTISED HP 150-173 HP 112-129 KW
PEAK TORQUE 453-580 LB-FT 614-786 NM
NUMBER OF CYLINDERS 6
OIL SYSTEM CAPACITY 17.2 U.S. QT 16.3 LITERS
WET WEIGHT 952-997 LB 432-452 KG
LENGTH 40.0 IN 1016 MM
WIDTH 24.9 IN 632 MM
HEIGHT 37.9 IN 963 MM

C8.3
ADVERTISED HORSEPOWER 185-260 BHP 138-194 KW
PEAK TORQUE 631-889 LB-FT 856-1205 N•M
NUMBER OF CYLINDERS 6
OIL SYSTEM CAPACITY 21 U.S. QT 19.9 LITERS
LENGTH 44.4 IN 1128 MM
WIDTH 29.5 IN 749 MM
HEIGHT 43.1 IN 1096 MM
NET WEIGHT (WET) 1,360 LB 617 KG

Well, it helps that the axles are 6.72 ratio. I think it would work, but may not for heavier towing. First gear is 6.00, second gear in the stock tranny is 3.31, and 3rd is 1.89.

I don't plan on towing. the biggest payload I'd commonly have would be people sitting on the troop seats at parades.

Can you get a different gearset for your tranny? Would have to pay attention to the torque curve of the 8.3, and see how far apart the shifts are.

See the attached horsepower and torque graphs. What do you think?

----
2LT KB Coleman

 

[Artanisman]

Oh, the ratios for the 4l80E are 2.48, 1.48, 1.00, 0.75, R2.08

so far the only non factory gearset i found changes 1st to 2.75 and 2nd to 1.57

 

[Artanisman]

With trip to my parts counter, I could change the curve to any other factory rating. the factory curves are attached.

 

[sweetk30]

4l80-e wont live behind the 8.3 .. scrap that idea and possibly get a allison1000 from a dmax truck in a 2x4 config. then use the stock deuce tcase as stated.

the 4l80-e was not realy used even behind a 8.1bb gas motor. thay liked the allison 1000 better for this.


oh ya if you can get a newer style allison. as first few years were 5 speed. then thay played with things and got 6 speed out of them.

and i have seen cummins with allison 1000 in a ford f650 stock . so it can be done no problems.

 

[WillWagner]

The only thing i'd be concerned with is a loss of road speed. Most mechanical Cs are 2200 rated. They don't like to have RPM turned up, they bend push tubes and take out cams. Not saying it won't work at higher RPM, it will, just not for a long period of extended operation. The C and the LDT are very close in dimensions. You might be able to stick it in there with an electric fan set up.

 

[nhdiesel]

1. The 8.3 should fit under the hood, its external dimensions aren't that much larger than the 5.9. Its extra weight comes from thicker castings, heavier crank, higher fluid capacity, etc. I know of at least a couple people who swapped them into Dodge Rams and they fit fine.

2. The 4l80e won't live behind an 8.3. Diesels are a whole different breed than a gas engine. A 4l80 will handle a high HP gas engine just fine, because they don't put out the very high low RPM torque of a diesel, which is what strains an auto trans. You need a trans specifically designed for a diesel...the Allison. I would go with a medium duty version, not the Duramax style. Its just not the same trans as the larger, higher torque rated autos. It sounds like you won't be using this for a long distance highway vehicle, so MPG isn't what you are after. Look for one out of a school bus or other medium duty truck.

Oh, and the 205 will NOT work. Its a great t-case for a 3/4 or 1-ton, but you are only talking about 6-10k lbs. I will be using one in my '96 Ram behind my 5.9, with Spicer 5-speed (Deuce trans), and 3-speed aux. trans. I'm crossing my fingers that it will live in this truck, and I'll only be at around 7k empty. Stick with the Deuce t-case. If they weren't so heavy, I'd consider one for my Ram!

Jim

 

[IronPig]

When it comes to MVs I'm as green as the paint on my M35A2, but I've been building similar vehicles (actually they are MV's in most other countries) for 15 years. We do a lot of repowers in my shop and here's my take on it:

You're talking about putting a motor with twice the HP and more importantly twice the torque in place of the existing powerplant. I don't think for the use you intend that you would regret the loss of the 6.00 first gear (mentioned in an earlier post) because I don't really need first in my M35 on the street. Not to mention you're comparing manual trans gear ratios with an automatic - the automatic has the advantage of the torque converter. You wouldn't want it to remain in shear all the time, but getting you rolling off the line is what it's supposed to do. The second gear (mentioned earlier) is not that far from the 4L80E so I think you'll actually enjoy more streetability with the drivetrain you mention. However, the allison would be better than the 4L80E for this application. Chevy had problems with the 4L80E not holding up to the duramax, thus the allison now standard with their HD line. I guess if you were easy on the combo you'd be fine. (we run the smaller 4L60E behind 350hp/400ftlb motors all the time and have no problems with adequate trans cooling and synthetic ATF) The NP205 can handle it, but from what I've read there are few complaints about the Rockwell case that comes with the M35 and as mentioned earlier it would mate right up to existing shafts and yield better driveline angles. (it's a divorced tcase, which the NP205 can be found in as well) If you're really looking for low-low range you can double up the NP205 with an NP203GRB, adapters are widely available. Of course, with a 20' long truck you could probably run dual divorced Rockwell cases too!

I've read all sorts of numbers here for rated GCVW so I'm not really sure what the M35 is really rated for but I would think somewhere between 20,000 and 30,000 lbs. My F350 dually runs the same even with it's rinky dink powestroke. You'll be fine, do it. Take pictures. Share them here.

 

[m-35tom]

sounds like you just need to get a 5 ton with a bad motor

 

[allrevup]

Hello. Just came upon your posting, about the LowMax 205 and 4L80e. We have a couple things in coummon. I whant to use this same parts on a CUCV. LowMax 205 and 4L80e combo. Have the tranfer case in a different truck allready. Also I'am from Dover so if you like a hand let me know. I am no mechanic but, I could use the experience. Good Luck!

 

[hot rod deuce]

I think the C series would be a sweet motor BUT I think you might have just a little too much motor. I am have my 5.9 set back down at 240 HP from 300hp with 53 inch tires and have NO problems running 65 MPH on the interstate. Im sure with smaller tires you would have much more power than you would know what to do with a 5.9. The 5.9 will also have no problems running 2500 RPM all day and up to 3000 for shorter runs. You could easily sell the 8.3 and pick up a nice Dodge 5.9 around 555-600 FT LBs of Tq and the stock tranny. The dodge tranny is only a 4 speed but its and OD with a higher low than the allison BUT dont forget like the other guy said you can use the converter plus if you get in a bind you can slip the t-case into low and double the ratio.

The big deal on the rockwell t-case is that the REAR out put is on the BOTTOM gear. Think of it as the same location as the FRONT out put on a 205, thats why they refer to bad drive line angles.

Tom hit the nail right on the head. The 8.3 would be a nice 5 ton motor.

tag on the dash says 22,000 Lbs max GVW I think, so really its no more than a big pick up truck.

 

[jeli]

I have to agree with Hot Rod Deuce. I've driven A3's and they have plenty of power with an automatic.

 

[cjtroutt]

Just jumping on bord The 4L80E is Great for Gaser but the Cummins B or C you will take main shaft out and or tork converter will blow out there is no way to set the trans to control Tork limits limiter gaser bulid tork with rpm Diesel build with BOOST
I run 6BTAA 259HP at the crankshaft & 658ft Tork & this stock for cummins by the cpl
I use TH400 with allison tork converter & allison Straight cut gears & planetary
NP205 with lomax gears.
My rig had 85,000 miles on this trans went to truck pulls & tow my race car every day driver
I pulled down this trans & just freshen it up red Eagle cluches Kolene steels new o rings misc rebuild front pump all the old stuff did not be replace at all but I had it down time to make it new again.
I was going to do 4L80E my frend has 6bt in chevy 4l80e 89 model year he on his #9
he ask me what to replace 4l80e & ask what he wanted to do with truck.
He replyed I just wanted to drive with pice of mind & I said Allison 1000 .2004 or later 6speed or allison 2000 is the way to go my self my plans is to install Allison 2000 with
divorce transfer case in my M1028A2 in the near future . This will be an New ground up restore BUILD JAN 2011 started to gathering parts up.
My old 86 M1028A2 runs great as it set up 6BTA Cummins TH400 NP205 runs great still strong .

 

[rustystud]

Artanisman, are you still working on this project ? I just came upon this thread today and I rebuild this transmission and transfer case a lot. They can handle massive amounts of HP and Torque. The 4L80E is just a Th400 with an extra clutch assembly mounted on the front and a lock-up torque converter. There are companies out there making 4L80E trans that can handle over 2000 HP ! The M35A3 has an Allison trans that is
a brother to the AT540. The AT540 uses the same clutches in fourth and Direct as the 4L80E does in 3rd and Direct. The gearsets are larger in the Allison but not that much more and now with the all Torrington bearing 4L80E that eliminates the one major weakness this tranny had (plus a few tweeks here and there ). The NP205 with the 32 spline input and output shafts can handle well over 500 hp all day long. Yes there
is the problem of shifting from high to low, but with the auto trans you would not need it anyway. They did make a NP205 that had synchros, but it didn't last long. 1984 to 1988 . I have one, and some day I might play with it to see if I can make it strong enough to handle my 383 High Torque . The problem with that TC was the synchros would fail unless you really baby it.
All this to say that the 4L80E tranny properly modified would last just fine in a M35. Would it be wise? The cost would be around $1400.00 in parts plus labor. So probably not. The transfer case also can be built to handle this , the cost would be around $1000.00 ,( I know I just finished building one) so again probably not.