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Author Topic: Will the 4L80E handle a mildly tuned 12 Valve Cummins?  (Read 1906 times)

GR Gold

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Will the 4L80E handle a mildly tuned 12 Valve Cummins?
« on: March 05, 2014, 11:12:11 PM »
I have a 1995 3500HD with a dead 6.5.  Truck has 83k miles on it and I want to put in a Cummins.  Truck has the 4L80E auto in it.  For simplicity, I would like to stay with an auto.  Will this trans take it?  I know I shouldn't, but quite often I gross about 30K with my 2000 F350 diesel 6 speed pulling my loaded gooseneck.  I have read several threads about the Allison 1000, but the cost and integration into the truck is rather spendy.  I also read about the Fuller FSO6406.  That seems the most interesting to me if I have to make an upgrade, but again the cost along with changing out the steering column and adding a clutch pedal probably make it prohibitive.  I greatly appreciate all of your wisdom on this and welcome all your replies!  Oops, by the way, will a NV4500 out of an 1993 3500HD with a 350 bolt to the Cummins with a Dodge bellhousing?  Is the input shaft different from a NV4500 bolted to a 6.5 diesel or big block or one bolted to a Dodge?  Can I use the steering column and pedals including the gas pedal, out of a 93 in a 95?  Sorry for so many questions.  Probably should have put about half of this in another thread!

someotherguy

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Re: Will the 4L80E handle a mildly tuned 12 Valve Cummins?
« Reply #1 on: March 06, 2014, 08:51:48 AM »
Factory specification on the 4L80E is that it can handle up to 440 lb-ft of torque.  Depending on what year the Cummins comes out of, torque spec ranges from 400 to 440 lb-ft.  For comparison, the Vortec 7.4 that came in 1996-up GM trucks make nearly the same torque - the L29 is rated at 410 lb-ft, the L21 at 390 lb-ft.  (L21 is the slightly detuned version used in the medium duty trucks.)

So you're right at the edge of its rated capacity; it would probably be fine, as long as it's in good condition.  How much work it is to adapt the 4L80E to the Cummins, I don't know.  You will need a standalone transmission controller which can range from $600ish to $1000 depending on brand/model, or some research may tell you if you can continue to use your 1995's computer to operate it.  The 1993 model HD has a TCM (transmission control module) which is a standalone computer from the factory for operating a 4L80E, but I don't believe you'll find it compatible with the 1995 model transmission.

1993 column will not easily work in the 1995 truck.  "Gas" pedal is the same across all years of this body style; as you know the 1994-up diesels use an electronic pedal assembly, earlier ones use the same pedal as the gas trucks.

Others have discussed what it takes to use a GM NV4500 with a Cummins so I'll leave that to them, I'm not experienced with these swaps.

Not really that big a deal to source a clutch pedal bracket assembly and master cylinder from a 1995-up truck to work properly in your 1995; making the correct type of hole in the firewall for the master cylinder to fit is kind of a chore as the factory hole is stepped in layers of sheetmetal, for the master cylinder to "clock" into, resting on a lip made of two different sized holes.  Been there, done that.

Richard
06 Silverado ISS / 06 Silverado SS / 06 300C SRT8

 


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