Which Tranny Should I get?

[Tongan310]

Hey guys no where near starting this pita project but just brain storming as I will once I get some other bugs worked out.

So on my 97 cclb c3500 Dually I plan on swapping out the 454 for a LMM/LLY/LBZ Duramax (I can get my hands on any of the 3 for fairly cheap haven't decided which one yet) . Problem I'm hearing/noticing is the Alison tranny is HUGE. As I want the truck to be dropped (haven't decided between bags or 5/7 static) The Alison might require more of a "bubble" in the cab than I am willing to cut into it. So my question is. Can a 4l80e be built to handle the duramax low end torque? or what other transmissions should I look at? . I saw hughes makes a 4l80e diesel trans but I think that was only good for the 6.5 (Haven't reached out to them about it yet and they're on my radar because they are local to me).

I thought about maybe using a 6l80e/90e but haven't had the time to really look into it.

 

[Supercharged111]

Are you willing to row your gears? Could do an NV4500 or ZF6 (I think that's what they called the Dmax manual). FWIW they did put the 4L85E behind the Dmax in the vans, but they were detuned. That said, I think a built 4L80 should be able to deal with a Dmax. The stock 4L80 has held up to a long life of supercharged 454 in my dually. PO bought it with around 50k and sold it to me at 130k and it was supercharged that whole time. Now I haul my near 5000# camper in the bed and hook up my ~9000# car hauler behind that and head to the track. So far, so good. I'm at 150k now.

 

[Tongan310]

I rather not row gears as I rather have that in a sports car (That project has already been sold off didn't quite like it.). I know the 4l80e is pretty tough stock (I put a 20k # Cyclone Toy Hauler on mine and it did fine.. Slow but pulled it great) but from what I read its the low end torque that kills it when it comes to this swap. Other than that no comments on it that i can find. Knowing that your SC hasn't blown it makes me feel a little better. Are you flooring it here and there?

When I do the swap the DMAX will be slightly more than stock power. (IE Fleece Turbo.. Yay whistle! and bolt ons mainly to make it sound good).

 

[Supercharged111]

I try not to floor it as it mostly makes noise, but I give it what it needs to get up a hill. I'm amazed it takes what it takes, but mine is usually singing at 2000-2500 in OD. It may be the 1500 RPM torque in OD that makes a Dmax tear them apart.

 

[L31MaxExpress]

Duramax's came with 4L85Es behind them. I tuned one to make about 800 ft/lbs of torque and 400 hp. The 85E had 80K on it when the Van was tuned. It has over 200K on it. Alot of it towing a 34 ft toyhauler. 85E was stock with a Transgo HD2 and a +3qt deep pan.

 

[Sparkysikes]

Can a stock 4L80E handle a 300/700 cummins?

 

[b454rat]

The 4l80 might hold up but it's doubtful. They can't handle the torque at just low RPMs. Biggest thing is the tranny can't "talk" to the engine, like it would with a V-8 or the dirtymax. AKA shift management.

 

[L31MaxExpress]

The 4l80 might hold up but it's doubtful. They can't handle the torque at just low RPMs. Biggest thing is the tranny can't "talk" to the engine, like it would with a V-8 or the dirtymax. AKA shift management.

Read my post please above. It has been holding up just fine to the 800 ft/lbs of the Duramax. Duramax/4L85E combination was available from the factory. It is tuned for a massive defuel during shifting. Once the clutches are applied it puts the fuel back on it.

 

[b454rat]

I was talking bout the cummins....

 

[L31MaxExpress]

I was talking bout the cummins....

Gotcha....I thought you were talking about the Duramax.

The 4L80E is pretty stout. The setup I have messed with that wanted to destroy the 80E was actually the PSI 8.8 I tuned. I had to pull some timing under 1,800 rpm from it. Those 8.8 PSI engines have instant torque even down at 1,000 rpm. More than a 6.7 Cummins does at lower engine speeds. At low rpm it is hard to get the line pressure to rise quickly enough to make the clutches hold.