Strong 6-speed?

[thirdstreettito]

I plan on running a 6-speed manual in a D350(2wd) Cummins with 500-800hp. I've considered the ZF6, the G56, and the NV5600. Which one can handle it? What are some good upgrades? I see all of these high hp trucks running autos and I'd much rather have a manual. Thanks, Bradley

 

[jaybuller]

I think a nv5600 with custom builit shafts and custom cut billit gears would hold 800hp reliably. but you would have to know someone that can make that stuff for you. a stock nv5600 with a big input will hold over 500 pretty easly but dont excpect to be doing power shifts or drag racing with it, sled pulling it should last at over 500 no problem but shifting uder power im sure it will bust.

 

[Signature600]

If you're just going to drive it, I know the NV5600 will hold that in a 2wd truck...even the G56 should. I don't know about the ZF6, just not familiar with them.


Custom shafts and gears in a NV5600?? $$$$$$$$$
Chris

 

[zstroken]

I was thinking the NV5600 held up well except for the 6th gear with high HP.

 

[Signature600]

I was thinking the NV5600 held up well except for the 6th gear with high HP.

On the pulling track at 8K lbs too

Chris

 

[not enoughsmoke]

hands down nv5600 sled pulled for 2 years on mine not one problem pulling 5th low and several dyno runs as well i have made 840hp

 

[thirdstreettito]

Thanks guys. Whats the GVWR on the NV5600? The truck will be a DD, some drags, plenty of towing, and some sled pulling. And I have a heavy foot and love goin through the gears. You guys positive on the NV5600?

 

[ENafziger]

Since the D350 is going to be a couple thousand pounds later than any of the later model quad cab 4x4s, I'd say either the NV5600 or the G56 would be fine. From what I understand, the main concern with the G56 is case flex, since it's aluminum. Mike at Lazarsmith offers a good looking girdle to address this.

I have run a G56 for just over 100k miles, much of the time at the 625 - 650 hp level. My truck weighs in at 9025 pounds empty, and I've not had any problems.

That being said, if your mating the G56 to a 12-valve, the more heavily biased low rpm torque pounding may not make the transmission very happy.

--Eric

 

[roachie]

I vote ZF6 if its an open table.

 

[LReiff]

Thanks guys. Whats the GVWR on the NV5600? The truck will be a DD, some drags, plenty of towing, and some sled pulling. And I have a heavy foot and love goin through the gears. You guys positive on the NV5600?

It's not about the GVWR rating. What you need to consider is the transmissions torque rating. 550ftlb. LOL

 

[8UPRACIN]

I have the NV5600 in mine with 5 years of abuse over 500hp. I daily drive it, drag race, tow, and currently make over 600hp. I lost 1 main shaft cause the tip bearing failed and other than that is got 153k on it and just has some slight bearing noise when you lug it really hard.

 

[kino_fab]

only real problem i see with the nv5600 is 6th gear and the end of the main shaft breaking. Most pullers run the low side of the t-case to help prevent this, but in a 2wd situation, idk if the main shaft will hold in stock form. Screw it, go with an air shifted lenco and be happy lol.

 

[Signature600]

That being said, if your mating the G56 to a 12-valve, the more heavily biased low rpm torque pounding may not make the transmission very happy.

--Eric

I would say the CR is the torque king at the moment...sure, some 12v's do, but the RPM limited CR makes some serious torque....

Chris

 

[thirdstreettito]

Since the D350 is going to be a couple thousand pounds later than any of the later model quad cab 4x4s, I'd say either the NV5600 or the G56 would be fine. From what I understand, the main concern with the G56 is case flex, since it's aluminum. Mike at Lazarsmith offers a good looking girdle to address this.

I have run a G56 for just over 100k miles, much of the time at the 625 - 650 hp level. My truck weighs in at 9025 pounds empty, and I've not had any problems.

That being said, if your mating the G56 to a 12-valve, the more heavily biased low rpm torque pounding may not make the transmission very happy.

--Eric

Dont just say neither is fine and not give a solution. Why would the NV5600 not be fine?

I vote ZF6 if its an open table.

Open table? Please explain your opinion.

It's not about the GVWR rating. What you need to consider is the transmissions torque rating. 550ftlb. LOL

If the trans is rated at #5000 I dont want it, it would barely be allowed to move the truck, let alone a trailer also, thats why I asked. The NV4500 for example is rated at #26000 GVWR

only real problem i see with the nv5600 is 6th gear and the end of the main shaft breaking. Most pullers run the low side of the t-case to help prevent this, but in a 2wd situation, idk if the main shaft will hold in stock form. Screw it, go with an air shifted lenco and be happy lol.

Whats wrong with the 6th gear? How could I beef up the mainshaft? Lenco, no thanks.

 

[ENafziger]

Dont just say neither is fine and not give a solution. Why would the NV5600 not be fine?

Hey there, I said EITHER would be fine...not NEITHER.

Spend some time searching here. Jason Czarak sp? cryoed some of his internals with good results. Mike at Lazarsmith is very knowledgable on the G56s and has upgrades available, and is working on the Gorilla internals. Contact Standard Transmission and talk to them a little.

Oh, and as menioned above, don't worry about the GVWR, worry about torque ratings. I, too, used to think like you. I ruined a gearbox rated for 30,000 lb gvwr with a little old 9,000 pound truck...making 1200 ft-lbs of torque!

Have a great weekend!!!

 

[inline]

2WD!!!!!!!!!! time to think outside the box. Fuller makes a 6 speed actually you could bolt up any SAE#2 trans behind a Cummins

 

[RJM06590]

I vote ZF6 if its an open table.

Agreed, the zf's shift very nicely especially with a short throw kit and handle some abuse.

Open table? Please explain your opinion.



If the trans is rated at #5000 I dont want it, it would barely be allowed to move the truck, let alone a trailer also, thats why I asked. The NV4500 for example is rated at #26000 GVWR

I believe he said open table because of cost. You will need an adapter plate etc.

My zf5 is only rated to 4XXft lbs, it's been over 1000ft lbs for a long time. Ratings are safety nets for the manufacturers.

 

[jlibert]

I ran the nv5600 over 800 hp/8000 lbs sled pulling, and never had an issue. The nv5600 doesn't shift as quick as a g56. In a 2wd, you could probably get away with any of them.

 

[TexasEOD]

sorry to hijack, but would a NV5600 hold up to occasional track runs and daily drive at 500-600hp?

how much is a zf6 swap and has anyone on here done it in a 3rd gen?

Im looking for a 6 speed since thats what I wanted originally and I dont feel like spending 6G+ on an auto...

:thankyou2:

 

[KeyWrench]

Since the D350 is going to be a couple thousand pounds later than any of the later model quad cab 4x4s, I'd say either the NV5600 or the G56 would be fine. From what I understand, the main concern with the G56 is case flex, since it's aluminum. Mike at Lazarsmith offers a good looking girdle to address this.

I have run a G56 for just over 100k miles, much of the time at the 625 - 650 hp level. My truck weighs in at 9025 pounds empty, and I've not had any problems.

That being said, if your mating the G56 to a 12-valve, the more heavily biased low rpm torque pounding may not make the transmission very happy.

--Eric

The G56 case will flex under high performance applications. Lazarsmith's Tork-Shield is a functional work of art which obviates case flex and can be installed with the transmission on or off the truck. Mike also offers custom internal modifications and enhancements according to your needs and budget. Check out the website or give him a call.