Need a rebuilt, mine is getting some pretty good slack in it. gonna put in prolly a con ofe ( not sure yet) and want to know which tranny to get the 5 or 6 speed. Which is better as far as durability, and shifting smoothness? thanks

 

I love my 6-speed! I hear that they are stronger than the 5-speed. That's why Dodge put the 6-speed in the HO.

 

6 spd had a GREAT gear split for towing with my 12valve. I will never go back to a 5 spd except to possibly race.

 

It all depends on how much more money you want to spend. You can buy a rebuilt NV4500 with the fully splined mainshaft and have a stout tranny.
An NV5600 will fit, but the trans itself will cost more, you'll get spanked on a core charge, and you'll need to get the rest of the conversion parts, shorten the rear driveshaft and legthen the front one.

Is one stronger than the other? That question is totally subjective, because look at the sled pullers...you'll see both do great and you'll see both occasionally break something.
I've had both, they both shift just as smooth as the other one, but I like speed, and with one less gear in the 5spd I get from stoplite to stoplite faster, as well as running the 1/4mi faster. But towing was nicer with the 6spd.

 

My new truck I will get a 6 spd.

Mike

 

thanks for the input. iv never driven a 6 speed but i figured it might be quicker because the 5 speed has a big gap between 3th and 4th but the extra shift prolly takes that advantage away. I didnt realize that the 6speed conversion was that much screwin around so ill prolly go with the 5 speed. thanks

 

NV4500 ithink had a GVW rating of 14000 or 17000 and a torque rating of 450 or 440 the NV5600 depending on the year and application has a GVW rating of 26000lbs and a torque rating of 650 ft/lbs.

Take that for what its worth. Ive seen longevity out of both and depending on where and how much you spend on your 6 spd that will dictate if its feasible. I paid 1000, 1200 w/ shipping for mine which was a warranty take out. 3 and 4th rattled. I poped it in and put another 187000 onto it without any problems other than the occassional syncro sratch and the 3/4 rattle when pulling hard.

I highly recommend it and aside from the drive lines and changinging of the crossmember there is not that much involved with putting one of these in.

I changed from the 5 spd to the 6 spd in about 4 hrs.

 

What are the gear ratios in the 5 and 6 spd?

Brian

 

Opinions, here is another one. I have had both in my truck and my observations.... The five speed shifts better, is lighter, cheaper to repair and cheaper clutch. The five speed is 14,600 pound rated. The six speed as above is rated for 26,000.

The big question is your use. If you are not loading heavy and just beating the ricers, the five speed is better for you. I got 187,000 miles on mine pulling 30,000 gross loads. The six speed is much better for pulling due to the heavier build and the even spaced gears. The Cummins will more than make up for the wide split between third and forth for normal driving and shifts faster and easier.

The ratios on the six speed are essentially the same as the five speed with another gear in between third and forth.

 

If the wide gap between 3rd and 4th on a 12 valve is what bugs you....$140 dollars fixes that problem. It's called a 3000rpm governer spring kit. Problem gone!

 

I have both. The gap between 3rd and 4th in the 5 Sp. is HORRIBLE !!! I absolutely hate it. For towing, no doubt whatsoever the 6 sp is the ticket. Now if you are allways running empty, like to hit the 1/4 mile a bit, and as was allready said, up the governor, than yes the 5 spd is just fine.


Zino

 

no, its a bit more different that just a gear between 3rd and 4th, its spread out MUCH better:

ratios:

NV4500 5sp: 5.61 , 3.04, 1.67, 1.0, 0.74

NV5600 6sp: 5.63, 3.38, 2.04, 1.39, 1.0, 0.73



Zino