5 or 6 Speed?
 

I am looking at buying another Cummins (Addicted :rocking:) I'm looking for another 2nd gen 24v and I want a manual with a short box to use as my fun truck. I've decided on all specifics I want except for the tranny. Should I prefer one over the other? I hear the 5 speed is easier to get replacement parts for... I'll mainly be using it for off road adventures, and (hopefully) will be building it up to compete in Baja style races. Any input is appreciated. Thanks!

it's really up to you.

So there's no major pitfalls with either transmission?

Third gear in the nv4500 is a weak gear. And 5th gear nut backs off but thats fixable. Still an awesome tranny though. If its a stock nv4500 it has a smaller input shaft. I have a couple buddys woth nv4500s and they love them. They are both just over 600 hp with dyno sheets to boot on vp trucks and they have broke gears a few times. The nv5600 has a larger stock input shaft and does not have a weak 3rd gear. The parts are a lot harder to find like you said. To each his own. If you are going sled pull with it I habe heard that a lot of the guys like using the nv4500 because its legit about 140lbs ligher than the nv5600.

What for speed and mpg differences are there between 5 speed and 6 speed?

The 5's and 6's are the same final gear ratio(well very close) On the 6 there is just an extra gear between 3rd and 4th compared to the 5 speed.

So not really much difference in mpgs?

No if anything you should be worried about having 4.10's. that's what I have with my 6 speed and I hate them.

For a fun truck that's not going to be towing heavy, the 5spd would be more user-friendly. The 6-spd's advantage is that it has that one additional ratio between 3 and 4. If the truck will have a leisurely life, that gap's not a big tragedy.

i have 4.10s with an nv5600 and i love it. i just dont drive over 70 on the expressway most of the time. i dont go on the expressway much any how. i do a lot of town driving the most. and in the summer time i average round 19mpg if i dont drive like a dummy. but thats with coasting to lights and all that happy stuff. not too bad if you ask me. in the winter time im lucky to see 16 though. winter fuel kills my mileage up her in the north east

The truck I'm hopin to get is a 6 speed with 3.55s. Should I get fairly good mileage?

All depends on the right foot. My G56/12v with 3.55's and 33"tall Ricksons (makes RPM to MPH ratio more similar to a stock tire and 3.23 gears) gets me about 15 in town. Haven't done much highway in the last two years since the G56 has been in it.

I rarely tow, and as a daily driver I love my 5-speed NV4500. I find it more fun to drive then my buddies 6-speed. The fluid is expensive, but its not like your changing it often. Just my opinion :tu:

i have a G56 in my bosses D max truck and I can tell ya that it runs out of rpm real quick .... and it has issues like needin g to be 1 qt over filled or they wont last ( from what I have been reading ) and everyone suggests the redline trans oil in it or else... I have heard issues like the ones listed above to for the nv4500 ... one weakness or another ..... would love to do a rock crusher and a gear vendors :rocking: .... break this :choochoo:

Mines a 5 Speed, not really much of a difference. I've driven them both.

shaft size on the 6spd depends on the year of the truck.

99-00.5 NV5600's have the same size input shafts as the NV4500 (1 1/4") with the S.O. motor.
the 01+ NV5600's have the larger 1 3/8" input shaft and the H.O. motor.

the NV5600 is not user serviceable where the NV4500 you could probably rebuild yourself.

everything in the 5600 is press fit and requires special tools and a press to work on, plus very hard to find parts makes it near impossible to work on yourself, however you can get a replacement trans for about $3000... I paid just under $3000 to have mine upgraded/replaced when my small shaft 5600 ripped all its teeth off of 6th gear and broke the intermediate shaft inside. I replaced it with the larger shaft NV5600 and had my clutch hubs swapped out by south bend to fit the larger input shaft.

so you can get the NV5600 replaced, and it is definitely a better trans if you need to tow heavy as it does not have that big rpm gap between 3rd and 4th like the NV4500.

NV5600 is heavy though. weighs 360lbs by itself.

for final drive ratio's they are close, but not the same.

NV4500 final drive ratio is .75
NV5600 final drive ratio is .73

Thanks for the input! I got a 5 speed! It has a hot rod vp 44 and the airdog 150 can't handle the IP's flow needed so I got a little bit of work to do on it before she's running good. I almost want to get a normal vp 44 for it.

how old is the airdog?

is it a newer one or an older one?? I ask because in recent years airdogs product quality has gone to hell and the newer pumps are suffering from leaking pump seals and steep fuel pressure drops. All of this was unheard of from the older pumps that were make 3+ years ago.

My Airdog150 is 4 years old and keeps up just fine with the fuel demand of a 576hp truck...I only drop 4psi with power turned all the way up. so 16psi WOT 20psi idle.

The pump looks 4 years old atleast. It was probably done with the edge juice and attitude (that are discontinued) and it's about 5 years old. The pump melted the fuse in it's harness (the fuse failed to blow :nshock:) and the pump made a nasty sound. The kid I got it from said the pump stopped running when you turn the key before starting. I opened up the inspection plate and the gear and insides were clean so it looks as if it's the electrical components that are going haywire. I was thinking maybe the hot rod vp44 was putting strain on the pump and caused it to not last as long. The batteries and a few connections under the hood need a good cleaning. It's a typical farm truck with mods.

an older airdog150 can keep up with anything a vp44 can throw at it... sounds like you had other issues like a wire short or something...

Yep, well I'm replacing it with an Airdog 2 200 and I'm in the process of cleaning up the electrical, starting at the battery connections. It was wired from the battery pos to neg posts so putting them away from any corrosion should help. The edge was discontinued for a reason so I'll get her running like a dream before I put it or another on again.

i would replace with a fass...like I said newer airdogs are riddled with problems...