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NV4500 to NV5600 Swap

49K views 54 replies 16 participants last post by  Truefat 
#1 ·
has anyone swapped a NV4500 to a Nv5600? I have a 4:10 gear ratio in my '96 dually and hwy speed out here is 75-80 posted. I know I drive under the speed limit to keep RPMS down but it would be nice to keep RPMS down and go atleast 75. I want to know if the splines need changing in the t case and if drive shafts need shortening or lengthening
 
#2 ·
Final gear in both are near/if not the same. A bigger tire will help you drop RPM's.
 
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#3 ·
Near is correct. NV4500 is 0.75, Nv5600 is 0.73
 
#4 ·
Not worth the swap, especially if you're running decent power. Final gear as mentioned above is pretty much the same, only difference between the two is that the 5600 has an extra gear between 4th and 5th to make grade towing easier.

Now if someone came up with an easy way to run a zf6 I'd consider it. That slight bit difference would be a few more MPH.

That being said, the Nv4500 is one of the strongest transmissions put in our trucks. Best to stick with it.

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#5 ·
That being said, the Nv4500 is one of the strongest transmissions put in our trucks. Best to stick with it.
Stronger than the automatics of the 2nd gen era, and possibly the Getrag, but that's about it. The NV5600 was put behind the first HO engines because of it's higher strength and the G56 IMO was an improvement on that. The only thing about the NV4500 making it better is that it is cheaper and easier to rebuild. I have a trail of 12 of them to attest to that.
 
#7 ·
12 NV4500s, and I'm only at 300HP. The NV4500's rated input is only 450 pounds of TQ. The NV5600 rating is 550. You need to learn about what you speak.

Exactly. It is an upgrade to a NV4500 to install a NV5600 sized input shaft and a bigger clutch.
 
#9 ·
Never broke my NV4500 in the pull truck, excess of over 1000ft lbs of torque under a heavy load. I just feel like when its in fifth gear at 2200 RPMS I can just drop it into 6th gear and let hwy speeds be generous to the RPMS. its a dually so I don't really feel like buying 6 new tires, little expensive. I do tow a 40ft toy hauler so I do need the gear ratio since its about 17000 lbs fully loaded. any other suggestions
 
#10 ·
Never broke my NV4500 in the pull truck, excess of over 1000ft lbs of torque under a heavy load. I just feel like when its in fifth gear at 2200 RPMS I can just drop it into 6th gear and let hwy speeds be generous to the RPMS. its a dually so I don't really feel like buying 6 new tires, little expensive. I do tow a 40ft toy hauler so I do need the gear ratio since its about 17000 lbs fully loaded. any other suggestions
I'm not into doing the math, but that extra .03 of a ratio is not going to make much of a difference. You may get comparably more out of larger diameter tires.

When I switched from stock size to my 35s, I gained about 15%. Took my highway rpm from 2200 down to 1900. This is on a truck running an Nv4500 and 4.10s.

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#15 ·
More than likely yes. My last dyno was 756 pounds of torque at the wheels. Considering driveline drag that puts crankshaft torque over 800. Stock engine was rated at 440. I wish I had dynoed it stock to get a baseline at the wheels.
 
#19 ·
The reason for a 6 speed is to bridge the gap between 3 and 4. Since the gear ratios are not that big a difference you won't see much of a drop in rpm. Easiest way to drop rpm is to get bigger tires. But other than that it looks like you won't be changing your setup.
 
#21 · (Edited)
What GAmes was saying is that 4th on a NV4500 and 5th on a NV5600 are identical. 6th on a NV5600 is only slightly lower than 5th on a NV4500.

If you reference the first graph, you'll see that the difference between the NV4500 and NV5600 OD's are maybe 50RRPM @ 70MPH, which is hardly worth a $3000 transmission swap if that's the sole purpose of doing it.

If you're only purpose is to drop your revs at highway speeds, gears would put you a lot further along for the money.
 
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#23 ·
Great Thank you, i was playing with the calculator of gear ratios and transmissions through the rock crawler websites, and it looked like bang for my buck would be a lower gear ratio in axles vs a trans swap.
 
#24 ·
I should add if you were to swap in a zf6 with it's 0.72 overdrive, it's hardly noticeable from the nv4500 I had in my truck. Or if your really determined maybe Fuller has highway lugging options.
 
#28 ·
My truck has 32" tires (stock height) and ZF6 trans along with 3.73 gears, this is a great towing combination.
3.73's lower engine rpm around 200 rpm less than 4.10's but still provide plenty of pulling power and easier start off than 3.55's.
3.55's lower engine rpm around 400 rpm less than 4.10's, for my size tire's I've found this gets rpm's to low to maintain 55-60 mph in OD and insufficient lugging power to maintain speed on simple over passes at 65-70 mph, there forth I found myself spending more time in direct (4th or 5th depending on the trans) at higher rpm's or else shifting gears a lot. Also starting off a heavy load with 3.55's put's more stress on a clutch.
Shorter tire's would help with some of the issues I had with 3.55's but 32" is the smallest they offer in 19.5

My friends 2012 Dodge 2500 came factory with 3.73's and 265 tires.

Play with the available speed calculator's and see what would work best, tire size or gear change.

Going from a 5 spd to a 6 spd isn't the answer for a speed problem, 6 spd is the answer for a 5 spds wide gear spacing.

If I had a Dodge and wanted a 6 spd, I'd go with a G56 over a nv5600.
 
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#29 ·
Yeah been playing with a the calculators some of the off road websites have where you can build your drivetrain and look at the charts to see speeds and RPMs. I may go with the semi wheel package to increase tire size, and sell the tires I have now, should be able to offset the cost a little.
 
#30 ·
Haven't done any price checks but I'd think switching to 22.5 semi tires and wheels would cost more than a double gear swap, unless you just want the look.
Most trucks I've seen with semi tires also appear to be lifted for tire clearance, what's the added height going to do to your toy hauler.
Not trying to tell you what to do, but other than the look I haven't heard anything good about swapping semi tires onto a pickup, I have heard about the extra unsprung weight causing problems with steering, bad ride and high cost of replacement tires.
As I said, not telling you what to do, just pointing out the big picture, it's your truck, your choice.
 
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#31 ·
No offense on tryin to tell me what to do, like I said price checking every option and doing the research is worth more than listening to people who have several thousands posts. That to me people with millions of posts is just someone who has more time to be on a computer than actually perform work. Let alone I spent 8 years in military listening to people who couldn't describe the difference to me of a whole in the ground and there own behind . Thsoe are the same people who try to talk down people on this forum seeking knowledge of personal experience, not google questions and answers or pictures.

I am not sure what that will do to the angle of the toy hauler on a lifted truck, have to do some measurements to figure out how bad my angle would be on the toy hauler with the height of the truck with semi tires. It will come in time little bit here and there and eventually it will be done. thanks for the input.
 
#32 ·
Down here in south fl , everyone has lifted trucks 6in or higher and they tow goosenecks and rv and even boats .. I don't think they ever had a problem .. but I will say the semi wheels are a little bit ruff ride due to the fact they are like load g .. on the bright side they will last like 100k miles
 
#33 ·
3.54 ring and pinions, 285/75/R16 tires. This will get the speed up to 70 mph and rpms at 2085. A over the winter I will drop the 6 speed in it and lower RPMS down to 1850 and be able to do 75, I don't want to go much fast than 70 mph when hooked up to the toy hauler.
 
#35 ·
3.54 ring and pinions, 285/75/R16 tires. This will get the speed up to 70 mph and rpms at 2085. A over the winter I will drop the 6 speed in it and lower RPMS down to 1850 and be able to do 75, I don't want to go much fast than 70 mph when hooked up to the toy hauler.
What 6 speed are you planning to go with that would to lower your RPMS from 2085 to 1850?
 
#36 ·
Numbers are off. The whole setup will put rpms down to 1850. I am playing around with grimmjeeper.coms calculator. Its a setup that wont happen in a weekend but over the course of 6 months or so. To me its worth the money and time.
 
#38 ·
Again, its not just putting a 6 speed in the truck, its a combination of several things that will lower the RPMs, not just a 6 speed swap alone that will magically drop the RPMS. Maybe others should read entire posts before putting there input in.
 
#41 ·
Again, its not just putting a 6 speed in the truck, its a combination of several things that will lower the RPMs, not just a 6 speed swap alone that will magically drop the RPMS. Maybe others should read entire posts before putting there input in.
Ah fair enough. By some of your other responses I gathered you were still under the impression that 6 speeds have one higher gear.

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#39 ·
Gear Ratio Calculator, you can use this calculator to change up drive train options to find out what RPMs and hwy speed with a pleather of different options. Like running 285 tires with a 3.54 gear ratio, with or without Nv4500 or a Nv5600 or a G56 and you will find out that at many different mph's, your rpms can and will vary with gear ratios and ring and pinions, transmission ETC.
 
#42 ·
yeah if it was a transmission swap that would drop the gear ratio, I would do the Eaton 10 speed swap. I guess I started the post thread all wrong, I mean I don't WANT to buy bigger tires, but when you run 60 mph and your turning 2000 rpms and normal speed are now 80 mph. Its time to change things up, WANTS and NEEDS are two different things. So I think when playing with the Calculator gear ratio it will be small things first and then the big swap during winter when I don't travel as much. I do appreciate all the input both good and bad.
 
#43 ·
yeah if it was a transmission swap that would drop the gear ratio, I would do the Eaton 10 speed swap.
Just FYI, in case you're somewhat serious, my limited research shows the OD model of the Eaton 10 speed has essentially the same over-drive gear ratio as the NV4500.
 
#44 ·
Go buy 3.54 ratio axles for $1000, swap them in and be done with it. Ive run 4.10's before and know what its like to be maxed out at 65 mph towing. I started my hotshot carrier with my 98 with 4.10's.
 
#46 ·
I really liked the RPM range in my 98 4.10 auto when i put on 285/75 tires. I tried not to enjoy it because i was about 2 weeks from doing my NV4500 swap in it.
 
#47 ·
I had a first gen 3.07 for a while but recently changed it out for a dana 80 with 3.31 went from 80 at 2000rpm to about 75 at 2000rpm

all the above was with 265/75/17s on 3rd gen wheels

I really like the 3.07 for highway and towing was not bad as you just leave it in direct but a dana 80 with disks was hard to pass up.
 
#48 ·
Parts Swap to Lower RPM's

I went through this drill 10 years ago when my 3rd NV5600 gave up. I haul my own equipment and it's never light. I wasn't going to install another NV5600 and I did not want to step into a NV4500 with the nut falling off at the time. The G56 wasn't out in 2008. There were few choices at the time.

I did the math and comparisons noted in this thread and also looked at Gear Vendors products, as well as tires and a diff change. As noted, cost for most swaps is not cheap and you want parts availability in the future.

I ended up installing an Eaton-Fuller FSO-8406A, 6 spd OD. The 7-8-10 speeds only give you more lower gears, the top end is nearly the same. The Eaton-Fuller offered many of the characteristics I was looking for, reliability, endurance, parts availability, and maintenance. So far all of these have proven true and the trans is still functioning great.

I had to sacrifice the RPM's to do 70 @ 2500, some mileage per gal lost, however the truck works the way I want it to work. If the features of the "Dream Truck" were available in any model, there would be a shortage of these jewels.
 
#49 ·
I went through this drill 10 years ago when my 3rd NV5600 gave up. I haul my own equipment and it's never light. I wasn't going to install another NV5600 and I did not want to step into a NV4500 with the nut falling off at the time. The G56 wasn't out in 2008. There were few choices at the time.

I did the math and comparisons noted in this thread and also looked at Gear Vendors products, as well as tires and a diff change. As noted, cost for most swaps is not cheap and you want parts availability in the future.

I ended up installing an Eaton-Fuller FSO-8406A, 6 spd OD. The 7-8-10 speeds only give you more lower gears, the top end is nearly the same. The Eaton-Fuller offered many of the characteristics I was looking for, reliability, endurance, parts availability, and maintenance. So far all of these have proven true and the trans is still functioning great.

I had to sacrifice the RPM's to do 70 @ 2500, some mileage per gal lost, however the truck works the way I want it to work. If the features of the "Dream Truck" were available in any model, there would be a shortage of these jewels.
I do have to say the FSO-8406A is the best option i have read about for a swap, the trick is finding one for a reasonable price. What kind of hydraulics did you have to run for your swap?
 
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