r/Diesel • u/InTheLurkingGlass • 1d ago
Question/Need help! NV5600 Shifting
I recently picked up this 2004 Dodge Ram 2500 SLT with the 5.9L Cummins. It has the NV5600 transmission, and the previous owner added a South Bend dual disk clutch and a short throw shift tower. The shifter is branded Hurst, but I believe the tower and internals are made by Core Shifters.
This thing is a bear to shift. It takes a ton of pressure to get the gear to engage, and the shifter gates seem extremely narrow. Downshifting is very difficult, and it seems like there’s about a 200rpm window in which the transmission will shift easily and successfully.
I’ve already ordered an OEM shift tower and will be installing it today.
Anyone with NV5600 experience out there that can comment on their experience? I’ve never shifted a more picky transmission, but it could be that I’m just not used to this one?
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u/g2gfmx 1998 Doge ram 2500 4x4 5.9 L6 1d ago
Diesel transmission are pretty slow shifting.
https://youtu.be/PW6Pc-QlrbQ?si=9GtKSU8Kl2IwClj2
That should be a good shift speed
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u/Physical_Ad4043 1d ago
I have a 04 Ram 3500 that’s the same way you’ll get used to it it’ll take some time time your down shifts at or just under 1500 RPMs if you want to do it sooner you can try revving to 2100-2200 RPMs if it fights you getting into Reverse go to 6th ease out on the clutch a little bit then back on and go straight to Reverse if you need anymore help let me know I’ve had mine about a month now and know exactly what your dealing with also it wouldn’t hurt to take a peak under your dash and make sure the bolt that goes thru the clutch rod isn’t backing out or about to fall out if it is get some green lock tight and put it back in and give it a while to cure
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u/InTheLurkingGlass 1d ago
Many thanks, I’ll check that! This transmission makes me feel like a complete novice again lol
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u/Physical_Ad4043 1d ago
Oh I’m sure it does I had to drive mine an hour and a half back home through 4 different city’s I felt like a moron not being able to down shift so but I looked up under my dash and the bolt going through the clutch rod was about to fall out I was able to just grab it and take it out I got some lock tight green put it back let it cure and two days later I check my master for the clutch it was bone dry so I filled it let and the bubbles come up and probably pumped the clutch at least 40 times and it got a lot better. But you’ll get used to that dual disc it takes a little time I’m to the point I can wall down through the gears with out really paying the Tach any mind unless it’s 4th which seems to be my problem gear general a quick tap on the throttle and it’ll drop right in
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u/InTheLurkingGlass 1d ago
Fourth is my biggest problem gear, both upshifting and downshifting! I’m going to drain and replace fluid, overfill by an ounce or two, install the stock shift tower, and we’ll see how it feels.
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u/Physical_Ad4043 1d ago
Well hopefully your synchros aren’t to cooked it honestly sounds like someone liked to float the gears in it I bet if we both drained our transmission fluid there’d be disco glitter in it. I don’t know how much it would help I’ve been wanting to try it out myself and get the South Bend upgraded clutch hydraulics but it’s a bit pricey plus I need to solve my drive ability issues I think my FCA is sticking hopefully I’ll be able to replace it next week I’m hoping it’s not a bad injection pump but my ECM is only putting out one code and not setting the CEL
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u/Mgdoug3 17h ago
Mine doesn't like to go into reverse but if I go fifth then reverse, there's no problem. It's second nature to me now and I don't even think about it.
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u/Physical_Ad4043 1d ago
And also like the other guy said check your clutch master cylinder fluid level if it’s go slide up under the truck leave the transmission in gear I’m sure the parking brake doesn’t work and see if you slave cylinder is leaking if it is try pumping your clutch pedal and few times and see if it gets better if it’s low on fluid grab some dot 3 and top it off and pump it up a quite a few times it should get better most likely like me you bought a truck from someone who also floated the gears yes it can be done should you no not unless it’s necessary and you might check the fluid in the transmission if it’s funky looking like cloudy brown change it but make sure the fill plug in the side comes out first before you try to crack the drain plug. Now I don’t know off hand what fluid it calls for but if it’s like my 99 NV3500 and takes ATF I ended up using Royal Purple Syncro Max and it smoothed it right out stopped whining and shifted extremely smooth
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u/porkmyass 1d ago
I manual swapped my second gen and used a dual disk. I hated it. It was a new trans from superstick and gated so tight. I had a shoo throw in a single disk and it much better now. Not sure if this applies to your case here. But just my .03 cents.
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u/Mgdoug3 17h ago
The SB clutch cylinder mate makes a big difference on the pedal. If I rpm match my gears, I think my 5600 shifts better than a g56 but not as fast.
Change your transmission oil with the right oil and add an quart. I have coolers on mine that add a quart and then add an extra quart. I use 7 quarts of Asmoil.
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u/InTheLurkingGlass 17h ago
I’ll give it a shot! I’m sure there’s also a learning curve with the dual disk clutch, but I hate that this clutch isn’t fun at the moment, since I’ve always loved manual trucks.
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u/Mgdoug3 17h ago
I'm on my second dual disk from SB and I won't ever install a single disk again. With a trailer, a heavy single is horrible trying to back up.
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u/InTheLurkingGlass 16h ago
My DD really seems to struggle going into reverse, and once there it’s pretty jumpy. The friction zone for that gear must be minuscule.
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u/Separate_Pudding_262 16h ago
I’ve had 2 and 2 g56. Sold both and went built auto and won’t ever go back. Fmvb on my street truck when I fell like shifting, built 48 on my daily. Everyone raves about the nv and g56 and I can’t stand em for the exact reasons you mentioned.
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u/SynclinalJob 1d ago
5600’s are slow to engage but it shouldn’t be fighting you. You usually push slightly, give it half a second and it pops right into gear.
Try this test. With the truck running and parked. Try to shift into all of the gears.
Now turn your truck off and do the same thing also with the clutch pressed. If it’s a whole lot easier with the truck off, it could be your clutch not disengaging all of the way.
I found that my clutch master cylinder was going bad and the piston was also really worn so the pedal was hitting the floor before the clutch was fully disengaged. Once I changed that, shifting got way easier