Engine/Transmission (1998.5 - 2002) Shifting my 01

[wrichards]

Just picked up the 2001 6 spd listed in sig. I have driven many manual transmissions but I am having a hard time getting this one to be smooth. I think the problem is the 4. 10 gears. What RPM do you guys with the 4. 10 shift at. If it is not screaming high rpms, letting out the clutch even with a little pedal slows the truck and makes for an uncomfortable ride. Any thoughts other than switching rear ends

 

[MKreiberg]

I've got 53k on mine and I still haven't gotten it figured out. 3. 54s here.

 

[B.G. Smith]

If the rpms are higher than the speed that the truck will be going in the next gear with the engine at idle when you shift then you will feel the slow down when you release the clutch. Unless you're drag raacing, try shifting at much lower rpms. bg

 

[SRadke]

I've never made a nv5600 shift smooth. They are pretty tough though...

-Scott

 

[DGerth]

189K ON MINE WITH NO PROBLEMS. SHIFTING FAST, IT DONT LIKE THAT A TALL!

dg

 

[dresslered]

I've read of this quite often regarding the NV5600 shifting. Mine has always shifted smooth as butter (I have the 3. 54's). I change and continue to use the OEM fluid, but others have claimed better performance with other fluids..... Use at your own risk.

 

[Bob Cochran]

Mine has been what I would describe as notchy when shifting since new. For me Amsoil helped having said that though for some Amsoil does not help. It appears every 5600 is unique and what works for one does not work for another. It seems to me trial and error to find the best lube that your transmission is happy with.

 

[PC12Driver]

Practice, practice, practice... Drive it like a non-synchro'd transmission (use the throttle to match gear speed while passing through neutral), but still use the clutch as not to burn up the synchros.



The Cummins has more rotational inertia than the old 7. 3 you have listed, so not having the engine rpm an exact match to the drivetrain when you let out the clutch will be noticed, unlike lighter engines where you can skate by.

 

[wrichards]

that means I would have to keep a higher RPM. I will try both and see what works. thanks for the tips.

 

[Sticks]

Practice, practice, practice... Drive it like a non-synchro'd transmission (use the throttle to match gear speed while passing through neutral), but still use the clutch as not to burn up the synchros.

The Cummins has more rotational inertia than the old 7. 3 you have listed, so not having the engine rpm an exact match to the drivetrain when you let out the clutch will be noticed, unlike lighter engines where you can skate by.

BINGO - We have a winner! Oo.

Easy way to figure out what your RPM's need to be is;

1. Find a road you can drive on with no other traffic to get in your way, or you get in theirs.

2. Start off in 1st gear, run up to 2500rpm, note your speed.

3. Shift to 2nd gear and match the speed in step 2, note your RPM.

4. Repeat steps 2 and 3 for each gear.

Example - (I'm fairly sure the RPMs between gears is much lower, I just chose these numbers for easy math)
1st gear, 2500 RPM = 10 mph
2nd gear 10 mph = 1000 rpm
1500 RPM between 1st and 2nd at any given speed.

2nd gear at 2500 = 20 mph
3rd gear at 20 mph = 1000 rpm
1500 RPM between 2nd and 3rd at any given speed

3rd gear to 2500 RPM = 35 mph
4th gear to 35 mph = 800 rpm
1700 RPM between 3rd and 4th at any given speed

Etc.

So when you shift up to the next gear, reduce the engine RPM (or increase RPM for down shifting) approximately the RPM difference between the two gears. READ - Don't just let off the throttle completely (return to idle) while shifting.

Eventually you will learn to hear what the engine sounds like when it is time to shift, and muscle memory will hold the throttle at the correct position for a smooth transition.

 

[JMetzger]

My NV 5600 shifts fairly smooth but then I do not speed shift it. I shift it slowly. Remember the NV 5600 is not a racing transmission.

 

[KSears]

I usually shift gears between 2000 and 2500 rpms, the lower if I am just tooling around and higher rpms if you are in a hurry. It is definately not a speed shifter kind of truck, I have had three diesel standard shift, 90 model/3:54 gears, 03 model/ 3:73 gears, and now an 05/4:10 gears , all are definately different as far as shifting smoothly. I also just upsized my tires and now it is something else to get used to. Also I am about to install the B/M short shift kit, we will see how that plays into shifting also.

 

[darkhorse]

I'm not sure what the axle ratio has to do with it. I have the 3. 54 & it's always been a smooth shifter. Not fast but smooth.

 

[DThibault]

I also have an 01 with a six speed. It shifts great but I don;t speed shift. I drive it like a big truck relying on the torque and rpms for the thrill. The edge ez and the large exhaust helps too. Forget about the speedometer and tach instead just use your ears and seat of pants to know when to shift. That engine with a red line of over 3000 rpms is very forgiving. Have fun.

 

[blacksheepdiesel]

wrichards,

To clarify, are you saying that the transmission is difficult to shift between gears? Or are you saying that the ride is jerky when letting out the clutch? Or both???

Having recently removed the NV5600 from my 2001 3. 55 truck and installed it in the 2004 4. 10 truck I can assure you that rear end ratio has nothing to do with how the transmission shifts. As pointed out above by Sticks, the main concern is engine rpm. The correct engine rpm to shift for your truck should be the same for every gear since the NV5600 gears are very evenly spaced.

As also noted by others, when shifting the 5600 it is crucial to smooth shifting action AND longevity of the synchronizers to allow time for engine rpm to drop to the proper level before engaging the next gear, whether shifting up or down. I find that a very short "pause" in neutral with slight pressure going into the next gear will allow time for the synchronizers to "do their thing" and then it just slips into gear effortlessly.

Engine rotational inertia is an important gear engagement consideration when shifting up or down. Vehicle mass is a consideration when letting out the clutch. Both of my dually's weigh 9000# each with nothing hitched to them. While finding the right engine rpm is essential to easy shifting, there is also the consideration of vehicle mass when letting out the clutch. While a certain rpm may be easiest to shift the transmission, that may not be the best road speed for smoothness of gear application and that can change when payload changes. A slight application of the accelerator pedal (VERY slight if you have a Smarty!) when letting the clutch out is useful at times to match the speed of the engine to the transmission/rear end/road speed.

Seeing that your truck has few miles on the odo might lead one to think the transmission fluid is still good. Being that it is 9 years old I would change it if it where mine. Drastic changes in shifting behavior have been achieved by simply changing the fluid. My current NV5600 was very hard to shift (physical exertion) and often had synchro or gear clashes. Changing the fluid made the transmission shift better than it had when it was a fresh reman, but it took 15,000 miles for the synchros to get cleaned out good with the new fluid. My preference is Royal Purple synchro mesh, but to each his own.

Oh, and make sure there is 6. 5 qts of fluid in the NV5600. The rear main shaft bearing lives a happier life when it gets more oil. Remove the shift tower to get that much fluid in.

Godspeed,
Trent

 

[KSears]

I assumed he was talking about shifting on the go and running smoothly between shifts, trying to make the speed transition. All the trucks I have had have always shifted fine as far as going in and out of gear, clutch working fine ,etc. But the shift points are greatly different for the rpm/ speed smoothness.

 

[TMorgan1]

I have found that tapping the throttle after pushing in the clutch prior to shifting to the next gear keeps your RPM's where they were prior to shifting and makes for a smooth shift. Just give the throttle a quick tap (burp?) and you will be surprised how smooth you shift with no jerking. It is happening with me now and I don't think about doing it.

Try it... ... ...